[clang][cli] Ensure plugin args are generated in deterministic order

[jansvoboda11]

Summary

The '-plugin-arg' command-line arguments are not being generated in deterministic order.

This patch changes the storage from std::unordered_map to std::map to enforce ordering.

[dexonsmith]

LGTM. Based on git-blame, this was added in 6c78974b298d619ec11e243fb6fdea0b16f87a66 (https://reviews.llvm.org/D17959) and the choice of unordered vs. ordered looks incidental (not motivated by performance).

[akhuang]

also just confirming that this fixes the issue we were seeing in Chrome

clang/include/clang/Frontend/FrontendOptions.h

 
 #include "clang/AST/ASTDumperUtils.h"
 #include "clang/Basic/LangStandard.h"
 #include "clang/Frontend/CommandLineSourceLoc.h"
 #include "clang/Sema/CodeCompleteOptions.h"
 #include "clang/Serialization/ModuleFileExtension.h"
 #include "llvm/ADT/StringRef.h"
 #include <cassert>
+#include <map>
 #include <memory>
 #include <string>
-#include <unordered_map>
 #include <vector>
 
 namespace llvm {
 
 class MemoryBuffer;
 
 } // namespace llvm
 
public:
 
   /// The frontend action to perform.
   frontend::ActionKind ProgramAction = frontend::ParseSyntaxOnly;
 
   /// The name of the action to run when using a plugin action.
   std::string ActionName;
 
   /// Args to pass to the plugins
-  std::unordered_map<std::string,std::vector<std::string>> PluginArgs;
+  std::map<std::string, std::vector<std::string>> PluginArgs;
 
   /// The list of plugin actions to run in addition to the normal action.
   std::vector<std::string> AddPluginActions;
 
   /// The list of plugins to load.
   std::vector<std::string> Plugins;
 
   /// The list of module file extensions.

clang/unittests/Frontend/CompilerInvocationTest.cpp

TEST_F(CommandLineTest, RoundTrip) {
   ASSERT_EQ(Invocation.getCodeGenOpts().getDebugInfo(),
             codegenoptions::DebugInfoKind::LimitedDebugInfo);
   ASSERT_TRUE(Invocation.getCodeGenOpts().MacroDebugInfo);
 
   ASSERT_EQ(Invocation.getDependencyOutputOpts().ShowIncludesDest,
             ShowIncludesDestination::Stdout);
   ASSERT_TRUE(Invocation.getDependencyOutputOpts().ShowHeaderIncludes);
 }
+
+TEST_F(CommandLineTest, PluginArgsRoundTripDeterminism) {
+  const char *Args[] = {
+      "-plugin-arg-blink-gc-plugin", "no-members-in-stack-allocated",
+      "-plugin-arg-find-bad-constructs", "checked-ptr-as-trivial-member",
+      "-plugin-arg-find-bad-constructs", "check-ipc",
+      // Enable round-trip to ensure '-plugin-arg' generation is deterministic.
+      "-round-trip-args"};
+
+  ASSERT_TRUE(CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags));
+}
 } // anonymous namespace