[PATCH 0/4] configure: bugfixes and cleanups for CFLAGS

[PATCH 0/4] configure: bugfixes and cleanups for CFLAGS

[Paolo Bonzini]

Meson is placing -pie after -shared rather than before, and this
causes linking to fail while building the ArchLinux package for
QEMU?

But why is -pie ending up in the flags?  Because LDFLAGS is an
environment variable, and changes to environment variables propagate
when configure does

  LDFLAGS="-pie $LDFLAGS"

This happens without having to export the env. var again.

The solution is to simply rename the CFLAGS and LDFLAGS variables
used for flags that Meson takes care of by itself.  The CFLAGS
variable was previously used for submodules as well, so patches
1 and 2 fix that as well.

Paolo Bonzini (4):
  configure: cleanup invocation of submodule Make
  configure: cleanup CFLAGS and LDFLAGS for submodules
  configure: do not clobber environment CFLAGS/CXXFLAGS/LDFLAGS
  configure: consistently pass CFLAGS/CXXFLAGS/LDFLAGS to meson

 Makefile    | 23 ++++++++++++++---------
 configure   | 47 ++++++++++++++++++++++++++++++-----------------
 meson.build | 13 ++++++++++++-
 3 files changed, 56 insertions(+), 27 deletions(-)

-- 
2.26.2

[PATCH 1/4] configure: cleanup invocation of submodule Make

[Paolo Bonzini]

Move common command line options to SUBDIR_MAKEFLAGS, thus simplifying
the rules themselves.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Makefile | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index 897246d77c..57fb63832f 100644
--- a/Makefile
+++ b/Makefile
@@ -137,7 +137,12 @@ configure: ;
 .PHONY: all clean distclean install \
 	recurse-all dist msi FORCE
 
-SUBDIR_MAKEFLAGS=$(if $(V),,--no-print-directory --quiet)
+SUBMODULE_CFLAGS = $(QEMU_CFLAGS) $(CFLAGS)
+SUBDIR_MAKEFLAGS = $(if $(V),,--no-print-directory --quiet)		\
+	PKG_CONFIG="$(PKG_CONFIG)" 					\
+	CC="$(CC)" AR="$(AR)" LD="$(LD)" RANLIB="$(RANLIB)"		\
+	CFLAGS="$(SUBMODULE_CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)"		\
+	ARFLAGS="$(ARFLAGS)"
 
 include $(SRC_PATH)/tests/Makefile.include
 
@@ -146,12 +151,12 @@ Makefile: $(addsuffix /all, $(SUBDIRS))
 
 # LIBFDT_lib="": avoid breaking existing trees with objects requiring -fPIC
 DTC_MAKE_ARGS=-I$(SRC_PATH)/dtc VPATH=$(SRC_PATH)/dtc -C dtc V="$(V)" LIBFDT_lib=""
-DTC_CFLAGS=$(CFLAGS) $(QEMU_CFLAGS)
 DTC_CPPFLAGS=-I$(SRC_PATH)/dtc/libfdt
 
 .PHONY: dtc/all
 dtc/all: .git-submodule-status dtc/libfdt
-	$(call quiet-command,$(MAKE) $(DTC_MAKE_ARGS) CPPFLAGS="$(DTC_CPPFLAGS)" CFLAGS="$(DTC_CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)" ARFLAGS="$(ARFLAGS)" CC="$(CC)" AR="$(AR)" LD="$(LD)" $(SUBDIR_MAKEFLAGS) libfdt,)
+	$(call quiet-command,$(MAKE) $(DTC_MAKE_ARGS)			\
+            CPPFLAGS="$(DTC_CPPFLAGS)" $(SUBDIR_MAKEFLAGS) libfdt,)
 
 dtc/%: .git-submodule-status
 	@mkdir -p $@
@@ -161,7 +166,7 @@ dtc/%: .git-submodule-status
 # Therefore we replicate some of the logic in the sub-makefile.
 # Remove all the extra -Warning flags that QEMU uses that Capstone doesn't;
 # no need to annoy QEMU developers with such things.
-CAP_CFLAGS = $(patsubst -W%,,$(CFLAGS) $(QEMU_CFLAGS)) $(CAPSTONE_CFLAGS)
+CAP_CFLAGS := $(patsubst -W%,,$(SUBMODULE_CFLAGS)) $(CAPSTONE_CFLAGS)
 CAP_CFLAGS += -DCAPSTONE_USE_SYS_DYN_MEM
 CAP_CFLAGS += -DCAPSTONE_HAS_ARM
 CAP_CFLAGS += -DCAPSTONE_HAS_ARM64
@@ -169,16 +174,17 @@ CAP_CFLAGS += -DCAPSTONE_HAS_POWERPC
 CAP_CFLAGS += -DCAPSTONE_HAS_X86
 
