Windows: Make environment variables case-insensitive when creating Wi…

…ndows process

If users pass the same environment variables with different cases,
the last one will override the previous ones.

Fixed #5285

Change-Id: Ieec857553bc54a4ad9809455687551303037e240
PiperOrigin-RevId: 198303684

src/main/java/com/google/devtools/build/lib/windows/WindowsSubprocessFactory.java

@@ -118,7 +118,7 @@ private String getSystemRoot(Map<String, String> env) {
    * Converts an environment map to the format expected in lpEnvironment by CreateProcess().
    */
   private byte[] convertEnvToNative(Map<String, String> env) throws IOException {
-    Map<String, String> realEnv = new TreeMap<>();
+    Map<String, String> realEnv = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
     realEnv.putAll(env == null ? System.getenv() : env);
     if (getSystemRoot(realEnv) == null) {
       // Some versions of MSVCRT.DLL require SystemRoot to be set. It's quite a common library to

src/test/py/bazel/bazel_windows_test.py

@@ -111,6 +111,38 @@ def testWindowsCompilesAssembly(self):
     self.AssertExitCode(exit_code, 0, stderr)
     self.assertTrue(os.path.exists(os.path.join(bazel_bin, 'x.exe')))
 
+  def testWindowsEnvironmentVariablesSetting(self):
+    self.ScratchFile('BUILD')
+    self.ScratchFile('WORKSPACE', [
+        'load(":repo.bzl", "my_repo")',
+        'my_repo(name = "env_test")',
+    ])
+    self.ScratchFile('repo.bzl', [
+        'def my_repo_impl(repository_ctx):',
+        '  repository_ctx.file("env.bat", "set FOO\\n")',
+        '  env = {"foo" : "bar2", "Foo": "bar3",}',
+        '  result = repository_ctx.execute(["./env.bat"], environment = env)',
+        '  print(result.stdout)',
+        '  repository_ctx.file("BUILD")',
+        '',
+        'my_repo = repository_rule(',
+        '    implementation = my_repo_impl,',
+        ')',
+    ])
+
+    exit_code, _, stderr = self.RunBazel(
+        [
+            'build',
+            '@env_test//...',
+        ],
+        env_add={'FOO': 'bar1'},
+    )
+    self.AssertExitCode(exit_code, 0, stderr)
+    result_in_lower_case = ''.join(stderr).lower()
+    self.assertNotIn('foo=bar1', result_in_lower_case)
+    self.assertNotIn('foo=bar2', result_in_lower_case)
+    self.assertIn('foo=bar3', result_in_lower_case)
+
 
 if __name__ == '__main__':
   unittest.main()