[clang][modules] Build inferred modules

This patch enables explicitly building inferred modules.

Effectively a cherry-pick of swiftlang#699 authored by @Bigcheese with libclang and dependency scanner changes omitted.

Contains the following changes:

1. [Clang] Fix the header paths in clang::Module for inferred modules.
  * The UmbrellaAsWritten and NameAsWritten fields in clang::Module are a lie for framework modules. For those they actually are the path to the header or umbrella relative to the clang::Module::Directory.
  * The exception to this case is for inferred modules. Here it actually is the name as written, because we print out the module and read it back in when implicitly building modules. This causes a problem when explicitly building an inferred module, as we skip the printing out step.
  * In order to fix this issue this patch adds a new field for the path we want to use in getInputBufferForModule. It also makes NameAsWritten actually be the name written in the module map file (or that would be, in the case of an inferred module).

2. [Clang] Allow explicitly building an inferred module.
  * Building the actual module still fails, but make sure it fails for the right reason.

Split from D100934.

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D102491

clang/include/clang/Basic/Module.h

@@ -141,6 +141,9 @@ class Module {
   /// The name of the umbrella entry, as written in the module map.
   std::string UmbrellaAsWritten;
 
+  // The path to the umbrella entry relative to the root module's \c Directory.
+  std::string UmbrellaRelativeToRootModuleDirectory;
+
   /// The module through which entities defined in this module will
   /// eventually be exposed, for use in "private" modules.
   std::string ExportAsModule;
@@ -188,6 +191,7 @@ class Module {
   /// file.
   struct Header {
     std::string NameAsWritten;
+    std::string PathRelativeToRootModuleDirectory;
     const FileEntry *Entry;
 
     explicit operator bool() { return Entry; }
@@ -197,6 +201,7 @@ class Module {
   /// file.
   struct DirectoryName {
     std::string NameAsWritten;
+    std::string PathRelativeToRootModuleDirectory;
     const DirectoryEntry *Entry;
 
     explicit operator bool() { return Entry; }
@@ -545,7 +550,8 @@ class Module {
   /// module.
   Header getUmbrellaHeader() const {
     if (auto *FE = Umbrella.dyn_cast<const FileEntry *>())
-      return Header{UmbrellaAsWritten, FE};
+      return Header{UmbrellaAsWritten, UmbrellaRelativeToRootModuleDirectory,
+                    FE};
     return Header{};
   }
 

clang/include/clang/Lex/ModuleMap.h

@@ -649,12 +649,14 @@ class ModuleMap {
   /// Sets the umbrella header of the given module to the given
   /// header.
   void setUmbrellaHeader(Module *Mod, const FileEntry *UmbrellaHeader,
-                         Twine NameAsWritten);
+                         const Twine &NameAsWritten,
+                         const Twine &PathRelativeToRootModuleDirectory);
 
   /// Sets the umbrella directory of the given module to the given
   /// directory.
   void setUmbrellaDir(Module *Mod, const DirectoryEntry *UmbrellaDir,
-                      Twine NameAsWritten);
+                      const Twine &NameAsWritten,
+                      const Twine &PathRelativeToRootModuleDirectory);
 
   /// Adds this header to the given module.
   /// \param Role The role of the header wrt the module.

clang/lib/Basic/Module.cpp

@@ -245,9 +245,10 @@ bool Module::fullModuleNameIs(ArrayRef<StringRef> nameParts) const {
 
 Module::DirectoryName Module::getUmbrellaDir() const {
   if (Header U = getUmbrellaHeader())
-    return {"", U.Entry->getDir()};
+    return {"", "", U.Entry->getDir()};
 
