Do not fail rc file loading if we aren't in a workspace.

Fixes #5906, removes the assert that the workspace exists, which I incorrectly added in the fix to #4502.

RELNOTES: None.
PiperOrigin-RevId: 209424088

src/main/cpp/option_processor.cc

@@ -258,7 +258,6 @@ blaze_exit_code::ExitCode OptionProcessor::GetRcFiles(
     std::string* error) const {
   assert(cmd_line != nullptr);
   assert(result_rc_files != nullptr);
-  assert(!workspace.empty());
 
   std::vector<std::string> rc_files;
 
@@ -272,8 +271,11 @@ blaze_exit_code::ExitCode OptionProcessor::GetRcFiles(
     rc_files.push_back(system_rc);
   }
 
-  // Get the workspace rc: %workspace%/.bazelrc (unless --noworkspace_rc)
-  if (SearchNullaryOption(cmd_line->startup_args, "workspace_rc", true)) {
+  // Get the workspace rc: %workspace%/.bazelrc (unless --noworkspace_rc), but
+  // only if we are in a workspace: invoking commands like "help" from outside
+  // a workspace should work.
+  if (!workspace.empty() &&
+      SearchNullaryOption(cmd_line->startup_args, "workspace_rc", true)) {
     const std::string workspaceRcFile =
         blaze_util::JoinPath(workspace, kRcBasename);
     rc_files.push_back(workspaceRcFile);

src/main/cpp/option_processor.h

@@ -117,7 +117,8 @@ class OptionProcessor {
 
   // Finds and parses the appropriate RcFiles:
   //   - system rc (unless --nosystem_rc)
-  //   - workspace, %workspace%/.bazelrc (unless --noworkspace_rc)
+  //   - workspace, %workspace%/.bazelrc (unless --noworkspace_rc, or we aren't
+  //     in a workspace directory, indicated by an empty workspace parameter)
   //   - user, $HOME/.bazelrc (unless --nohome_rc)
   //   - command-line provided, if a value is passed with --bazelrc.
   virtual blaze_exit_code::ExitCode GetRcFiles(