 .PHONY: capstone/all
+capstone/all: SUBMODULE_CFLAGS = $(CAP_CFLAGS)
 capstone/all: .git-submodule-status
-	$(call quiet-command,$(MAKE) -C $(SRC_PATH)/capstone CAPSTONE_SHARED=no BUILDDIR="$(BUILD_DIR)/capstone" CC="$(CC)" AR="$(AR)" LD="$(LD)" RANLIB="$(RANLIB)" CFLAGS="$(CAP_CFLAGS)" $(SUBDIR_MAKEFLAGS) $(BUILD_DIR)/capstone/$(LIBCAPSTONE))
+	$(call quiet-command,$(MAKE) -C $(SRC_PATH)/capstone 		\
+            CAPSTONE_SHARED=no BUILDDIR="$(BUILD_DIR)/capstone" 	\
+            $(SUBDIR_MAKEFLAGS) $(BUILD_DIR)/capstone/$(LIBCAPSTONE))
 
 .PHONY: slirp/all
 slirp/all: .git-submodule-status
 	$(call quiet-command,$(MAKE) -C $(SRC_PATH)/slirp		\
-		BUILD_DIR="$(BUILD_DIR)/slirp" 			\
-		PKG_CONFIG="$(PKG_CONFIG)" 				\
-		CC="$(CC)" AR="$(AR)" 	LD="$(LD)" RANLIB="$(RANLIB)"	\
-		CFLAGS="$(QEMU_CFLAGS) $(CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)")
+		BUILD_DIR="$(BUILD_DIR)/slirp" 				\
+		$(SUBDIR_MAKEFLAGS))
 
 ROM_DIRS = $(addprefix pc-bios/, $(ROMS))
 ROM_DIRS_RULES=$(foreach t, all clean, $(addsuffix /$(t), $(ROM_DIRS)))
-- 
2.26.2

Re: [PATCH 1/4] configure: cleanup invocation of submodule Make

[Richard Henderson]

On 9/20/20 2:30 AM, Paolo Bonzini wrote:
> Move common command line options to SUBDIR_MAKEFLAGS, thus simplifying
> the rules themselves.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  Makefile | 24 +++++++++++++++---------
>  1 file changed, 15 insertions(+), 9 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH 2/4] configure: cleanup CFLAGS and LDFLAGS for submodules

[Paolo Bonzini]

The -g and -O2 flags that configure adds to CFLAGS are only used by submodules,
so do not put anymore the confusing CFLAGS variable in config-host.mak and
replace it with more explicit SUBMODULE_CFLAGS variable.

There was also no equivalent SUBMODULE_LDFLAGS variable, add it.  This would
theoretically help with LTO if we want -g and -O2 options on the command line.
I say "theoretically" because submodules should not be linking anything; but
since we were passing an "LD" variable we might as well get its flags right.

CFLAGS are now synthesized in the configuration summary as a quick way to present
--enable-debug and --enable-debug-info.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Makefile    |  3 +--
 configure   | 13 +++++++++----
 meson.build |  3 ++-
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/Makefile b/Makefile
index 57fb63832f..3367ca520c 100644
--- a/Makefile
+++ b/Makefile
@@ -137,11 +137,10 @@ configure: ;
 .PHONY: all clean distclean install \
 	recurse-all dist msi FORCE
 
