[Frontend] Add flag to allow PCM generation despite compiler errors

As with precompiled headers, it's useful for indexers to be able to
continue through compiler errors in dependent modules.

Resolves rdar://69816264

Reviewed By: akyrtzi

Differential Revision: https://reviews.llvm.org/D91580

clang/include/clang/Driver/Options.td

@@ -4356,6 +4356,8 @@ def fno_validate_pch : Flag<["-"], "fno-validate-pch">,
   HelpText<"Disable validation of precompiled headers">;
 def fallow_pch_with_errors : Flag<["-"], "fallow-pch-with-compiler-errors">,
   HelpText<"Accept a PCH file that was created with compiler errors">;
+def fallow_pcm_with_errors : Flag<["-"], "fallow-pcm-with-compiler-errors">,
+  HelpText<"Accept a PCM file that was created with compiler errors">;
 def dump_deserialized_pch_decls : Flag<["-"], "dump-deserialized-decls">,
   HelpText<"Dump declarations that are deserialized from PCH, for testing">;
 def error_on_deserialized_pch_decl : Separate<["-"], "error-on-deserialized-decl">,

clang/include/clang/Frontend/ASTUnit.h

@@ -694,7 +694,7 @@ class ASTUnit {
       const FileSystemOptions &FileSystemOpts, bool UseDebugInfo = false,
       bool OnlyLocalDecls = false, ArrayRef<RemappedFile> RemappedFiles = None,
       CaptureDiagsKind CaptureDiagnostics = CaptureDiagsKind::None,
-      bool AllowPCHWithCompilerErrors = false,
+      bool AllowASTWithCompilerErrors = false,
       bool UserFilesAreVolatile = false);
 
 private:

clang/include/clang/Frontend/FrontendActions.h

@@ -117,6 +117,8 @@ class GenerateModuleAction : public ASTFrontendAction {
   }
 
   bool hasASTFileSupport() const override { return false; }
+
+  bool shouldEraseOutputFiles() override;
 };
 
 class GenerateInterfaceStubsAction : public ASTFrontendAction {

clang/include/clang/Frontend/FrontendOptions.h

@@ -303,6 +303,9 @@ class FrontendOptions {
   /// When using -emit-module, treat the modulemap as a system module.
   unsigned IsSystemModule : 1;
 
+  /// Output (and read) PCM files regardless of compiler errors.
+  unsigned AllowPCMWithCompilerErrors : 1;
+
   CodeCompleteOptions CodeCompleteOpts;
 
   /// Specifies the output format of the AST.
@@ -457,7 +460,8 @@ class FrontendOptions {
         UseGlobalModuleIndex(true), GenerateGlobalModuleIndex(true),
         ASTDumpDecls(false), ASTDumpLookups(false),
         BuildingImplicitModule(false), ModulesEmbedAllFiles(false),
-        IncludeTimestamps(true), UseTemporary(true), TimeTraceGranularity(500) {}
+        IncludeTimestamps(true), UseTemporary(true),
+        AllowPCMWithCompilerErrors(false), TimeTraceGranularity(500) {}
 
   /// getInputKindForExtension - Return the appropriate input kind for a file
   /// extension. For example, "c" would return Language::C.

clang/lib/Frontend/ASTUnit.cpp

@@ -759,7 +759,7 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
     WhatToLoad ToLoad, IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
     const FileSystemOptions &FileSystemOpts, bool UseDebugInfo,
     bool OnlyLocalDecls, ArrayRef<RemappedFile> RemappedFiles,
-    CaptureDiagsKind CaptureDiagnostics, bool AllowPCHWithCompilerErrors,
+    CaptureDiagsKind CaptureDiagnostics, bool AllowASTWithCompilerErrors,
     bool UserFilesAreVolatile) {
   std::unique_ptr<ASTUnit> AST(new ASTUnit(true));
 
@@ -819,7 +819,7 @@ std::unique_ptr<ASTUnit> ASTUnit::LoadFromASTFile(
   AST->Reader = new ASTReader(
       PP, *AST->ModuleCache, AST->Ctx.get(), PCHContainerRdr, {},
       /*isysroot=*/"",
-      /*DisableValidation=*/disableValid, AllowPCHWithCompilerErrors);
+      /*DisableValidation=*/disableValid, AllowASTWithCompilerErrors);
 
