[modules] Fix incorrect diagnostic mapping computation when a module changes

diagnostic settings using _Pragma within a macro.

The AST writer had previously been assuming that all diagnostic state
transitions would occur within a FileID corresponding to a file. When a
diagnostic state change occured within a macro, it was unable to form a
location for that state change and would instead corrupt the diagnostic state
of the "root" node (and thus that of the main compilation).

Also introduce a "#pragma clang __debug diag_mapping" debugging utility
that I added to track this issue down.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@324695 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 0 deletions

diff --git a/include/clang/Basic/SourceManager.h b/include/clang/Basic/SourceManager.h
index 397ad2e77f..fe5aedaf20 100644
--- a/include/clang/Basic/SourceManager.h
+++ b/include/clang/Basic/SourceManager.h
@@ -1137,6 +1137,18 @@ public:
   /// be used by clients.
   SourceLocation getImmediateSpellingLoc(SourceLocation Loc) const;
 
+  /// \brief Form a SourceLocation from a FileID and Offset pair.
+  SourceLocation getComposedLoc(FileID FID, unsigned Offset) const {
+    bool Invalid = false;
+    const SrcMgr::SLocEntry &Entry = getSLocEntry(FID, &Invalid);
+    if (Invalid)
+      return SourceLocation();
+
+    unsigned GlobalOffset = Entry.getOffset() + Offset;
+    return Entry.isFile() ? SourceLocation::getFileLoc(GlobalOffset)
+                          : SourceLocation::getMacroLoc(GlobalOffset);
+  }
+
   /// \brief Decompose the specified location into a raw FileID + Offset pair.
   ///
   /// The first element is the FileID, the second is the offset from the