Recover better from an incompatible .pcm file being provided by -fmodule-file=.

We try to include the headers of the module textually in this case, still
enforcing the modules semantic rules. In order to make that work, we need to
still track that we're entering and leaving the module. Also, if the module was
also marked as unavailable (perhaps because it was missing a file), we
shouldn't mark the module unavailable -- we don't need the module to be
complete if we're going to enter it textually.

llvm-svn: 288449

clang/include/clang/Lex/ModuleLoader.h

@@ -31,13 +31,22 @@ typedef ArrayRef<std::pair<IdentifierInfo *, SourceLocation> > ModuleIdPath;
 
 /// \brief Describes the result of attempting to load a module.
 class ModuleLoadResult {
-  llvm::PointerIntPair<Module *, 1, bool> Storage;
-
 public:
-  ModuleLoadResult() : Storage() { }
+  enum LoadResultKind {
+    // We either succeeded or failed to load the named module.
+    Normal,
+    // The module exists, but does not actually contain the named submodule.
+    // This should only happen if the named submodule was inferred from an
+    // umbrella directory, but not actually part of the umbrella header.
+    MissingExpected,
+    // The module exists but cannot be imported due to a configuration mismatch.
+    ConfigMismatch
+  };
+  llvm::PointerIntPair<Module *, 2, LoadResultKind> Storage;
 
-  ModuleLoadResult(Module *module, bool missingExpected)
-    : Storage(module, missingExpected) { }
+  ModuleLoadResult() : Storage() { }
+  ModuleLoadResult(Module *M) : Storage(M, Normal) {}
+  ModuleLoadResult(LoadResultKind Kind) : Storage(nullptr, Kind) {}
 
   operator Module *() const { return Storage.getPointer(); }
 
@@ -45,7 +54,11 @@ public:
   /// actually a submodule that we expected to see (based on implying the
   /// submodule from header structure), but didn't materialize in the actual
   /// module.
-  bool isMissingExpected() const { return Storage.getInt(); }
+  bool isMissingExpected() const { return Storage.getInt() == MissingExpected; }
+
+  /// \brief Determines whether the module failed to load due to a configuration
+  /// mismatch with an explicitly-named .pcm file from the command line.
+  bool isConfigMismatch() const { return Storage.getInt() == ConfigMismatch; }
 };
 
 /// \brief Abstract interface for a module loader.

clang/lib/Frontend/CompilerInstance.cpp

@@ -1393,8 +1393,21 @@ bool CompilerInstance::loadModuleFile(StringRef FileName) {
         if (Module *M = CI.getPreprocessor()
                             .getHeaderSearchInfo()
                             .getModuleMap()
-                            .findModule(II->getName()))
+                            .findModule(II->getName())) {
           M->HasIncompatibleModuleFile = true;
+
+          // Mark module as available if the only reason it was unavailable
+          // was missing headers.
+          SmallVector<Module *, 2> Stack;
+          Stack.push_back(M);
+          while (!Stack.empty()) {
+            Module *Current = Stack.pop_back_val();
+            if (Current->IsMissingRequirement) continue;
+            Current->IsAvailable = true;
+            Stack.insert(Stack.end(),
+                         Current->submodule_begin(), Current->submodule_end());
+          }
+        }
       }
       LoadedModules.clear();
     }
@@ -1498,7 +1511,7 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
       if (Module && Module->HasIncompatibleModuleFile) {
         // We tried and failed to load a module file for this module. Fall
         // back to textual inclusion for its headers.
-        return ModuleLoadResult(nullptr, /*missingExpected*/true);
+        return ModuleLoadResult::ConfigMismatch;
       }
 
       getDiagnostics().Report(ModuleNameLoc, diag::err_module_build_disabled)
@@ -1705,7 +1718,7 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
         << Module->getFullModuleName()
         << SourceRange(Path.front().second, Path.back().second);
 
-      return ModuleLoadResult(nullptr, true);
+      return ModuleLoadResult::MissingExpected;
     }
 
     // Check whether this module is available.
@@ -1739,7 +1752,7 @@ CompilerInstance::loadModule(SourceLocation ImportLoc,
   }
 
   LastModuleImportLoc = ImportLoc;
-  LastModuleImportResult = ModuleLoadResult(Module, false);
+  LastModuleImportResult = ModuleLoadResult(Module);
   return LastModuleImportResult;
 }
 

clang/lib/Lex/PPDirectives.cpp

@@ -1866,10 +1866,7 @@ void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
     // unavailable, diagnose the situation and bail out.
     // FIXME: Remove this; loadModule does the same check (but produces
     // slightly worse diagnostics).
-    if (!SuggestedModule.getModule()->isAvailable() &&
-        !SuggestedModule.getModule()
-             ->getTopLevelModule()
-             ->HasIncompatibleModuleFile) {
+    if (!SuggestedModule.getModule()->isAvailable()) {
       Module::Requirement Requirement;
       Module::UnresolvedHeaderDirective MissingHeader;
       Module *M = SuggestedModule.getModule();
@@ -1918,9 +1915,12 @@ void Preprocessor::HandleIncludeDirective(SourceLocation HashLoc,
     else if (Imported.isMissingExpected()) {
       // We failed to find a submodule that we assumed would exist (because it
       // was in the directory of an umbrella header, for instance), but no
-      // actual module exists for it (because the umbrella header is
+      // actual module containing it exists (because the umbrella header is
       // incomplete).  Treat this as a textual inclusion.
       SuggestedModule = ModuleMap::KnownHeader();
+    } else if (Imported.isConfigMismatch()) {
+      // On a configuration mismatch, enter the header textually. We still know
+      // that it's part of the corresponding module.
     } else {
       // We hit an error processing the import. Bail out.
       if (hadModuleLoaderFatalFailure()) {

clang/test/Modules/config-mismatch.cpp

@@ -0,0 +1,10 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: echo 'module M { header "foo.h" header "bar.h" }' > %t/map
+// RUN: echo 'template<typename T> void f(T t) { int n; t.f(n); }' > %t/foo.h
+// RUN: touch %t/bar.h
+// RUN: %clang_cc1 -fmodules -fmodules-local-submodule-visibility -x c++ %t/map -emit-module -fmodule-name=M -o %t/pcm
+// RUN: %clang_cc1 -fmodules -fmodules-local-submodule-visibility -fmodule-map-file=%t/map -fmodule-file=%t/pcm -I%t %s -fsyntax-only -fexceptions -Wno-module-file-config-mismatch
+// RUN: rm %t/bar.h
+// RUN: %clang_cc1 -fmodules -fmodules-local-submodule-visibility -fmodule-map-file=%t/map -fmodule-file=%t/pcm -I%t %s -fsyntax-only -fexceptions -Wno-module-file-config-mismatch
+#include "foo.h"