summaryrefslogtreecommitdiff
path: root/gdbsupport
diff options
context:
space:
mode:
authorTom de Vries <tdevries@suse.de>2021-10-04 18:51:09 +0200
committerTom de Vries <tdevries@suse.de>2021-10-04 18:51:09 +0200
commit77252bf26e98bda49baffc2657bd99143e1c7626 (patch)
tree869b7066cea9501daae69b61babe6046188e55d1 /gdbsupport
parentb0b8879e292218bfb27584515e98a46379c9c666 (diff)
downloadbinutils-gdb-77252bf26e98bda49baffc2657bd99143e1c7626.tar.gz
[gdb/build] Add CXX_DIALECT to CXX
Say we use a gcc version that (while supporting c++11) does not support c++11 by default, and needs an -std setting to enable it. If gdb would use the default AX_CXX_COMPILE_STDCXX from autoconf-archive, then we'd have: ... CXX="g++ -std=gnu++11" ... That mechanism however has the following problem (quoting from commit 0bcda685399): ... the top level Makefile passes CXX down to subdirs, and that overrides whatever gdb/Makefile may set CXX to. The result would be that a make invocation from the build/gdb/ directory would use "g++ -std=gnu++11" as expected, while a make invocation at the top level would not. ... Commit 0bcda685399 fixes this by using a custom AX_CXX_COMPILE_STDCXX which does: ... CXX=g++ CXX_DIALECT=-std=gnu++11 ... The problem reported in PR28318 is that using the custom instead of the default AX_CXX_COMPILE_STDCXX makes the configure test for std::thread support fail. We could simply add $CXX_DIALECT to the test for std::thread support, but that would have to be repeated for each added c++ support test. Instead, fix this by doing: ... CXX="g++ -std=gnu++11" CXX_DIALECT=-std=gnu++11 ... This is somewhat awkward, since it results in -std=gnu++11 occuring twice in some situations: ... $ touch src/gdb/dwarf2/read.c $ ( cd build/gdb; make V=1 dwarf2/read.o ) g++-4.8 -std=gnu++11 -x c++ -std=gnu++11 ... ... However, both settings are needed: - the switch in CXX for the std::thread tests (and other tests) - the switch in CXX_DIALECT so it can be appended in Makefiles, to counteract the fact that the top-level Makefile overrides CXX The code added in gdb/ax_cxx_compile_stdcxx.m4 is copied from the default AX_CXX_COMPILE_STDCXX from autoconf-archive. Tested on x86_64-linux. Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28318
Diffstat (limited to 'gdbsupport')
-rwxr-xr-xgdbsupport/configure8
1 files changed, 8 insertions, 0 deletions
diff --git a/gdbsupport/configure b/gdbsupport/configure
index 08800228aa5..f13ae76641f 100755
--- a/gdbsupport/configure
+++ b/gdbsupport/configure
@@ -6520,6 +6520,10 @@ eval ac_res=\$$cachevar
$as_echo "$ac_res" >&6; }
if eval test x\$$cachevar = xyes; then
CXX_DIALECT="$switch"
+ CXX="$CXX $switch"
+ if test -n "$CXXCPP" ; then
+ CXXCPP="$CXXCPP $switch"
+ fi
ac_success=yes
break
fi
@@ -6839,6 +6843,10 @@ eval ac_res=\$$cachevar
$as_echo "$ac_res" >&6; }
if eval test x\$$cachevar = xyes; then
CXX_DIALECT="$switch"
+ CXX="$CXX $switch"
+ if test -n "$CXXCPP" ; then
+ CXXCPP="$CXXCPP $switch"
+ fi
ac_success=yes
break
fi