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

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

[Owen LaGarde]

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Am I using --extra-cflags and --extra-ldflags wrong in the configure call?

I'd like to source build several pre-reqs specific to supporting the qemu
source
build.  I'd specifically not like to install neither the qemu or re-req
builds
at the system level.  Normally I'd expect the --extra-cflags and
--extra-ldflags
configure options to do this but they do not appear to propagate to meson.
There
was an approved meson patch back in 2018 for extra-cflags / extra-ldflags
and qemu
is currently using meson >5.8(?) but it doesn't look like configure is
adding the
args anywhere in the build tree.  There are a number of ways to do this,
what's
appropriate / future-proof wrt building qemu from source?  And why is
configure
supporting --extra-[c,ld]args but not doing anything with the values?

---------

As an example assume I've installed lzfse from source with a homedir
prefix, no
other copies elsewhere, no ldconfig reference, no associated env vars, and
force
the qemu build to require it.  Yeah, but this is just an dumb example.

    $ ls -l ~/include/* ~/lib/*
    /home/olagarde/include/lzfse.h
    /home/olagarde/lib/liblzfse.so

    $ env |grep -i flags

    $ set |grep -i flags

        local flags_color="$c_lblue";
            s="$flags_color$s";

    $ git clone https://gitlab.com/qemu-project/qemu.git

        <...snipsnip...>

    $ mkdir qemu/build && cd qemu/build

    $ ../configure --prefix=/home/olagarde \
        --extra-cflags="-I /home/olagarde/include" \
        --extra-ldflags="-L /home/olagarde/lib" \
        --enable-lzfse

        <...snipsnip...>
        ../meson.build:898:2: ERROR: C header 'lzfse.h' not found
        A full log can be found at {a_really_long_path}meson-log.txt
        ERROR: meson setup failed

Per the meson logs the command was

    cc -m64 -mcx16 {a_really_long_path}testfile.c -E -P \
        -D_FILE_OFFSET_BITS=64 -P -O0 -std=gnu11

and the testfile.c was

    #ifdef __has_include
     #if !__has_include("lzfse.h")
      #error "Header 'lzfse.h' could not be found"
     #endif
    #else
     #include <lzfse.h>
    #endif

which obviously should fail exactly as it did, but should and does succeed
if the --extra-cflags value is added to the cc call.

All four args arrays in the config-meson.cross are empty so configure
didn't pass the cli extra-args in?  Also 'find' doesn't report any files
in the tree containing /home/olagarde/include or /home/olagarde/lib, so
the option values passed to configure never made it into mesa (or anything
else)?

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

[Thomas Huth]

On 22/10/2021 13.20, Owen LaGarde wrote:
> Am I using --extra-cflags and --extra-ldflags wrong in the configure call?
> 
> I'd like to source build several pre-reqs specific to supporting the qemu source
> build.  I'd specifically not like to install neither the qemu or re-req builds
> at the system level.  Normally I'd expect the --extra-cflags and --extra-ldflags
> configure options to do this but they do not appear to propagate to meson.  
> There
> was an approved meson patch back in 2018 for extra-cflags / extra-ldflags 
> and qemu
> is currently using meson >5.8(?) but it doesn't look like configure is 
> adding the
> args anywhere in the build tree.  There are a number of ways to do this, what's
> appropriate / future-proof wrt building qemu from source?  And why is configure
> supporting --extra-[c,ld]args but not doing anything with the values?

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?

  Thomas


PS: As a work-around, it seems to be fine to pass the flags via the CFLAGS 
environment variable instead:

CFLAGS=-I/path/to/netmap/sys .../configure --enable-netmap

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

[Paolo Bonzini]

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