-  return {UmbrellaAsWritten, Umbrella.dyn_cast<const DirectoryEntry *>()};
+  return {UmbrellaAsWritten, UmbrellaRelativeToRootModuleDirectory,
+          Umbrella.dyn_cast<const DirectoryEntry *>()};
 }
 
 void Module::addTopHeader(const FileEntry *File) {

clang/lib/Frontend/FrontendAction.cpp

@@ -342,7 +342,8 @@ static std::error_code collectModuleHeaderIncludes(
       // file relative to the module build directory (the directory containing
       // the module map file) so this will find the same file that we found
       // while parsing the module map.
-      addHeaderInclude(H.NameAsWritten, Includes, LangOpts, Module->IsExternC);
+      addHeaderInclude(H.PathRelativeToRootModuleDirectory, Includes, LangOpts,
+                       Module->IsExternC);
     }
   }
   // Note that Module->PrivateHeaders will not be a TopHeader.
@@ -351,8 +352,8 @@ static std::error_code collectModuleHeaderIncludes(
     Module->addTopHeader(UmbrellaHeader.Entry);
     if (Module->Parent)
       // Include the umbrella header for submodules.
-      addHeaderInclude(UmbrellaHeader.NameAsWritten, Includes, LangOpts,
-                       Module->IsExternC);
+      addHeaderInclude(UmbrellaHeader.PathRelativeToRootModuleDirectory,
+                       Includes, LangOpts, Module->IsExternC);
   } else if (Module::DirectoryName UmbrellaDir = Module->getUmbrellaDir()) {
     // Add all of the headers we find in this subdirectory.
     std::error_code EC;
@@ -386,7 +387,8 @@ static std::error_code collectModuleHeaderIncludes(
       auto PathIt = llvm::sys::path::rbegin(Dir->path());
       for (int I = 0; I != Dir.level() + 1; ++I, ++PathIt)
         Components.push_back(*PathIt);
-      SmallString<128> RelativeHeader(UmbrellaDir.NameAsWritten);
+      SmallString<128> RelativeHeader(
+          UmbrellaDir.PathRelativeToRootModuleDirectory);
       for (auto It = Components.rbegin(), End = Components.rend(); It != End;
            ++It)
         llvm::sys::path::append(RelativeHeader, *It);
@@ -470,7 +472,7 @@ static Module *prepareToBuildModule(CompilerInstance &CI,
   // Dig out the module definition.
   HeaderSearch &HS = CI.getPreprocessor().getHeaderSearchInfo();
   Module *M = HS.lookupModule(CI.getLangOpts().CurrentModule,
-                              /*AllowSearch=*/false);
+                              /*AllowSearch=*/true);
   if (!M) {
     CI.getDiagnostics().Report(diag::err_missing_module)
       << CI.getLangOpts().CurrentModule << ModuleMapFilename;
@@ -528,8 +530,8 @@ getInputBufferForModule(CompilerInstance &CI, Module *M) {
   SmallString<256> HeaderContents;
   std::error_code Err = std::error_code();
   if (Module::Header UmbrellaHeader = M->getUmbrellaHeader())
-    addHeaderInclude(UmbrellaHeader.NameAsWritten, HeaderContents,
-                     CI.getLangOpts(), M->IsExternC);
+    addHeaderInclude(UmbrellaHeader.PathRelativeToRootModuleDirectory,
+                     HeaderContents, CI.getLangOpts(), M->IsExternC);
   Err = collectModuleHeaderIncludes(
       CI.getLangOpts(), FileMgr, CI.getDiagnostics(),
       CI.getPreprocessor().getHeaderSearchInfo().getModuleMap(), M,

clang/lib/Frontend/FrontendActions.cpp

@@ -297,7 +297,8 @@ bool GenerateHeaderModuleAction::BeginSourceFileAction(
         << Name;
       continue;
     }
-    Headers.push_back({std::string(Name), &FE->getFileEntry()});
+    Headers.push_back(
+        {std::string(Name), std::string(Name), &FE->getFileEntry()});
   }
   HS.getModuleMap().createHeaderModule(CI.getLangOpts().CurrentModule, Headers);
 

clang/lib/Lex/ModuleMap.cpp

@@ -260,9 +260,10 @@ void ModuleMap::resolveHeader(Module *Mod,
           << UmbrellaMod->getFullModuleName();
       else
         // Record this umbrella header.
-        setUmbrellaHeader(Mod, *File, RelativePathName.str());
+        setUmbrellaHeader(Mod, *File, Header.FileName, RelativePathName.str());
     } else {
-      Module::Header H = {std::string(RelativePathName.str()), *File};
+      Module::Header H = {Header.FileName, std::string(RelativePathName.str()),
+                          *File};
       if (Header.Kind == Module::HK_Excluded)
         excludeHeader(Mod, H);
       else
@@ -305,7 +306,7 @@ bool ModuleMap::resolveAsBuiltinHeader(
     return false;
 
