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Showing content from https://releases.llvm.org/14.0.0/tools/clang/docs/DiagnosticsReference.html below:

Diagnostic flags in Clang — Clang 14.0.0 documentation

This page lists the diagnostic flags currently supported by Clang.

This diagnostic is enabled by default.

Diagnostic text:

The text of this diagnostic is not controlled by Clang.

This diagnostic is enabled by default.

Diagnostic text:

The text of this diagnostic is not controlled by Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: input conversion stopped due to an input byte that does not belong to the input codeset UTF-8

Some of the diagnostics controlled by this flag are enabled by default.

Controls -Wall, -Wextra.

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘objc_independent_class’ attribute may be put on a typedef only; attribute is ignored

warning: ‘objc_independent_class’ attribute may be put on Objective-C object pointer type only; attribute is ignored

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘NSObject’ attribute may be put on a typedef only; attribute is ignored

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: absolute value function A given an argument of type B but has parameter of type C which may cause truncation of value

warning: taking the absolute value of 

pointer

function

array

 type B is suspicious

warning: taking the absolute value of unsigned type A has no effect

warning: using 

integer

floating point

complex

 absolute value function A when argument is of 

integer

floating point

complex

 type

This diagnostic is enabled by default.

Diagnostic text:

warning: abstract class is marked ‘

final

sealed

‘

Diagnostic text:

warning: initializer for virtual base class A of abstract class B will never be used

This diagnostic is enabled by default.

Diagnostic text:

warning: taking address of packed member A of class or structure B may result in an unaligned pointer value

This diagnostic is an error by default, but the flag -Wno-address-of-temporary can be used to disable the error.

Diagnostic text:

error: taking the address of a temporary object of type A

This diagnostic is enabled by default.

Diagnostic text:

warning: requesting an alignment of 16 bytes or greater for struct members is not binary compatible with IBM XL C/C++ for AIX 16.1.0 and older

warning: #pragma align(packed) may not be compatible with objects generated with AIX XL C/C++

This diagnostic is enabled by default.

Diagnostic text:

warning: passing A-byte aligned argument to B-byte aligned parameter C

 of E

 may result in an unaligned pointer access

Diagnostic text:

warning: use of function A is discouraged; there is no way to check for failure but failure may still occur, resulting in a possibly exploitable security vulnerability

This diagnostic is enabled by default.

Diagnostic text:

warning: second argument to __builtin_alloca_with_align is supposed to be in bits

This diagnostic is enabled by default.

Diagnostic text:

warning: multiple suitable A functions for B; no ‘operator delete’ function will be invoked if initialization throws an exception

This diagnostic is enabled by default.

Diagnostic text:

warning: ’…’ in this location creates a C-style varargs function

, not a function parameter pack

This diagnostic is enabled by default.

Diagnostic text:

warning: ambiguous expansion of macro A

This diagnostic is enabled by default.

Diagnostic text:

warning: lookup of A in member access expression is ambiguous; using member of B

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++20 considers use of overloaded operator ‘A’ (with operand types B and C) to be ambiguous despite there being a unique best viable function

 with non-reversed arguments

This diagnostic is enabled by default.

Diagnostic text:

warning: checker plugin ‘A’ is not compatible with this version of the analyzer

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wdeprecated-anon-enum-enum-conversion.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++11 requires a parenthesized pack declaration to have a name

Diagnostic text:

warning: weak 

variable

property

implicit property

instance variable

 B may be accessed multiple times in this 

function

method

block

lambda

 and may be unpredictably set to nil; assign to a strong variable to keep the object alive

This diagnostic is enabled by default.

Diagnostic text:

warning: 

destination for

source of

 this B call is a pointer to ownership-qualified type C

This diagnostic is enabled by default.

Diagnostic text:

warning: performSelector may cause a leak because its selector is unknown

Also controls -Warc-maybe-repeated-use-of-weak.

Diagnostic text:

warning: weak 

variable

property

implicit property

instance variable

 B is accessed multiple times in this 

function

method

block

lambda

 but may be unpredictably set to nil; assign to a strong variable to keep the object alive

This diagnostic is enabled by default.

Diagnostic text:

warning: capturing A strongly in this block is likely to lead to a retain cycle

This diagnostic is enabled by default.

Diagnostic text:

warning: assigning 

array literal

dictionary literal

numeric literal

boxed expression

<should not happen>

block literal

 to a weak 

property

variable

; object will be released after assignment

warning: assigning retained object to 

weak

unsafe_unretained

 

property

variable

; object will be released after assignment

warning: assigning retained object to unsafe property; object will be released after assignment

This diagnostic is an error by default, but the flag -Wno-argument-outside-range can be used to disable the error.

Diagnostic text:

error: argument value A is outside the valid range [B, C]

This diagnostic is enabled by default.

Diagnostic text:

warning: array index A is past the end of the array (which contains B element

s

)

warning: array index A refers past the last possible element for an array in B-bit address space containing C-bit (D-byte) elements (max possible E element

s

)

warning: array index A is before the beginning of the array

warning: the pointer incremented by A refers past the last possible element for an array in B-bit address space containing C-bit (D-byte) elements (max possible E element

s

)

warning: array argument is too small; 

contains A elements

is of size A

, callee requires at least B

Diagnostic text:

warning: the pointer incremented by A refers past the end of the array (that contains B element

s

)

warning: the pointer decremented by A refers before the beginning of the array

This diagnostic is enabled by default.

Diagnostic text:

warning: value size does not match register size specified by the constraint and modifier

Diagnostic text:

warning: integer constant not in range of enumerated type A

This diagnostic is enabled by default.

Diagnostic text:

warning: the argument to A has side effects that will be discarded

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: misaligned atomic operation may incur significant performance penalty; the expected alignment (A bytes) exceeds the actual alignment (B bytes)

warning: large atomic operation may incur significant performance penalty; the access size (A bytes) exceeds the max lock-free size (B  bytes)

Diagnostic text:

warning: implicit use of sequentially-consistent atomic may incur stronger memory barriers than necessary

This diagnostic is enabled by default.

Diagnostic text:

warning: memory order argument to atomic operation is invalid

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘packed’ attribute was ignored on bit-fields with single-byte alignment in older versions of GCC and Clang

This diagnostic is enabled by default.

Diagnostic text:

warning: call to A declared with ‘warning’ attribute: B

This diagnostic is enabled by default.

Diagnostic text:

warning: implicitly disabling vptr sanitizer because rtti wasn’t enabled

Diagnostic text:

warning: treating #

include

import

include_next

__include_macros

 as an import of module ‘B’

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘auto’ storage class specifier is not permitted in C++11, and will not be supported in future releases

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘auto’ deduced as ‘id’ in declaration of A

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘unavailable’ availability overrides all other availability information

warning: Fuchsia API Level prohibits specifying a minor or sub-minor version

warning: ignoring availability attribute 

on ‘+load’ method

with constructor attribute

with destructor attribute

warning: only ‘unavailable’ and ‘deprecated’ are supported for Swift availability

warning: unknown platform A in availability macro

warning: feature cannot be 

introduced

deprecated

obsoleted

 in B version C before it was 

introduced

deprecated

obsoleted

 in version E; attribute ignored

warning: use same version number separators ‘_’ or ‘.’; as in ‘major[.minor[.subminor]]’

warning: availability does not match previous declaration

warning: 

overriding 

method 

introduced after

deprecated before

obsoleted before

 

the protocol method it implements

overridden method

 on B (C vs. D)

warning: 

overriding 

method cannot be unavailable on A when 

the protocol method it implements

its overridden method

 is available

This diagnostic is enabled by default.

Diagnostic text:

warning: support for linking stdlibs for microcontroller ‘A’ is not implemented

warning: no avr-gcc installation can be found on the system, cannot link standard libraries

warning: no avr-libc installation can be found on the system, cannot link standard libraries

warning: support for passing the data section address to the linker for microcontroller ‘A’ is not implemented

warning: no target microcontroller specified on command line, cannot link standard libraries, please pass -mmcu=<mcu name>

warning: standard library not linked and so no interrupt vector table or compiler runtime routines will be linked

This diagnostic is enabled by default.

Diagnostic text:

The text of this diagnostic is not controlled by Clang.

Diagnostic text:

warning: cast from function call of type A to non-matching type B

Also controls -Wc++98-compat-bind-to-temporary-copy.

Diagnostic text:

warning: C++98 requires an accessible copy constructor for class C when binding a reference to a temporary; was 

private

protected

warning: no viable constructor 

copying variable

copying parameter

initializing template parameter

returning object

initializing statement expression result

throwing object

copying member subobject

copying array element

allocating object

copying temporary

initializing base subobject

initializing vector element

capturing value

 of type B; C++98 requires a copy constructor when binding a reference to a temporary

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++17 does not permit structured binding declaration in a condition

Diagnostic text:

warning: ’_BitInt’ in 

C17 and earlier

C++

 is a Clang extension

This diagnostic is enabled by default.

Diagnostic text:

warning: implicit truncation from C to bit-field changes value from A to B

Diagnostic text:

warning: bit-field A is not wide enough to store all enumerators of B

warning: signed bit-field A needs an extra bit to represent the largest positive enumerators of B

warning: assigning value of signed enum type B to unsigned bit-field A; negative enumerators of enum B will be converted to positive values

This diagnostic is enabled by default.

Diagnostic text:

warning: width of bit-field A (B bits) exceeds the width of its type; value will be truncated to C bit

s

This diagnostic is enabled by default.

Diagnostic text:

warning: operator ‘?:’ has lower precedence than ‘A’; ‘A’ will be evaluated first

This diagnostic is enabled by default.

Diagnostic text:

warning: block captures an autoreleasing out-parameter, which may result in use-after-free bugs

This diagnostic is enabled by default.

Diagnostic text:

warning: braces around 

scalar 

initializer

This diagnostic is enabled by default.

Diagnostic text:

warning: ’-mbranch-protection=’ option is incompatible with the ‘A’ architecture

warning: ignoring the ‘branch-protection’ attribute because the ‘A’ architecture does not support it

warning: invalid branch protection option ‘A’ in ‘B’

warning: unsupported branch protection specification ‘A’

This diagnostic is enabled by default.

Diagnostic text:

warning: A bridges to B, not C

warning: A cannot bridge to B

This diagnostic is enabled by default.

Diagnostic text:

warning: redefining builtin macro

warning: undefining builtin macro

This diagnostic is enabled by default.

Diagnostic text:

warning: ’A’ will always overflow; destination buffer has size B, but size argument is C

Diagnostic text:

warning: 

empty 

struct

union

 has size 0 in C, 

size 1

non-zero size

 in C++

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc++11-compat-deprecated-writable-strings, -Wc++11-compat-reserved-user-defined-literal, -Wc++11-narrowing, -Wpre-c++14-compat, -Wpre-c++17-compat, -Wpre-c++20-compat, -Wpre-c++2b-compat.

