[clang-rename] Fix non-functional offset check.

Adding something to a SourceLocation will only produce an invalid
SourceLocation in edge cases (overflow or adding 0 to an invalid one).
Check that the offset is inside the file instead and add a test case to
verify that the error message works.

llvm-svn: 287758

1 files changed, 6 insertions, 7 deletions

diff --git a/clang-tools-extra/clang-rename/USRFindingAction.cpp b/clang-tools-extra/clang-rename/USRFindingAction.cpp
index e04362b969e..8fd19667777 100644
--- a/clang-tools-extra/clang-rename/USRFindingAction.cpp
+++ b/clang-tools-extra/clang-rename/USRFindingAction.cpp
@@ -150,21 +150,20 @@ private:
   bool FindSymbol(ASTContext &Context, const SourceManager &SourceMgr,
                   unsigned SymbolOffset, const std::string &QualifiedName) {
     DiagnosticsEngine &Engine = Context.getDiagnostics();
+    const FileID MainFileID = SourceMgr.getMainFileID();
 
-    const SourceLocation Point =
-        SourceMgr.getLocForStartOfFile(SourceMgr.getMainFileID())
-            .getLocWithOffset(SymbolOffset);
-
-    if (!Point.isValid()) {
+    if (SymbolOffset >= SourceMgr.getFileIDSize(MainFileID)) {
       ErrorOccurred = true;
       unsigned InvalidOffset = Engine.getCustomDiagID(
           DiagnosticsEngine::Error,
           "SourceLocation in file %0 at offset %1 is invalid");
-      Engine.Report(Point, InvalidOffset) << SourceMgr.getFilename(Point)
-                                          << SymbolOffset;
+      Engine.Report(SourceLocation(), InvalidOffset)
+          << SourceMgr.getFileEntryForID(MainFileID)->getName() << SymbolOffset;
       return false;
     }
 
+    const SourceLocation Point = SourceMgr.getLocForStartOfFile(MainFileID)
+                                     .getLocWithOffset(SymbolOffset);
     const NamedDecl *FoundDecl = QualifiedName.empty()
                                      ? getNamedDeclAt(Context, Point)
                                      : getNamedDeclFor(Context, QualifiedName);