From 9b4d030ed52b52fe208edaa8be640f4dd359defc Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Mon, 4 Oct 2021 18:56:42 +0200 Subject: [PATCH] [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 gdb/ChangeLog: 2021-10-04 Tom de Vries PR build/28318 * ax_cxx_compile_stdcxx.m4: Add CXX_DIALECT to CXX. * configure: Regenerate. gdbserver/ChangeLog: 2021-10-04 Tom de Vries PR build/28318 * configure: Regenerate. gdbsupport/ChangeLog: 2021-10-04 Tom de Vries PR build/28318 * configure: Regenerate. --- gdb/ChangeLog | 6 ++++++ gdb/ax_cxx_compile_stdcxx.m4 | 8 ++++++++ gdb/configure | 8 ++++++++ gdbserver/ChangeLog | 5 +++++ gdbserver/configure | 8 ++++++++ gdbsupport/ChangeLog | 5 +++++ gdbsupport/configure | 8 ++++++++ 7 files changed, 48 insertions(+) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 0974273183e..21c305cddf5 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2021-10-04 Tom de Vries + + PR build/28318 + * ax_cxx_compile_stdcxx.m4: Add CXX_DIALECT to CXX. + * configure: Regenerate. + 2021-09-13 Joel Brobecker * version.in: Set GDB version number to 11.1.90.DATE-git. diff --git a/gdb/ax_cxx_compile_stdcxx.m4 b/gdb/ax_cxx_compile_stdcxx.m4 index 413755a2e88..29d8e10bcc4 100644 --- a/gdb/ax_cxx_compile_stdcxx.m4 +++ b/gdb/ax_cxx_compile_stdcxx.m4 @@ -94,6 +94,10 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl CXX="$ac_save_CXX"]) if eval test x\$$cachevar = xyes; then CXX_DIALECT="$switch" + CXX="$CXX $switch" + if test -n "$CXXCPP" ; then + CXXCPP="$CXXCPP $switch" + fi ac_success=yes break fi @@ -118,6 +122,10 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl CXX="$ac_save_CXX"]) if eval test x\$$cachevar = xyes; then CXX_DIALECT="$switch" + CXX="$CXX $switch" + if test -n "$CXXCPP" ; then + CXXCPP="$CXXCPP $switch" + fi ac_success=yes break fi diff --git a/gdb/configure b/gdb/configure index 5d89635c043..6d4c2b17ed2 100755 --- a/gdb/configure +++ b/gdb/configure @@ -5841,6 +5841,10 @@ eval ac_res=\$$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 $switch" + fi ac_success=yes break fi @@ -6160,6 +6164,10 @@ eval ac_res=\$$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 $switch" + fi ac_success=yes break fi diff --git a/gdbserver/ChangeLog b/gdbserver/ChangeLog index f6a49f37e70..8061f7e83d7 100644 --- a/gdbserver/ChangeLog +++ b/gdbserver/ChangeLog @@ -1,3 +1,8 @@ +2021-10-04 Tom de Vries + + PR build/28318 + * configure: Regenerate. + 2021-07-05 Simon Marchi * config.in, configure: Re-generate. diff --git a/gdbserver/configure b/gdbserver/configure index b227167e270..f05c1a9b976 100755 --- a/gdbserver/configure +++ b/gdbserver/configure @@ -5625,6 +5625,10 @@ eval ac_res=\$$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 $switch" + fi ac_success=yes break fi @@ -5944,6 +5948,10 @@ eval ac_res=\$$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 $switch" + fi ac_success=yes break fi diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog index 7f17e7a57e5..d4a545b4a18 100644 --- a/gdbsupport/ChangeLog +++ b/gdbsupport/ChangeLog @@ -1,3 +1,8 @@ +2021-10-04 Tom de Vries + + PR build/28318 + * configure: Regenerate. + 2021-07-30 Tom de Vries * common-defs.h (ATTRIBUTE_NONNULL): Disable. diff --git a/gdbsupport/configure b/gdbsupport/configure index a9dd02c5b72..ae6047865ae 100755 --- a/gdbsupport/configure +++ b/gdbsupport/configure @@ -6520,6 +6520,10 @@ eval ac_res=\$$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 -- 2.47.3