Diagnostic text:

warning: integer literal is too large to be represented in type ‘long’ and is subject to undefined behavior under C++98, interpreting as ‘unsigned long’; this literal will 

have type ‘long long’

be ill-formed

 in C++11 onwards

warning: ‘auto’ storage class specifier is redundant and incompatible with C++11

warning: identifier after literal will be treated as a user-defined literal suffix in C++11

warning: ’A’ is a keyword in C++11

warning: use of right-shift operator (‘>>’) in template argument will require parentheses in C++11

warning: explicit instantiation cannot be ‘inline’

warning: explicit instantiation of A must occur at global scope

warning: explicit instantiation of A not in a namespace enclosing B

warning: explicit instantiation of A must occur in namespace B

warning: integer literal is too large to be represented in type ‘long’, interpreting as ‘unsigned long’ per C++98; this literal will 

have type ‘long long’

be ill-formed

 in C++11 onwards

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc++11-extra-semi, -Wc++11-inline-namespace, -Wc++11-long-long.

Diagnostic text:

warning: alias declarations are a C++11 extension

warning: implicit conversion from array size expression of type A to 

integral

enumeration

 type C is a C++11 extension

warning: ‘auto’ type specifier is a C++11 extension

warning: enumeration types with a fixed underlying type are a C++11 extension

warning: 

defaulted

deleted

 function definitions are a C++11 extension

warning: befriending enumeration type A is a C++11 extension

warning: commas at the end of enumerator lists are a C++11 extension

warning: explicit conversion functions are a C++11 extension

warning: extern templates are a C++11 extension

warning: range-based for loop is a C++11 extension

warning: generalized initializer lists are a C++11 extension

warning: use of enumeration in a nested name specifier is a C++11 extension

warning: non-class friend type A is a C++11 extension

warning: default member initializer for non-static data member is a C++11 extension

warning: ’A’ keyword is a C++11 extension

warning: reference qualifiers on functions are a C++11 extension

warning: rvalue references are a C++11 extension

warning: scoped enumerations are a C++11 extension

warning: static data member A in union is a C++11 extension

warning: non-type template argument referring to 

function

object

 B with internal linkage is a C++11 extension

warning: ‘template’ keyword outside of a template

warning: default template arguments for a function template are a C++11 extension

warning: ‘typename’ occurs outside of a template

warning: unelaborated friend declaration is a C++11 extension; specify ‘

struct

interface

union

class

enum

‘ to befriend B

warning: variadic templates are a C++11 extension

This diagnostic is enabled by default.

Diagnostic text:

warning: inline namespaces are a C++11 feature

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

error: 

case value

enumerator value

non-type template argument

array size

explicit specifier argument

noexcept specifier argument

 

cannot be narrowed from type C to D

evaluates to C, which cannot be narrowed to type D

error: constant expression evaluates to A which cannot be narrowed to type B

error: type A cannot be narrowed to B in initializer list

error: non-constant-expression cannot be narrowed from type A to B in initializer list

warning: constant expression evaluates to A which cannot be narrowed to type B in C++11

warning: type A cannot be narrowed to B in initializer list in C++11

warning: non-constant-expression cannot be narrowed from type A to B in initializer list in C++11

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc++14-attribute-extensions, -Wc++14-binary-literal.

Diagnostic text:

warning: use of this statement in a constexpr 

function

constructor

 is a C++14 extension

warning: multiple return statements in constexpr function is a C++14 extension

warning: variable declaration in a constexpr 

function

constructor

 is a C++14 extension

warning: type definition in a constexpr 

function

constructor

 is a C++14 extension

warning: ‘decltype(auto)’ type specifier is a C++14 extension

warning: initialized lambda captures are a C++14 extension

warning: variable templates are a C++14 extension

This diagnostic is enabled by default.

Diagnostic text:

warning: mangled name of A will change in C++17 due to non-throwing exception specification in function signature

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc++17-attribute-extensions.

Diagnostic text:

warning: ISO C++ standards before C++17 do not allow new expression for type A to use list-initialization

warning: constexpr if is a C++17 extension

warning: ‘constexpr’ on lambda expressions is a C++17 extension

warning: ‘static_assert’ with no message is a C++17 extension

warning: decomposition declarations are a C++17 extension

warning: pack fold expression is a C++17 extension

warning: ‘begin’ and ‘end’ returning different types (A and B) is a C++17 extension

warning: hexadecimal floating literals are a C++17 feature

warning: ’

if

switch

‘ initialization statements are a C++17 extension

warning: inline variables are a C++17 extension

warning: use of multiple declarators in a single using declaration is a C++17 extension

warning: nested namespace definition is a C++17 extension; define each namespace separately

warning: attributes on 

a namespace

an enumerator

 declaration are a C++17 extension

warning: capture of ‘*this’ by copy is a C++17 extension

warning: template template parameter using ‘typename’ is a C++17 extension

warning: default scope specifier for attributes is a C++17 extension

warning: pack expansion of using declaration is a C++17 extension

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wpre-c++2b-compat.

Diagnostic text:

warning: aggregate initialization of type A with user-declared constructors is incompatible with C++20

warning: ‘consteval’ specifier is incompatible with C++ standards before C++20

warning: ‘constinit’ specifier is incompatible with C++ standards before C++20

warning: this expression will be parsed as explicit(bool) in C++20

warning: ’<=>’ is a single token in C++20; add a space to avoid a change in behavior

warning: type of UTF-8 string literal will change from array of const char to array of const char8_t in C++20

warning: ’A’ is a keyword in C++20

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc++20-attribute-extensions, -Wc++20-designator.

Diagnostic text:

warning: use of function template name with no prior declaration in function call with explicit template arguments is a C++20 extension

warning: default member initializer for bit-field is a C++20 extension

warning: use of this statement in a constexpr 

function

constructor

 is a C++20 extension

warning: constexpr constructor that does not initialize all members is a C++20 extension

warning: function try block in constexpr 

function

constructor

 is a C++20 extension

warning: uninitialized variable in a constexpr 

function

constructor

 is a C++20 extension

warning: constexpr union constructor that does not initialize any member is a C++20 extension

warning: decomposition declaration declared 

‘B’

with ‘B’ specifiers

 is a C++20 extension

warning: defaulted comparison operators are a C++20 extension

warning: explicit capture of ‘this’ with a capture default of ‘=’ is a C++20 extension

warning: explicit(bool) is a C++20 extension

warning: range-based for loop initialization statements are a C++20 extension

warning: initialized lambda pack captures are a C++20 extension

warning: inline nested namespace definition is a C++20 extension

warning: explicit template parameter list for lambdas is a C++20 extension

warning: invoking a pointer to a ‘const &’ member function on an rvalue is a C++20 extension

warning: member using declaration naming a non-member enumerator is a C++20 extension

warning: using declaration naming a scoped enumerator is a C++20 extension

warning: using enum declaration is a C++20 extension

This diagnostic is enabled by default.

Diagnostic text:

warning: alias declaration in this context is a C++2b extension

warning: consteval if is a C++2b extension

warning: ‘size_t’ suffix for literals is a C++2b extension

warning: an attribute specifier sequence in this position is a C++2b extension

warning: lambda without a parameter clause is a C++2b extension

Also controls -Wc++98-compat-local-type-template-args, -Wc++98-compat-unnamed-type-template-args, -Wpre-c++14-compat, -Wpre-c++17-compat, -Wpre-c++20-compat, -Wpre-c++2b-compat.

Diagnostic text:

warning: alias declarations are incompatible with C++98

warning: ‘alignas’ is incompatible with C++98

warning: alignof expressions are incompatible with C++98

warning: C++11 attribute syntax is incompatible with C++98

warning: ‘auto’ type specifier is incompatible with C++98

warning: ‘constexpr’ specifier is incompatible with C++98

warning: constructor call from initializer list is incompatible with C++98

warning: ‘decltype’ type specifier is incompatible with C++98

warning: 

defaulted

deleted

 function definitions are incompatible with C++98

warning: delegating constructors are incompatible with C++98

warning: scalar initialized from empty initializer list is incompatible with C++98

warning: initializing A from an empty initializer list is incompatible with C++98

warning: enumeration types with a fixed underlying type are incompatible with C++98

warning: befriending enumeration type A is incompatible with C++98

warning: enumeration type in nested name specifier is incompatible with C++98

warning: explicit conversion functions are incompatible with C++98

warning: range-based for loop is incompatible with C++98

warning: friend declaration naming a member of the declaring class is incompatible with C++98

warning: generalized initializer lists are incompatible with C++98

warning: jump from this goto statement to its label is incompatible with C++98

warning: jump from this 

indirect

asm

 goto statement to one of its possible targets is incompatible with C++98

warning: initialization of initializer_list object is incompatible with C++98

warning: inline namespaces are incompatible with C++98

warning: lambda expressions are incompatible with C++98

warning: ’<::’ is treated as digraph ‘<:’ (aka ‘[‘) followed by ‘:’ in C++98

warning: literal operators are incompatible with C++98

warning: universal character name referring to a control character is incompatible with C++98

warning: specifying character ‘A’ with a universal character name is incompatible with C++98

warning: noexcept specifications are incompatible with C++98

warning: noexcept expressions are incompatible with C++98

warning: use of non-static data member A in an unevaluated context is incompatible with C++98

warning: non-class friend type A is incompatible with C++98

warning: default member initializer for non-static data members is incompatible with C++98

warning: 

anonymous struct

union

 member B with a non-trivial 

default constructor

copy constructor

move constructor

copy assignment operator

move assignment operator

destructor

 is incompatible with C++98

warning: ‘nullptr’ is incompatible with C++98

warning: ’A’ keyword is incompatible with C++98

warning: passing object of trivial but non-POD type A through variadic 

function

block

method

constructor

 is incompatible with C++98

warning: raw string literals are incompatible with C++98

warning: reference qualifiers on functions are incompatible with C++98

warning: reference initialized from initializer list is incompatible with C++98

warning: rvalue references are incompatible with C++98

warning: scoped enumerations are incompatible with C++98

warning: substitution failure due to access control is incompatible with C++98

warning: static_assert declarations are incompatible with C++98

warning: static data member A in union is incompatible with C++98

warning: jump from switch statement to this case label is incompatible with C++98

warning: redundant parentheses surrounding address non-type template argument are incompatible with C++98

warning: use of null pointer as non-type template argument is incompatible with C++98

warning: non-type template argument referring to 

function

object

 B with internal linkage is incompatible with C++98

warning: use of ‘template’ keyword outside of a template is incompatible with C++98

warning: default template arguments for a function template are incompatible with C++98

warning: trailing return types are incompatible with C++98

warning: consecutive right angle brackets are incompatible with C++98 (use ‘> >’)

warning: use of ‘typename’ outside of a template is incompatible with C++98

warning: befriending B without ‘

struct

interface

union

class

enum

‘ keyword is incompatible with C++98

warning: unicode literals are incompatible with C++98

warning: ’A’ type specifier is incompatible with C++98

warning: inheriting constructors are incompatible with C++98

warning: variadic templates are incompatible with C++98

Diagnostic text:

warning: 

copying variable

copying parameter

initializing template parameter

returning object

initializing statement expression result

throwing object

copying member subobject

copying array element

allocating object

copying temporary

initializing base subobject

initializing vector element

capturing value

 of type C when binding a reference to a temporary would 

invoke an inaccessible constructor

find no viable constructor

find ambiguous constructors

invoke a deleted constructor

 in C++98

Diagnostic text:

warning: anonymous unions are a C11 extension

warning: anonymous structs are a C11 extension

warning: ’A’ is a C11 extension

warning: pointer comparisons before C11 need to be between two complete or two incomplete types; A is 

in

complete and B is 

in

complete

This diagnostic is enabled by default.