   auto Role = headerKindToRole(Header.Kind);
-  Module::Header H = {std::string(Path.str()), *File};
+  Module::Header H = {Header.FileName, std::string(Path.str()), *File};
   addHeader(Mod, H, Role);
   return true;
 }
@@ -1038,11 +1039,13 @@ Module *ModuleMap::inferFrameworkModule(const DirectoryEntry *FrameworkDir,
   Result->NoUndeclaredIncludes |= Attrs.NoUndeclaredIncludes;
   Result->Directory = FrameworkDir;
 
+  // Chop off the first framework bit, as that is implied.
+  StringRef RelativePath = UmbrellaName.str().substr(
+      Result->getTopLevelModule()->Directory->getName().size());
+  RelativePath = llvm::sys::path::relative_path(RelativePath);
+
   // umbrella header "umbrella-header-name"
-  //
-  // The "Headers/" component of the name is implied because this is
-  // a framework module.
-  setUmbrellaHeader(Result, *UmbrellaHeader, ModuleName + ".h");
+  setUmbrellaHeader(Result, *UmbrellaHeader, ModuleName + ".h", RelativePath);
 
   // export *
   Result->Exports.push_back(Module::ExportDecl(nullptr, true));
@@ -1121,11 +1124,14 @@ Module *ModuleMap::createShadowedModule(StringRef Name, bool IsFramework,
   return Result;
 }
 
-void ModuleMap::setUmbrellaHeader(Module *Mod, const FileEntry *UmbrellaHeader,
-                                  Twine NameAsWritten) {
+void ModuleMap::setUmbrellaHeader(
+    Module *Mod, const FileEntry *UmbrellaHeader, const Twine &NameAsWritten,
+    const Twine &PathRelativeToRootModuleDirectory) {
   Headers[UmbrellaHeader].push_back(KnownHeader(Mod, NormalHeader));
   Mod->Umbrella = UmbrellaHeader;
   Mod->UmbrellaAsWritten = NameAsWritten.str();
+  Mod->UmbrellaRelativeToRootModuleDirectory =
+      PathRelativeToRootModuleDirectory.str();
   UmbrellaDirs[UmbrellaHeader->getDir()] = Mod;
 
   // Notify callbacks that we just added a new header.
@@ -1134,9 +1140,12 @@ void ModuleMap::setUmbrellaHeader(Module *Mod, const FileEntry *UmbrellaHeader,
 }
 
 void ModuleMap::setUmbrellaDir(Module *Mod, const DirectoryEntry *UmbrellaDir,
-                               Twine NameAsWritten) {
+                               const Twine &NameAsWritten,
+                               const Twine &PathRelativeToRootModuleDirectory) {
   Mod->Umbrella = UmbrellaDir;
   Mod->UmbrellaAsWritten = NameAsWritten.str();
+  Mod->UmbrellaRelativeToRootModuleDirectory =
+      PathRelativeToRootModuleDirectory.str();
   UmbrellaDirs[UmbrellaDir] = Mod;
 }
 
@@ -2405,6 +2414,7 @@ void ModuleMapParser::parseUmbrellaDirDecl(SourceLocation UmbrellaLoc) {
   }
 
   std::string DirName = std::string(Tok.getString());
+  std::string DirNameAsWritten = DirName;
   SourceLocation DirNameLoc = consumeToken();
 
   // Check whether we already have an umbrella.
@@ -2446,7 +2456,7 @@ void ModuleMapParser::parseUmbrellaDirDecl(SourceLocation UmbrellaLoc) {
     for (llvm::vfs::recursive_directory_iterator I(FS, Dir->getName(), EC), E;
          I != E && !EC; I.increment(EC)) {
       if (auto FE = SourceMgr.getFileManager().getFile(I->path())) {
-        Module::Header Header = {std::string(I->path()), *FE};
+        Module::Header Header = {"", std::string(I->path()), *FE};
         Headers.push_back(std::move(Header));
       }
     }
@@ -2467,7 +2477,7 @@ void ModuleMapParser::parseUmbrellaDirDecl(SourceLocation UmbrellaLoc) {
   }
 
