https://github.com/AidanGoldfarb created https://github.com/llvm/llvm-project/pull/117507
This PR addresses #116880 Updated [LanguageExtensions.rst](https://github.com/llvm/llvm-project/blob/main/clang/docs/LanguageExtensions.rst) to include support for C++11 enumerations with a fixed underlying type in C. Included a note that this is only a language extension in <C23. Updated [Features.def](https://github.com/llvm-mirror/clang/blob/master/include/clang/Basic/Features.def) to support for `__has_extension(c_fixed_enum)`. Updated [enum.c](https://github.com/llvm/llvm-project/blob/main/clang/test/Sema/enum.c) to ensure support of C++11 enumerations with a fixed underlying type in both <C23 and C23, as well as the functionality of `__has_extension(c_fixed_enum)`. --- In enum.c, I encountered a warning when testing enumerations with a fixed underlying type in pre-C23 modes. Specifically, the test produces the warning: `enumeration types with a fixed underlying type are a C23 extension`. I am unsure if this warning is expected behavior, as enumerations with a fixed underlying type should behave identically in pre-C23 and C23 modes. Feedback on whether this is correct or requires adjustment would be appreciated. Note that this is my first PR to LLVM, so please liberally critique it! >From a6c9b5ca52f35fe451a52c590ce93584c2b4f3ac Mon Sep 17 00:00:00 2001 From: Aidan Goldfarb <47676355+aidangoldf...@users.noreply.github.com> Date: Fri, 22 Nov 2024 19:06:29 -0500 Subject: [PATCH 1/2] Update LanguageExtensions.rst --- clang/docs/LanguageExtensions.rst | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst index 3c9078bcdf8118..1c400d87c4948b 100644 --- a/clang/docs/LanguageExtensions.rst +++ b/clang/docs/LanguageExtensions.rst @@ -1986,7 +1986,7 @@ Enumerations with a fixed underlying type ----------------------------------------- Clang provides support for C++11 enumerations with a fixed underlying type -within Objective-C. For example, one can write an enumeration type as: +within Objective-C and C `prior to C23 <https://open-std.org/JTC1/SC22/WG14/www/docs/n3030.htm>`_. For example, one can write an enumeration type as: .. code-block:: c++ @@ -1998,6 +1998,9 @@ value, is ``unsigned char``. Use ``__has_feature(objc_fixed_enum)`` to determine whether support for fixed underlying types is available in Objective-C. +Use ``__has_extension(c_fixed_enum)`` to determine whether support for fixed +underlying types is available in C. + Interoperability with C++11 lambdas ----------------------------------- >From d9e06150893a723cfeee0e08a7b8e652f2facf5c Mon Sep 17 00:00:00 2001 From: Aidan <aidan.goldf...@mail.mcgill.ca> Date: Sun, 24 Nov 2024 15:09:02 -0500 Subject: [PATCH 2/2] Updated Features.def to include c_fixed_enum. Updated enum.c test to check for support of enums with a fixed underlying type in C23 and <C23. --- clang/include/clang/Basic/Features.def | 1 + clang/test/Sema/enum.c | 12 ++++++++++++ 2 files changed, 13 insertions(+) diff --git a/clang/include/clang/Basic/Features.def b/clang/include/clang/Basic/Features.def index 9088c867d53ce4..c63f4ab75deda2 100644 --- a/clang/include/clang/Basic/Features.def +++ b/clang/include/clang/Basic/Features.def @@ -131,6 +131,7 @@ FEATURE(objc_arc_fields, true) FEATURE(objc_arc_weak, LangOpts.ObjCWeak) FEATURE(objc_default_synthesize_properties, LangOpts.ObjC) FEATURE(objc_fixed_enum, LangOpts.ObjC) +FEATURE(c_fixed_enum, true) FEATURE(objc_instancetype, LangOpts.ObjC) FEATURE(objc_kindof, LangOpts.ObjC) FEATURE(objc_modules, LangOpts.ObjC && LangOpts.Modules) diff --git a/clang/test/Sema/enum.c b/clang/test/Sema/enum.c index 4f6d04ba7f9182..053053192e4ad5 100644 --- a/clang/test/Sema/enum.c +++ b/clang/test/Sema/enum.c @@ -121,6 +121,17 @@ int NegativeShortTest[NegativeShort == -1 ? 1 : -1]; enum Color { Red, Green, Blue }; // expected-note{{previous use is here}} typedef struct Color NewColor; // expected-error {{use of 'Color' with tag type that does not match previous declaration}} +// Enumerations with a fixed underlying type. +// https://github.com/llvm/llvm-project/issues/116880 +#if __STDC_VERSION__ >= 202311L + typedef enum : unsigned char { Pink, Black, Cyan } Color; +#else + _Static_assert(__has_extension(c_fixed_enum), "Ensure language extension support for enumerations with a fixed underlying type in <C23"); + typedef enum : unsigned char { Pink, Black, Cyan } Color; // expected-warning {{enumeration types with a fixed underlying type are a C23 extension}} +#endif + + + // PR28903 // In C it is valid to define tags inside enums. struct PR28903 { @@ -174,6 +185,7 @@ enum IncOverflow { V3 // pre-c23-warning {{incremented enumerator value which exceeds the range of 'int' is a C23 extension}} }; + #if __STDC_VERSION__ >= 202311L // FIXME: GCC picks __uint128_t as the underlying type for the enumeration // value and Clang picks unsigned long long. _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