Diagnostic text:

warning: ’_Static_assert’ with no message is a C2x extension

warning: omitting the parameter name in a function definition is a C2x extension

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: 

using this character in an identifier

starting an identifier with this character

 is incompatible with C99

warning: unicode literals are incompatible with C99

warning: integer literal is too large to be represented in type ‘long’, interpreting as ‘unsigned long’ per C89; this literal will 

have type ‘long long’

be ill-formed

 in C99 onwards

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc++20-designator.

Diagnostic text:

warning: designated initializers are a C99 feature

warning: array designators are a C99 extension

warning: brace elision for designated initializer is a C99 extension

warning: mixture of designated and non-designated initializers in the same initializer list is a C99 extension

warning: nested designators are a C99 extension

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wc99-designator.

Diagnostic text:

warning: initializer for aggregate is not a compile-time constant

warning: 

qualifier in 

static 

array size 

‘[*] ‘

is a C99 feature

warning: compound literals are a C99-specific feature

warning: ’A’ is a C99 extension

warning: flexible array members are a C99 feature

warning: variable declaration in for loop is a C99-specific feature

warning: ISO C99 requires whitespace after the macro name

warning: empty macro arguments are a C99 feature

warning: commas at the end of enumerator lists are a C99-specific feature

warning: hexadecimal floating constants are a C99 feature

This diagnostic is enabled by default.

Diagnostic text:

warning: call to pure virtual member function A has undefined behavior; overrides of A in subclasses are not available in the 

constructor

destructor

 of C

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wcompletion-handler.

Diagnostic text:

warning: A parameter marked ‘called_once’ is called twice

warning: 

captured 

A parameter marked ‘called_once’ is never called

warning: A parameter marked ‘called_once’ is never 

used

called

 when 

taking true branch

taking false branch

handling this case

none of the cases applies

entering the loop

skipping the loop

taking one of the branches

Diagnostic text:

warning: cast from A to B increases required alignment from C to D

This diagnostic is enabled by default.

Diagnostic text:

warning: cast between incompatible calling conventions ‘A’ and ‘B’; calls through this pointer may abort at runtime

Diagnostic text:

warning: cast 

from A to B 

converts to incompatible function type

This diagnostic is enabled by default.

Diagnostic text:

warning: cast of type A to B is deprecated; use sel_getName instead

Diagnostic text:

warning: cast from A to B drops 

const and volatile qualifiers

const qualifier

volatile qualifier

warning: cast from A to B must have all intermediate pointers const qualified to be safe

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

Diagnostic text:

warning: array section 

lower bound

length

 is of type ‘char’

warning: array subscript is of type ‘char’

This diagnostic is enabled by default.

Diagnostic text:

warning: support for ‘/Yc’ with more than one source file not implemented yet; flag ignored

warning: support for ‘/Yc’ and ‘/Yu’ with different filenames not implemented yet; flags ignored

warning: #pragma hdrstop filename not supported, /Fp can be used to specify precompiled header filename

warning: definition of macro A does not match definition in precompiled header

This diagnostic is enabled by default.

Diagnostic text:

warning: conversion function converting A to its base class B will never be used

warning: conversion function converting A to itself will never be used

warning: conversion function converting A to B will never be used

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wnon-pod-varargs.

Diagnostic text:

warning: passing object of class type A through variadic 

function

block

method

constructor

; did you mean to call ‘D’?

This diagnostic is enabled by default.

Diagnostic text:

warning: passing union across security boundary via 

parameter B

return value

 may leak information

Diagnostic text:

warning: possible misuse of comma operator here

Diagnostic text:

warning: completion handler is called twice

warning: 

captured 

completion handler is never called

warning: completion handler is never 

used

called

 when 

taking true branch

taking false branch

handling this case

none of the cases applies

entering the loop

skipping the loop

taking one of the branches

Diagnostic text:

warning: complex initialization specifying real and imaginary components is an extension

This diagnostic is enabled by default.

Diagnostic text:

warning: 

B and 

C tokens 

introducing statement expression

terminating statement expression

introducing attribute

terminating attribute

forming pointer to member type

 appear in different macro expansion contexts

Diagnostic text:

warning: 

B and 

C tokens 

introducing statement expression

terminating statement expression

introducing attribute

terminating attribute

forming pointer to member type

 are separated by whitespace

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++20 does not permit the ‘bool’ keyword after ‘concept’

This diagnostic is enabled by default.

Diagnostic text:

warning: pointer/integer type mismatch in conditional expression

 (A and B)

This diagnostic is enabled by default.

Diagnostic text:

warning: 

definition

#undef

 of configuration macro ‘B’ has no effect on the import of ‘C’; pass ‘

-DB=…

-UB

‘ on the command line to configure the module

This diagnostic is enabled by default.

Diagnostic text:

warning: ’A’ will always evaluate to ‘true’ in a manifestly constant-evaluated expression

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘constexpr’ non-static member function will not be implicitly ‘const’ in C++14; add ‘const’ to avoid a change in behavior

Diagnostic text:

warning: consumed analysis attribute is attached to member of class A which isn’t marked as consumable

warning: state of variable ‘A’ must match at the entry and exit of loop

warning: parameter ‘A’ not in expected state when the function returns: expected ‘B’, observed ‘C’

warning: argument not in expected state; expected ‘A’, observed ‘B’

warning: return state set for an unconsumable type ‘A’

warning: return value not in expected state; expected ‘A’, observed ‘B’

warning: invalid invocation of method ‘A’ on object ‘B’ while it is in the ‘C’ state

warning: invalid invocation of method ‘A’ on a temporary object while it is in the ‘B’ state

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wbitfield-enum-conversion, -Wbool-conversion, -Wconstant-conversion, -Wenum-conversion, -Wfloat-conversion, -Wimplicit-float-conversion, -Wimplicit-int-conversion, -Wint-conversion, -Wliteral-conversion, -Wnon-literal-null-conversion, -Wnull-conversion, -Wobjc-literal-conversion, -Wshorten-64-to-32, -Wsign-conversion, -Wstring-conversion.

Diagnostic text:

warning: implicit conversion discards imaginary component: A to B

warning: implicit conversion turns vector to scalar: A to B

warning: passing non-generic address space pointer to A may cause dynamic conversion affecting performance

warning: non-type template argument with value ‘A’ converted to ‘B’ for unsigned template parameter of type C

warning: non-type template argument value ‘A’ truncated to ‘B’ for template parameter of type C

Diagnostic text:

warning: using A directive in 

NSString

CFString

 which is being passed as a formatting argument to the formatting 

method

CFfunction

This diagnostic is enabled by default.

Diagnostic text:

warning: imported AST from ‘A’ had been generated for a different target, current: B, imported: C

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: A attribute parameter B is negative and will be ignored

warning: nvcc does not allow ‘__A__’ to appear after the parameter list in lambdas

warning: ignored ‘inline’ attribute on kernel function A

warning: kernel function A is a member function; this may not be accepted by nvcc

warning: argument to ‘#pragma unroll’ should not be in parentheses in CUDA C/C++

Diagnostic text:

warning: atomic by default property A has a user defined 

getter

setter

 (property should be marked ‘atomic’ if this is intended)

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++ does not allow an attribute list to appear here

This diagnostic is enabled by default.

Also controls -Wdangling-field, -Wdangling-gsl, -Wdangling-initializer-list, -Wreturn-stack-address.

Diagnostic text:

warning: 

temporary 

whose address is used as value of

implicitly 

bound to

 

reference 

member of local variable

local 

variable

reference

array backing 

initializer list subobject of local variable

local initializer list

 

D 

will be destroyed at the end of the full-expression

warning: sorry, lifetime extension of 

temporary

backing array of initializer list

 created by aggregate initialization using default member initializer is not supported; lifetime of 

temporary

backing array

 will end at the end of the full-expression

This diagnostic is enabled by default.

Diagnostic text:

warning: add explicit braces to avoid dangling else

This diagnostic is enabled by default.

Diagnostic text:

warning: binding reference member A to stack allocated 

variable

parameter

 B

warning: 

reference

backing array for ‘std::initializer_list’

 

subobject of 

member A 

binds to

is

 a temporary object whose lifetime is shorter than the lifetime of the constructed object

warning: initializing pointer member A with the stack address of 

variable

parameter

 B

warning: temporary bound to reference member of allocated object will be destroyed at the end of the full-expression

This diagnostic is enabled by default.

Diagnostic text:

warning: object backing the pointer will be destroyed at the end of the full-expression

warning: initializing pointer member A to point to a temporary object whose lifetime is shorter than the lifetime of the constructed object

This diagnostic is enabled by default.

Diagnostic text:

warning: array backing 

initializer list subobject of the allocated object

the allocated initializer list

 will be destroyed at the end of the full-expression

This diagnostic is enabled by default.

Diagnostic text:

warning: SDK settings were ignored as ‘SDKSettings.json’ could not be parsed

Diagnostic text:

warning: expansion of date or time macro is not reproducible

This diagnostic is enabled by default.

Diagnostic text:

warning: -dealloc is being overridden in a category

Diagnostic text:

warning: mixing declarations and code is a C99 extension

warning: mixing declarations and code is incompatible with standards before C99

This diagnostic is enabled by default.

Diagnostic text:

warning: explicitly defaulted 

<ERROR>

equality

three-way

equality

relational

 comparison operator is implicitly deleted

warning: explicitly defaulted 

default constructor

copy constructor

move constructor

copy assignment operator

move assignment operator

destructor

 is implicitly deleted

This diagnostic is an error by default, but the flag -Wno-delegating-ctor-cycles can be used to disable the error.

Diagnostic text:

error: constructor for A creates a delegation cycle

This diagnostic is enabled by default.

