[Modules] Resolve top-headers of modules lazily.

This allows resolving top-header filenames of modules to FileEntries when
we need them, not eagerly.

Note that that this breaks ABI for libclang functions
clang_Module_getTopLevelHeader / clang_Module_getNumTopLevelHeaders
but this is fine because they are experimental and not widely used yet.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176975 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 815cf12f11..8f48d5870a 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -2170,11 +2170,13 @@ void ASTWriter::WriteSubmodules(Module *WritingModule) {
       Stream.EmitRecordWithBlob(ExcludedHeaderAbbrev, Record, 
                                 Mod->ExcludedHeaders[I]->getName());
     }
-    for (unsigned I = 0, N = Mod->TopHeaders.size(); I != N; ++I) {
+    ArrayRef<const FileEntry *>
+      TopHeaders = Mod->getTopHeaders(PP->getFileManager());
+    for (unsigned I = 0, N = TopHeaders.size(); I != N; ++I) {
       Record.clear();
       Record.push_back(SUBMODULE_TOPHEADER);
       Stream.EmitRecordWithBlob(TopHeaderAbbrev, Record,
-                                Mod->TopHeaders[I]->getName());
+                                TopHeaders[I]->getName());
     }
 
     // Emit the imports.