diff options
| author | Pedro Alves <palves@redhat.com> | 2016-10-13 00:27:45 +0100 |
|---|---|---|
| committer | Pedro Alves <palves@redhat.com> | 2016-10-28 16:03:19 +0100 |
| commit | 0bcda68539948828795564b35a497dc69c27f768 (patch) | |
| tree | ffba724695a70ecf58bd556ee6f39cf52af099f2 /gdb/Makefile.in | |
| parent | 87106a7b0a3c403832f15aa316d5d6d2434e323f (diff) | |
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.in | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/gdb/Makefile.in b/gdb/Makefile.in index 2c884345eb..d035d8e242 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)" \ |