Diagnostic text:

warning: 

delete

destructor

 called on B that is abstract but has non-virtual destructor

This diagnostic is enabled by default.

Diagnostic text:

warning: cannot delete expression with pointer-to-‘void’ type A

warning: deleting pointer to incomplete type A may cause undefined behavior

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wdeprecated-anon-enum-enum-conversion, -Wdeprecated-array-compare, -Wdeprecated-attributes, -Wdeprecated-comma-subscript, -Wdeprecated-copy, -Wdeprecated-copy-with-dtor, -Wdeprecated-declarations, -Wdeprecated-dynamic-exception-spec, -Wdeprecated-enum-compare, -Wdeprecated-enum-compare-conditional, -Wdeprecated-enum-enum-conversion, -Wdeprecated-enum-float-conversion, -Wdeprecated-increment-bool, -Wdeprecated-pragma, -Wdeprecated-register, -Wdeprecated-this-capture, -Wdeprecated-type, -Wdeprecated-volatile, -Wdeprecated-writable-strings.

Diagnostic text:

warning: -O4 is equivalent to -O3

warning: access declarations are deprecated; use using declarations instead

warning: out-of-line definition of constexpr static data member is redundant in C++17 and is deprecated

warning: argument ‘A’ is deprecated, use ‘B’ instead

warning: treating ‘A’ input as ‘B’ when in C++ mode, this behavior is deprecated

warning: -fconcepts-ts is deprecated - use ‘-std=c++20’ for Concepts support

warning: A does not support the option ‘B’

warning: Use of ‘long’ with ‘__vector’ is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: Current handling of vector bool and vector pixel types in this context are deprecated. The default behaviour will soon change to that implied by the ‘-altivec-compat=xl’ option

This diagnostic is enabled by default.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

 is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: comparison between two arrays is deprecated; to compare array addresses, use unary ‘+’ to decay operands to pointers

This diagnostic is enabled by default.

Diagnostic text:

warning: specifying vector types with the ‘mode’ attribute is deprecated; use the ‘vector_size’ attribute instead

This diagnostic is enabled by default.

Diagnostic text:

warning: top-level comma expression in array subscript is deprecated

Diagnostic text:

warning: definition of implicit copy 

constructor

assignment operator

 for A is deprecated because it has a user-provided copy 

assignment operator

constructor

This diagnostic is enabled by default.

Diagnostic text:

warning: specifying ‘uuid’ as an ATL attribute is deprecated; use __declspec instead

warning: use of C-style parameters in Objective-C method declarations is deprecated

warning: A is deprecated

warning: A may be deprecated because the receiver type is unknown

warning: A is deprecated: B

warning: property access is using A method which is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

 is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

 is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

 is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 

floating-point

enumeration

 type C 

with

from

and

 

enumeration

floating-point

 type D is deprecated

This diagnostic is enabled by default.

Diagnostic text:

warning: support for std::experimental::A will be removed in LLVM 15; use std::A instead

This diagnostic is enabled by default.

Diagnostic text:

warning: incrementing expression of type bool is deprecated and incompatible with C++17

This diagnostic is enabled by default.

Diagnostic text:

warning: assignment to Objective-C’s isa is deprecated in favor of object_setClass()

warning: direct access to Objective-C’s isa is deprecated in favor of object_getClass()

This diagnostic is enabled by default.

Diagnostic text:

warning: macro A has been marked as deprecated

: C

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘register’ storage class specifier is deprecated and incompatible with C++17

This diagnostic is enabled by default.

Diagnostic text:

warning: ’_ExtInt’ is deprecated; use ‘_BitInt’ instead

This diagnostic is enabled by default.

Diagnostic text:

warning: compound assignment to object of volatile-qualified type A is deprecated

warning: 

decrement

increment

 of object of volatile-qualified type B is deprecated

warning: use of result of assignment to object of volatile-qualified type A is deprecated

warning: volatile-qualified parameter type A is deprecated

warning: volatile-qualified return type A is deprecated

warning: volatile qualifier in structured binding declaration is deprecated

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: conflicting distributed object modifiers on parameter type in implementation of A

warning: conflicting distributed object modifiers on return type in implementation of A

This diagnostic is enabled by default.

Diagnostic text:

warning: 

remainder

division

 by zero is undefined

Also controls -Wdocumentation-deprecated-sync, -Wdocumentation-html.

Diagnostic text:

warning: ’

\

@

class

interface

protocol

struct

union

‘ command should not be used in a comment attached to a non-

class

interface

protocol

struct

union

 declaration

warning: duplicated command ‘

\

@

B’

warning: empty paragraph passed to ‘

\

@

B’ command

warning: ’

\

@

classdesign

coclass

dependency

helper

helperclass

helps

instancesize

ownership

performance

security

superclass

‘ command should not be used in a comment attached to a non-container declaration

warning: ’

\

@

function

functiongroup

method

methodgroup

callback

‘ command should be used in a comment attached to 

a function

a function

an Objective-C method

an Objective-C method

a pointer to function

 declaration

warning: HTML start tag prematurely ended, expected attribute name or ‘>’

warning: expected quoted string after equals sign

warning: ’

\

@

B’ command does not have a valid word argument

warning: parameter ‘A’ is already documented

warning: unrecognized parameter passing direction, valid directions are ‘[in]’, ‘[out]’ and ‘[in,out]’

warning: ’

\

@

param’ command used in a comment that is not attached to a function declaration

warning: parameter ‘A’ not found in the function declaration

warning: ’

\

@

B’ command used in a comment that is attached to a 

function returning void

constructor

destructor

method returning void

warning: ’

\

@

B’ command used in a comment that is not attached to a function or method declaration

warning: template parameter ‘A’ is already documented

warning: ’

\

@

tparam’ command used in a comment that is not attached to a template declaration

warning: template parameter ‘A’ not found in the template declaration

warning: not a Doxygen trailing comment

warning: ’

\

@

B’ command does not terminate a verbatim text block

Diagnostic text:

warning: HTML end tag ‘A’ is forbidden

warning: HTML end tag does not match any start tag

warning: HTML tag ‘A’ requires an end tag

warning: HTML start tag ‘A’ closed by ‘B’

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: ISO C++ considers this destructor name lookup to be ambiguous

warning: ISO C++ requires the name after ‘::~’ to be found in the same scope as the name before ‘::~’

warning: qualified destructor name only found in lexical scope; omit the qualifier to find this type name by unqualified lookup

This diagnostic is an error by default, but the flag -Wno-dtor-typedef can be used to disable the error.

Diagnostic text:

error: destructor cannot be declared using a 

typedef

type alias

 A of the class name

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: duplicate ‘A’ declaration specifier

warning: duplicate ‘A’ declaration specifier

warning: multiple identical address spaces specified for type

warning: duplicate ‘A’ declaration specifier

Diagnostic text:

warning: element A has been implicitly assigned B which another element has been assigned

This diagnostic is enabled by default.

Diagnostic text:

warning: duplicate protocol definition of A is ignored

This diagnostic is enabled by default.

Diagnostic text:

warning: 

destination for

source of

first operand of

second operand of

 this B call is a pointer to 

class containing a 

dynamic class D; vtable pointer will be 

overwritten

copied

moved

compared

This diagnostic is an error by default, but the flag -Wno-elaborated-enum-base can be used to disable the error.

Diagnostic text:

error: non-defining declaration of enumeration with a fixed underlying type is only permitted as a standalone declaration

; missing list of enumerators?

This diagnostic is an error by default, but the flag -Wno-elaborated-enum-class can be used to disable the error.

Diagnostic text:

error: reference to enumeration must use ‘enum’ not ‘enum 

struct

class

‘

Diagnostic text:

warning: embedding a directive within macro arguments has undefined behavior

This diagnostic is enabled by default.

Diagnostic text:

warning: for loop has empty body

warning: if statement has empty body

warning: range-based for loop has empty body

warning: switch statement has empty body

warning: while loop has empty body

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++17 does not allow a decomposition group to be empty

Diagnostic text:

warning: empty initialization statement of ‘

if

switch

range-based for

‘ has no effect

This diagnostic is enabled by default.

Diagnostic text:

warning: encoding of A type is incomplete because B component has unknown encoding

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wdeprecated-enum-compare-conditional.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

This diagnostic is enabled by default.

Diagnostic text:

warning: comparison of different enumeration types in switch statement

 (A and B)

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wdeprecated-enum-enum-conversion.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 different enumeration types

 (B and C)

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wdeprecated-enum-float-conversion.

Diagnostic text:

warning: 

arithmetic between

bitwise operation between

comparison of

conditional expression between

compound assignment of

 

floating-point

enumeration

 type C 

with

from

and

 

enumeration

floating-point

 type D

This diagnostic is enabled by default.

Diagnostic text:

warning: enumeration values exceed range of largest integer

warning: incremented enumerator value A is not representable in the largest integer type

This diagnostic is enabled by default.

Diagnostic text:

warning: cannot refer to a non-static member from the handler of a 

constructor

destructor

 function try block

warning: exception of type A will be caught by earlier handler

warning: A has a non-throwing exception specification but can still throw

This diagnostic is enabled by default.

Diagnostic text:

warning: excess elements in 

array

vector

scalar

union

struct

 initializer

warning: excess elements in initializer for indivisible sizeless type A

warning: excess elements in char array initializer

warning: initializer-string for char array is too long

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: macro expansion producing ‘defined’ has undefined behavior

warning: macro expansion producing ‘defined’ has undefined behavior

This diagnostic is enabled by default.

Diagnostic text:

warning: explicit call to +initialize results in duplicate call to +initialize

warning: explicit call to [super initialize] should only be in implementation of +initialize

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++20 does not permit 

an empty

a static_assert

 declaration to appear in an export block

warning: ISO C++20 does not permit a declaration that does not introduce any names to be exported

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++20 does not permit using directive to be exported

This diagnostic is enabled by default.

Diagnostic text:

warning: 

empty 

struct

union

 has size 0 in C, 

size 1

non-zero size

 in C++

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘extern’ variable has an initializer

This diagnostic is enabled by default.

Diagnostic text:

warning: class with destructor marked ‘

final

sealed

‘ cannot be inherited from

This diagnostic is enabled by default.

Diagnostic text:

warning: macro A has been marked as final and should not be 

undefined

redefined

Diagnostic text:

warning: enumeration types with a fixed underlying type are a Clang extension

This diagnostic is enabled by default.

Diagnostic text:

warning: overflow in expression; result is A with type B

This diagnostic is enabled by default.

