Windows, native launcher: Rlocation knows external

The native launcher's own Rlocation()
implementation correctly handles runfile paths
that start with "external/".

Fixes #7809

This PR subsumes #7853.
That PR changed the launcher to use the C++
runfiles library. Alas that broke some tests.

Closes #7873.

PiperOrigin-RevId: 240782949

src/tools/launcher/java_launcher.cc

@@ -301,7 +301,7 @@ ExitCode JavaBinaryLauncher::Launch() {
 
   // Print Java binary path if needed
   wstring java_bin = this->Rlocation(this->GetLaunchInfoByKey(JAVA_BIN_PATH),
-                                     /*need_workspace_name =*/false);
+                                     /*has_workspace_name =*/true);
   if (this->print_javabin ||
       this->GetLaunchInfoByKey(JAVA_START_CLASS) == L"--print_javabin") {
     wprintf(L"%s\n", java_bin.c_str());

src/tools/launcher/launcher.cc

@@ -139,42 +139,35 @@ void BinaryLauncherBase::ParseManifestFile(ManifestFileMap* manifest_file_map,
   }
 }
 
-wstring BinaryLauncherBase::Rlocation(const wstring& path,
-                                      bool need_workspace_name) const {
+wstring BinaryLauncherBase::Rlocation(wstring path,
+                                      bool has_workspace_name) const {
   // No need to do rlocation if the path is absolute.
   if (blaze_util::IsAbsolute(path)) {
     return path;
   }
 
+  if (path.find(L"external/") == 0) {
+    // Ignore 'has_workspace_name' when the path is under "external/". Such
+    // paths already have a workspace name in the next path component.
+    path = path.substr(9);
+  } else if (!has_workspace_name) {
+    path = this->workspace_name + L"/" + path;
+  }
+
   // If the manifest file map is empty, then we're using the runfiles directory
   // instead.
   if (manifest_file_map.empty()) {
-    wstring query_path = runfiles_dir;
-    if (need_workspace_name) {
-      query_path += L"/" + this->workspace_name;
-    }
-    query_path += L"/" + path;
-    return query_path;
+    return runfiles_dir + L"/" + path;
   }
 
-  wstring query_path = path;
-  if (need_workspace_name) {
-    query_path = this->workspace_name + L"/" + path;
-  }
-  auto entry = manifest_file_map.find(query_path);
+  auto entry = manifest_file_map.find(path);
   if (entry == manifest_file_map.end()) {
     die(L"Rlocation failed on %s, path doesn't exist in MANIFEST file",
-        query_path.c_str());
+        path.c_str());
   }
   return entry->second;
 }
 
-wstring BinaryLauncherBase::Rlocation(const string& path,
-                                      bool need_workspace_name) const {
-  return this->Rlocation(blaze_util::CstringToWstring(path),
-                         need_workspace_name);
-}
-
 wstring BinaryLauncherBase::GetLaunchInfoByKey(const string& key) {
   auto item = launch_info.find(key);
   if (item == launch_info.end()) {

src/tools/launcher/launcher.h

@@ -54,14 +54,13 @@ class BinaryLauncherBase {
 
   // Map a runfile path to its absolute path.
   //
-  // If need_workspace_name is true, then this method prepend workspace name to
-  // path before doing rlocation.
-  // If need_workspace_name is false, then this method uses path directly.
-  // The default value of need_workspace_name is true.
-  std::wstring Rlocation(const std::wstring& path,
-                         bool need_workspace_name = true) const;
-  std::wstring Rlocation(const std::string& path,
-                         bool need_workspace_name = true) const;
+  // 'has_workspace_name' indicates whether 'path' already starts with the
+  // runfile's workspace name. (This is implicitly true when 'path' is under
+  // "external/".) If the path does not have a workspace name (and does not
+  // start with "external/"), this method prepends the main repository's name to
+  // it before looking up the runfile.
+  std::wstring Rlocation(std::wstring path,
+                         bool has_workspace_name = false) const;
 
   // Lauch a process with given executable and command line arguments.
   // If --print_launcher_command exists in arguments, then we print the full