From b485458e00dae4af5e2b7b1c17521e2885180544 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 8 Nov 2021 12:31:52 +0100
Subject: [PATCH] configure, meson: move C++ compiler detection to meson.build
MIME-Version: 1.0
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The test is slightly weaker than before, because it does not
call an extern "C" function from a C source file. However,
in practice what we seek to detect is ABI compatibility of the
various sanitizer flags, and for that it is enough to compile
anything with CC and link it with CXX.
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
configure | 57 --------------------------------------------------
meson.build | 37 ++++++++++++++++++++++----------
scripts/main.c | 1 +
3 files changed, 27 insertions(+), 68 deletions(-)
create mode 100644 scripts/main.c
diff --git a/configure b/configure
index c5069775db4..3e3c0f36c90 100755
--- a/configure
+++ b/configure
@@ -75,7 +75,6 @@ fi
TMPB="qemu-conf"
TMPC="${TMPDIR1}/${TMPB}.c"
TMPO="${TMPDIR1}/${TMPB}.o"
-TMPCXX="${TMPDIR1}/${TMPB}.cxx"
TMPM="${TMPDIR1}/${TMPB}.m"
TMPE="${TMPDIR1}/${TMPB}.exe"
@@ -158,10 +157,6 @@ do_cc() {
do_compiler_werror "$cc" $CPU_CFLAGS "$@"
}
-do_cxx() {
- do_compiler_werror "$cxx" $CPU_CFLAGS "$@"
-}
-
do_objc() {
do_compiler_werror "$objcc" $CPU_CFLAGS "$@"
}
@@ -171,24 +166,6 @@ add_to() {
eval $1=\${$1:+\"\$$1 \"}\$2
}
-update_cxxflags() {
- # Set QEMU_CXXFLAGS from QEMU_CFLAGS by filtering out those
- # options which some versions of GCC's C++ compiler complain about
- # because they only make sense for C programs.
- QEMU_CXXFLAGS="-D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS"
- CONFIGURE_CXXFLAGS=$(echo "$CONFIGURE_CFLAGS" | sed s/-std=gnu11/-std=gnu++11/)
- for arg in $QEMU_CFLAGS; do
- case $arg in
- -Wstrict-prototypes|-Wmissing-prototypes|-Wnested-externs|\
- -Wold-style-declaration|-Wold-style-definition|-Wredundant-decls)
- ;;
- *)
- QEMU_CXXFLAGS=${QEMU_CXXFLAGS:+$QEMU_CXXFLAGS }$arg
- ;;
- esac
- done
-}
-
compile_object() {
local_cflags="$1"
do_cc $CFLAGS $EXTRA_CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
@@ -2362,38 +2339,6 @@ fi
#######################################
# generate config-host.mak
-# Check that the C++ compiler exists and works with the C compiler.
-# All the QEMU_CXXFLAGS are based on QEMU_CFLAGS. Keep this at the end to don't miss any other that could be added.