-SUBMODULE_CFLAGS = $(QEMU_CFLAGS) $(CFLAGS)
 SUBDIR_MAKEFLAGS = $(if $(V),,--no-print-directory --quiet)		\
 	PKG_CONFIG="$(PKG_CONFIG)" 					\
 	CC="$(CC)" AR="$(AR)" LD="$(LD)" RANLIB="$(RANLIB)"		\
-	CFLAGS="$(SUBMODULE_CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)"		\
+	CFLAGS="$(SUBMODULE_CFLAGS)" LDFLAGS="$(SUBMODULE_LDFLAGS)"	\
 	ARFLAGS="$(ARFLAGS)"
 
 include $(SRC_PATH)/tests/Makefile.include
diff --git a/configure b/configure
index ffc28e392f..5fabc77fb3 100755
--- a/configure
+++ b/configure
@@ -6108,12 +6108,16 @@ elif test "$fortify_source" = "yes" ; then
   QEMU_CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $QEMU_CFLAGS"
   debug=no
 fi
+
+SUBMODULE_CFLAGS=-Wall
+SUBMODULE_LDFLAGS=
 if test "$debug_info" = "yes"; then
-  CFLAGS="-g $CFLAGS"
-  LDFLAGS="-g $LDFLAGS"
+  SUBMODULE_CFLAGS="$SUBMODULE_CFLAGS -g"
+  SUBMODULE_LDFLAGS="$SUBMODULE_LDFLAGS -g"
 fi
 if test "$debug" = "no"; then
-  CFLAGS="-O2 $CFLAGS"
+  SUBMODULE_CFLAGS="$SUBMODULE_CFLAGS -O2"
+  SUBMODULE_LDFLAGS="$SUBMODULE_LDFLAGS -O2"
 fi
 
 case "$ARCH" in
@@ -7288,7 +7292,8 @@ echo "RANLIB=$ranlib" >> $config_host_mak
 echo "NM=$nm" >> $config_host_mak
 echo "PKG_CONFIG=$pkg_config_exe" >> $config_host_mak
 echo "WINDRES=$windres" >> $config_host_mak
-echo "CFLAGS=$CFLAGS" >> $config_host_mak
+echo "SUBMODULE_CFLAGS=$CFLAGS \$(QEMU_CFLAGS) $SUBMODULE_CFLAGS" >> $config_host_mak
+echo "SUBMODULE_LDFLAGS=$LDFLAGS \$(QEMU_LDFLAGS) $SUBMODULE_LDFLAGS" >> $config_host_mak
 echo "CFLAGS_NOPIE=$CFLAGS_NOPIE" >> $config_host_mak
 echo "QEMU_CFLAGS=$QEMU_CFLAGS" >> $config_host_mak
 echo "QEMU_CXXFLAGS=$QEMU_CXXFLAGS" >> $config_host_mak
diff --git a/meson.build b/meson.build
index 1b1cde8725..1099f2a87c 100644
--- a/meson.build
+++ b/meson.build
@@ -1476,7 +1476,8 @@ if targetos == 'darwin'
   summary_info += {'Objective-C compiler': meson.get_compiler('objc').cmd_array()[0]}
 endif
 summary_info += {'ARFLAGS':           config_host['ARFLAGS']}
-summary_info += {'CFLAGS':            config_host['CFLAGS']}
+summary_info += {'CFLAGS':            '-O' + get_option('optimization')
+                                           + (get_option('debug') ? ' -g' : '')}
 summary_info += {'QEMU_CFLAGS':       config_host['QEMU_CFLAGS']}
 summary_info += {'QEMU_LDFLAGS':      config_host['QEMU_LDFLAGS']}
 summary_info += {'make':              config_host['MAKE']}
-- 
2.26.2

Re: [PATCH 2/4] configure: cleanup CFLAGS and LDFLAGS for submodules

[Richard Henderson]

On 9/20/20 2:30 AM, Paolo Bonzini wrote:
> The -g and -O2 flags that configure adds to CFLAGS are only used by submodules,
> so do not put anymore the confusing CFLAGS variable in config-host.mak and
> replace it with more explicit SUBMODULE_CFLAGS variable.
> 
> There was also no equivalent SUBMODULE_LDFLAGS variable, add it.  This would
> theoretically help with LTO if we want -g and -O2 options on the command line.
> I say "theoretically" because submodules should not be linking anything; but
> since we were passing an "LD" variable we might as well get its flags right.
> 
> CFLAGS are now synthesized in the configuration summary as a quick way to present
> --enable-debug and --enable-debug-info.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH 3/4] configure: do not clobber environment CFLAGS/CXXFLAGS/LDFLAGS

[Paolo Bonzini]

If the CFLAGS, CXXFLAGS or LDFLAGS variables are present in the environment,
any modification made within the configure script is passed down to Meson.
This is particularly undesirable for the "-pie" option, since it overrides
"-shared" and thus messes up the linker flags for shared modules.

