[PATCH] libcpp: Adjust __STDC_VERSION__ for C23

[PATCH] libcpp: Adjust __STDC_VERSION__ for C23

[Jakub Jelinek]

Hi!

While the C23 standard isn't officially release yet,
in 2011 we've changed __STDC_VERSION__ value for C11 already
in the month in which the new __STDC_VERSION__ value has been
finalized, so we want to change this now or wait
until we implement all the C23 features?

Note, seems Clang up to 17 also used 202000L for -std=c2x but
Clang 18+ uses 202311L as specified in the latest C23 drafts.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for
trunk?

2024-04-25  Jakub Jelinek  <jakub@redhat.com>

	* init.cc (cpp_init_builtins): Change __STDC_VERSION__
	for C23 from 202000L to 202311L.

	* doc/cpp.texi (__STDC_VERSION__): Document 202311L value
	for -std=c23/-std=gnu23.

--- libcpp/init.cc.jj	2024-01-03 12:07:27.552378565 +0100
+++ libcpp/init.cc	2024-04-24 23:54:32.613204591 +0200
@@ -594,7 +594,7 @@ cpp_init_builtins (cpp_reader *pfile, in
     _cpp_define_builtin (pfile, "__STDC_VERSION__ 199409L");
   else if (CPP_OPTION (pfile, lang) == CLK_STDC23
 	   || CPP_OPTION (pfile, lang) == CLK_GNUC23)
-    _cpp_define_builtin (pfile, "__STDC_VERSION__ 202000L");
+    _cpp_define_builtin (pfile, "__STDC_VERSION__ 202311L");
   else if (CPP_OPTION (pfile, lang) == CLK_STDC17
 	   || CPP_OPTION (pfile, lang) == CLK_GNUC17)
     _cpp_define_builtin (pfile, "__STDC_VERSION__ 201710L");
--- gcc/doc/cpp.texi.jj	2024-01-03 11:38:23.583695795 +0100
+++ gcc/doc/cpp.texi	2024-04-25 00:28:08.144182645 +0200
@@ -1886,8 +1886,8 @@ the 1999 revision of the C standard; the
 signifies the 2011 revision of the C standard; the value
 @code{201710L} signifies the 2017 revision of the C standard (which is
 otherwise identical to the 2011 version apart from correction of
-defects).  An unspecified value larger than @code{201710L} is used for
-the experimental @option{-std=c23} and @option{-std=gnu23} modes.
+defects).  The value @code{202311L} is used for the experimental
+@option{-std=c23} and @option{-std=gnu23} modes.
 
 This macro is not defined if the @option{-traditional-cpp} option is
 used, nor when compiling C++ or Objective-C@.

	Jakub

Re: [PATCH] libcpp: Adjust __STDC_VERSION__ for C23

[Joseph Myers]

On Thu, 25 Apr 2024, Jakub Jelinek wrote:

> Hi!
> 
> While the C23 standard isn't officially release yet,
> in 2011 we've changed __STDC_VERSION__ value for C11 already
> in the month in which the new __STDC_VERSION__ value has been
> finalized, so we want to change this now or wait
> until we implement all the C23 features?
> 
> Note, seems Clang up to 17 also used 202000L for -std=c2x but
> Clang 18+ uses 202311L as specified in the latest C23 drafts.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?

In the spirit of the principle that these macros indicate intent rather 
than completeness, it's probably reasonable to change now.  The main 
missing feature still to be implemented is #embed, hopefully we can get 
that done for GCC 15.

-- 
Joseph S. Myers
josmyers@redhat.com