   AST->Reader->setListener(std::make_unique<ASTInfoCollector>(
       *AST->PP, AST->Ctx.get(), *AST->HSOpts, *AST->PPOpts, *AST->LangOpts,

clang/lib/Frontend/CompilerInstance.cpp

@@ -1523,7 +1523,9 @@ void CompilerInstance::createASTReader() {
   HeaderSearchOptions &HSOpts = getHeaderSearchOpts();
   std::string Sysroot = HSOpts.Sysroot;
   const PreprocessorOptions &PPOpts = getPreprocessorOpts();
+  const FrontendOptions &FEOpts = getFrontendOpts();
   std::unique_ptr<llvm::Timer> ReadTimer;
+
   if (FrontendTimerGroup)
     ReadTimer = std::make_unique<llvm::Timer>("reading_modules",
                                                 "Reading modules",
@@ -1532,7 +1534,7 @@ void CompilerInstance::createASTReader() {
       getPreprocessor(), getModuleCache(), &getASTContext(),
       getPCHContainerReader(), getFrontendOpts().ModuleFileExtensions,
       Sysroot.empty() ? "" : Sysroot.c_str(), PPOpts.DisablePCHValidation,
-      /*AllowASTWithCompilerErrors=*/false,
+      /*AllowASTWithCompilerErrors=*/FEOpts.AllowPCMWithCompilerErrors,
       /*AllowConfigurationMismatch=*/false, HSOpts.ModulesValidateSystemHeaders,
       HSOpts.ValidateASTInputFilesContent,
       getFrontendOpts().UseGlobalModuleIndex, std::move(ReadTimer));

clang/lib/Frontend/CompilerInvocation.cpp

@@ -2027,6 +2027,7 @@ static InputKind ParseFrontendArgs(FrontendOptions &Opts, ArgList &Args,
   Opts.IncludeTimestamps = !Args.hasArg(OPT_fno_pch_timestamp);
   Opts.UseTemporary = !Args.hasArg(OPT_fno_temp_file);
   Opts.IsSystemModule = Args.hasArg(OPT_fsystem_module);
+  Opts.AllowPCMWithCompilerErrors = Args.hasArg(OPT_fallow_pcm_with_errors);
 
   if (Opts.ProgramAction != frontend::GenerateModule && Opts.IsSystemModule)
     Diags.Report(diag::err_drv_argument_only_allowed_with) << "-fsystem-module"
@@ -3611,7 +3612,8 @@ static void ParsePreprocessorArgs(PreprocessorOptions &Opts, ArgList &Args,
   Opts.UsePredefines = !Args.hasArg(OPT_undef);
   Opts.DetailedRecord = Args.hasArg(OPT_detailed_preprocessing_record);
   Opts.DisablePCHValidation = Args.hasArg(OPT_fno_validate_pch);
-  Opts.AllowPCHWithCompilerErrors = Args.hasArg(OPT_fallow_pch_with_errors);
+  Opts.AllowPCHWithCompilerErrors =
+      Args.hasArg(OPT_fallow_pch_with_errors, OPT_fallow_pcm_with_errors);
 
   Opts.DumpDeserializedPCHDecls = Args.hasArg(OPT_dump_deserialized_pch_decls);
   for (const auto *A : Args.filtered(OPT_error_on_deserialized_pch_decl))

clang/lib/Frontend/FrontendActions.cpp

@@ -177,7 +177,8 @@ GenerateModuleAction::CreateASTConsumer(CompilerInstance &CI,
   Consumers.push_back(std::make_unique<PCHGenerator>(
       CI.getPreprocessor(), CI.getModuleCache(), OutputFile, Sysroot, Buffer,
       CI.getFrontendOpts().ModuleFileExtensions,
-      /*AllowASTWithErrors=*/false,
+      /*AllowASTWithErrors=*/
+      +CI.getFrontendOpts().AllowPCMWithCompilerErrors,
       /*IncludeTimestamps=*/
       +CI.getFrontendOpts().BuildingImplicitModule,
       /*ShouldCacheASTInMemory=*/
@@ -187,6 +188,11 @@ GenerateModuleAction::CreateASTConsumer(CompilerInstance &CI,
   return std::make_unique<MultiplexConsumer>(std::move(Consumers));
 }
 
