Track the RequestingModule in the HeaderSearch LookupFile cache.

Different requesting modules can have different lookup results, so don't
cache results across modules.

Fixes a regression introduced in reviews.llvm.org/D132779.

Test case based on one provided by Jan Svoboda.

Reviewed By: jansvoboda11

Differential Revision: https://reviews.llvm.org/D156000

1 files changed, 6 insertions, 4 deletions

diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 3200d3d..a5e8b02 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1008,7 +1008,8 @@ OptionalFileEntryRef HeaderSearch::LookupFile(
   ConstSearchDirIterator NextIt = std::next(It);
 
   if (!SkipCache) {
-    if (CacheLookup.StartIt == NextIt) {
+    if (CacheLookup.StartIt == NextIt &&
+        CacheLookup.RequestingModule == RequestingModule) {
       // HIT: Skip querying potentially lots of directories for this lookup.
       if (CacheLookup.HitIt)
         It = CacheLookup.HitIt;
@@ -1021,7 +1022,7 @@ OptionalFileEntryRef HeaderSearch::LookupFile(
       // MISS: This is the first query, or the previous query didn't match
       // our search start.  We will fill in our found location below, so prime
       // the start point value.
-      CacheLookup.reset(/*NewStartIt=*/NextIt);
+      CacheLookup.reset(RequestingModule, /*NewStartIt=*/NextIt);
 
       if (It == search_dir_begin() && FirstNonHeaderMapSearchDirIdx > 0) {
         // Handle cold misses of user includes in the presence of many header
@@ -1036,8 +1037,9 @@ OptionalFileEntryRef HeaderSearch::LookupFile(
           It = search_dir_nth(Iter->second);
       }
     }
-  } else
-    CacheLookup.reset(/*NewStartIt=*/NextIt);
+  } else {
+    CacheLookup.reset(RequestingModule, /*NewStartIt=*/NextIt);
+  }
 
   SmallString<64> MappedName;