https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125956
Jonathan Wakely <redi at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org
Status|WAITING |ASSIGNED
Target Milestone|--- |15.4
--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
This version actually compiles and works:
--- a/libstdc++-v3/src/c++20/format.cc
+++ b/libstdc++-v3/src/c++20/format.cc
@@ -58,6 +58,15 @@ struct mutex
};
#endif
+#ifdef _GLIBCXX_HAVE_ICONV
+// Detect whether type T* can be used as the second argument to iconv.
+// SUSv2 used 'const char**', but glibc 2.2 and POSIX.1-2003 uses 'char**'.
+template<typename T>
+ concept iconv_input = requires (::iconv_t cd, T in, size_t n, char** out) {
+ ::iconv(cd, &in, &n, out, &n);
+ };
+#endif
+
// A non-standard locale::facet that caches the locale's std::text_encoding
// and an iconv descriptor for converting from that encoding to UTF-8.
struct __encoding : locale::facet
@@ -111,12 +120,13 @@ struct __encoding : locale::facet
bool done = false;
auto overwrite = [&](char* p, size_t n) {
+ using input_t = __conditional_t<iconv_input<char*>, char*, const char*>;
auto inbytes
- = const_cast<char*>(input.data()) + input.size() - inbytesleft;
+ = const_cast<input_t>(input.data()) + input.size() - inbytesleft;
char* outbytes = p + written;
size_t outbytesleft = n - written;
- size_t res = ::iconv(_M_cd, &inbytes, &inbytesleft,
- &outbytes, &outbytesleft);
+ size_t res = ::iconv(_M_cd, &inbytes, &inbytesleft, &outbytes,
+ &outbytesleft);
if (res == (size_t)-1)
{
if (errno != E2BIG)
