[PATCH] D121098: [C++20][Modules][HU 4/5] Handle pre-processed header units.

[Iain Sandoe via Phabricator via cfe-commits]

iains updated this revision to Diff 413612.
iains added a comment.

rebased


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D121098/new/

https://reviews.llvm.org/D121098

Files:
  clang/lib/Frontend/FrontendAction.cpp
  clang/lib/Sema/SemaModule.cpp


Index: clang/lib/Sema/SemaModule.cpp
===================================================================
--- clang/lib/Sema/SemaModule.cpp
+++ clang/lib/Sema/SemaModule.cpp
@@ -109,10 +109,18 @@
     const_cast<LangOptions &>(getLangOpts()).CurrentModule = HUName.str();
   }
 
-  auto &Map = PP.getHeaderSearchInfo().getModuleMap();
   // TODO: Make the C++20 header lookup independent.
-  Module::Header H{getLangOpts().CurrentModule, getLangOpts().CurrentModule,
-                   SourceMgr.getFileEntryForID(SourceMgr.getMainFileID())};
+  // When the input is pre-processed source, we need a file ref to the original
+  // file for the header map.
+  auto F = SourceMgr.getFileManager().getFile(HUName);
+  // For the sake of error recovery (if someone has moved the original header
+  // after creating the pre-processed output) fall back to obtaining the file
+  // ref for the input file, which must be present.
+  if (!F)
+    F = SourceMgr.getFileEntryForID(SourceMgr.getMainFileID());
+  assert(F && "failed to find the header unit source?");
+  Module::Header H{HUName.str(), HUName.str(), *F};
+  auto &Map = PP.getHeaderSearchInfo().getModuleMap();
   Module *Mod = Map.createHeaderUnit(StartOfTU, HUName, H);
   assert(Mod && "module creation should not fail");
   ModuleScopes.push_back({}); // No GMF
Index: clang/lib/Frontend/FrontendAction.cpp
===================================================================
--- clang/lib/Frontend/FrontendAction.cpp
+++ clang/lib/Frontend/FrontendAction.cpp
@@ -843,6 +843,21 @@
   if (!CI.InitializeSourceManager(Input))
     return false;
 
+  if (CI.getLangOpts().CPlusPlusModules && Input.getKind().isHeaderUnit() &&
+      Input.getKind().isPreprocessed() && !usesPreprocessorOnly()) {
+    // We have an input filename like foo.iih, but we want to find the right
+    // module name (and original file, to build the map entry).
+    // Check if the first line specifies the original source file name with a
+    // linemarker.
+    std::string PresumedInputFile = std::string(getCurrentFileOrBufferName());
+    ReadOriginalFileName(CI, PresumedInputFile);
+    // Unless the user overrides this, the module name is the name by which the
+    // original file was known.
+    if (CI.getLangOpts().ModuleName.empty())
+      CI.getLangOpts().ModuleName = std::string(PresumedInputFile);
+    CI.getLangOpts().CurrentModule = CI.getLangOpts().ModuleName;
+  }
+
   // For module map files, we first parse the module map and synthesize a
   // "<module-includes>" buffer before more conventional processing.
   if (Input.getKind().getFormat() == InputKind::ModuleMap) {


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