-if has $cxx; then
- cat > $TMPC <<EOF
-int c_function(void);
-int main(void) { return c_function(); }
-EOF
-
- compile_object
-
- cat > $TMPCXX <<EOF
-extern "C" {
- int c_function(void);
-}
-int c_function(void) { return 42; }
-EOF
-
- update_cxxflags
-
- if do_cxx $CXXFLAGS $EXTRA_CXXFLAGS $CONFIGURE_CXXFLAGS $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $QEMU_LDFLAGS; then
- # C++ compiler $cxx works ok with C compiler $cc
- :
- else
- echo "C++ compiler $cxx does not work with C compiler $cc"
- echo "Disabling C++ specific optional code"
- cxx=
- fi
-else
- echo "No C++ compiler available; disabling C++ specific optional code"
- cxx=
-fi
-
if ! (GIT="$git" "$source_path/scripts/git-submodule.sh" "$git_submodules_action" "$git_submodules"); then
exit 1
fi
@@ -2474,7 +2419,6 @@ echo "MESON=$meson" >> $config_host_mak
echo "NINJA=$ninja" >> $config_host_mak
echo "CC=$cc" >> $config_host_mak
echo "QEMU_CFLAGS=$QEMU_CFLAGS" >> $config_host_mak
-echo "QEMU_CXXFLAGS=$QEMU_CXXFLAGS" >> $config_host_mak
echo "QEMU_OBJCFLAGS=$QEMU_OBJCFLAGS" >> $config_host_mak
echo "GLIB_CFLAGS=$glib_cflags" >> $config_host_mak
echo "GLIB_LIBS=$glib_libs" >> $config_host_mak
@@ -2665,7 +2609,6 @@ if test "$skip_meson" = no; then
echo "${a}-softmmu = '$c'" >> $cross
done
- test -z "$cxx" && echo "link_language = 'c'" >> $cross
echo "[built-in options]" >> $cross
echo "c_args = [$(meson_quote $CFLAGS $EXTRA_CFLAGS)]" >> $cross
echo "cpp_args = [$(meson_quote $CXXFLAGS $EXTRA_CXXFLAGS)]" >> $cross
diff --git a/meson.build b/meson.build
index 780654b00c7..9c57ebdfb99 100644
--- a/meson.build
+++ b/meson.build
@@ -180,7 +180,6 @@ endif
##################
qemu_cflags = config_host['QEMU_CFLAGS'].split()
-qemu_cxxflags = config_host['QEMU_CXXFLAGS'].split()
qemu_objcflags = config_host['QEMU_OBJCFLAGS'].split()
qemu_ldflags = config_host['QEMU_LDFLAGS'].split()
@@ -194,7 +193,6 @@ endif
if get_option('gprof')
qemu_cflags += ['-p']
- qemu_cxxflags += ['-p']
qemu_objcflags += ['-p']
qemu_ldflags += ['-p']
endif
@@ -240,8 +238,33 @@ if get_option('fuzzing')
endif
add_global_arguments(qemu_cflags, native: false, language: ['c'])
-add_global_arguments(qemu_cxxflags, native: false, language: ['cpp'])
add_global_arguments(qemu_objcflags, native: false, language: ['objc'])
+
+# Check that the C++ compiler exists and works with the C compiler.
+link_language = 'c'
+linker = cc
+qemu_cxxflags = []
+if add_languages('cpp', required: false, native: false)
+ cxx = meson.get_compiler('cpp')
+ add_global_arguments(['-D__STDC_LIMIT_MACROS', '-D__STDC_CONSTANT_MACROS', '-D__STDC_FORMAT_MACROS'],
+ native: false, language: 'cpp')
+ foreach k: qemu_cflags
+ if k not in ['-Wstrict-prototypes', '-Wmissing-prototypes', '-Wnested-externs',
+ '-Wold-style-declaration', '-Wold-style-definition', '-Wredundant-decls']
+ qemu_cxxflags += [k]
+ endif
+ endforeach
+ add_global_arguments(qemu_cxxflags, native: false, language: 'cpp')
+
+ if cxx.links(files('scripts/main.c'), args: qemu_cflags)
+ link_language = 'cpp'
+ linker = cxx
+ else
+ message('C++ compiler does not work with C compiler')
+ message('Disabling C++-specific optional code')
+ endif
+endif
+
add_global_link_arguments(qemu_ldflags, native: false, language: ['c', 'cpp', 'objc'])
if targetos == 'linux'
@@ -255,14 +278,6 @@ add_project_arguments('-iquote', '.',
'-iquote', meson.current_source_dir() / 'include',
language: ['c', 'cpp', 'objc'])
-link_language = meson.get_external_property('link_language', 'cpp')
-if link_language == 'cpp'
- add_languages('cpp', required: true, native: false)
- cxx = meson.get_compiler('cpp')
- linker = cxx
-else
- linker = cc
-endif
if host_machine.system() == 'darwin'
add_languages('objc', required: false, native: false)
endif
diff --git a/scripts/main.c b/scripts/main.c
new file mode 100644
index 00000000000..b552c8e4ed7
--- /dev/null
+++ b/scripts/main.c
@@ -0,0 +1 @@
+int main(void) {}
--
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