[clang][modules] Preserve the module map that allowed inferring

clang/include/clang/Serialization/ASTBitCodes.h

@@ -44,7 +44,7 @@ namespace serialization {
 /// Version 4 of AST files also requires that the version control branch and
 /// revision match exactly, since there is no backward compatibility of
 /// AST files at this time.
-const unsigned VERSION_MAJOR = 31;
+const unsigned VERSION_MAJOR = 32;
 
 /// AST file minor version number supported by this version of
 /// Clang.
@@ -54,7 +54,7 @@ const unsigned VERSION_MAJOR = 31;
 /// for the previous version could still support reading the new
 /// version by ignoring new kinds of subblocks), this number
 /// should be increased.
-const unsigned VERSION_MINOR = 1;
+const unsigned VERSION_MINOR = 0;
 
 /// An ID number that refers to an identifier in an AST file.
 ///

clang/include/clang/Serialization/ASTReader.h

@@ -2335,6 +2335,8 @@ class ASTReader
   /// Translate a FileID from another module file's FileID space into ours.
   FileID TranslateFileID(ModuleFile &F, FileID FID) const {
     assert(FID.ID >= 0 && "Reading non-local FileID.");
+    if (FID.isInvalid())
+      return FID;
     return FileID::get(F.SLocEntryBaseID + FID.ID - 1);
   }
 

clang/lib/Frontend/FrontendAction.cpp

@@ -534,7 +534,6 @@ static Module *prepareToBuildModule(CompilerInstance &CI,
     }
     if (*OriginalModuleMap != CI.getSourceManager().getFileEntryRefForID(
                                   CI.getSourceManager().getMainFileID())) {
-      M->IsInferred = true;
       auto FileCharacter =
           M->IsSystem ? SrcMgr::C_System_ModuleMap : SrcMgr::C_User_ModuleMap;
       FileID OriginalModuleMapFID = CI.getSourceManager().getOrCreateFileID(

clang/lib/Lex/ModuleMap.cpp

@@ -657,8 +657,7 @@ ModuleMap::findOrCreateModuleForHeaderInUmbrellaDir(FileEntryRef File) {
             llvm::sys::path::stem(SkippedDir.getName()), NameBuf);
         Result = findOrCreateModule(Name, Result, /*IsFramework=*/false,
                                     Explicit).first;
-        InferredModuleAllowedBy[Result] = UmbrellaModuleMap;
-        Result->IsInferred = true;
+        setInferredModuleAllowedBy(Result, UmbrellaModuleMap);
 
         // Associate the module and the directory.
         UmbrellaDirs[SkippedDir] = Result;
@@ -675,8 +674,7 @@ ModuleMap::findOrCreateModuleForHeaderInUmbrellaDir(FileEntryRef File) {
                          llvm::sys::path::stem(File.getName()), NameBuf);
       Result = findOrCreateModule(Name, Result, /*IsFramework=*/false,
                                   Explicit).first;
-      InferredModuleAllowedBy[Result] = UmbrellaModuleMap;
-      Result->IsInferred = true;
+      setInferredModuleAllowedBy(Result, UmbrellaModuleMap);
       Result->addTopHeader(File);
 
       // If inferred submodules export everything they import, add a
@@ -1097,8 +1095,7 @@ Module *ModuleMap::inferFrameworkModule(DirectoryEntryRef FrameworkDir,
   Module *Result = new (ModulesAlloc.Allocate())
       Module(ModuleConstructorTag{}, ModuleName, SourceLocation(), Parent,
              /*IsFramework=*/true, /*IsExplicit=*/false, NumCreatedModules++);
-  InferredModuleAllowedBy[Result] = ModuleMapFID;
-  Result->IsInferred = true;
+  setInferredModuleAllowedBy(Result, ModuleMapFID);
   if (!Parent) {
     if (LangOpts.CurrentModule == ModuleName)
       SourceModule = Result;
@@ -1345,7 +1342,7 @@ ModuleMap::getModuleMapFileForUniquing(const Module *M) const {
 }
 
 void ModuleMap::setInferredModuleAllowedBy(Module *M, FileID ModMapFID) {
-  assert(M->IsInferred && "module not inferred");
+  M->IsInferred = true;
   InferredModuleAllowedBy[M] = ModMapFID;
 }
 

clang/lib/Serialization/ASTReader.cpp

@@ -5826,6 +5826,7 @@ llvm::Error ASTReader::ReadSubmoduleBlock(ModuleFile &F,
       SubmoduleID Parent = getGlobalSubmoduleID(F, Record[Idx++]);
       Module::ModuleKind Kind = (Module::ModuleKind)Record[Idx++];
       SourceLocation DefinitionLoc = ReadSourceLocation(F, Record[Idx++]);
+      FileID InferredAllowedBy = ReadFileID(F, Record, Idx);
       bool IsFramework = Record[Idx++];
       bool IsExplicit = Record[Idx++];
       bool IsSystem = Record[Idx++];
@@ -5847,8 +5848,6 @@ llvm::Error ASTReader::ReadSubmoduleBlock(ModuleFile &F,
           ModMap.findOrCreateModule(Name, ParentModule, IsFramework, IsExplicit)
               .first;
 
