Re: configure --extra-cflags and --extra-ldflags values not propagating to meson?

[Paolo Bonzini <pbonzini@redhat.com>]

On 25/10/21 15:10, Thomas Huth wrote:
> 
> I see a similar behavior with netmap now - I've got the corresponding 
> header file in a non-standard directory, and up to commit 
> 837b84b1c078bf3e909 it used to work fine to do:
> 
> .../configure --enable-netmap \
>      --extra-cflags=-I/path/to/netmap/sys
> 
> but since the conversion to meson, this does not seem to work anymore.
> 
> Paolo, any ideas?

Meson (intentionally) does not add QEMU_CFLAGS to cc.compiles/cc.links
tests, as they are supposed to be  independent.  This however is not
true of CFLAGS.

The fix should be to add --extra-cflags/--extra-ldflags to the c_args
and c_link_args of config-meson.cross, instead of adding them to
QEMU_CFLAGS/QEMU_LDFLAGS:

diff --git a/configure b/configure
index 99051f3254..94224b9931 100755
--- a/configure
+++ b/configure
@@ -174,14 +174,14 @@ update_cxxflags() {
  
  compile_object() {
    local_cflags="$1"
-  do_cc $CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
+  do_cc $CFLAGS $EXTRA_CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -c -o $TMPO $TMPC
  }
  
  compile_prog() {
    local_cflags="$1"
    local_ldflags="$2"
-  do_cc $CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC \
-      $LDFLAGS $CONFIGURE_LDFLAGS $QEMU_LDFLAGS $local_ldflags
+  do_cc $CFLAGS $EXTRA_CFLAGS $CONFIGURE_CFLAGS $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC \
+      $LDFLAGS $EXTRA_LDFLAGS $CONFIGURE_LDFLAGS $QEMU_LDFLAGS $local_ldflags
  }
  
  # symbolically link $1 to $2.  Portable version of "ln -sf".
@@ -285,6 +285,9 @@ for opt do
    esac
  done
  
+EXTRA_CFLAGS=""
+EXTRA_LDFLAGS=""
+
  xen_ctrl_version="$default_feature"
  xfs="$default_feature"
  membarrier="$default_feature"
@@ -357,13 +360,11 @@ for opt do
    ;;
    --cpu=*) cpu="$optarg"
    ;;
-  --extra-cflags=*) QEMU_CFLAGS="$QEMU_CFLAGS $optarg"
-                    QEMU_LDFLAGS="$QEMU_LDFLAGS $optarg"
+  --extra-cflags=*) EXTRA_CFLAGS="$EXTRA_CFLAGS $optarg"
    ;;
    --extra-cxxflags=*) QEMU_CXXFLAGS="$QEMU_CXXFLAGS $optarg"
    ;;
-  --extra-ldflags=*) QEMU_LDFLAGS="$QEMU_LDFLAGS $optarg"
-                     EXTRA_LDFLAGS="$optarg"
+  --extra-ldflags=*) EXTRA_LDFLAGS="$EXTRA_LDFLAGS $optarg"
    ;;
    --enable-debug-info) debug_info="yes"
    ;;
@@ -3508,10 +3509,10 @@ if test "$skip_meson" = no; then
  
    test -z "$cxx" && echo "link_language = 'c'" >> $cross
    echo "[built-in options]" >> $cross
-  echo "c_args = [${CFLAGS:+$(meson_quote $CFLAGS)}]" >> $cross
-  echo "cpp_args = [${CXXFLAGS:+$(meson_quote $CXXFLAGS)}]" >> $cross
-  echo "c_link_args = [${LDFLAGS:+$(meson_quote $LDFLAGS)}]" >> $cross
-  echo "cpp_link_args = [${LDFLAGS:+$(meson_quote $LDFLAGS)}]" >> $cross
+  echo "c_args = [${CFLAGS:+$(meson_quote $CFLAGS $EXTRA_CFLAGS)}]" >> $cross
+  echo "cpp_args = [${CXXFLAGS:+$(meson_quote $CXXFLAGS $EXTRA_CFLAGS)}]" >> $cross
+  echo "c_link_args = [${LDFLAGS:+$(meson_quote $LDFLAGS $EXTRA_LDFLAGS)}]" >> $cross
+  echo "cpp_link_args = [${LDFLAGS:+$(meson_quote $LDFLAGS $EXTRA_LDFLAGS)}]" >> $cross
    echo "[binaries]" >> $cross
    echo "c = [$(meson_quote $cc $CPU_CFLAGS)]" >> $cross
    test -n "$cxx" && echo "cpp = [$(meson_quote $cxx $CPU_CFLAGS)]" >> $cross

except that I haven't figured out the exact (current) behavior of
--extra-cxxflags.  Also, it would require a re-configure of any tree that
includes --extra-cflags or --extra-ldflags.

Thanks,

Paolo