WIP: Fixup for !1

Author: tbirdso

action.yml

@@ -1,10 +1,6 @@
 name: 'Build, test, package'
 description: 'Build, test, and package distributions for an ITK external module.'
 inputs:
-  c-compiler:
-    required: true
-  cxx-compiler:
-    required: true
   cmake-build-type:
     required: false
     default: 'MinSizeRel'
@@ -23,6 +19,30 @@ inputs:
 runs:
   using: "composite"
   steps:
+    - name: Define OS-dependent environment variables
+      if: runner.os == 'Windows'
+      shell: bash
+      run: |
+        echo "C_COMPILER=gcc" >> $GITHUB_ENV       # defines env.C_COMPILER
+        echo "CXX_COMPILER=g++" >> $GITHUB_ENV     # defines env.CXX_COMPILER
+        echo "Set env.C_COMPILER=${{ env.C_COMPILER}} and env.CXX_COMPILER=${{ env.CXX_COMPILER }}"
+
+    - name: Define OS-dependent environment variables
+      if: runner.os == 'macOS'
+      shell: bash
+      run: |
+        echo "C_COMPILER=clang" >> $GITHUB_ENV
+        echo "CXX_COMPILER=clang++" >> $GITHUB_ENV
+        echo "Set env.C_COMPILER=${{ env.C_COMPILER}} and env.CXX_COMPILER=${{ env.CXX_COMPILER }}"
+
+    - name: Define OS-dependent environment variables
+      if: ${{ runner.os != 'Windows' && runner.os != 'macOS' }}   # default to Linux
+      shell: bash
+      run: |
+        echo "C_COMPILER=clang" >> $GITHUB_ENV
+        echo "CXX_COMPILER=clang++" >> $GITHUB_ENV
+        echo "Set env.C_COMPILER=${{ env.C_COMPILER}} and env.CXX_COMPILER=${{ env.CXX_COMPILER }}"
+
     - name: Set up Python 3.8
       uses: actions/setup-python@v2
       with:
@@ -54,7 +74,7 @@ runs:
         cd ..
         mkdir ITK-build
         cd ITK-build
-        cmake -DCMAKE_C_COMPILER:FILEPATH="${{ inputs.c-compiler }}" -DBUILD_SHARED_LIBS:BOOL=ON -DCMAKE_CXX_COMPILER="${{ inputs.cxx-compiler }}" -DCMAKE_BUILD_TYPE:STRING=${{ inputs.cmake-build-type }} -DBUILD_TESTING:BOOL=OFF ${{ inputs.itk-cmake-options }} -GNinja ../ITK
+        cmake -DCMAKE_C_COMPILER:FILEPATH="${{ env.C_COMPILER }}" -DBUILD_SHARED_LIBS:BOOL=ON -DCMAKE_CXX_COMPILER="${{ env.CXX_COMPILER }}" -DCMAKE_BUILD_TYPE:STRING=${{ inputs.cmake-build-type }} -DBUILD_TESTING:BOOL=OFF ${{ inputs.itk-cmake-options }} -GNinja ../ITK
         ninja
 
     - name: Build ITK
@@ -65,7 +85,7 @@ runs:
         mkdir ITK-build
         cd ITK-build
         call "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Auxiliary\Build\vcvars64.bat"
-        cmake -DCMAKE_C_COMPILER:FILEPATH="${{ inputs.c-compiler }}" -DBUILD_SHARED_LIBS:BOOL=ON -DCMAKE_CXX_COMPILER="${{ inputs.cxx-compiler }}" -DCMAKE_BUILD_TYPE:STRING=${{ inputs.cmake-build-type }} -DBUILD_TESTING:BOOL=OFF ${{ inputs.itk-cmake-options }} -GNinja ../ITK
+        cmake -DCMAKE_C_COMPILER:FILEPATH="${{ env.C_COMPILER }}" -DBUILD_SHARED_LIBS:BOOL=ON -DCMAKE_CXX_COMPILER="${{ env.CXX_COMPILER }}" -DCMAKE_BUILD_TYPE:STRING=${{ inputs.cmake-build-type }} -DBUILD_TESTING:BOOL=OFF ${{ inputs.itk-cmake-options }} -GNinja ../ITK
         ninja
 
     - name: Fetch CTest driver script
@@ -102,8 +122,8 @@ runs:
           "ld: warning: text-based stub file"
           )
         set(dashboard_no_clean 1)
-        set(ENV{CC} ${{ inputs.c-compiler }})
-        set(ENV{CXX} ${{ inputs.cxx-compiler }})
+        set(ENV{CC} ${{ env.C_COMPILER }})
+        set(ENV{CXX} ${{ env.CXX_COMPILER }})
         if(WIN32)
           set(ENV{PATH} "\${CTEST_DASHBOARD_ROOT}/ITK-build/bin;\$ENV{PATH}")
         endif()