-      // FIXME: Call ModMap.setInferredModuleAllowedBy()
-
       SubmoduleID GlobalIndex = GlobalID - NUM_PREDEF_SUBMODULE_IDS;
       if (GlobalIndex >= SubmodulesLoaded.size() ||
           SubmodulesLoaded[GlobalIndex])
@@ -5879,6 +5878,8 @@ llvm::Error ASTReader::ReadSubmoduleBlock(ModuleFile &F,
       CurrentModule->DefinitionLoc = DefinitionLoc;
       CurrentModule->Signature = F.Signature;
       CurrentModule->IsFromModuleFile = true;
+      if (InferredAllowedBy.isValid())
+        ModMap.setInferredModuleAllowedBy(CurrentModule, InferredAllowedBy);
       CurrentModule->IsSystem = IsSystem || CurrentModule->IsSystem;
       CurrentModule->IsExternC = IsExternC;
       CurrentModule->InferSubmodules = InferSubmodules;

clang/lib/Serialization/ASTWriter.cpp

@@ -2914,6 +2914,7 @@ void ASTWriter::WriteSubmodules(Module *WritingModule) {
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // Parent
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 4)); // Kind
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Definition location
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 4)); // Inferred allowed by
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsFramework
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsExplicit
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // IsSystem
@@ -3018,13 +3019,19 @@ void ASTWriter::WriteSubmodules(Module *WritingModule) {
     SourceLocationEncoding::RawLocEncoding DefinitionLoc =
         getRawSourceLocationEncoding(getAdjustedLocation(Mod->DefinitionLoc));
 
+    ModuleMap &ModMap = PP->getHeaderSearchInfo().getModuleMap();
+    FileID InferredFID =
+        Mod->IsInferred ? ModMap.getModuleMapFileIDForUniquing(Mod) : FileID();
+    int Inferred = getAdjustedFileID(InferredFID).getOpaqueValue();
+
     // Emit the definition of the block.
     {
       RecordData::value_type Record[] = {SUBMODULE_DEFINITION,
                                          ID,
                                          ParentID,
                                          (RecordData::value_type)Mod->Kind,
                                          DefinitionLoc,
+                                         (RecordData::value_type)Inferred,
                                          Mod->IsFramework,
                                          Mod->IsExplicit,
                                          Mod->IsSystem,

clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

@@ -587,9 +587,7 @@ ModuleDepCollectorPP::handleTopLevelModule(const Module *M) {
   ModuleMap &ModMapInfo =
       MDC.ScanInstance.getPreprocessor().getHeaderSearchInfo().getModuleMap();
 
-  OptionalFileEntryRef ModuleMap = ModMapInfo.getModuleMapFileForUniquing(M);
-
-  if (ModuleMap) {
+  if (auto ModuleMap = ModMapInfo.getModuleMapFileForUniquing(M)) {
     SmallString<128> Path = ModuleMap->getNameAsRequested();
     ModMapInfo.canonicalizeModuleMapPath(Path);
     MD.ClangModuleMapFile = std::string(Path);
@@ -601,15 +599,13 @@ ModuleDepCollectorPP::handleTopLevelModule(const Module *M) {
   MDC.ScanInstance.getASTReader()->visitInputFileInfos(
       *MF, /*IncludeSystem=*/true,
       [&](const serialization::InputFileInfo &IFI, bool IsSystem) {
-        // __inferred_module.map is the result of the way in which an implicit
-        // module build handles inferred modules. It adds an overlay VFS with
-        // this file in the proper directory and relies on the rest of Clang to
-        // handle it like normal. With explicitly built modules we don't need
-        // to play VFS tricks, so replace it with the correct module map.
-        if (StringRef(IFI.Filename).ends_with("__inferred_module.map")) {
-          MDC.addFileDep(MD, ModuleMap->getName());
+        // The __inferred_module.map file is an insignificant implementation
+        // detail of implicitly-built modules. The PCM will also report the
+        // actual on-disk module map file that allowed inferring the module,
+        // which is what we need for building the module explicitly
+        // Let's ignore this file.
+        if (StringRef(IFI.Filename).ends_with("__inferred_module.map"))
           return;
-        }
         MDC.addFileDep(MD, IFI.Filename);
       });
 

clang/test/ClangScanDeps/link-libraries.c

@@ -39,14 +39,13 @@ module transitive {
 // CHECK-NEXT:   "modules": [
 // CHECK-NEXT:     {
 // CHECK-NEXT:       "clang-module-deps": [],
-// CHECK-NEXT:       "clang-modulemap-file": "{{.*}}/__inferred_module.map",
+// CHECK-NEXT:       "clang-modulemap-file": "[[PREFIX]]/Inputs/frameworks/module.modulemap",
 // CHECK-NEXT:       "command-line": [
 // CHECK:            ],
 // CHECK-NEXT:       "context-hash": "{{.*}}",
 // CHECK-NEXT:       "file-deps": [
-// CHECK-NEXT:         "{{.*}}/Framework.h"
-// CHECK-NEXT:         "{{.*}}/__inferred_module.map"
-// CHECK-NEXT:         "{{.*}}/module.modulemap"
+// CHECK-NEXT:         "[[PREFIX]]/Inputs/frameworks/Framework.framework/Headers/Framework.h"
+// CHECK-NEXT:         "[[PREFIX]]/Inputs/frameworks/module.modulemap"
 // CHECK-NEXT:       ],
 // CHECK-NEXT:       "link-libraries": [
 // CHECK-NEXT:         {