   // Record this umbrella directory.
-  Map.setUmbrellaDir(ActiveModule, Dir, DirName);
+  Map.setUmbrellaDir(ActiveModule, Dir, DirNameAsWritten, DirName);
 }
 
 /// Parse a module export declaration.

clang/lib/Serialization/ASTReader.cpp

@@ -1921,10 +1921,9 @@ HeaderFileInfoTrait::ReadData(internal_key_ref key, const unsigned char *d,
     std::string Filename = std::string(key.Filename);
     if (key.Imported)
       Reader.ResolveImportedPath(M, Filename);
-    // FIXME: This is not always the right filename-as-written, but we're not
-    // going to use this information to rebuild the module, so it doesn't make
-    // a lot of difference.
-    Module::Header H = {std::string(key.Filename), *FileMgr.getFile(Filename)};
+    // FIXME: NameAsWritten
+    Module::Header H = {std::string(key.Filename), "",
+                        *FileMgr.getFile(Filename)};
     ModMap.addHeader(Mod, H, HeaderRole, /*Imported*/true);
     HFI.isModuleHeader |= !(HeaderRole & ModuleMap::TextualHeader);
   }
@@ -5618,7 +5617,8 @@ ASTReader::ReadSubmoduleBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
       ResolveImportedPath(F, Filename);
       if (auto Umbrella = PP.getFileManager().getFile(Filename)) {
         if (!CurrentModule->getUmbrellaHeader())
-          ModMap.setUmbrellaHeader(CurrentModule, *Umbrella, Blob);
+          // FIXME: NameAsWritten
+          ModMap.setUmbrellaHeader(CurrentModule, *Umbrella, Blob, "");
         else if (CurrentModule->getUmbrellaHeader().Entry != *Umbrella) {
           if ((ClientLoadCapabilities & ARR_OutOfDate) == 0)
             Error("mismatched umbrella headers in submodule");
@@ -5651,7 +5651,8 @@ ASTReader::ReadSubmoduleBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
       ResolveImportedPath(F, Dirname);
       if (auto Umbrella = PP.getFileManager().getDirectory(Dirname)) {
         if (!CurrentModule->getUmbrellaDir())
-          ModMap.setUmbrellaDir(CurrentModule, *Umbrella, Blob);
+          // FIXME: NameAsWritten
+          ModMap.setUmbrellaDir(CurrentModule, *Umbrella, Blob, "");
         else if (CurrentModule->getUmbrellaDir().Entry != *Umbrella) {
           if ((ClientLoadCapabilities & ARR_OutOfDate) == 0)
             Error("mismatched umbrella directories in submodule");

clang/test/Modules/Inputs/explicit-build-inferred/frameworks/Inferred.framework/Headers/Inferred.h

@@ -0,0 +1 @@
+typedef int inferred;

clang/test/Modules/Inputs/explicit-build-inferred/frameworks/module.modulemap

@@ -0,0 +1 @@
+framework module * {}

clang/test/Modules/explicit-build-inferred.cpp

@@ -0,0 +1,13 @@
+// RUN: rm -rf %t && mkdir %t
+//
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -fimplicit-module-maps \
+// RUN:   -emit-module -x c++ %S/Inputs/explicit-build-inferred/frameworks/module.modulemap \
+// RUN:   -fmodule-name=Inferred -o %t/Inferred.pcm -F %S/Inputs/explicit-build-inferred/frameworks
+//
+// RUN: %clang_cc1 -fmodules -fno-implicit-modules -fsyntax-only %s \
+// RUN:   -fmodule-map-file=%S/Inputs/explicit-build-inferred/frameworks/module.modulemap \
+// RUN:   -fmodule-file=%t/Inferred.pcm -F %S/Inputs/explicit-build-inferred/frameworks
+
+#include <Inferred/Inferred.h>
+
+inferred a = 0;