Change how rust target works

Author: alexcrichton

.github/workflows/main.yml

@@ -90,11 +90,9 @@ jobs:
           - arch: x64
             sys: clang64
             env: clang-x86_64
-            rust_target: x86_64-pc-windows-msvc
           - arch: x86
             sys: clang32
             env: clang-i686
-            rust_target: i686-pc-windows-msvc
     steps:
       - uses: actions/cache@v3
         with:
@@ -122,7 +120,13 @@ jobs:
       - name: Build
         shell: msys2 {0}
         run: |
-          make package LLVM_CMAKE_FLAGS=-DLLVM_CCACHE_BUILD=ON RUST_TARGET=${{ matrix.rust_target }}
+          if [ ${{ matrix.arch }} = x64 ]; then
+            export RUST_TARGET=x86_64-pc-windows-msvc
+          else
+            export RUST_TARGET=i686-pc-windows-msvc
+          fi
+          rustup target add $RUST_TARGET
+          make package LLVM_CMAKE_FLAGS=-DLLVM_CCACHE_BUILD=ON
           make check
       - name: Does it work sans msys2?
         run: |