[gcc r14-10127] libstdc++: Fix run_doxygen for Doxygen 1.10 man page format

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:c9cc1c850c6d084752207b6cf247a0a48bae0d52

commit r14-10127-gc9cc1c850c6d084752207b6cf247a0a48bae0d52
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Apr 25 13:24:56 2024 +0100

    libstdc++: Fix run_doxygen for Doxygen 1.10 man page format
    
    Doxygen switched from \fC to \fR in its man page output:
    https://github.com/doxygen/doxygen/pull/10497
    
    This breaks our script that expects \fC so change the regaulr expression
    to work with either style.
    
    libstdc++-v3/ChangeLog:
    
            * scripts/run_doxygen: Adjust sed pattern to match '\fR' for
            new man output that Doxygen 1.10 generates.

Diff:
---
 libstdc++-v3/scripts/run_doxygen | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/scripts/run_doxygen b/libstdc++-v3/scripts/run_doxygen
index fbd601b11cc..ea9bcb56553 100644
--- a/libstdc++-v3/scripts/run_doxygen
+++ b/libstdc++-v3/scripts/run_doxygen
@@ -294,7 +294,11 @@ $gxx $cppflags $cxxflags ${srcdir}/doc/doxygen/stdheader.cc -o ./stdheader || ex
 problematic=`grep -E -l '#include <.*h>' [a-z]*.3`
 for f in $problematic; do
     # this is also slow, but safe and easy to debug
-    oldh=`sed -n '/fC#include </s/.*<\(.*\)>.*/\1/p' $f`
+    oldh=`sed -n '/f[CR]#include </s/.*<\(.*\)>.*/\1/p' $f`
+    if [ "$oldh" == "" ]; then
+      echo "ERROR: Doxygen man page formatting changed" 2>&1
+      continue
+    fi
     newh=`echo $oldh | sed 's/\\\\&\\././g' | ./stdheader`
     sed "s=${oldh/\\/.}=${newh}=" $f > TEMP && mv TEMP $f
 done