Fix the expansion of the Linux host arch matrix

Author: jakepetroules

.github/workflows/pull_request.yml

@@ -26,7 +26,6 @@ jobs:
     with:
       # Linux
       linux_os_versions: '["jammy", "rhel-ubi9", "amazonlinux2"]'
-      linux_host_archs: '["x86_64", "aarch64"]'
       linux_build_command: |
         cd tests/TestPackage
         swift build

.github/workflows/swift_package_test.yml

@@ -53,7 +53,11 @@ on:
       linux_host_archs:
         type: string
         description: "Linux arch list (JSON)"
-        default: "[\"x86_64\"]"
+        default: "[\"x86_64\", \"aarch64\"]"
+      linux_exclude_host_archs:
+        type: string
+        description: "Exclude Linux arch list (JSON)"
+        default: "[{\"arch\": \"aarch64\"}]"
       linux_static_sdk_versions:
         type: string
         description: "Static Linux Swift SDK version list (JSON)"
@@ -302,25 +306,47 @@ jobs:
         run: ${{ inputs.ios_build_command }} ${{ (contains(matrix.swift_version, 'nightly') && inputs.swift_nightly_flags) || inputs.swift_flags }}
         timeout-minutes: 60
 
+  define-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix_json: ${{ steps.set-matrix.outputs.matrix_json }}
+    steps:
+      - id: set-matrix
+        run: |
+          ARCHES=($(echo '${{ github.event.inputs.linux_host_archs }}' | jq -r '.[]'))
+
+          MATRIX=()
+          for a in "${ARCHES[@]}"; do
+            case $a in
+              x86_64) runner="ubuntu-24.04" ;;
+              aarch64) runner="ubuntu-24.04-arm" ;;
+              *) runner="ubuntu-24.04" ;;
+            esac
+            MATRIX+=("$(jq -nc --arg s "$s" --arg o "$o" --arg a "$a" --arg r "$runner" \
+              '{arch:$a,runner:$r}')")
+          done
+
+          # Combine array elements into JSON array
+          MATRIX_JSON=$(jq -nc '$ARGS.positional' --args "${MATRIX[@]}")
+          echo "matrix_json=$MATRIX_JSON" >> $GITHUB_OUTPUT
+
   linux-build:
     name: Linux (${{ matrix.swift_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})
+    needs: define-matrix
     runs-on: ${{ matrix.runner }}
     strategy:
       fail-fast: false
       matrix:
         swift_version: ${{ fromJson(inputs.linux_swift_versions) }}
         os_version: ${{ fromJson(inputs.linux_os_versions) }}
         arch: ${{ fromJson(inputs.linux_host_archs) }}
+        include: ${{ fromJson(needs.define-matrix.outputs.matrix_json) }}
         exclude:
           - ${{ fromJson(inputs.linux_exclude_swift_versions) }}
+          - ${{ fromJson(inputs.linux_exclude_host_archs) }}
           - ${{ fromJson((!inputs.enable_linux_checks && inputs.linux_swift_versions) || '[]') }}
           - ${{ fromJson((!inputs.enable_linux_checks && inputs.linux_os_versions) || '[]') }}
           - ${{ fromJson((!inputs.enable_linux_checks && inputs.linux_host_archs) || '[]') }}
-        include:
-          - arch: x86_64
-            runner: ubuntu-24.04
-          - arch: aarch64
-            runner: ubuntu-24.04-arm
     container:
       image: ${{ (contains(matrix.swift_version, 'nightly') && 'swiftlang/swift') || 'swift' }}:${{ matrix.swift_version }}-${{ matrix.os_version }}
     steps:
@@ -378,23 +404,21 @@ jobs:
 
   linux-static-sdk-build:
     name: Static Linux Swift SDK Build (${{ matrix.swift_version }} - ${{ matrix.os_version }} - ${{ matrix.arch }})
+    needs: define-matrix
     runs-on: ${{ matrix.runner }}
     strategy:
       fail-fast: false
       matrix:
         swift_version: ${{ fromJson(inputs.linux_static_sdk_versions) }}
         os_version: ${{ fromJson(inputs.linux_os_versions) }}
         arch: ${{ fromJson(inputs.linux_host_archs) }}
+        include: ${{ fromJson(needs.define-matrix.outputs.matrix_json) }}
         exclude:
           - ${{ fromJson(inputs.linux_static_sdk_exclude_swift_versions) }}
+          - ${{ fromJson(inputs.linux_exclude_host_archs) }}
           - ${{ fromJson((!inputs.enable_linux_static_sdk_build && inputs.linux_static_sdk_versions) || '[]') }}
           - ${{ fromJson((!inputs.enable_linux_static_sdk_build && inputs.linux_os_versions) || '[]') }}
           - ${{ fromJson((!inputs.enable_linux_static_sdk_build && inputs.linux_host_archs) || '[]') }}
-        include:
-          - arch: x86_64
-            runner: ubuntu-24.04
-          - arch: aarch64
-            runner: ubuntu-24.04-arm
     container:
       image: ${{ (contains(matrix.swift_version, 'nightly') && 'swiftlang/swift') || 'swift' }}:${{ matrix.swift_version }}-${{ matrix.os_version }}
     steps: