libstd++: : Add workaround for as Error: file number less than one error [PR98708]

As mentioned in the PR, since the switch to DWARF5 by default instead of
DWARF4, gcc fails to build when configured against recent binutils.

The problem is that cxx11-ios_failure* is built in separate steps,
-S compilation (with -g -O2) followed by some sed and followed by
-c -g -O2 -g0 assembly.  When gcc is configured against recent binutils
and DWARF5 is the default, we emit .file 0 "..." directive on which the
assembler then fails (unless --gdwarf-5 is passed to it, but we don't want
that generally because on the other side older assemblers don't like -g*
passed to it when invoked on *.s file with compiler generated debug info.

I hope the bug will be fixed soon on the binutils side, but it would be nice
to have a workaround.

The following patch is one of the possibilities, another one is to do that
but add configure check for whether it is needed,
essentially
echo 'int main () { return 0; }' > conftest.c
${CXX} ${CXXFLAGS} -g -O2 -S conftest.c -o conftest.s
${CXX} ${CXXFLAGS} -g -O2 -g0 -c conftest.s -o conftest.o
and if the last command fails, we need that -gno-as-loc-support.
Or yet another option would be I think do a different check, whether
${CXX} ${CXXFLAGS} -g -O2 -S conftest.c -o conftest.s
${CXX} ${CXXFLAGS} -g -O2 -c conftest.s -o conftest.o
works and if yes, don't add the -g0 to cxx11-ios_failure*.s assembly.

2021-01-18  Jakub Jelinek  <jakub@redhat.com>

	PR debug/98708
	* src/c++11/Makefile.am (cxx11-ios_failure-lt.s, cxx11-ios_failure.s):
	Compile with -gno-as-loc-support.
	* src/c++11/Makefile.in: Regenerated.

diff --git a/libstdc++-v3/src/c++11/Makefile.am b/libstdc++-v3/src/c++11/Makefile.am
index 7e4bc66d906474c78a2e16a501753554003c5436..a26903db6bcc2bdf1217aaf69f098b0d7bedaaaa 100644 (file)
--- a/libstdc++-v3/src/c++11/Makefile.am
+++ b/libstdc++-v3/src/c++11/Makefile.am
@@ -141,12 +141,12 @@ if ENABLE_DUAL_ABI
 rewrite_ios_failure_typeinfo = sed -e '/^_*_ZTISt13__ios_failure:/,/_ZTVN10__cxxabiv120__si_class_type_infoE/s/_ZTVN10__cxxabiv120__si_class_type_infoE/_ZTVSt19__iosfail_type_info/'
 
 cxx11-ios_failure-lt.s: cxx11-ios_failure.cc
-       $(LTCXXCOMPILE) -S $< -o tmp-cxx11-ios_failure-lt.s
+       $(LTCXXCOMPILE) -gno-as-loc-support -S $< -o tmp-cxx11-ios_failure-lt.s
        -test -f tmp-cxx11-ios_failure-lt.o && mv -f tmp-cxx11-ios_failure-lt.o tmp-cxx11-ios_failure-lt.s
        $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
        -rm -f tmp-$@
 cxx11-ios_failure.s: cxx11-ios_failure.cc
-       $(CXXCOMPILE) -S $< -o tmp-$@
+       $(CXXCOMPILE) -gno-as-loc-support -S $< -o tmp-$@
        $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
        -rm -f tmp-$@
 

diff --git a/libstdc++-v3/src/c++11/Makefile.in b/libstdc++-v3/src/c++11/Makefile.in
index ae3a2fd5b4e71f8e9c3a63e9b85bc16b04de7dfa..86540509e81a9fa642e0f95a145c38412f6f2bc3 100644 (file)
--- a/libstdc++-v3/src/c++11/Makefile.in
+++ b/libstdc++-v3/src/c++11/Makefile.in
@@ -852,12 +852,12 @@ limits.o: limits.cc
        $(CXXCOMPILE) -fchar8_t -c $<
 
 @ENABLE_DUAL_ABI_TRUE@cxx11-ios_failure-lt.s: cxx11-ios_failure.cc
-@ENABLE_DUAL_ABI_TRUE@ $(LTCXXCOMPILE) -S $< -o tmp-cxx11-ios_failure-lt.s
+@ENABLE_DUAL_ABI_TRUE@ $(LTCXXCOMPILE) -gno-as-loc-support -S $< -o tmp-cxx11-ios_failure-lt.s
 @ENABLE_DUAL_ABI_TRUE@ -test -f tmp-cxx11-ios_failure-lt.o && mv -f tmp-cxx11-ios_failure-lt.o tmp-cxx11-ios_failure-lt.s
 @ENABLE_DUAL_ABI_TRUE@ $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
 @ENABLE_DUAL_ABI_TRUE@ -rm -f tmp-$@
 @ENABLE_DUAL_ABI_TRUE@cxx11-ios_failure.s: cxx11-ios_failure.cc
-@ENABLE_DUAL_ABI_TRUE@ $(CXXCOMPILE) -S $< -o tmp-$@
+@ENABLE_DUAL_ABI_TRUE@ $(CXXCOMPILE) -gno-as-loc-support -S $< -o tmp-$@
 @ENABLE_DUAL_ABI_TRUE@ $(rewrite_ios_failure_typeinfo) tmp-$@ > $@
 @ENABLE_DUAL_ABI_TRUE@ -rm -f tmp-$@