gnu17 and earlier modes automatically expose several POSIX C APIs, and
this was accidentally disabled for gnu2x in
7d644e1215b376ec5e915df9ea2eeb56e2d94626.
This restores the behavior for gnu2x mode (without changing the
behavior in C standards modes instead of GNU modes).
Fixes #56607
result in a stack overflow.
`Issue 44304 <https://github.com/llvm/llvm-project/issues/44304>`_
`Issue 50891 <https://github.com/llvm/llvm-project/issues/50891>`_
+- Clang 14 predeclared some builtin POSIX library functions in ``gnu2x`` mode,
+ and Clang 15 accidentally stopped predeclaring those functions in that
+ language mode. Clang 16 now predeclares those functions again. This fixes
+ `Issue 56607 <https://github.com/llvm/llvm-project/issues/56607>`_.
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
// If this is a builtin on this (or all) targets, create the decl.
if (unsigned BuiltinID = II->getBuiltinID()) {
- // In C++, C2x, and OpenCL (spec v1.2 s6.9.f), we don't have any
- // predefined library functions like 'malloc'. Instead, we'll just
- // error.
- if ((getLangOpts().CPlusPlus || getLangOpts().OpenCL ||
- getLangOpts().C2x) &&
+ // In C++ and OpenCL (spec v1.2 s6.9.f), we don't have any predefined
+ // library functions like 'malloc'. Instead, we'll just error.
+ if ((getLangOpts().CPlusPlus || getLangOpts().OpenCL) &&
Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
return false;
--- /dev/null
+// RUN: %clang_cc1 -fsyntax-only -verify=gnu -std=gnu17 %s
+// RUN: %clang_cc1 -fsyntax-only -verify=gnu -std=gnu2x %s
+// RUN: %clang_cc1 -fsyntax-only -verify=std -std=c17 %s
+// RUN: %clang_cc1 -fsyntax-only -verify=std -std=c2x %s
+
+// std-no-diagnostics
+
+// 'index' is a builtin library function, but only in GNU mode. So this should
+// give an error in GNU modes but be okay in non-GNU mode.
+// FIXME: the error is correct, but these notes are pretty awful.
+int index; // gnu-error {{redefinition of 'index' as different kind of symbol}} \
+ gnu-note {{unguarded header; consider using #ifdef guards or #pragma once}} \
+ gnu-note {{previous definition is here}}