Using a separate variable therefore fixes the bug, while clarifying that
the scope of these CFLAGS is just the configure script.

Reported-by: Frederic Bezies
Analyzed-by: Toolybird
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/configure b/configure
index 5fabc77fb3..9a0bbd2a69 100755
--- a/configure
+++ b/configure
@@ -155,7 +155,7 @@ update_cxxflags() {
     # options which some versions of GCC's C++ compiler complain about
     # because they only make sense for C programs.
     QEMU_CXXFLAGS="$QEMU_CXXFLAGS -D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS"
-    CXXFLAGS=$(echo "$CFLAGS" | sed s/-std=gnu99/-std=gnu++11/)
+    CONFIGURE_CXXFLAGS=$(echo "$CONFIGURE_CFLAGS" | sed s/-std=gnu99/-std=gnu++11/)
     for arg in $QEMU_CFLAGS; do
         case $arg in
             -Wstrict-prototypes|-Wmissing-prototypes|-Wnested-externs|\
@@ -170,13 +170,14 @@ update_cxxflags() {
 
 compile_object() {
   local_cflags="$1"
-  do_cc $CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
+  do_cc $CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
 }
 
 compile_prog() {
   local_cflags="$1"
   local_ldflags="$2"
-  do_cc $CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC $LDFLAGS $QEMU_LDFLAGS $local_ldflags
+  do_cc $CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC \
+      $LDFLAGS $CONFIGURE_LDFLAGS $QEMU_LDFLAGS $local_ldflags
 }
 
 # symbolically link $1 to $2.  Portable version of "ln -sf".
@@ -632,7 +633,10 @@ QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
 QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
 QEMU_INCLUDES="-iquote . -iquote ${source_path} -iquote ${source_path}/accel/tcg -iquote ${source_path}/include"
 QEMU_INCLUDES="$QEMU_INCLUDES -iquote ${source_path}/disas/libvixl"
-CFLAGS="-std=gnu99 -Wall"
+
+# Flags that are needed during configure but later taken care of by Meson
+CONFIGURE_CFLAGS="-std=gnu99 -Wall"
+CONFIGURE_LDFLAGS=
 
 
 check_define() {
@@ -960,7 +964,7 @@ if test "$mingw32" = "yes" ; then
   EXESUF=".exe"
   HOST_DSOSUF=".dll"
   # MinGW needs -mthreads for TLS and macro _MT.
-  CFLAGS="-mthreads $CFLAGS"
+  CONFIGURE_CFLAGS="-mthreads $CONFIGURE_CFLAGS"
   write_c_skeleton;
   prefix="/qemu"
   qemu_suffix=""
@@ -2230,7 +2234,7 @@ fi
 
 if test "$static" = "yes"; then
   if test "$pie" != "no" && compile_prog "-Werror -fPIE -DPIE" "-static-pie"; then
-    CFLAGS="-fPIE -DPIE $CFLAGS"
+    CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
     QEMU_LDFLAGS="-static-pie $QEMU_LDFLAGS"
     pie="yes"
   elif test "$pie" = "yes"; then
@@ -2240,11 +2244,11 @@ if test "$static" = "yes"; then
     pie="no"
   fi
 elif test "$pie" = "no"; then
-  CFLAGS="$CFLAGS_NOPIE $CFLAGS"
-  LDFLAGS="$LDFLAGS_NOPIE $LDFLAGS"
+  CONFIGURE_CFLAGS="$CFLAGS_NOPIE $CONFIGURE_CFLAGS"
+  CONFIGURE_LDFLAGS="$LDFLAGS_NOPIE $CONFIGURE_LDFLAGS"
 elif compile_prog "-Werror -fPIE -DPIE" "-pie"; then
-  CFLAGS="-fPIE -DPIE $CFLAGS"
-  LDFLAGS="-pie $LDFLAGS"
+  CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
+  CONFIGURE_LDFLAGS="-pie $CONFIGURE_LDFLAGS"
   pie="yes"
 elif test "$pie" = "yes"; then
   error_exit "PIE not available due to missing toolchain support"
@@ -3808,7 +3812,7 @@ EOF
 if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then
     if cc_has_warning_flag "-Wno-unknown-attributes"; then
         glib_cflags="-Wno-unknown-attributes $glib_cflags"
-        CFLAGS="-Wno-unknown-attributes $CFLAGS"
+        CONFIGURE_CFLAGS="-Wno-unknown-attributes $CONFIGURE_CFLAGS"
     fi
 fi
 
