[gcc r12-3597] libstdc++: Regenerate the src/debug Makefiles as needed

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

https://gcc.gnu.org/g:fce4e12f8efb3b3db959b807201e08786b001f39

commit r12-3597-gfce4e12f8efb3b3db959b807201e08786b001f39
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Sep 16 21:21:56 2021 +0100

    libstdc++: Regenerate the src/debug Makefiles as needed
    
    When the build configuration changes and Makefiles are recreated, the
    src/debug/Makefile and src/debug/*/Makefile files are not recreated,
    because they're not managed in the usual way by automake. This can lead
    to build failures or surprising inconsistencies between the main and
    debug versions of the library when doing incremental builds.
    
    This causes them to be regenerated if any of the corresponding non-debug
    makefiles is newer.
    
    Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
    
    libstdc++-v3/ChangeLog:
    
            * src/Makefile.am (stamp-debug): Add all Makefiles as
            prerequisites.
            * src/Makefile.in: Regenerate.

Diff:
---
 libstdc++-v3/src/Makefile.am | 2 +-
 libstdc++-v3/src/Makefile.in | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index 16f4cc6eff4..f27d3f8c87e 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -369,7 +369,7 @@ endif
 # Build a debug variant.
 # Take care to fix all possibly-relative paths.
 debugdir = ${glibcxx_builddir}/src/debug
-stamp-debug:
+stamp-debug: Makefile $(foreach dir,$(SUBDIRS),$(dir)/Makefile)
 	if test ! -d ${debugdir} || test ! -f ${debugdir}/Makefile ; then \
 	  mkdir -p ${debugdir}; \
 	  for d in $(SUBDIRS); do mkdir -p  ${debugdir}/$$d; done; \
diff --git a/libstdc++-v3/src/Makefile.in b/libstdc++-v3/src/Makefile.in
index 4df5c829a7f..05b25ed5e9d 100644
--- a/libstdc++-v3/src/Makefile.in
+++ b/libstdc++-v3/src/Makefile.in
@@ -1090,7 +1090,7 @@ libstdc++convenience.la: $(toolexeclib_LTLIBRARIES)
 	  cp .libs/libstdc++convenience.a .libs/libstdc++.a; \
 	fi; \
 	echo `date` > stamp-libstdc++convenience;
-stamp-debug:
+stamp-debug: Makefile $(foreach dir,$(SUBDIRS),$(dir)/Makefile)
 	if test ! -d ${debugdir} || test ! -f ${debugdir}/Makefile ; then \
 	  mkdir -p ${debugdir}; \
 	  for d in $(SUBDIRS); do mkdir -p  ${debugdir}/$$d; done; \