Bug 802469 - Make misuse of NS_LITERAL_{C,}STRING a compile error. r=bsmedberg
authorJustin Lebar <justin.lebar@gmail.com>
Wed, 24 Oct 2012 12:53:22 -0400
changeset 111398 dd21d25200082c25fe7c2beed93fb1fe17c2283e
parent 111397 0c5a474a56b23b1e06a0b8c8959fa220d6ad2bec
child 111399 5bd4c4bac9f1874285e82caa69980de8f2e04e09
push id93
push usernmatsakis@mozilla.com
push dateWed, 31 Oct 2012 21:26:57 +0000
reviewersbsmedberg
bugs802469
milestone19.0a1
Bug 802469 - Make misuse of NS_LITERAL_{C,}STRING a compile error. r=bsmedberg
xpcom/string/public/nsLiteralString.h
--- a/xpcom/string/public/nsLiteralString.h
+++ b/xpcom/string/public/nsLiteralString.h
@@ -40,33 +40,62 @@ literal_string( const nsACString::char_t
 inline
 const nsDependentCString
 literal_string( const nsACString::char_type* aPtr, uint32_t aLength )
   {
     return nsDependentCString(aPtr, aLength);
   }
 #endif
 
+namespace mozilla {
+namespace internal {
+
+// This is the same as sizeof(c) - 1, except it won't compile if c isn't a
+// string literal.  This ensures that NS_LITERAL_CSTRING doesn't compile if you
+// pass it a char* (or something else for that matter).
+template<int n>
+inline uint32_t LiteralStringLength(const char (&c)[n])
+{
+  return n - 1;
+}
+
+#if defined(HAVE_CPP_CHAR16_T)
+template<int n>
+inline uint32_t LiteralWStringLength(const char16_t (&c)[n])
+{
+  return n - 1;
+}
+#elif defined(HAVE_CPP_2BYTE_WCHAR_T)
+template<int n>
+inline uint32_t LiteralWStringLength(const wchar_t (&c)[n])
+{
+  return n - 1;
+}
+#endif
+
+} // namespace internal
+} // namespace mozilla
+
 #if defined(HAVE_CPP_CHAR16_T) || defined(HAVE_CPP_2BYTE_WCHAR_T)
 #if defined(HAVE_CPP_CHAR16_T)
   //PR_STATIC_ASSERT(sizeof(char16_t) == 2);
   #define NS_LL(s)                                u##s
 #else
   //PR_STATIC_ASSERT(sizeof(wchar_t) == 2);
   #define NS_LL(s)                                L##s
 #endif
-  #define NS_MULTILINE_LITERAL_STRING(s)          nsDependentString(reinterpret_cast<const nsAString::char_type*>(s), uint32_t((sizeof(s)/2)-1))
-  #define NS_MULTILINE_LITERAL_STRING_INIT(n,s)   n(reinterpret_cast<const nsAString::char_type*>(s), uint32_t((sizeof(s)/2)-1))
-  #define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)  const nsDependentString n(reinterpret_cast<const nsAString::char_type*>(s), uint32_t((sizeof(s)/2)-1))
+  #define NS_MULTILINE_LITERAL_STRING(s)          nsDependentString(reinterpret_cast<const nsAString::char_type*>(s), mozilla::internal::LiteralWStringLength(s))
+  #define NS_MULTILINE_LITERAL_STRING_INIT(n,s)   n(reinterpret_cast<const nsAString::char_type*>(s), mozilla::internal::LiteralWStringLength(s))
+  #define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)  const nsDependentString n(reinterpret_cast<const nsAString::char_type*>(s), mozilla::internal::LiteralWStringLength(s))
   typedef nsDependentString nsLiteralString;
 #else
   #define NS_LL(s)                                s
-  #define NS_MULTILINE_LITERAL_STRING(s)          NS_ConvertASCIItoUTF16(s, uint32_t(sizeof(s)-1))
-  #define NS_MULTILINE_LITERAL_STRING_INIT(n,s)   n(s, uint32_t(sizeof(s)-1))
-  #define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)  const NS_ConvertASCIItoUTF16 n(s, uint32_t(sizeof(s)-1))
+  #define NS_MULTILINE_LITERAL_STRING(s)          NS_ConvertASCIItoUTF16(s, mozilla::internal::LiteralStringLength(s))
+  #define NS_MULTILINE_LITERAL_STRING_INIT(n,s)   n(s, mozilla::internal::LiteralStringLength(s))
+  #define NS_NAMED_MULTILINE_LITERAL_STRING(n,s)  const NS_ConvertASCIItoUTF16 n(s, mozilla::internal::LiteralStringLength(s))
   typedef NS_ConvertASCIItoUTF16 nsLiteralString;
 #endif
 
 /*
  * Macro arguments used in concatenation or stringification won't be expanded.
  * Therefore, in order for |NS_L(FOO)| to work as expected (which is to expand
  * |FOO| before doing whatever |NS_L| needs to do to it) a helper macro needs
  * to be inserted in between to allow the macro argument to expand.
@@ -75,15 +104,15 @@ literal_string( const nsACString::char_t
  */
 
 #define NS_L(s)                                   NS_LL(s)
 
 #define NS_LITERAL_STRING(s)                      static_cast<const nsAFlatString&>(NS_MULTILINE_LITERAL_STRING(NS_LL(s)))
 #define NS_LITERAL_STRING_INIT(n,s)               NS_MULTILINE_LITERAL_STRING_INIT(n, NS_LL(s))
 #define NS_NAMED_LITERAL_STRING(n,s)              NS_NAMED_MULTILINE_LITERAL_STRING(n, NS_LL(s))
 
-#define NS_LITERAL_CSTRING(s)                     static_cast<const nsDependentCString&>(nsDependentCString(s, uint32_t(sizeof(s)-1)))
-#define NS_LITERAL_CSTRING_INIT(n,s)              n(s, uint32_t(sizeof(s)-1))
-#define NS_NAMED_LITERAL_CSTRING(n,s)             const nsDependentCString n(s, uint32_t(sizeof(s)-1))
+#define NS_LITERAL_CSTRING(s)                     static_cast<const nsDependentCString&>(nsDependentCString(s, mozilla::internal::LiteralStringLength(s)))
+#define NS_LITERAL_CSTRING_INIT(n,s)              n(s, mozilla::internal::LiteralStringLength(s))
+#define NS_NAMED_LITERAL_CSTRING(n,s)             const nsDependentCString n(s, mozilla::internal::LiteralStringLength(s))
 
 typedef nsDependentCString nsLiteralCString;
 
 #endif /* !defined(nsLiteralString_h___) */