Detect when we end up trying to load conflicting module files.

This can happen when one abuses precompiled headers by passing more -D
options when using a precompiled hedaer than when it was built. This
is intentionally permitted by precompiled headers (and is exploited by
some build environments), but causes problems for modules.

First part of <rdar://problem/13165109>, detecting when something when
horribly wrong.

llvm-svn: 174554

1 files changed, 12 insertions, 1 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index dd2d5d12bcc..aa4c448e989 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3408,7 +3408,18 @@ bool ASTReader::ReadSubmoduleBlock(ModuleFile &F) {
         Error("too many submodules");
         return true;
       }
-      
+
+      if (const FileEntry *CurFile = CurrentModule->getASTFile()) {
+        if (CurFile != F.File) {
+          if (!Diags.isDiagnosticInFlight()) {
+            Diag(diag::err_module_file_conflict)
+              << CurrentModule->getTopLevelModuleName()
+              << CurFile->getName()
+              << F.File->getName();
+          }
+          return true;
+        }
+      }
       CurrentModule->setASTFile(F.File);
       CurrentModule->IsFromModuleFile = true;
       CurrentModule->IsSystem = IsSystem || CurrentModule->IsSystem;