@@ -3828,7 +3832,7 @@ EOF
 if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then
     if cc_has_warning_flag "-Wno-unused-function"; then
         glib_cflags="$glib_cflags -Wno-unused-function"
-        CFLAGS="$CFLAGS -Wno-unused-function"
+        CONFIGURE_CFLAGS="$CONFIGURE_CFLAGS -Wno-unused-function"
     fi
 fi
 
@@ -6359,7 +6363,7 @@ EOF
 
     update_cxxflags
 
-    if do_cxx $CXXFLAGS $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $QEMU_LDFLAGS; then
+    if do_cxx $CONFIGURE_CXXFLAGS $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $QEMU_LDFLAGS; then
         # C++ compiler $cxx works ok with C compiler $cc
         :
     else
-- 
2.26.2

Re: [PATCH 3/4] configure: do not clobber environment CFLAGS/CXXFLAGS/LDFLAGS

[Richard Henderson]

On 9/20/20 2:30 AM, Paolo Bonzini wrote:
> If the CFLAGS, CXXFLAGS or LDFLAGS variables are present in the environment,
> any modification made within the configure script is passed down to Meson.
> This is particularly undesirable for the "-pie" option, since it overrides
> "-shared" and thus messes up the linker flags for shared modules.
> 
> Using a separate variable therefore fixes the bug, while clarifying that
> the scope of these CFLAGS is just the configure script.
> 
> Reported-by: Frederic Bezies
> Analyzed-by: Toolybird
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH 4/4] configure: consistently pass CFLAGS/CXXFLAGS/LDFLAGS to meson

[Paolo Bonzini]

Environment variables like CFLAGS are easy to accidentally change.  Meson
warns if that happens, but in a project with a lot of configuration that
is easy to lose.  It is also surprising behavior since meson caches -D
options and remembers those on reconfiguration (which we rely on,
since configure options become -D options).

By placing the user-provided CFLAGS, CXXFLAGS and LDFLAGS in the
cross file, we at least get consistent behavior.  These environment
variables are still ugly and not really recommended, but there are
distros that rely on them.  For the gory details, refer to
https://github.com/mesonbuild/meson/issues/4664.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure   |  4 ++++
 meson.build | 14 ++++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 9a0bbd2a69..952a7479ab 100755
--- a/configure
+++ b/configure
@@ -7794,6 +7794,10 @@ meson_quote() {
 echo "# Automatically generated by configure - do not modify" > $cross
 echo "[properties]" >> $cross
 test -z "$cxx" && echo "link_language = 'c'" >> $cross
+echo "c_args = $(meson_quote $CFLAGS)" >> $cross
+echo "cpp_args = $(meson_quote $CXXFLAGS)" >> $cross
+echo "c_link_args = $(meson_quote $LDFLAGS)" >> $cross
+echo "cpp_link_args = $(meson_quote $LDFLAGS)" >> $cross
 echo "[binaries]" >> $cross
 echo "c = $(meson_quote $cc)" >> $cross
 test -n "$cxx" && echo "cpp = $(meson_quote $cxx)" >> $cross
diff --git a/meson.build b/meson.build
index 1099f2a87c..4d6ef64adf 100644
--- a/meson.build
+++ b/meson.build
@@ -1476,8 +1476,18 @@ if targetos == 'darwin'
   summary_info += {'Objective-C compiler': meson.get_compiler('objc').cmd_array()[0]}
 endif
 summary_info += {'ARFLAGS':           config_host['ARFLAGS']}
-summary_info += {'CFLAGS':            '-O' + get_option('optimization')
-                                           + (get_option('debug') ? ' -g' : '')}
+summary_info += {'CFLAGS':            ' '.join(get_option('c_args')
+                                               + ['-O' + get_option('optimization')]
+                                               + (get_option('debug') ? ['-g'] : []))}
+if link_language == 'cpp'
+  summary_info += {'CXXFLAGS':        ' '.join(get_option('cpp_args')
+                                               + ['-O' + get_option('optimization')]
+                                               + (get_option('debug') ? ['-g'] : []))}
+endif
+link_args = get_option(link_language + '_link_args')
+if link_args.length() > 0
+  summary_info += {'LDFLAGS':         ' '.join(link_args)}
+endif
 summary_info += {'QEMU_CFLAGS':       config_host['QEMU_CFLAGS']}
 summary_info += {'QEMU_LDFLAGS':      config_host['QEMU_LDFLAGS']}
 summary_info += {'make':              config_host['MAKE']}
-- 
2.26.2

