Print NULL as "(null)" in diagnostic message

[andusy]

Summary

Passing a null pointer to the printf family for a %s format specifier leads to undefined behaviour. The tests currently expect (null). Explicitly test for a null pointer and provide the expected string.

[hubert.reinterpretcast]

LGTM. I have some minor style comments that could be fixed as part of the commit.

clang/tools/c-index-test/c-index-test.c

4648 ↗

(On Diff #206514)

Minor nit: The blank line that was removed helps readability (at least for me). Also, FileNameStr should be declared first to match the corresponding CXStrings.

cfe/trunk/tools/c-index-test/c-index-test.c

if (num_overridden) {
       }
       printf("]");
       clang_disposeOverriddenCursors(overridden);
     }
     
     if (Cursor.kind == CXCursor_InclusionDirective) {
       CXFile File = clang_getIncludedFile(Cursor);
       CXString Included = clang_getFileName(File);
-      printf(" (%s)", clang_getCString(Included));
+      const char *IncludedString = clang_getCString(Included);
+      printf(" (%s)", IncludedString ? IncludedString : "(null)");
       clang_disposeString(Included);
       
       if (clang_isFileMultipleIncludeGuarded(TU, File))
         printf("  [multi-include guarded]");
     }
     
     CursorExtent = clang_getCursorExtent(Cursor);
     RefNameRange = clang_getCursorReferenceNameRange(Cursor, 
static void printDiagnosticSet(CXDiagnosticSet Diags, unsigned indent) {
   
   n = clang_getNumDiagnosticsInSet(Diags);
   for (i = 0; i < n; ++i) {
     CXSourceLocation DiagLoc;
     CXDiagnostic D;
     CXFile File;
     CXString FileName, DiagSpelling, DiagOption, DiagCat;
     unsigned line, column, offset;
-    const char *DiagOptionStr = 0, *DiagCatStr = 0;
+    const char *FileNameStr = 0, *DiagOptionStr = 0, *DiagCatStr = 0;
     
     D = clang_getDiagnosticInSet(Diags, i);
     DiagLoc = clang_getDiagnosticLocation(D);
     clang_getExpansionLocation(DiagLoc, &File, &line, &column, &offset);
     FileName = clang_getFileName(File);
+    FileNameStr = clang_getCString(FileName);
     DiagSpelling = clang_getDiagnosticSpelling(D);
-    
     printIndent(indent);
     
     fprintf(stderr, "%s:%d:%d: %s: %s",
-            clang_getCString(FileName),
+            FileNameStr ? FileNameStr : "(null)",
             line,
             column,
             getSeverityString(clang_getDiagnosticSeverity(D)),
             clang_getCString(DiagSpelling));
 
     DiagOption = clang_getDiagnosticOption(D, 0);
     DiagOptionStr = clang_getCString(DiagOption);
     if (DiagOptionStr) {