Diagnostic text:

warning: enumeration value A is out of range of flags in enumeration type B

Diagnostic text:

warning: A may not be used as an array element due to flexible array member

warning: A may not be nested in a struct due to flexible array member

Diagnostic text:

warning: comparing floating point with == or != is unsafe

Diagnostic text:

warning: implicit conversion from A to B changes value from C to D

warning: implicit conversion of out of range value from A to B is undefined

Diagnostic text:

warning: implicit conversion from A to B changes non-zero value from C to D

Diagnostic text:

warning: variable A is 

decremented

incremented

 both in the loop header and in the loop body

warning: variable

s

 B

s B and C

s B, C, and D

s B, C, D, and E

 used in loop condition not modified in loop body

This diagnostic is enabled by default.

Also controls -Wformat-extra-args, -Wformat-insufficient-args, -Wformat-invalid-specifier, -Wformat-security, -Wformat-y2k, -Wformat-zero-length, -Wnonnull.

Diagnostic text:

warning: using ‘%%P’ format specifier without precision

warning: 

values of type

enum values with underlying type

 ’A’ should not be used as format arguments; add an explicit cast to B instead

warning: using ‘A’ format specifier, but argument has boolean value

warning: format specifies type A but the argument has 

type

underlying type

 B

warning: using ‘A’ format specifier annotation outside of os_log()/os_trace()

warning: invalid position specified for 

field width

field precision

warning: cannot mix positional and non-positional arguments in format string

warning: length modifier ‘A’ results in undefined behavior or no effect with ‘B’ conversion specifier

warning: format string should not be a wide string

warning: position arguments in format strings start counting at 1 (not 0)

warning: format string missing

warning: object format flags cannot be used with ‘A’ conversion specifier

warning: ’

*

.*

‘ specified field 

width

precision

 is missing a matching ‘int’ argument

warning: field 

width

precision

 should have type B, but argument has type C

warning: missing object format flag

warning: format string contains ‘\0’ within the string body

warning: format string is not null-terminated

warning: flag ‘A’ is ignored when flag ‘B’ is present

warning: incomplete format specifier

warning: ’A’ is not a valid object format flag

warning: ’%%n’ specifier not supported on this platform

warning: flag ‘A’ results in undefined behavior with ‘B’ conversion specifier

warning: 

field width

precision

 used with ‘B’ conversion specifier, resulting in undefined behavior

warning: data argument position ‘A’ exceeds the number of data arguments (B)

warning: zero field width in scanf format string is unused

warning: no closing ‘]’ for ‘%%[‘ in scanf format string

This diagnostic is enabled by default.

Diagnostic text:

warning: more ‘%%’ conversions than data arguments

Diagnostic text:

warning: ’A’ 

length modifier

conversion specifier

 is not supported by ISO C

warning: using length modifier ‘A’ with conversion specifier ‘B’ is not supported by ISO C

warning: positional arguments are not supported by ISO C

Diagnostic text:

warning: 

values of type

enum values with underlying type

 ’A’ should not be used as format arguments; add an explicit cast to B instead

warning: format specifies type A but the argument has 

type

underlying type

 B

This diagnostic is enabled by default.

Diagnostic text:

warning: format string is not a string literal (potentially insecure)

Diagnostic text:

warning: format specifies type A but the argument has 

type

underlying type

 B

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: format string is empty

This diagnostic is enabled by default.

Diagnostic text:

warning: ’A’ may overflow; destination buffer in argument B has size C, but the corresponding specifier may require size D

warning: ’A’ will always overflow; destination buffer has size B, but format string expands to at least C

warning: ’A’ will always overflow; destination buffer has size B, but size argument is C

warning: ’A’ size argument is too large; destination buffer has size B, but size argument is C

warning: ’A’ will always overflow; destination buffer has size B, but the source string has length C (including NUL byte)

Diagnostic text:

warning: calling ‘A’ with a nonzero argument is unsafe

This diagnostic is enabled by default.

Diagnostic text:

The text of this diagnostic is not controlled by Clang.

warning: stack frame size (A) exceeds limit (B) in ‘C’

This diagnostic is enabled by default.

Diagnostic text:

warning: attempt to call A on non-heap 

object C

object: block expression

object: lambda-to-function-pointer conversion

This diagnostic is enabled by default.

Also controls -Wtarget-clones-mixed-specifiers.

Diagnostic text:

warning: body of cpu_dispatch function will be ignored

warning: CPU list contains duplicate entries; attribute ignored

warning: version list contains duplicate entries

Diagnostic text:

warning: ’-fuse-ld=’ taking a path is deprecated; use ‘–ld-path=’ instead

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: ‘diagnose_if’ is a clang extension

warning: ‘enable_if’ is a clang extension

warning: __final is a GNU extension, consider using C++11 final

warning: GCC does not allow A attribute in this position on a function definition

warning: ‘break’ is bound to loop, GCC binds it to switch

warning: GCC does not allow the ‘cleanup’ attribute argument to be anything other than a simple identifier

warning: GCC does not allow an attribute in this position on a function declaration

warning: GCC does not allow the A attribute to be written on a type

warning: GCC does not allow variable declarations in for loop initializers before C99

warning: ’A’ is bound to current loop, GCC binds it to the enclosing loop

Diagnostic text:

warning: declaration requires a global constructor

warning: declaration requires a global destructor

This diagnostic is enabled by default.

Diagnostic text:

warning: -fglobal-isel support for the ‘A’ architecture is incomplete

warning: -fglobal-isel support is incomplete for this architecture at the current optimization level

Some of the diagnostics controlled by this flag are enabled by default.

Controls -Wgnu-alignof-expression, -Wgnu-anonymous-struct, -Wgnu-auto-type, -Wgnu-binary-literal, -Wgnu-case-range, -Wgnu-complex-integer, -Wgnu-compound-literal-initializer, -Wgnu-conditional-omitted-operand, -Wgnu-designator, -Wgnu-empty-initializer, -Wgnu-empty-struct, -Wgnu-flexible-array-initializer, -Wgnu-flexible-array-union-member, -Wgnu-folding-constant, -Wgnu-imaginary-constant, -Wgnu-include-next, -Wgnu-label-as-value, -Wgnu-redeclared-enum, -Wgnu-statement-expression, -Wgnu-static-float-init, -Wgnu-string-literal-operator-template, -Wgnu-union-cast, -Wgnu-variable-sized-type-not-at-end, -Wgnu-zero-line-directive, -Wgnu-zero-variadic-macro-arguments, -Wredeclared-class-member, -Wvla-extension, -Wzero-length-array.

This diagnostic is enabled by default.

Diagnostic text:

warning: A applied to an expression is a GNU extension

This diagnostic is an error by default, but the flag -Wno-gnu-array-member-paren-init can be used to disable the error.

Diagnostic text:

error: parenthesized initialization of a member array is a GNU extension

Diagnostic text:

warning: initialization of an array 

of type A from a compound literal of type B

from a compound literal

 is a GNU extension

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: use of GNU array range extension

warning: use of GNU ‘missing =’ extension in designator

warning: use of GNU old-style field designator extension

Diagnostic text:

warning: empty 

struct

union

 is a GNU extension

warning: flexible array member A in otherwise empty 

struct

interface

union

class

enum

 is a GNU extension

warning: 

struct

union

 without named members is a GNU extension

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: expression is not an 

integer

integral

 constant expression; folding it to a constant is a GNU extension

warning: in-class initializer for static data member is not a constant expression; folding it to a constant is a GNU extension

warning: variable length array folded to constant array as an extension

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘gnu_inline’ attribute without ‘extern’ in C++ treated as externally available, this changed in Clang 10

Diagnostic text:

warning: use of GNU address-of-label extension

warning: use of GNU indirect-goto extension

This diagnostic is enabled by default.

Diagnostic text:

warning: in-class initializer for static data member of type A is a GNU extension

This diagnostic is enabled by default.

Diagnostic text:

warning: field A with variable sized type B not at the end of a struct or class is a GNU extension

Diagnostic text:

warning: must specify at least one argument for ‘…’ parameter of variadic macro

warning: token pasting of ‘,’ and __VA_ARGS__ is a GNU extension

This diagnostic is enabled by default.

Diagnostic text:

warning: capture host side class data member by this pointer in device or host device lambda function may result in invalid memory access if this pointer is not accessible on device side

This diagnostic is enabled by default.

Diagnostic text:

warning: ’A’ is ignored since it is only supported for HIP

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘trivial_abi’ cannot be applied to A

warning: 

alias

ifunc

 will always resolve to A even if weak definition of B is overridden

warning: 

alias

ifunc

 will not be in section ‘A’ but in the same section as the 

aliasee

resolver

warning: requested alignment is less than minimum alignment of B for type A

warning: ‘abi_tag’ attribute on 

non-inline

anonymous

 namespace ignored

warning: attribute A after definition is ignored

warning: ‘cmse_nonsecure_entry’ cannot be applied to functions with internal linkage

warning: ‘dllexport’ attribute ignored on explicit instantiation definition

warning: attribute A has no effect when annotating an ‘if 

constexpr

consteval

‘ statement

warning: attribute A has no effect when annotating an infinite loop

warning: A attribute can only be applied to instance variables or properties

warning: A attribute ignored

warning: A attribute ignored for field of type B

warning: A attribute ignored on inline function

warning: A attribute ignored on a non-definition declaration

warning: ’A’ attribute cannot be specified on a definition

warning: attribute A ignored, because it is not attached to a declaration

warning: ‘nonnull’ attribute applied to function with no pointer arguments

warning: ‘nonnull’ attribute when used on parameters takes no arguments

warning: A attribute ignored when parsing type

warning: A attribute only applies to a pointer or reference (B is invalid)

warning: A attribute only applies to

 constant

 pointer arguments

warning: attribute declaration must precede definition

warning: A attribute only applies to return values that are pointers

warning: A attribute only applies to return values that are pointers or references

warning: ‘sentinel’ attribute requires named arguments

warning: ‘sentinel’ attribute only supported for variadic 

functions

blocks

warning: A attribute argument not supported: B

warning: unknown visibility A

warning: attribute A cannot be applied to 

functions

Objective-C method

 without return value

warning: __weak attribute cannot be specified on a field declaration

warning: __weak attribute cannot be specified on an automatic variable when ARC is not enabled

warning: A attribute only applies to 

functions

unions

variables and functions

functions and methods

functions, methods and blocks

functions, methods, and parameters

variables

variables and fields

variables, data members and tag types

types and namespaces

variables, functions and classes

kernel functions

non-K&R-style functions

warning: A attribute only applies to B

warning: conflicting attributes A are ignored

warning: attribute A ignored, because it cannot be applied to omitted return type

warning: A calling convention is not supported 

for this target

on variadic function

on constructor/destructor

on builtin function

warning: attribute A ignored, because it cannot be applied to a type

warning: ignoring __declspec(allocator) because the function return type A is not a pointer or reference type

warning: attribute A is ignored, place it after “

class

struct

interface

union

enum

” to apply attribute to type declaration

warning: ‘deprecated’ attribute on anonymous namespace ignored

warning: A currently has no effect on a using declaration

warning: A redeclared inline; B attribute ignored

warning: attribute A is already applied with different arguments

warning: attribute A is already applied

warning: Objective-C GC does not allow weak variables on the stack

warning: ‘gnu_inline’ attribute requires function to be marked ‘inline’, attribute ignored

warning: inheritance model ignored on 

primary template

partial specialization

warning: ‘objc_externally_retained’ can only be applied to local variables 

of retainable type

with strong ownership

warning: import 

module

name

 cannot be applied to a function with a definition

warning: ‘internal_linkage’ attribute on a non-static local variable is ignored

warning: 