Re: [PATCH 4/4] configure: consistently pass CFLAGS/CXXFLAGS/LDFLAGS to meson

[Richard Henderson]

On 9/20/20 2:30 AM, Paolo Bonzini wrote:
> Environment variables like CFLAGS are easy to accidentally change.  Meson
> warns if that happens, but in a project with a lot of configuration that
> is easy to lose.  It is also surprising behavior since meson caches -D
> options and remembers those on reconfiguration (which we rely on,
> since configure options become -D options).
> 
> By placing the user-provided CFLAGS, CXXFLAGS and LDFLAGS in the
> cross file, we at least get consistent behavior.  These environment
> variables are still ugly and not really recommended, but there are
> distros that rely on them.  For the gory details, refer to
> https://github.com/mesonbuild/meson/issues/4664.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  configure   |  4 ++++
>  meson.build | 14 ++++++++++++--
>  2 files changed, 16 insertions(+), 2 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~

[PATCH 0/4] Convert remaining submodules to meson, cleanup env var handling

[Paolo Bonzini]

The main purpose of this series is to have a correct and consistent
handling of CFLAGS/CXXFLAGS/LDFLAGS environment variables:

- correct: avoid that the -pie flag, used for the compiler checks in
the configure script, ends up being passed to Meson if an LDFLAGS
environment variable exists (patch 3)

- consistent: ensure that CFLAGS that are set in the configure
script are persistent even if Meson is restarted; to do so,
make the configure script store them in the cross file it generates.

In order to avoid having to deal with recursive make, patches 1
and 2 integrate the Meson-based build system with the build of
embedded slirp and libfdt.  This follows the lead of Richard's
patches to do the same with Capstone.

Based-on: <20201003093851.324923-1-richard.henderson@linaro.org>
Supersedes: <20200923092617.1593722-1-pbonzini@redhat.com>

Paolo Bonzini (4):
  slirp: Convert Makefile bits to meson bits
  dtc: Convert Makefile bits to meson bits
  configure: do not clobber environment CFLAGS/CXXFLAGS/LDFLAGS
  configure: consistently pass CFLAGS/CXXFLAGS/LDFLAGS to meson

 Makefile                                      |  28 +--
 configure                                     | 222 +++++-------------
 default-configs/targets/aarch64-softmmu.mak   |   1 +
 default-configs/targets/arm-softmmu.mak       |   1 +
 .../targets/microblaze-softmmu.mak            |   1 +
 .../targets/microblazeel-softmmu.mak          |   1 +
 default-configs/targets/mips64el-softmmu.mak  |   1 +
 default-configs/targets/ppc-softmmu.mak       |   1 +
 default-configs/targets/ppc64-softmmu.mak     |   1 +
 default-configs/targets/riscv32-softmmu.mak   |   1 +
 default-configs/targets/riscv64-softmmu.mak   |   1 +
 default-configs/targets/rx-softmmu.mak        |   1 +
 meson.build                                   | 164 +++++++++++--
 meson_options.txt                             |   6 +
 net/meson.build                               |   2 +-
 tests/qtest/meson.build                       |   6 +-
 16 files changed, 225 insertions(+), 213 deletions(-)

-- 
2.26.2

[PATCH 3/4] configure: do not clobber environment CFLAGS/CXXFLAGS/LDFLAGS

[Paolo Bonzini]

If the CFLAGS, CXXFLAGS or LDFLAGS variables are present in the environment,
any modification made within the configure script is passed down to Meson.
This is particularly undesirable for the "-pie" option, since it overrides
"-shared" and thus messes up the linker flags for shared modules.

