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

1 files changed, 17 insertions, 4 deletions

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index d314f6d..991e9ef 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/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;
 }