[gcc r16-6532] Allow disabling -gctf non-C warning [PR123259]

[Rainer Orth]

https://gcc.gnu.org/g:026c00babbe16d5a8525d2e59066d381615705c4

commit r16-6532-g026c00babbe16d5a8525d2e59066d381615705c4
Author: Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
Date:   Wed Jan 7 06:53:23 2026 +0100

    Allow disabling -gctf non-C warning [PR123259]
    
    In mixed-language builds it may be difficult to restrict -gctf to only
    C-language sources.  However, the
    
    cc1plus: note: CTF debug info requested, but not supported for ‘GNU C++17’ frontend
    
    warning for non-C languages, which is perfectly benign, may confuse
    parts of the build, so it may be useful to disable it.
    
    This patch applies the existing -Wno-complain-wrong-lang option to
    suppress it.
    
    Bootstrapped without regressions on i386-pc-solaris2.11
    sparc-sun-solaris2.11, also with C/C++-only bootstraps that apply
    -gctf/-gsctf via STAGE[23]_CFLAGS and STAGE[23]_TFLAGS.
    
    2025-12-25  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
    
            gcc:
            PR debug/123259
            * toplev.cc (process_options): Guard CTF non-C warning by
            -Wcomplain-wrong-lang.
    
            * doc/invoke.texi (Warning Options, -Wno-complain-wrong-lang):
            Document effect on -gctf/-gsctf.

Diff:
---
 gcc/doc/invoke.texi | 4 ++++
 gcc/toplev.cc       | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index bae66ba6c45f..f6c79b051d06 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10153,6 +10153,10 @@ The latter front end diagnoses
 @samp{f951: Warning: command-line option '-fno-rtti' is valid for C++/D/ObjC++ but not for Fortran},
 which may be disabled with @option{-Wno-complain-wrong-lang}.
 
+This option can also be used to disable warnings like
+@samp{cc1plus: note: CTF debug info requested, but not supported for 'GNU C++20' frontend}
+produced by @option{-gctf} or @option{-gsctf} for unsupported languages.
+
 @opindex Wcompare-distinct-pointer-types
 @item -Wcompare-distinct-pointer-types @r{(C and Objective-C only)}
 Warn if pointers of distinct types are compared without a cast.  This
diff --git a/gcc/toplev.cc b/gcc/toplev.cc
index 1eaaffdb3cf2..9c93eb8ce1dc 100644
--- a/gcc/toplev.cc
+++ b/gcc/toplev.cc
@@ -1436,7 +1436,8 @@ process_options ()
 
   /* CTF is supported for only C at this time.  */
   if (!lang_GNU_C ()
-      && ctf_debug_info_level > CTFINFO_LEVEL_NONE)
+      && ctf_debug_info_level > CTFINFO_LEVEL_NONE
+      && warn_complain_wrong_lang)
     {
       /* Compiling with -flto results in frontend language of GNU GIMPLE.  It
 	 is not useful to warn in that case.  */