http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50941
Bug #: 50941
Summary: [C++0x] user-defined string literals provide incorrect
length for wchar_t, char16_t, and char32_t
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: daniel.krueg...@googlemail.com
CC: ja...@redhat.com
gcc 4.7.0 20111029 (experimental) in C++0x mode rejects the following code:
//---
typedef decltype(sizeof(0)) size_type;
constexpr size_type operator "" _len(const char*, size_type len)
{
return len;
}
constexpr size_type operator "" _len(const wchar_t*, size_type len)
{
return len;
}
constexpr size_type operator "" _len(const char16_t*, size_type len)
{
return len;
}
constexpr size_type operator "" _len(const char32_t*, size_type len)
{
return len;
}
static_assert( ""_len == 0, "Ouch"); // OK
static_assert(u8""_len == 0, "Ouch"); // OK
static_assert( L""_len == 0, "Ouch"); // Error
static_assert( u""_len == 0, "Ouch"); // Error
static_assert( U""_len == 0, "Ouch"); // Error
//---
With
"error: static assertion failed: "Ouch""
at the marked lines.
The code should be accepted.
It turns out that for wchar_t, char16_t, and char32_t string literals the
provided length is 1, not 0. But according to N3290 2.14.8 p5 and 2.14.5 p15
the provided length value should also be 0 in above examples. This problem also
occurs for non-empty strings: The length value is always too large by 1 for the
mentioned string types.
