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";
   }
 

clang/test/FixIt/fixit-vexing-parse-cxx0x.cpp

@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -verify -x c++ -std=c++11 %s
+// RUN: %clang_cc1 -fdiagnostics-parseable-fixits -x c++ -std=c++11 %s 2>&1 | FileCheck %s
+
+struct X {
+  int i;
+};
+
+void func() {
+  // CHECK: fix-it:"{{.*}}":{10:6-10:8}:"{}"
+  X x(); // expected-warning {{function declaration}} expected-note{{replace parentheses with an initializer}}
+  
+  typedef int *Ptr;
+  // CHECK: fix-it:"{{.*}}":{14:8-14:10}:" = nullptr"
+  Ptr p(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
+
+  // CHECK: fix-it:"{{.*}}":{17:15-17:17}:" = u'\\0'"
+  char16_t u16(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
+
+  // CHECK: fix-it:"{{.*}}":{20:15-20:17}:" = U'\\0'"
+  char32_t u32(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
+}

clang/test/FixIt/fixit-vexing-parse.cpp

@@ -76,5 +76,14 @@ namespace N {
 #define NULL 0
     // CHECK: fix-it:"{{.*}}":{78:10-78:12}:" = NULL"
     Ptr p(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
+
+    // CHECK: fix-it:"{{.*}}":{81:11-81:13}:" = false"
+    bool b(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
+
+    // CHECK: fix-it:"{{.*}}":{84:11-84:13}:" = '\\0'"
+    char c(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
+
+    // CHECK: fix-it:"{{.*}}":{87:15-87:17}:" = L'\\0'"
+    wchar_t wc(); // expected-warning {{function declaration}} expected-note {{replace parentheses with an initializer}}
   }
 }