Disallow formatting of multibyte strings into a wide buffer (#606)

include/fmt/core.h

@@ -546,7 +546,7 @@ template <typename Context, typename T>
 FMT_CONSTEXPR basic_arg<Context> make_arg(const T &value);
 
 #define FMT_MAKE_VALUE(TAG, ArgType, ValueType) \
-  template <typename C, typename Char = typename C::char_type> \
+  template <typename C> \
   FMT_CONSTEXPR typed_value<C, TAG> make_value(ArgType val) { \
     return static_cast<ValueType>(val); \
   }
@@ -589,20 +589,22 @@ FMT_MAKE_VALUE(long_double_type, long double, long double)
 
 // Formatting of wide strings into a narrow buffer and multibyte strings
 // into a wide buffer is disallowed (https://github.com/fmtlib/fmt/pull/606).
-FMT_MAKE_VALUE(cstring_type, Char*, const Char*)
-FMT_MAKE_VALUE(cstring_type, const Char*, const Char*)
+FMT_MAKE_VALUE(cstring_type, typename C::char_type*,
+               const typename C::char_type*)
+FMT_MAKE_VALUE(cstring_type, const typename C::char_type*,
+               const typename C::char_type*)
 
 FMT_MAKE_VALUE(cstring_type, signed char*, const signed char*)
 FMT_MAKE_VALUE(cstring_type, const signed char*, const signed char*)
 FMT_MAKE_VALUE(cstring_type, unsigned char*, const unsigned char*)
 FMT_MAKE_VALUE(cstring_type, const unsigned char*, const unsigned char*)
 FMT_MAKE_VALUE(string_type, basic_string_view<typename C::char_type>,
-               basic_string_view<Char>)
+               basic_string_view<typename C::char_type>)
 FMT_MAKE_VALUE(string_type,
                typename basic_string_view<typename C::char_type>::type,
-               basic_string_view<Char>)
+               basic_string_view<typename C::char_type>)
 FMT_MAKE_VALUE(string_type, const std::basic_string<typename C::char_type>&,
-               basic_string_view<Char>)
+               basic_string_view<typename C::char_type>)
 FMT_MAKE_VALUE(pointer_type, void*, const void*)
 FMT_MAKE_VALUE(pointer_type, const void*, const void*)
 

test/compile-test/CMakeLists.txt

@@ -47,22 +47,12 @@ endfunction ()
 # check if the source file skeleton compiles
 expect_compile("")
 
-# MakeArg doesn't accept [const] volatile char *.
-expect_compile_error("volatile char s[] = \"test\"; (fmt::internal::MakeArg<char>)(s);")
-expect_compile_error("const volatile char s[] = \"test\"; (fmt::internal::MakeArg<char>)(s);")
-
-# MakeArg<char> doesn't accept wchar_t.
-expect_compile_error("fmt::internal::MakeValue<char>(L'a');")
-expect_compile_error("fmt::internal::MakeValue<char>(L\"test\");")
-
-# Writing a wide character to a character stream Writer is forbidden.
-expect_compile_error("fmt::MemoryWriter() << L'a';")
-expect_compile_error("fmt::MemoryWriter() << fmt::pad(\"abc\", 5, L' ');")
-expect_compile_error("fmt::MemoryWriter() << fmt::pad(42, 5, L' ');")
-
 # Formatting a wide character with a narrow format string is forbidden.
 expect_compile_error("fmt::format(\"{}\", L'a';")
 
+# Formatting a wide string with a narrow format string is forbidden.
+expect_compile_error("fmt::format(\"{}\", L\"foo\";")
+
 # Make sure that compiler features detected in the header
 # match the features detected in CMake.
 if (SUPPORTS_USER_DEFINED_LITERALS)