[clang] Make sure argument expansion locations are correct in presence of predefined buffer

Summary:
Macro argument expansion logic relies on skipping file IDs that created
as a result of an include. Unfortunately it fails to do that for
predefined buffer since it doesn't have a valid insertion location.

As a result of that any file ID created for an include inside the
predefined buffers breaks the traversal logic in
SourceManager::computeMacroArgsCache.

To fix this issue we first record number of created FIDs for predefined
buffer, and then skip them explicitly in source manager.

Another solution would be to just give predefined buffers a valid source
location, but it is unclear where that should be..

Reviewers: sammccall

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D78649

1 files changed, 16 insertions, 8 deletions

diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 8ba5815..e42c3f4 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -1800,15 +1800,23 @@ void SourceManager::computeMacroArgsCache(MacroArgsMap &MacroArgsCache,
       return;
     if (Entry.isFile()) {
       SourceLocation IncludeLoc = Entry.getFile().getIncludeLoc();
-      if (IncludeLoc.isInvalid())
+      bool IncludedInFID =
+          (IncludeLoc.isValid() && isInFileID(IncludeLoc, FID)) ||
+          // Predefined header doesn't have a valid include location in main
+          // file, but any files created by it should still be skipped when
+          // computing macro args expanded in the main file.
+          (FID == MainFileID && Entry.getFile().Filename == "<built-in>");
+      if (IncludedInFID) {
+        // Skip the files/macros of the #include'd file, we only care about
+        // macros that lexed macro arguments from our file.
+        if (Entry.getFile().NumCreatedFIDs)
+          ID += Entry.getFile().NumCreatedFIDs - 1 /*because of next ++ID*/;
         continue;
-      if (!isInFileID(IncludeLoc, FID))
-        return; // No more files/macros that may be "contained" in this file.
-
-      // Skip the files/macros of the #include'd file, we only care about macros
-      // that lexed macro arguments from our file.
-      if (Entry.getFile().NumCreatedFIDs)
-        ID += Entry.getFile().NumCreatedFIDs - 1/*because of next ++ID*/;
+      } else if (IncludeLoc.isValid()) {
+        // If file was included but not from FID, there is no more files/macros
+        // that may be "contained" in this file.
+        return;
+      }
       continue;
     }