Re: [PATCH RESEND v9 3/9] configure, meson: detect Rust toolchain

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Aug 28, 2024 at 07:11:44AM +0300, Manos Pitsidianakis wrote:
> From: Paolo Bonzini <pbonzini@redhat.com>
> 
> Include the correct path and arguments to rustc in the native
> and cross files (native compilation is needed for procedural
> macros).
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  configure   | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
>  meson.build |  8 +++-----
>  2 files changed, 51 insertions(+), 7 deletions(-)
> 
> diff --git a/configure b/configure
> index 019fcbd0ef7b07e7b0280b358099cae72c73aa98..9ef6005c557fc627c7c6c732b4c92ed1b934f474 100755
> --- a/configure
> +++ b/configure
> @@ -207,6 +207,8 @@ for opt do
>    ;;
>    --objcc=*) objcc="$optarg"
>    ;;
> +  --rustc=*) RUSTC="$optarg"
> +  ;;
>    --cpu=*) cpu="$optarg"
>    ;;
>    --extra-cflags=*)
> @@ -252,6 +254,9 @@ python=
>  download="enabled"
>  skip_meson=no
>  use_containers="yes"
> +# do not enable by default because cross compilation requires --rust-target-triple
> +rust="disabled"
> +rust_target_triple=""
>  gdb_bin=$(command -v "gdb-multiarch" || command -v "gdb")
>  gdb_arches=""
>  
> @@ -317,6 +322,8 @@ windmc="${WINDMC-${cross_prefix}windmc}"
>  pkg_config="${PKG_CONFIG-${cross_prefix}pkg-config}"
>  sdl2_config="${SDL2_CONFIG-${cross_prefix}sdl2-config}"
>  
> +rustc="${RUSTC-rustc}"
> +
>  check_define() {
>  cat > $TMPC <<EOF
>  #if !defined($1)
> @@ -636,6 +643,8 @@ for opt do
>    ;;
>    --objcc=*)
>    ;;
> +  --rustc=*)
> +  ;;
>    --make=*)
>    ;;
>    --install=*)
> @@ -755,8 +764,14 @@ for opt do
>    ;;
>    --container-engine=*) container_engine="$optarg"
>    ;;
> +  --rust-target-triple=*) rust_target_triple="$optarg"
> +  ;;
>    --gdb=*) gdb_bin="$optarg"
>    ;;
> +  --enable-rust) rust=enabled
> +  ;;
> +  --disable-rust) rust=disabled
> +  ;;
>    # everything else has the same name in configure and meson
>    --*) meson_option_parse "$opt" "$optarg"
>    ;;
> @@ -859,6 +874,7 @@ Advanced options (experts only):
>                             at build time [$host_cc]
>    --cxx=CXX                use C++ compiler CXX [$cxx]
>    --objcc=OBJCC            use Objective-C compiler OBJCC [$objcc]
> +  --rustc=RUSTC            use Rust compiler RUSTC [$rustc]
>    --extra-cflags=CFLAGS    append extra C compiler flags CFLAGS
>    --extra-cxxflags=CXXFLAGS append extra C++ compiler flags CXXFLAGS
>    --extra-objcflags=OBJCFLAGS append extra Objective C compiler flags OBJCFLAGS
> @@ -869,8 +885,9 @@ Advanced options (experts only):
>    --python=PYTHON          use specified python [$python]
>    --ninja=NINJA            use specified ninja [$ninja]
>    --static                 enable static build [$static]
> -  --without-default-features default all --enable-* options to "disabled"
> -  --without-default-devices  do not include any device that is not needed to
> +  --rust-target-triple=TRIPLE  target for Rust cross compilation
> +  --without-default-features   default all --enable-* options to "disabled"
> +  --without-default-devices    do not include any device that is not needed to
>                             start the emulator (only use if you are including
>                             desired devices in configs/devices/)
>    --with-devices-ARCH=NAME override default configs/devices
> @@ -1139,6 +1156,21 @@ EOF
>  fi
>  
>  ##########################################
> +# detect rust triple
> +
> +if test "$rust" != disabled && has "$rustc" && $rustc -vV > "${TMPDIR1}/${TMPB}.out"; then
> +  rust_host_triple=$(sed -n 's/^host: //p' "${TMPDIR1}/${TMPB}.out")
> +else
> +  if test "$rust" = enabled; then
> +    error_exit "could not execute rustc binary \"$rustc\""
> +  fi
> +  rust=disabled
> +fi
> +if test "$rust" != disabled && test -z "$rust_target_triple"; then
> +  rust_target_triple=$rust_host_triple
> +fi

Defaulting to the $rust_host_triple is incorrect when QEMU has been
told to build for a non-host target.

Either we need todo the right thing and auto-set rust target based
on QEMU target (preferred), or we need to make it a fatal error
when rust target is omitted & QEMU is building a non-host target.


With regards,
Daniel
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