use clang-cl as build machine compiler

.github/workflows/build-and-test.yml

@@ -233,22 +233,31 @@ jobs:
         uses: ilammy/[email protected]
       - name: build
         run: |
-          if ("${{matrix.arch}}" -eq 'ARM64') {
-            $buildcc = "--native-file=.github/workflows/meson-vs-gcc.txt"
-            $hostarch = "--cross-file=.github/workflows/meson-vs-aarch64.txt"
-            $hostcc = "--cross-file=.github/workflows/meson-vs-${{matrix.cc}}.txt"
-            # clang-cl needs extra args to target a particular architecture.
-            $hostcc_args = if (${{matrix.cc}} -eq 'clang-cl') {
-              "--cross-file=.github/workflows/meson-vs-clang-cl-aarch64.txt"
+          if ("${{matrix.arch}}" -eq 'x64') { # Native compilation.
+            $hostcc = `
+              "--native-file=.github/workflows/meson-vs-${{matrix.cc}}.txt"
+          } else { # Cross compilation.
+            # The build machine compiler is always clang-cl, and it needs flags 
+            # to specify the build machine.
+            $buildcc = "--native-file=.github/workflows/meson-vs-clang-cl.txt"
+            $buildcc_args = "--native-file=meson-vs-clang-cl-amd64.txt"
+            # The host compiler could be clang-cl or cl
+            # clang-cl needs flags to target the host machine.
+            # cl already targets the host machine.
+            $hostcc = `
+              "--cross-file=.github/workflows/meson-vs-${{matrix.cc}}.txt"
+            if (${{matrix.cc}} -eq 'clang-cl') {
+              $hostcc_args = `
+                "--cross-file=.github/workflows/meson-vs-clang-cl-${{matrix.arch}}.txt"
+              $hostcc_arch = `
+                "--cross-file=.github/workflows/meson-vs-${{matrix.arch}}.txt"
             }
-          } else {
-            $hostcc = "--native-file=.github/workflows/meson-vs-${{matrix.cc}}.txt"
           }
           # Don't do debug builds because that triggers a Windows bug:
           # https://developercommunity.visualstudio.com/t/_setmaxstdio-hangs-the-program-if-the/10164855?space=62&q=setmaxstdio&viewtype=all
           meson setup build -Dbuildtype=release `
             -Db_vscrt=static_from_buildtype `
-            $buildcc $hostarch $hostcc $hostcc_args
+            $buildcc_args $buildcc $host_arch $hostcc_args $hostcc
           meson compile -C build
       - name: test
         run: meson test -C build

.github/workflows/meson-vs-clang-cl-ARM64.txt

@@ -0,0 +1,2 @@
+[constants]
+clang_cl_target = 'aarch64-win32-msvc'

.github/workflows/meson-vs-clang-cl-x64.txt

@@ -0,0 +1,2 @@
+[constants]
+clang_cl_target = 'x86_64-pc-windows-msvc'

.github/workflows/meson-vs-clang-cl.txt

@@ -1,5 +1,5 @@
 [binaries]
-c = 'clang-cl'
+c = ['clang-cl', '--target=' + clang_cl_target]
 c_ld = 'lld-link'
 cpp = c
 cpp_ld = c_ld