[llvm] Fix assertion when stat fails in remove_directories

[benlangmuir]

Summary

We were dereferencing an empty Optional if IgnoreErrors was true and the
stat failed.

rdar://60887887

llvm/lib/Support/Unix/Path.inc

 static std::error_code remove_directories_impl(const T &Entry,
                                                bool IgnoreErrors) {
   std::error_code EC;
   directory_iterator Begin(Entry, EC, false);
   directory_iterator End;
   while (Begin != End) {
     auto &Item = *Begin;
     ErrorOr<basic_file_status> st = Item.status();
-    if (!st && !IgnoreErrors)
-      return st.getError();
-
+    if (st) {
       if (is_directory(*st)) {
         EC = remove_directories_impl(Item, IgnoreErrors);
         if (EC && !IgnoreErrors)
           return EC;
       }
 
       EC = fs::remove(Item.path(), true);
       if (EC && !IgnoreErrors)
         return EC;
+    } else if (!IgnoreErrors) {
+      return st.getError();
+    }
 
     Begin.increment(EC);
     if (EC && !IgnoreErrors)
       return EC;
   }
   return std::error_code();
 }
 

llvm/unittests/Support/Path.cpp

TEST_F(FileSystemTest, RealPathNoReadPerm) {
   fs::setPermissions(Twine(TestDirectory) + "/noreadperm", fs::no_perms);
   fs::setPermissions(Twine(TestDirectory) + "/noreadperm", fs::all_exe);
 
   ASSERT_NO_ERROR(fs::real_path(Twine(TestDirectory) + "/noreadperm", Expanded,
                                 false));
 
   ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) + "/noreadperm"));
 }
+TEST_F(FileSystemTest, RemoveDirectoriesNoExePerm) {
+  SmallString<64> Expanded;
+
+  ASSERT_NO_ERROR(
+      fs::create_directories(Twine(TestDirectory) + "/noexeperm/foo"));
+  ASSERT_TRUE(fs::exists(Twine(TestDirectory) + "/noexeperm/foo"));
+
+  fs::setPermissions(Twine(TestDirectory) + "/noexeperm",
+                     fs::all_read | fs::all_write);
+
+  ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
+                                         /*IgnoreErrors=*/true));
+  ASSERT_TRUE(fs::exists(Twine(TestDirectory) + "/noexeperm"));
+  ASSERT_EQ(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
+                                   /*IgnoreErrors=*/false),
+            errc::permission_denied);
+
+  fs::setPermissions(Twine(TestDirectory) + "/noexeperm", fs::all_perms);
+
+  ASSERT_NO_ERROR(fs::remove_directories(Twine(TestDirectory) + "/noexeperm",
+                                         /*IgnoreErrors=*/false));
+}
 #endif
 
 
 TEST_F(FileSystemTest, TempFileKeepDiscard) {
   // We can keep then discard.
   auto TempFileOrError = fs::TempFile::create(TestDirectory + "/test-%%%%");
   ASSERT_TRUE((bool)TempFileOrError);
   fs::TempFile File = std::move(*TempFileOrError);