Using a separate variable therefore fixes the bug, while clarifying that
the scope of these CFLAGS is just the configure script.

We also do not need to pass those variables in config-host.mak; they
were only used for printing the summary now that all submodules are
built with handwritten Meson rules).  For now synthesize CFLAGS in the
configuration summary, the next patch will also pass them in a cleaner
way using the cross file.

Reported-by: Frederic Bezies
Analyzed-by: Toolybird
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923092617.1593722-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure   | 38 +++++++++++++++++---------------------
 meson.build |  3 ++-
 2 files changed, 19 insertions(+), 22 deletions(-)

diff --git a/configure b/configure
index 2fdb4339e8..1b173276ea 100755
--- a/configure
+++ b/configure
@@ -155,7 +155,7 @@ update_cxxflags() {
     # options which some versions of GCC's C++ compiler complain about
     # because they only make sense for C programs.
     QEMU_CXXFLAGS="$QEMU_CXXFLAGS -D__STDC_LIMIT_MACROS -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS"
-    CXXFLAGS=$(echo "$CFLAGS" | sed s/-std=gnu99/-std=gnu++11/)
+    CONFIGURE_CXXFLAGS=$(echo "$CONFIGURE_CFLAGS" | sed s/-std=gnu99/-std=gnu++11/)
     for arg in $QEMU_CFLAGS; do
         case $arg in
             -Wstrict-prototypes|-Wmissing-prototypes|-Wnested-externs|\
@@ -170,13 +170,14 @@ update_cxxflags() {
 
 compile_object() {
   local_cflags="$1"
-  do_cc $CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
+  do_cc $CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
 }
 
 compile_prog() {
   local_cflags="$1"
   local_ldflags="$2"
-  do_cc $CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC $LDFLAGS $QEMU_LDFLAGS $local_ldflags
+  do_cc $CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC \
+      $LDFLAGS $CONFIGURE_LDFLAGS $QEMU_LDFLAGS $local_ldflags
 }
 
 # symbolically link $1 to $2.  Portable version of "ln -sf".
@@ -537,7 +538,10 @@ QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
 QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
 QEMU_INCLUDES="-iquote . -iquote ${source_path} -iquote ${source_path}/accel/tcg -iquote ${source_path}/include"
 QEMU_INCLUDES="$QEMU_INCLUDES -iquote ${source_path}/disas/libvixl"
-CFLAGS="-std=gnu99 -Wall"
+
+# Flags that are needed during configure but later taken care of by Meson
+CONFIGURE_CFLAGS="-std=gnu99 -Wall"
+CONFIGURE_LDFLAGS=
 
 
 check_define() {
@@ -851,7 +855,7 @@ if test "$mingw32" = "yes" ; then
   EXESUF=".exe"
   HOST_DSOSUF=".dll"
   # MinGW needs -mthreads for TLS and macro _MT.
-  CFLAGS="-mthreads $CFLAGS"
+  CONFIGURE_CFLAGS="-mthreads $CONFIGURE_CFLAGS"
   write_c_skeleton;
   prefix="/qemu"
   qemu_suffix=""
@@ -2109,7 +2113,7 @@ fi
 
