Module gnu 

The GNU extensions’ name tables.

Two questions are asked of this module, and it matters that both are answered from the same place: the parser and sema ask “what does this attribute or builtin mean?”, and the preprocessor answers __has_attribute, __has_builtin, __has_feature and __has_extension from it — so a program that guards a construct with #if __has_attribute(packed) gets an answer that is true of this implementation rather than of GCC’s.

The one set of names that is not here is the atomic builtins’, which live beside the code that implements them in crate::sema::is_atomic_builtin — for the same reason: one table, asked by both.

doc/gnu-extensions.md is the prose version of the same tables.

Enums

Attribute

What an __attribute__ (or a C23 [[…]]) asks for.

Constants

CINRS_ATTRIBUTES

The names [[cinrs::…]] knows, for the diagnostic that lists them.

LIBRARY_BUILTINS

The library functions __builtin_X may name.

SPECIAL_BUILTINS

The builtins the front end implements itself.

UNSUPPORTED_ATTRIBUTES

The attributes that are refused rather than ignored, with the reason.

Functions

attribute

The attribute a name spells, accepting both the name and the __name__ forms GCC does.

cinrs_attribute

What a [[cinrs::name]] attribute asks for.

has_attribute

Whether __has_attribute(name) answers yes.

has_builtin

Whether __has_builtin(name) answers yes.

has_c_attribute

The value __has_c_attribute(name) answers with.

has_feature

Whether __has_feature(name) / __has_extension(name) answers yes.

long_double_math

The maths functions whose long double form is the double one here.

typed_overflow

The operation a typed overflow builtin performs, if the name spells one.

unsupported_reason

The reason an Attribute::Unsupported one is refused.