MIPS

MSP430

RISC-V

 ‘interrupt’ attribute only applies to functions that have 

no parameters

a ‘void’ return type

warning: qualifiers after comma in declarator list are ignored

warning: ‘mig_server_routine’ attribute only applies to routines that return a kern_return_t

warning: import 

module

name

 (B) does not match the import 

module

name

 (C) of the previous declaration

warning: unknown attribute ‘A’

warning: ‘nocf_check’ attribute ignored; use -fcf-protection to enable the attribute

warning: ‘noderef’ can only be used on an array or pointer type

warning: A attribute is ignored because there exists no call expression inside the statement

warning: ‘nothrow’ attribute conflicts with exception specification; attribute ignored

warning: A attribute only applies to 

Objective-C object

pointer

pointer-to-CF-pointer

pointer/reference-to-OSObject-pointer

 parameters

warning: A attribute only applies to 

functions

methods

properties

 that return 

an Objective-C object

a pointer

a non-retainable pointer

warning: A attribute isn’t implemented by this Objective-C runtime

warning: direct attribute on property A ignored (not implemented by this Objective-C runtime)

warning: A attribute is deprecated and ignored in B

warning: ‘require_constant_initialization’ attribute added after initialization of variable

warning: repeated RISC-V ‘interrupt’ attribute

warning: template parameter of a function template with the ‘sycl_kernel’ attribute cannot be a non-type template parameter

warning: function template with ‘sycl_kernel’ attribute must have a single parameter

warning: ‘sycl_kernel’ attribute only applies to a function template with at least two template parameters

warning: function template with ‘sycl_kernel’ attribute must have a ‘void’ return type

warning: 

alignment

size

 of field B (C bits) does not match the 

alignment

size

 of the first field in transparent union; transparent_union attribute ignored

warning: first field of a transparent union cannot have 

floating point

vector

 type B; transparent_union attribute ignored

warning: transparent_union attribute can only be applied to a union definition; attribute ignored

warning: transparent union definition must contain at least one field; transparent_union attribute ignored

warning: ’A’ only applies to 

function

pointer

Objective-C object or block pointer

 types; type here is C

warning: __declspec attribute A is not supported

warning: 

unsupported

duplicate

unknown

 architecture

 tune CPU

 ’C’ in the ‘

target

target_clones

‘ attribute string; ‘

target

target_clones

‘ attribute ignored

warning: ’__clang__’ is a predefined macro name, not an attribute scope specifier; did you mean ‘_Clang’ instead?

This diagnostic is enabled by default.

Diagnostic text:

warning: optimization flag ‘A’ is not supported for target ‘B’

warning: optimization flag ‘A’ is not supported

This diagnostic is enabled by default.

Diagnostic text:

warning: A is not a recognized builtin

; consider including <intrin.h> to access non-builtin intrinsics

This diagnostic is enabled by default.

Also controls -Wignored-pragma-intrinsic, -Wignored-pragma-optimize.

Diagnostic text:

warning: expected ‘=’ following ‘#pragma 

align

options align

‘ - ignored

warning: invalid alignment option in ‘#pragma 

align

options align

‘ - ignored

warning: ’#pragma comment A’ ignored

warning: missing argument to debug command ‘A’

warning: unexpected debug command ‘A’

warning: unknown module ‘A’

warning: expected action or ‘)’ in ‘#pragma A’ - ignored

warning: missing ‘:’ after A - ignoring

warning: missing ‘:’ or ‘)’ after A - ignoring

warning: expected ‘,’ in ‘#pragma A’

warning: expected identifier in ‘#pragma A’ - ignored

warning: expected ‘compiler’, ‘lib’, ‘user’, or a string literal for the section name in ‘#pragma A’ - ignored

warning: expected integer between A and B inclusive in ‘#pragma C’ - ignored

warning: missing ‘(‘ after ‘#pragma A’ - ignoring

warning: expected non-wide string literal in ‘#pragma A’

warning: expected 

‘enable’, ‘disable’, ‘begin’ or ‘end’

‘disable’

 - ignoring

warning: expected ‘)’ or ‘,’ in ‘#pragma A’

warning: missing ‘)’ after ‘#pragma A’ - ignoring

warning: expected a stack label or a string literal for the section name in ‘#pragma A’ - ignored

warning: expected a string literal for the section name in ‘#pragma A’ - ignored

warning: expected push, pop or a string literal for the section name in ‘#pragma A’ - ignored

warning: expected string literal in ‘#pragma A’ - ignoring

warning: extra tokens at end of ‘#pragma A’ - ignored

warning: incorrect use of #pragma clang force_cuda_host_device begin|end

warning: ’#pragma A’ is not supported on this target - ignored

warning: ’#pragma init_seg’ is only supported when targeting a Microsoft environment

warning: unknown action for ‘#pragma A’ - ignored

warning: unexpected argument ‘A’ to ‘#pragma B’

; expected D

warning: unknown action ‘B’ for ‘#pragma A’ - ignored

warning: missing argument to ‘#pragma A’

; expected C

warning: incorrect use of ‘#pragma fenv_access (on|off)’ - ignored

warning: incorrect use of ‘#pragma ms_struct on|off’ - ignored

warning: #pragma options align=reset failed: A

warning: expected ‘align’ following ‘#pragma options’ - ignored

warning: expected #pragma pack parameter to be ‘1’, ‘2’, ‘4’, ‘8’, or ‘16’

warning: expected integer or identifier in ‘#pragma pack’ - ignored

warning: #pragma A(pop, …) failed: B

warning: pragma pop_macro could not pop ‘A’, no matching push_macro

warning: unknown OpenCL extension A - ignoring

warning: known but unsupported action ‘B’ for ‘#pragma A’ - ignored

warning: unsupported OpenCL extension A - ignoring

warning: expected ‘#pragma unused’ argument to be a variable name

warning: only variables can be arguments to ‘#pragma unused’

warning: undeclared variable A used as an argument for ‘#pragma unused’

warning: invalid or unsupported rounding mode in ‘#pragma STDC FENV_ROUND’ - ignored

Some of the diagnostics controlled by this flag are enabled by default.

Also controls -Wignored-reference-qualifiers.

Diagnostic text:

warning: ARC 

unused

__unsafe_unretained

__strong

__weak

__autoreleasing

 lifetime qualifier on return type is ignored

warning: ’A’ qualifier on omitted return type B has no effect

warning: ’A’ type qualifier

s

 on return type 

has

have

 no effect

warning: ’A’ qualifier on function type B has no effect

Diagnostic text:

warning: property is assumed atomic when auto-synthesizing the property

warning: property is assumed atomic by default

This diagnostic is enabled by default.

Diagnostic text:

warning: function previously declared with an 

explicit

implicit

 exception specification redeclared with an 

implicit

explicit

 exception specification

This diagnostic is enabled by default.

Diagnostic text:

warning: implicit conversion from A cannot fit within the range of values for B

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: implicit declaration of function A is invalid in C99

warning: implicitly declaring library function ‘A’ with type B

error: use of unknown builtin A

warning: implicit declaration of function A

This diagnostic is enabled by default.

Diagnostic text:

warning: type specifier missing, defaults to ‘int’

Diagnostic text:

warning: block implicitly retains ‘self’; explicitly mention ‘self’ to indicate this is intended behavior

This diagnostic is enabled by default.

Diagnostic text:

warning: integer literal is too large to be represented in a signed integer type, interpreting as unsigned

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: direct base A is inaccessible due to ambiguity:B

This diagnostic is enabled by default.

Diagnostic text:

warning: #include_next in file found relative to primary source file or found by absolute path; will search from start of include path

This diagnostic is enabled by default.

Diagnostic text:

warning: exception specifications of 

return

argument

 types differ

warning: target exception specification is not superset of source

This diagnostic is enabled by default.

Diagnostic text:

warning: incompatible function pointer types 

assigning to A from B

assigning to different types

passing A to parameter of type B

passing to parameter of different type

returning A from a function with result type B

returning from function with different return type

converting A to type B

converting between types

initializing A with an expression of type B

initializing with expression of different type

sending A to parameter of type B

sending to parameter of different type

casting A to type B

casting between types

; dereference with *

; take the address with &

; remove *

; remove &

This diagnostic is an error by default, but the flag -Wno-incompatible-ms-struct can be used to disable the error.

Diagnostic text:

error: ms_struct may not produce Microsoft-compatible layouts for classes with base classes or virtual functions

error: ms_struct may not produce Microsoft-compatible layouts with fundamental data types with sizes that aren’t a power of two

This diagnostic is enabled by default.

Also controls -Wincompatible-function-pointer-types, -Wincompatible-pointer-types-discards-qualifiers.

Diagnostic text:

warning: incompatible pointer types 

assigning to A from B

assigning to different types

passing A to parameter of type B

passing to parameter of different type

returning A from a function with result type B

returning from function with different return type

converting A to type B

converting between types

initializing A with an expression of type B

initializing with expression of different type

sending A to parameter of type B

sending to parameter of different type

casting A to type B

casting between types

; dereference with *

; take the address with &

; remove *

; remove &

This diagnostic is enabled by default.

Diagnostic text:

warning: 

assigning to A from B

assigning to different types

passing A to parameter of type B

passing to parameter of different type

returning A from a function with result type B

returning from function with different return type

converting A to type B

converting between types

initializing A with an expression of type B

initializing with expression of different type

sending A to parameter of type B

sending to parameter of different type

casting A to type B

casting between types

 discards qualifiers in nested pointer types

warning: 

assigning to A from B

assigning to different types

passing A to parameter of type B

passing to parameter of different type

returning A from a function with result type B

returning from function with different return type

converting A to type B

converting between types

initializing A with an expression of type B

initializing with expression of different type

sending A to parameter of type B

sending to parameter of different type

casting A to type B

casting between types

 discards qualifiers

warning: 

reinterpret_cast

C-style cast

 from B to C changes address space of nested pointers

This diagnostic is enabled by default.

Diagnostic text:

warning: property type A is incompatible with type B inherited from C

This diagnostic is enabled by default.

Diagnostic text:

warning: using sysroot for ‘A’ but targeting ‘B’

This diagnostic is enabled by default.

