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 019fcbd0ef..9ef6005c55 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
+
+##########################################
 # functions to probe cross compilers
 
 container="no"
@@ -1604,6 +1636,9 @@ if test "$container" != no; then
     echo "RUNC=$runc" >> $config_host_mak
 fi
 echo "SUBDIRS=$subdirs" >> $config_host_mak
+if test "$rust" != disabled; then
+  echo "RUST_TARGET_TRIPLE=$rust_target_triple" >> $config_host_mak
+fi
 echo "PYTHON=$python" >> $config_host_mak
 echo "MKVENV_ENSUREGROUP=$mkvenv ensuregroup $mkvenv_online_flag" >> $config_host_mak
 echo "GENISOIMAGE=$genisoimage" >> $config_host_mak
@@ -1735,6 +1770,13 @@ if test "$skip_meson" = no; then
   echo "c = [$(meson_quote $cc $CPU_CFLAGS)]" >> $cross
   test -n "$cxx" && echo "cpp = [$(meson_quote $cxx $CPU_CFLAGS)]" >> $cross
   test -n "$objcc" && echo "objc = [$(meson_quote $objcc $CPU_CFLAGS)]" >> $cross
+  if test "$rust" != disabled; then
+    if test "$rust_host_triple" != "$rust_target_triple"; then
+      echo "rust = [$(meson_quote $rustc --target "$rust_target_triple")]" >> $cross
+    else
+      echo "rust = [$(meson_quote $rustc)]" >> $cross
+    fi
+  fi
   echo "ar = [$(meson_quote $ar)]" >> $cross
   echo "dlltool = [$(meson_quote $dlltool)]" >> $cross
   echo "nm = [$(meson_quote $nm)]" >> $cross
@@ -1770,6 +1812,9 @@ if test "$skip_meson" = no; then
     echo "# Automatically generated by configure - do not modify" > $native
     echo "[binaries]" >> $native
     echo "c = [$(meson_quote $host_cc)]" >> $native
+    if test "$rust" != disabled; then
+      echo "rust = [$(meson_quote $rustc)]" >> $cross
+    fi
     mv $native config-meson.native
     meson_option_add --native-file
     meson_option_add config-meson.native
@@ -1788,6 +1833,7 @@ if test "$skip_meson" = no; then
   test "$pie" = no && meson_option_add -Db_pie=false
 
   # QEMU options
+  test "$rust" != "auto" && meson_option_add "-Drust=$rust"
   test "$cfi" != false && meson_option_add "-Dcfi=$cfi" "-Db_lto=$cfi"
   test "$docs" != auto && meson_option_add "-Ddocs=$docs"
   test -n "${LIB_FUZZING_ENGINE+xxx}" && meson_option_add "-Dfuzzing_engine=$LIB_FUZZING_ENGINE"
diff --git a/meson.build b/meson.build
index 67eb4eda64..065739ccb7 100644
--- a/meson.build
+++ b/meson.build
@@ -70,9 +70,6 @@ if host_os == 'darwin' and \
   all_languages += ['objc']
   objc = meson.get_compiler('objc')
 endif
-if get_option('rust').enabled() and meson.version().version_compare('<1.0.0')
-  error('Rust support requires Meson version >=1.0.0')
-endif
 have_rust = false
 if not get_option('rust').disabled() and add_languages('rust', required: get_option('rust'), native: false)
   rustc = meson.get_compiler('rust')
@@ -4307,8 +4304,9 @@ else
 endif
 summary_info += {'Rust support':      have_rust}
 if have_rust
-  summary_info += {'rustc version':      rustc.version()}
-  summary_info += {'rustc':      ' '.join(rustc.cmd_array())}
+  summary_info += {'rustc version':   rustc.version()}
+  summary_info += {'rustc':           ' '.join(rustc.cmd_array())}
+  summary_info += {'Rust target':     config_host['RUST_TARGET_TRIPLE']}
 endif
 option_cflags = (get_option('debug') ? ['-g'] : [])
 if get_option('optimization') != 'plain'

-- 
2.44.0