Merging r309503:

------------------------------------------------------------------------
r309503 | rsmith | 2017-07-29 23:31:29 -0700 (Sat, 29 Jul 2017) | 6 lines

PR33902: Invalidate line number cache when adding more text to existing buffer.

This led to crashes as the line number cache would report a bogus line number
for a line of code, and we'd try to find a nonexistent column within the line
when printing diagnostics.

------------------------------------------------------------------------


git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_50@309580 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 13 insertions, 0 deletions

diff --git a/lib/Lex/ScratchBuffer.cpp b/lib/Lex/ScratchBuffer.cpp
index cd8a27e76c..e0f3966fce 100644
--- a/lib/Lex/ScratchBuffer.cpp
+++ b/lib/Lex/ScratchBuffer.cpp
@@ -35,6 +35,14 @@ SourceLocation ScratchBuffer::getToken(const char *Buf, unsigned Len,
                                        const char *&DestPtr) {
   if (BytesUsed+Len+2 > ScratchBufSize)
     AllocScratchBuffer(Len+2);
+  else {
+    // Clear out the source line cache if it's already been computed.
+    // FIXME: Allow this to be incrementally extended.
+    auto *ContentCache = const_cast<SrcMgr::ContentCache *>(
+        SourceMgr.getSLocEntry(SourceMgr.getFileID(BufferStartLoc))
+                 .getFile().getContentCache());
+    ContentCache->SourceLineCache = nullptr;
+  }
 
   // Prefix the token with a \n, so that it looks like it is the first thing on
   // its own virtual line in caret diagnostics.
diff --git a/test/Misc/caret-diags-multiline.cpp b/test/Misc/caret-diags-multiline.cpp
index 4826d9beaa..90b50ff398 100644
--- a/test/Misc/caret-diags-multiline.cpp
+++ b/test/Misc/caret-diags-multiline.cpp
@@ -232,3 +232,8 @@ void multiple_ranges(int a, int b) {
   b
   );
 }
+
+#define pr33902_a(b) #b
+#define pr33902_c(d) _Pragma(pr33902_a(d))
+#define pr33902_e(f) pr33902_c(GCC warning #f)
+pr33902_e() pr33902_e()