Use character literals for vexing initialization fixit hints.

Instead of suggesting " = 0" for "char c();", suggest " = '\0'", and similarly
for other char types (wide, 16, and 32). Add tests for all these, and since
this means testing such hints under C++0x, add tests for some untested C++0x
hint cases in the existing code, including suggesting nullptr for pointer
initialization.

This sets up the initialization helper to provide better type fidelity that
will be especially helpful for non-assignment cases (such as fixit-correcting
NULL usage in function calls (eg: foo(char) + foo(NULL) => foo('\0') instead
of the less informative foo(0)))

llvm-svn: 153008

clang/lib/Sema/SemaFixItUtils.cpp

@@ -182,6 +182,14 @@ const char *Sema::getFixItZeroInitializerForType(QualType T) const {
       else if (isMacroDefined(*this, "NULL"))
         return " = NULL";
     }
+    if (T->isCharType())
+      return " = '\\0'";
+    if (T->isWideCharType())
+      return " = L'\\0'";
+    if (T->isChar16Type())
+      return " = u'\\0'";
+    if (T->isChar32Type())
+      return " = U'\\0'";
     return " = 0";
   }