+bool GenerateModuleAction::shouldEraseOutputFiles() {
+  return !getCompilerInstance().getFrontendOpts().AllowPCMWithCompilerErrors &&
+         ASTFrontendAction::shouldEraseOutputFiles();
+}
+
 bool GenerateModuleFromModuleMapAction::BeginSourceFileAction(
     CompilerInstance &CI) {
   if (!CI.getLangOpts().Modules) {
@@ -339,7 +345,7 @@ void VerifyPCHAction::ExecuteAction() {
       CI.getPCHContainerReader(), CI.getFrontendOpts().ModuleFileExtensions,
       Sysroot.empty() ? "" : Sysroot.c_str(),
       /*DisableValidation*/ false,
-      /*AllowPCHWithCompilerErrors*/ false,
+      /*AllowASTWithCompilerErrors*/ false,
       /*AllowConfigurationMismatch*/ true,
       /*ValidateSystemInputs*/ true));
 

clang/test/Modules/Inputs/error.h

@@ -0,0 +1,8 @@
+@import undefined
+
+@interface Error
+- (int)method;
+undefined
+@end
+
+undefined

clang/test/Modules/Inputs/module.map

@@ -483,3 +483,4 @@ module template_nontrivial1 {
   header "template-nontrivial1.h"
   export *
 }
+module error { header "error.h" }

clang/test/Modules/load-module-with-errors.m

@@ -0,0 +1,25 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+
+// Write out a module with errors make sure it can be read
+// RUN: %clang_cc1 -fmodules -fallow-pcm-with-compiler-errors \
+// RUN:   -fmodules-cache-path=%t -x objective-c -emit-module \
+// RUN:   -fmodule-name=error %S/Inputs/module.map
+// RUN: %clang_cc1 -fmodules -fallow-pcm-with-compiler-errors \
+// RUN:   -fmodules-cache-path=%t -x objective-c -I %S/Inputs \
+// RUN:   -fimplicit-module-maps -ast-print %s | FileCheck %s
+
+// allow-pcm-with-compiler-errors should also allow errors in PCH
+// RUN: %clang_cc1 -fallow-pcm-with-compiler-errors -x c++ -emit-pch \
+// RUN:   -o %t/check.pch %S/Inputs/error.h
+
+@import error;
+
+void test(id x) {
+  [x method];
+}
+
+// CHECK: @interface Error
+// CHECK-NEXT: - (int)method;
+// CHECK-NEXT: @end
+// CHECK: void test(id x)

clang/tools/c-index-test/core_main.cpp

@@ -263,7 +263,7 @@ static bool printSourceSymbolsFromModule(StringRef modulePath,
       std::string(modulePath), *pchRdr, ASTUnit::LoadASTOnly, Diags,
       FileSystemOpts, /*UseDebugInfo=*/false,
       /*OnlyLocalDecls=*/true, None, CaptureDiagsKind::None,
-      /*AllowPCHWithCompilerErrors=*/true,
+      /*AllowASTWithCompilerErrors=*/true,
       /*UserFilesAreVolatile=*/false);
   if (!AU) {
     errs() << "failed to create TU for: " << modulePath << '\n';

clang/tools/libclang/CIndex.cpp

@@ -3476,7 +3476,7 @@ enum CXErrorCode clang_createTranslationUnit2(CXIndex CIdx,
       ast_filename, CXXIdx->getPCHContainerOperations()->getRawReader(),
       ASTUnit::LoadEverything, Diags, FileSystemOpts, /*UseDebugInfo=*/false,
       CXXIdx->getOnlyLocalDecls(), None, CaptureDiagsKind::All,
-      /*AllowPCHWithCompilerErrors=*/true,
+      /*AllowASTWithCompilerErrors=*/true,
       /*UserFilesAreVolatile=*/true);
   *out_TU = MakeCXTranslationUnit(CXXIdx, std::move(AU));
   return *out_TU ? CXError_Success : CXError_Failure;