Fix pip cache error handling on Windows. (#1040)

* Add error handling for Windows 'pip cache dir' execution

* Add comments

dist/setup/index.js

@@ -54331,24 +54331,29 @@ class PipCache extends cache_distributor_1.default {
         this.pythonVersion = pythonVersion;
     }
     async getCacheGlobalDirectories() {
-        let exitCode = 1;
+        let exitCode = 0;
         let stdout = '';
         let stderr = '';
         // Add temporary fix for Windows
-        // On windows it is necessary to execute through an exec
-        // because the getExecOutput gives a non zero code or writes to stderr for pip 22.0.2,
+        // On Windows, it is necessary to execute through an exec
+        // because the getExecOutput gives a non-zero code or writes to stderr for pip 22.0.2,
         // or spawn must be started with the shell option enabled for getExecOutput
         // Related issue: https://github.com/actions/setup-python/issues/328
         if (utils_1.IS_WINDOWS) {
             const execPromisify = util_1.default.promisify(child_process.exec);
-            ({ stdout: stdout, stderr: stderr } = await execPromisify('pip cache dir'));
+            try {
+                ({ stdout, stderr } = await execPromisify('pip cache dir'));
+            }
+            catch (err) {
+                // Pip outputs warnings to stderr (e.g., --no-python-version-warning flag deprecation warning), causing false failure detection
+                // Related issue: https://github.com/actions/setup-python/issues/1034
+                // If an error occurs, capture stderr and set exitCode to 1 to indicate failure
+                stderr = err.stderr ?? err.message;
+                exitCode = 1;
+            }
         }
         else {
-            ({
-                stdout: stdout,
-                stderr: stderr,
-                exitCode: exitCode
-            } = await exec.getExecOutput('pip cache dir'));
+            ({ stdout, stderr, exitCode } = await exec.getExecOutput('pip cache dir'));
         }
         if (exitCode && stderr) {
             throw new Error(`Could not get cache folder path for pip package manager`);

src/cache-distributions/pip-cache.ts

@@ -21,24 +21,28 @@ class PipCache extends CacheDistributor {
   }
 
   protected async getCacheGlobalDirectories() {
-    let exitCode = 1;
+    let exitCode = 0;
     let stdout = '';
     let stderr = '';
 
     // Add temporary fix for Windows
-    // On windows it is necessary to execute through an exec
-    // because the getExecOutput gives a non zero code or writes to stderr for pip 22.0.2,
+    // On Windows, it is necessary to execute through an exec
+    // because the getExecOutput gives a non-zero code or writes to stderr for pip 22.0.2,
     // or spawn must be started with the shell option enabled for getExecOutput
     // Related issue: https://github.com/actions/setup-python/issues/328
     if (IS_WINDOWS) {
       const execPromisify = utils.promisify(child_process.exec);
-      ({stdout: stdout, stderr: stderr} = await execPromisify('pip cache dir'));
+      try {
+        ({stdout, stderr} = await execPromisify('pip cache dir'));
+      } catch (err) {
+        // Pip outputs warnings to stderr (e.g., --no-python-version-warning flag deprecation warning), causing false failure detection
+        // Related issue: https://github.com/actions/setup-python/issues/1034
+        // If an error occurs, capture stderr and set exitCode to 1 to indicate failure
+        stderr = (err as any).stderr ?? (err as Error).message;
+        exitCode = 1;
+      }
     } else {
-      ({
-        stdout: stdout,
-        stderr: stderr,
-        exitCode: exitCode
-      } = await exec.getExecOutput('pip cache dir'));
+      ({stdout, stderr, exitCode} = await exec.getExecOutput('pip cache dir'));
     }
 
     if (exitCode && stderr) {