[cassepipe]

It is surprisingly hard to find information about it, do you have any ? From what I can guess it's a new syntax but it's the feature itself is still an extension ?

[ksherlock]

[[ ]] attributes were added in C++11 and later C23. There are 7 standard(C32) attributes but GCC has hundreds of them.

https://en.cppreference.com/w/c/language/attributes.html

https://en.cppreference.com/w/cpp/language/attributes.html

https://gcc.gnu.org/onlinedocs/gcc/Attributes.html

https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attribute...

[fuhsnn]

Also clang's https://clang.llvm.org/docs/AttributeReference.html

[SAI_Peregrinus]

The `[[attribute]]` syntax is new, the builtin ones in C23 are `[[deprecated]]`, `[[fallthrough]]`, `[[maybe_unused]]`, `[[nodiscard]]`, `[[noreturn]]`, `[[reproducible]]`, and `[[unsequenced]]`.

[kccqzy]

The feature itself is probably still __attribute__((cleanup(f))). That’s documented at https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attribute...

[crosser]

C standard _may_ eventually have a feature semantically equivalent, but very different syntactically:

https://thephd.dev/_vendor/future_cxx/technical%20specificat...

Discussion:

https://thephd.dev/_vendor/future_cxx/papers/C%20-%20Improve...