 if test "$static" = "yes"; then
   if test "$pie" != "no" && compile_prog "-Werror -fPIE -DPIE" "-static-pie"; then
-    CFLAGS="-fPIE -DPIE $CFLAGS"
+    CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
     QEMU_LDFLAGS="-static-pie $QEMU_LDFLAGS"
     pie="yes"
   elif test "$pie" = "yes"; then
@@ -2119,11 +2123,11 @@ if test "$static" = "yes"; then
     pie="no"
   fi
 elif test "$pie" = "no"; then
-  CFLAGS="$CFLAGS_NOPIE $CFLAGS"
-  LDFLAGS="$LDFLAGS_NOPIE $LDFLAGS"
+  CONFIGURE_CFLAGS="$CFLAGS_NOPIE $CONFIGURE_CFLAGS"
+  CONFIGURE_LDFLAGS="$LDFLAGS_NOPIE $CONFIGURE_LDFLAGS"
 elif compile_prog "-Werror -fPIE -DPIE" "-pie"; then
-  CFLAGS="-fPIE -DPIE $CFLAGS"
-  LDFLAGS="-pie $LDFLAGS"
+  CONFIGURE_CFLAGS="-fPIE -DPIE $CONFIGURE_CFLAGS"
+  CONFIGURE_LDFLAGS="-pie $CONFIGURE_LDFLAGS"
   pie="yes"
 elif test "$pie" = "yes"; then
   error_exit "PIE not available due to missing toolchain support"
@@ -3667,7 +3671,7 @@ EOF
 if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then
     if cc_has_warning_flag "-Wno-unknown-attributes"; then
         glib_cflags="-Wno-unknown-attributes $glib_cflags"
-        CFLAGS="-Wno-unknown-attributes $CFLAGS"
+        CONFIGURE_CFLAGS="-Wno-unknown-attributes $CONFIGURE_CFLAGS"
     fi
 fi
 
@@ -3687,7 +3691,7 @@ EOF
 if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then
     if cc_has_warning_flag "-Wno-unused-function"; then
         glib_cflags="$glib_cflags -Wno-unused-function"
-        CFLAGS="$CFLAGS -Wno-unused-function"
+        CONFIGURE_CFLAGS="$CONFIGURE_CFLAGS -Wno-unused-function"
     fi
 fi
 
@@ -5814,13 +5818,6 @@ elif test "$fortify_source" = "yes" ; then
   QEMU_CFLAGS="-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $QEMU_CFLAGS"
   debug=no
 fi
-if test "$debug_info" = "yes"; then
-  CFLAGS="-g $CFLAGS"
-  LDFLAGS="-g $LDFLAGS"
-fi
-if test "$debug" = "no"; then
-  CFLAGS="-O2 $CFLAGS"
-fi
 
 case "$ARCH" in
 alpha)
@@ -6043,7 +6040,7 @@ EOF
 
     update_cxxflags
 
-    if do_cxx $CXXFLAGS $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $QEMU_LDFLAGS; then
+    if do_cxx $CXXFLAGS $CONFIGURE_CXXFLAGS $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $QEMU_LDFLAGS; then
         # C++ compiler $cxx works ok with C compiler $cc
         :
     else
@@ -6953,7 +6950,6 @@ echo "RANLIB=$ranlib" >> $config_host_mak
 echo "NM=$nm" >> $config_host_mak
 echo "PKG_CONFIG=$pkg_config_exe" >> $config_host_mak
 echo "WINDRES=$windres" >> $config_host_mak
-echo "CFLAGS=$CFLAGS" >> $config_host_mak
 echo "CFLAGS_NOPIE=$CFLAGS_NOPIE" >> $config_host_mak
 echo "QEMU_CFLAGS=$QEMU_CFLAGS" >> $config_host_mak
 echo "QEMU_CXXFLAGS=$QEMU_CXXFLAGS" >> $config_host_mak
diff --git a/meson.build b/meson.build
index 426b73d31f..d9377f371d 100644
--- a/meson.build
+++ b/meson.build
@@ -1758,7 +1758,8 @@ if targetos == 'darwin'
   summary_info += {'Objective-C compiler': meson.get_compiler('objc').cmd_array()[0]}
 endif
 summary_info += {'ARFLAGS':           config_host['ARFLAGS']}
-summary_info += {'CFLAGS':            config_host['CFLAGS']}
+summary_info += {'CFLAGS':            '-O' + get_option('optimization')
+                                           + (get_option('debug') ? ' -g' : '')}
 summary_info += {'QEMU_CFLAGS':       config_host['QEMU_CFLAGS']}
 summary_info += {'QEMU_LDFLAGS':      config_host['QEMU_LDFLAGS']}
 summary_info += {'make':              config_host['MAKE']}
-- 
2.26.2