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authorPedro Alves <palves@redhat.com>2016-10-13 00:27:45 +0100
committerPedro Alves <palves@redhat.com>2016-10-28 16:03:19 +0100
commit0bcda68539948828795564b35a497dc69c27f768 (patch)
treeffba724695a70ecf58bd556ee6f39cf52af099f2 /gdb/Makefile.in
parent87106a7b0a3c403832f15aa316d5d6d2434e323f (diff)
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gdb: Require C++11
Use AX_CXX_COMPILE_STDCXX to detect if the compiler supports C++11, and if -std=xxx switches are necessary to enable C++11. We need to tweak AX_CXX_COMPILE_STDCXX a bit though. Pristine upstream AX_CXX_COMPILE_STDCXX appends -std=gnu++11 to CXX directly. That doesn't work for us, because 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. So instead of having AX_CXX_COMPILE_STDCXX set CXX directly, tweak it to AC_SUBST a separate variable -- CXX_DIALECT -- and use '$(CXX) (CXX_DIALECT)' to compile/link. Confirmed that this enables C++11 starting with gcc 4.8, the first gcc release with full C++11 support. Also confirmed that configure errors out gracefully with older GCC releases: checking whether /opt/gcc-4.7/bin/g++ supports C++11 features by default... no checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=gnu++11... no checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=gnu++0x... no checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=c++11... no checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -std=c++0x... no checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with +std=c++11... no checking whether /opt/gcc-4.7/bin/g++ supports C++11 features with -h std=c++11... no configure: error: *** A compiler with support for C++11 language features is required. Makefile:9451: recipe for target 'configure-gdb' failed make[1]: *** [configure-gdb] Error 1 make[1]: Leaving directory '/home/pedro/brno/pedro/gdb/mygit/cxx-convertion/build-gcc-4.7' If we need to revert back to making C++11 optional, all that's necessary is to change the "mandatory" to "optional" in configure.ac and regenerate configure (both gdb and gdbserver). gdb/ChangeLog: 2016-10-28 Pedro Alves <palves@redhat.com> * Makefile.in (CXX_DIALECT): Get from configure. (COMPILE.pre, CC_LD): Append $(CXX_DIALECT). (FLAGS_TO_PASS): Pass CXX_DIALECT. * acinclude.m4: Include ax_cxx_compile_stdcxx.m4. * ax_cxx_compile_stdcxx.m4: Add FSF copyright header. Set and AC_SUBST CXX_DIALECT instead of changing CXX/CXXCPP. * configure.ac: Call AX_CXX_COMPILE_STDCXX. * config.in: Regenerate. * configure: Regenerate. gdb/gdbserver/ChangeLog: 2016-10-28 Pedro Alves <palves@redhat.com> * Makefile.in (CXX_DIALECT): Get from configure. (COMPILE.pre, CC_LD): Append $(CXX_DIALECT). * acinclude.m4: Include ../ax_cxx_compile_stdcxx.m4. * configure.ac: Call AX_CXX_COMPILE_STDCXX. * config.in: Regenerate. * configure: Regenerate.
Diffstat (limited to 'gdb/Makefile.in')
-rw-r--r--gdb/Makefile.in6
1 files changed, 4 insertions, 2 deletions
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 2c88434..d035d8e 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -86,6 +86,7 @@ CATALOGS = @CATALOGS@
# distribution will fix your include files up.
CC=@CC@
CXX=@CXX@
+CXX_DIALECT= @CXX_DIALECT@
# Dependency tracking information.
DEPMODE = @CCDEPMODE@
@@ -94,7 +95,7 @@ depcomp = $(SHELL) $(srcdir)/../depcomp
# Note that these are overridden by GNU make-specific code below if
# GNU make is used. The overrides implement dependency tracking.
-COMPILE.pre = $(CXX)
+COMPILE.pre = $(CXX) $(CXX_DIALECT)
COMPILE.post = -c -o $@
COMPILE = $(COMPILE.pre) $(INTERNAL_CFLAGS) $(COMPILE.post)
POSTCOMPILE = @true
@@ -125,7 +126,7 @@ MAKEHTMLFLAGS =
# Set this up with gcc if you have gnu ld and the loader will print out
# line numbers for undefined references.
#CC_LD=g++ -static
-CC_LD=$(CXX)
+CC_LD=$(CXX) $(CXX_DIALECT)
# Where is our "include" directory? Typically $(srcdir)/../include.
# This is essentially the header file directory for the library
@@ -742,6 +743,7 @@ FLAGS_TO_PASS = \
"CC=$(CC)" \
"CFLAGS=$(CFLAGS)" \
"CXX=$(CXX)" \
+ "CXX_DIALECT=$(CXX_DIALECT)" \
"CXXFLAGS=$(CXXFLAGS)" \
"DLLTOOL=$(DLLTOOL)" \
"LDFLAGS=$(LDFLAGS)" \