add probing for x64 msbuild binaries

action.yml

@@ -14,6 +14,10 @@ inputs:
   vs-prerelease:
     description: 'Enable searching for pre-release versions of Visual Studio/MSBuild'
     required: false
+  msbuild-architecture:
+    description: 'The processor architecture to prefer of msbuild. Can be either "x86" or "x64". "x64" is only available from Visual Studio version 17.0 an onwards.'
+    required: false
+    default: 'x86'
 outputs:
   msbuildPath:
     description: 'The resulting location of msbuild for your inputs'

src/main.ts

@@ -9,6 +9,7 @@ const IS_WINDOWS = process.platform === 'win32'
 const VS_VERSION = core.getInput('vs-version') || 'latest'
 const VSWHERE_PATH = core.getInput('vswhere-path')
 const ALLOW_PRERELEASE = core.getInput('vs-prerelease') || 'false'
+const MSBUILD_ARCH = core.getInput('msbuild-architecture') || 'x86';
 
 // if a specific version of VS is requested
 let VSWHERE_EXEC = '-products * -requires Microsoft.Component.MSBuild -property installationPath -latest '
@@ -70,6 +71,18 @@ async function run(): Promise<void> {
         const installationPath = data.toString().trim()
         core.debug(`Found installation path: ${installationPath}`)
 
+        // x64 only exists in one possible location, so no fallback probing
+        if(MSBUILD_ARCH === "x64") {
+          let toolPath = path.join(
+            installationPath,
+            'MSBuild\\Current\\Bin\\amd64\\MSBuild.exe'
+          );
+          core.debug(`Checking for path: ${toolPath}`)
+          if (!fs.existsSync(toolPath)) {
+            return
+          }
+          foundToolPath = toolPath
+        } else {
           let toolPath = path.join(
             installationPath,
             'MSBuild\\Current\\Bin\\MSBuild.exe'
@@ -91,6 +104,7 @@ async function run(): Promise<void> {
           foundToolPath = toolPath
         }
       }
+    }
 
     // execute the find putting the result of the command in the options foundToolPath
     await exec.exec(`"${vswhereToolExe}" ${VSWHERE_EXEC}`, [], options)