When inferring a submodule ID during module creation, look up the

include stack to find the first file that is known to be part of the
module. This copes with situations where the module map doesn't
completely specify all of the headers that are involved in the module,
which can come up when there are very strange #include_next chains
(e.g., with weird compiler/stdlib headers like stdarg.h or float.h).

llvm-svn: 147662

clang/lib/Lex/ModuleMap.cpp

@@ -426,12 +426,23 @@ Module *ModuleMap::inferModuleFromLocation(FullSourceLoc Loc) {
   
   const SourceManager &SrcMgr = Loc.getManager();
   FileID ExpansionFileID = ExpansionLoc.getFileID();
-  const FileEntry *ExpansionFile = SrcMgr.getFileEntryForID(ExpansionFileID);
-  if (!ExpansionFile)
-    return 0;
   
-  // Find the module that owns this header.
-  return findModuleForHeader(ExpansionFile);
+  while (const FileEntry *ExpansionFile
+           = SrcMgr.getFileEntryForID(ExpansionFileID)) {
+    // Find the module that owns this header (if any).
+    if (Module *Mod = findModuleForHeader(ExpansionFile))
+      return Mod;
+    
+    // No module owns this header, so look up the inclusion chain to see if
+    // any included header has an associated module.
+    SourceLocation IncludeLoc = SrcMgr.getIncludeLoc(ExpansionFileID);
+    if (IncludeLoc.isInvalid())
+      return 0;
+    
+    ExpansionFileID = SrcMgr.getFileID(IncludeLoc);
+  }
+  
+  return 0;
 }
 
 //----------------------------------------------------------------------------//

clang/test/Modules/Inputs/def-include.h

@@ -0,0 +1,13 @@
+
+
+
+
+
+
+
+
+
+
+struct B {
+  int b1;
+};

clang/test/Modules/Inputs/def.h

@@ -1,4 +1,4 @@
-
+#include "def-include.h"
 
 
 
@@ -8,7 +8,4 @@
 }
 @end
 
-struct B {
-  int b1;
-};