Diagnostic text:

warning: declaration of built-in function ‘A’ requires the declaration of the ‘jmp_buf’ type, commonly provided in the header <setjmp.h>.

This diagnostic is enabled by default.

Diagnostic text:

warning: missing submodule ‘A’

warning: umbrella directory ‘A’ not found

warning: umbrella header for module ‘A’ does not include header ‘B’

This diagnostic is enabled by default.

Diagnostic text:

warning: A redeclared without B attribute: previous B ignored

warning: A redeclared without ‘dllimport’ attribute: ‘dllexport’ attribute added

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: initializer 

partially 

overrides prior initialization of this subobject

warning: initializer 

partially 

overrides prior initialization of this subobject

This diagnostic is enabled by default.

Diagnostic text:

warning: ISO C++ specifies that qualified reference to A is a constructor name rather than a 

template name

type

 in this context, despite preceding 

‘typename’

‘template’

 keyword

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

The text of this diagnostic is not controlled by Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: replacement function A cannot be declared ‘inline’

This diagnostic is enabled by default.

Diagnostic text:

warning: explicit instantiation of A that occurs after an explicit specialization has no effect

This diagnostic is enabled by default.

Diagnostic text:

warning: incompatible integer to pointer conversion 

assigning to A from B

assigning to different types

passing A to parameter of type B

passing to parameter of different type

returning A from a function with result type B

returning from function with different return type

converting A to type B

converting between types

initializing A with an expression of type B

initializing with expression of different type

sending A to parameter of type B

sending to parameter of different type

casting A to type B

casting between types

; dereference with *

; take the address with &

; remove *

; remove &

warning: incompatible pointer to integer conversion 

assigning to A from B

assigning to different types

passing A to parameter of type B

passing to parameter of different type

returning A from a function with result type B

returning from function with different return type

converting A to type B

converting between types

initializing A with an expression of type B

initializing with expression of different type

sending A to parameter of type B

sending to parameter of different type

casting A to type B

casting between types

; dereference with *

; take the address with &

; remove *

; remove &

Diagnostic text:

warning: converting the enum constant to a boolean

warning: converting the result of ‘<<’ to a boolean; did you mean ‘(A) != 0’?

This diagnostic is enabled by default.

Diagnostic text:

warning: overflow in expression; result is A with type B

This diagnostic is enabled by default.

Diagnostic text:

warning: interrupt service routine should only call a function with attribute ‘no_caller_saved_registers’

This diagnostic is enabled by default.

Also controls -Wignored-optimization-argument.

Diagnostic text:

warning: missing plugin argument for plugin A in B

warning: missing plugin name in A

warning: the given MCU supports A hardware multiply, but ‘-mhwmult’ is set to B

warning: no MCU device specified, but ‘-mhwmult’ is set to ‘auto’, assuming no hardware multiply; use ‘-mmcu’ to specify an MSP430 device, or ‘-mhwmult’ to set the hardware multiply type explicitly

warning: the given MCU does not support hardware multiply, but ‘-mhwmult’ is set to A

warning: the object size sanitizer has no effect at -O0, but is explicitly enabled: A

warning: optimization level ‘A’ is not supported; using ‘BC’ instead

warning: ignoring extension ‘A’ because the ‘B’ architecture does not support it

This diagnostic is an error by default, but the flag -Wno-invalid-constexpr can be used to disable the error.

Diagnostic text:

error: 

constexpr

consteval

 

function

constructor

 never produces a constant expression

This diagnostic is enabled by default.

Diagnostic text:

warning: 

instance variable

property

 with A attribute must be an object type (invalid B)

warning: IBOutletCollection properties should be copy/strong and not assign

This diagnostic is an error by default, but the flag -Wno-invalid-ios-deployment-target can be used to disable the error.

Diagnostic text:

error: invalid iOS deployment version ‘A’, iOS 10 is the maximum deployment target for 32-bit targets

This diagnostic is enabled by default.

Diagnostic text:

warning: function declared ‘noreturn’ should not return

warning: function A declared ‘noreturn’ should not return

This diagnostic is enabled by default.

Diagnostic text:

warning: offset of on non-POD type A

warning: offset of on non-standard-layout type A

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: environment variable SCE_ORBIS_SDK_DIR is set, but points to invalid or nonexistent directory ‘A’

warning: unable to find A directory, expected to be in ‘B’

This diagnostic is an error by default, but the flag -Wno-invalid-partial-specialization can be used to disable the error.

Diagnostic text:

error: 

class

variable

 template partial specialization is not more specialized than the primary template

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: empty character constant

warning: missing terminating 

‘

‘”’

 character

This diagnostic is enabled by default.

Diagnostic text:

warning: illegal character encoding in character literal

warning: illegal character encoding in string literal

This diagnostic is an error by default, but the flag -Wno-invalid-token-paste can be used to disable the error.

Diagnostic text:

error: pasting formed ‘A’, an invalid preprocessing token

This diagnostic is enabled by default.

Diagnostic text:

warning: jump out of __finally block has undefined behavior

This diagnostic is enabled by default.

Diagnostic text:

warning: keyword ‘A’ will be made available as an identifier 

here

for the remainder of the translation unit

This diagnostic is enabled by default.

Diagnostic text:

warning: A is a large (B bytes) pass-by-value argument; pass it by reference instead ?

warning: return value of A is a large (B bytes) pass-by-value object; pass it by reference instead ?

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: linking module ‘A’: B

This diagnostic is enabled by default.

Diagnostic text:

warning: implicit conversion from A to B changes value from C to D

warning: implicit conversion of out of range value from A to B is undefined

This diagnostic is enabled by default.

Diagnostic text:

warning: magnitude of floating-point constant too large for type A; maximum is B

warning: magnitude of floating-point constant too small for type A; minimum is B

This diagnostic is enabled by default.

Diagnostic text:

warning: logical not is only applied to the left hand side of this 

comparison

bitwise operator

This diagnostic is enabled by default.

Diagnostic text:

warning: A macro redefined

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: ISO C++ does not allow ‘main’ to be used by a program

warning: ‘main’ is not allowed to be declared _Noreturn

warning: ‘main’ is not allowed to be declared variadic

warning: only one parameter on ‘main’ declaration

warning: variable named ‘main’ with external linkage has undefined behavior

warning: bool literal returned from ‘main’

warning: ‘main’ should not be declared static

This diagnostic is enabled by default.

Diagnostic text:

warning: return type of ‘main’ is not ‘int’

This diagnostic is enabled by default.

Diagnostic text:

warning: __has_warning expected option name (e.g. “-Wundef”)

Diagnostic text:

warning: the number of preprocessor source tokens (A) exceeds this token limit (B)

warning: the total number of preprocessor source tokens (A) exceeds the token limit (B)

The warning is issued if the number of pre-processor tokens exceeds the token limit, which can be set in three ways:

1. As a limit at a specific point in a file, using the clang max_tokens_here pragma:

2. As a per-translation unit limit, using the -fmax-tokens= command-line flag:

3. As a per-translation unit limit using the clang max_tokens_total pragma, which works like and overrides the -fmax-tokens= flag:

These limits can be helpful in limiting code growth through included files.

Setting a token limit of zero means no limit.

Note that the warning is disabled by default, so -Wmax-tokens must be used in addition with the pragmas or -fmax-tokens flag to get any warnings.

This diagnostic is enabled by default.

Diagnostic text:

warning: taking the max of 

a value and unsigned zero

unsigned zero and a value

 is always equal to the other value

This diagnostic is enabled by default.

Diagnostic text:

warning: 

‘size’ argument to memset is ‘0’

setting buffer to a ‘sizeof’ expression

; did you mean to transpose the last two arguments?

This diagnostic is enabled by default.

Diagnostic text:

warning: size argument in A call is a comparison

Diagnostic text:

warning: conflicting parameter types in implementation of A: B vs C

warning: conflicting return type in implementation of A: B vs C

Some of the diagnostics controlled by this flag are enabled by default.

Controls -Winconsistent-dllimport, -Wmicrosoft-abstract, -Wmicrosoft-anon-tag, -Wmicrosoft-cast, -Wmicrosoft-charize, -Wmicrosoft-comment-paste, -Wmicrosoft-const-init, -Wmicrosoft-cpp-macro, -Wmicrosoft-default-arg-redefinition, -Wmicrosoft-drectve-section, -Wmicrosoft-end-of-file, -Wmicrosoft-enum-forward-reference, -Wmicrosoft-enum-value, -Wmicrosoft-exception-spec, -Wmicrosoft-explicit-constructor-call, -Wmicrosoft-extra-qualification, -Wmicrosoft-fixed-enum, -Wmicrosoft-flexible-array, -Wmicrosoft-goto, -Wmicrosoft-include, -Wmicrosoft-mutable-reference, -Wmicrosoft-pure-definition, -Wmicrosoft-redeclare-static, -Wmicrosoft-sealed, -Wmicrosoft-static-assert, -Wmicrosoft-template, -Wmicrosoft-union-member-reference, -Wmicrosoft-unqualified-friend, -Wmicrosoft-using-decl, -Wmicrosoft-void-pseudo-dtor.

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘abstract’ keyword is a Microsoft extension

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: types declared in an anonymous 

struct

union

 are a Microsoft extension

warning: anonymous 

structs

unions

 are a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: static_cast between pointer-to-function and pointer-to-object is a Microsoft extension

warning: implicit conversion between pointer-to-function and pointer-to-object is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: default initialization of an object of const type A

 without a user-provided default constructor

 is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: #pragma A(“.drectve”) has undefined behavior, use #pragma comment(linker, …) instead

Some of the diagnostics controlled by this flag are enabled by default.

Diagnostic text:

warning: exception specification of ‘…’ is a Microsoft extension

warning: 

pointer to 

reference to 

incomplete type B is not allowed in exception specification

warning: exception specification in declaration does not match previous declaration

warning: exception specification in explicit instantiation does not match instantiated one

warning: exception specification of overriding function is more lax than base version

This diagnostic is enabled by default.

Diagnostic text:

warning: dependent 

__if_not_exists

__if_exists

 declarations are ignored

Diagnostic text:

warning: enumeration types with a fixed underlying type are a Microsoft extension

Diagnostic text:

warning: flexible array member A in otherwise empty 

struct

interface

union

class

enum

 is a Microsoft extension

warning: flexible array member A in a union is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: jump from this goto statement to its label is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: accessing inaccessible direct base A of B is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: #include resolved using non-portable Microsoft search rules as: A

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘mutable’ on a reference type is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: function definition with pure-specifier is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘sealed’ keyword is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: use of ‘static_assert’ without inclusion of <assert.h> is a Microsoft extension

This diagnostic is enabled by default.

Also controls -Wmicrosoft-template-shadow.

Diagnostic text:

warning: duplicate explicit instantiation of A ignored as a Microsoft extension

warning: use of member A found via unqualified lookup into dependent bases of class templates is a Microsoft extension

warning: use of member A before its declaration is a Microsoft extension

warning: using the undeclared type A as a default template argument is a Microsoft extension

warning: non-type template argument containing a dereference operation is a Microsoft extension

warning: 

class template

class template partial

variable template

variable template partial

function template

member function

static data member

member class

member enumeration

 specialization of B not in 

a namespace enclosing C

class C or an enclosing namespace

 is a Microsoft extension

warning: template argument for template type parameter must be a type; omitted ‘typename’ is a Microsoft extension

warning: ‘static’ can only be specified inside the class definition

warning: use of undeclared identifier A; unqualified lookup into dependent bases of class template B is a Microsoft extension

This diagnostic is enabled by default.

Diagnostic text:

warning: unqualified friend declaration referring to type outside of the nearest enclosing namespace is a Microsoft extension; add a nested name specifier

This diagnostic is enabled by default.

Diagnostic text:

warning: using declaration referring to inaccessible member ‘A’ (which refers to accessible member ‘B’) is a Microsoft compatibility extension

This diagnostic is enabled by default.

Diagnostic text:

warning: pseudo-destructors on type void are a Microsoft extension

Diagnostic text:

warning: misleading indentation; statement is not part of the previous ‘

if

else

for

while

‘

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘delete

[]

‘ applied to a pointer that was allocated with ‘new

[]

‘; did you mean ‘delete

[]

‘?

This diagnostic is enabled by default.

Diagnostic text:

warning: conflicting parameter types in implementation of A

: B vs C

This diagnostic is enabled by default.

Diagnostic text:

warning: conflicting return type in implementation of A

: B vs C

Diagnostic text:

warning: suggest braces around initialization of subobject

This diagnostic is enabled by default.

Diagnostic text:

warning: ‘constinit’ specifier missing on initializing declaration of A

This diagnostic is enabled by default.

Diagnostic text:

warning: declaration does not declare anything

warning: ’A’ is not permitted on a declaration of a type

warning: typedef requires a name

warning: ’A’ ignored on this declaration

This diagnostic is enabled by default.

Diagnostic text:

warning: A is missing exception specification ‘B’

This diagnostic is enabled by default.

Diagnostic text:

warning: parameter of overriding method should be annotated with __attribute__((noescape))

Diagnostic text:

warning: block could be declared with attribute ‘noreturn’

warning: 

function

method

 B could be declared with attribute ‘noreturn’

This diagnostic is enabled by default.

Diagnostic text:

warning: function with no prototype cannot use the A calling convention

This diagnostic is enabled by default.

Diagnostic text:

warning: A used as the name of the previous parameter rather than as part of the selector

This diagnostic is enabled by default.

Diagnostic text:

warning: no such sysroot directory: ‘A’

This diagnostic is enabled by default.

Diagnostic text:

warning: unknown assumption string ‘A’ may be misspelled; attribute is potentially ignored, did you mean ‘B’?

Diagnostic text:

 building module ‘A’ as ‘B’

 finished building module ‘A’

 could not acquire lock file for module ‘A’: B

 timed out waiting to acquire lock file for module ‘A’

This diagnostic is enabled by default.

Diagnostic text:

warning: module ‘A’ conflicts with already-imported module ‘B’: C

warning: module file ‘A’ was validated as a system module and is now being imported as a non-system module; any difference in diagnostic options will be ignored

This diagnostic is an error by default, but the flag -Wno-module-file-config-mismatch can be used to disable the error.

Diagnostic text:

error: module file A cannot be loaded due to a configuration mismatch with the current compilation

This diagnostic is enabled by default.

Diagnostic text:

warning: duplicate module file extension block name ‘A’

Diagnostic text:

 importing module ‘A’

 into ‘D’

 from ‘B’

This diagnostic is an error by default, but the flag -Wno-module-import-in-extern-c can be used to disable the error.

Diagnostic text:

error: import of C++ module ‘A’ appears within extern “C” language linkage specification

This diagnostic is an error by default, but the flag -Wno-modules-import-nested-redundant can be used to disable the error.

Diagnostic text:

error: redundant #include of module ‘A’ appears within B

Some of the diagnostics controlled by this flag are enabled by default.

Controls -Wbool-operation, -Wcast-of-sel-type, -Wchar-subscripts, -Wcomment, -Wdelete-non-virtual-dtor, -Wextern-c-compat, -Wfor-loop-analysis, -Wformat, -Wframe-address, -Wimplicit, -Winfinite-recursion, -Wint-in-bool-context, -Wmismatched-tags, -Wmissing-braces, -Wmove, -Wmultichar, -Wobjc-designated-initializers, -Wobjc-flexible-array, -Wobjc-missing-super-calls, -Woverloaded-virtual, -Wprivate-extern, -Wrange-loop-construct, -Wreorder, -Wreturn-type, -Wself-assign, -Wself-move, -Wsizeof-array-argument, -Wsizeof-array-decay, -Wstring-plus-int, -Wtautological-compare, -Wtrigraphs, -Wuninitialized, -Wunknown-pragmas, -Wunused, -Wuser-defined-warnings, -Wvolatile-register-var.

This diagnostic is enabled by default.

Diagnostic text:

warning: unable to find a Visual Studio installation; try running Clang from a developer command prompt

This diagnostic is enabled by default.

Diagnostic text:

warning: multi-character character constant

This diagnostic is enabled by default.

Diagnostic text:

warning: defaulted move assignment operator of A will move assign virtual base class B multiple times

Diagnostic text:

warning: anonymous types declared in an anonymous 

struct

union

 are an extension

This diagnostic flag exists for GCC compatibility, and has no effect in Clang.

This diagnostic is enabled by default.

Diagnostic text:

warning: A should not return a null pointer unless it is declared ‘throw()’

 or ‘noexcept’

Diagnostic text:

warning: no newline at end of file

warning: no newline at end of file

This diagnostic is enabled by default.

Diagnostic text:

warning: dereferencing A; was declared with a ‘noderef’ type

warning: dereferencing expression marked as ‘noderef’

warning: casting to dereferenceable pointer removes ‘noderef’ attribute

This diagnostic is enabled by default.

Diagnostic text:

warning: anonymous non-C-compatible type given name for linkage purposes by 

typedef

alias

 declaration; add a tag name here

This diagnostic is enabled by default.

Diagnostic text:

warning: expression which evaluates to zero treated as a null pointer constant of type A

This diagnostic is an error by default, but the flag -Wno-non-pod-varargs can be used to disable the error.

Diagnostic text:

error: cannot pass object of 

non-POD

non-trivial

 type B through variadic 

function

block

method

constructor

; call will abort at runtime

error: cannot pass 

non-POD

non-trivial

 object of type B to variadic 

function

block

method

constructor

; expected type from format string was D

error: second argument to ‘va_arg’ is of non-POD type A

error: second argument to ‘va_arg’ is of ARC ownership-qualified type A

This diagnostic is enabled by default.

Diagnostic text:

warning: null passed to a callee that requires a non-null argument

warning: null returned from 

function

method

 that requires a non-null return value

This diagnostic is enabled by default.

Diagnostic text:

warning: non-portable path to file ‘A’; specified path differs in case from file name on disk

This diagnostic is enabled by default.

Diagnostic text:

warning: 

destination for

source of

first operand of

second operand of

 this B call is a pointer to record C that is not trivial to 

primitive-default-initialize

primitive-copy

This diagnostic is enabled by default.

Diagnostic text:

warning: overriding method has mismatched ns_consumed attribute on its parameter

This diagnostic is enabled by default.

Diagnostic text:

warning: overriding method has mismatched ns_returns_

not_retained

retained

 attributes

This diagnostic is enabled by default.

Diagnostic text:

warning: use of NULL in arithmetic operation

warning: comparison between NULL and non-pointer 

(B and NULL)

(NULL and B)

This diagnostic is enabled by default.

Diagnostic text:

warning: null character(s) preserved in 

char

string

 literal

warning: null character ignored

This diagnostic is enabled by default.

Diagnostic text:

warning: implicit conversion of 

NULL

nullptr

 constant to B

This diagnostic is enabled by default.

Diagnostic text:

warning: binding dereferenced null pointer to reference has undefined behavior

warning: indirection of non-volatile null pointer will be deleted, not trap

Diagnostic text:

warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension

warning: performing pointer arithmetic on a null pointer has undefined behavior

 if the offset is nonzero

Diagnostic text:

warning: performing pointer subtraction with a null pointer 

has

may have

 undefined behavior

This diagnostic is enabled by default.

Diagnostic text:

warning: conflicting nullability specifier on parameter types, A conflicts with existing specifier B

warning: conflicting nullability specifier on return types, A conflicts with existing specifier B

warning: nullability specifier A conflicts with existing specifier B

warning: synthesized setter A for null_resettable property B does not handle nil

warning: duplicate nullability specifier A

This diagnostic is enabled by default.

Diagnostic text:

warning: array parameter is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified)

This diagnostic is an error by default, but the flag -Wno-nullability-declspec can be used to disable the error.

Diagnostic text:

error: nullability specifier A cannot be applied to non-pointer type B; did you mean to apply the specifier to the 

pointer

block pointer

member pointer

function pointer

member function pointer

?

This diagnostic is enabled by default.

Diagnostic text:

warning: implicit conversion from constant value A to ‘BOOL’; the only well defined values for ‘BOOL’ are YES and NO

This diagnostic is enabled by default.

Diagnostic text:

warning: string is ill-formed as UTF-8 and will become a null A when boxed

This diagnostic is enabled by default.

Diagnostic text:

warning: adding A to B might cause circular dependency in container

This diagnostic is enabled by default.

Diagnostic text:

warning: designated initializer missing a ‘super’ call to a designated initializer of the super class

warning: designated initializer invoked a non-designated initializer

warning: designated initializer should only invoke a designated initializer on ‘super’

warning: method override for the designated initializer of the superclass A not found

warning: convenience initializer missing a ‘self’ call to another initializer

warning: convenience initializer should not invoke an initializer on ‘super’

This diagnostic is enabled by default.

Diagnostic text:

warning: field A can overwrite instance variable B with variable sized type C in superclass D

warning: field A with variable sized type B is not visible to subclasses and can conflict with their instance variables

This diagnostic is enabled by default.

Diagnostic text:

warning: redefinition of forward class A of a typedef name of an object type is ignored

This diagnostic is enabled by default.

Also controls -Wobjc-string-compare.

Diagnostic text:

warning: direct comparison of 

an array literal

a dictionary literal

a numeric literal

a boxed expression

 has undefined behavior

This diagnostic is enabled by default.

Diagnostic text:

warning: implicit boolean conversion of Objective-C object literal always evaluates to true

warning: object of type A is not compatible with