This fixes:
FAIL: 17_intro/headers/c++1998/operator_names.cc -std=gnu++23 (test for excess
errors)
FAIL: 17_intro/headers/c++1998/operator_names.cc -std=gnu++26 (test for excess
errors)
The purpose of 'not defined<format_kind<R>>' is to be ill-formed (as
required by [format.range.fmtkind]) and to give an error that includes
the string "not defined<format_kind<R>>". That was intended to tell you
that format_kind<R> is not defined, just like it says!
But user code can use -fno-operator-names so we can't use 'not' here,
and "! defined" in the diagnostic doesn't seem as user-friendly. It also
raises questions about whether it was intended to be the preprocessor
token 'defined' (it's not) or where 'defined' is defined (it's not).
Replace it with __no_primary_template<format_kind<R>> and a comment,
which seems almost as good. The diagnostic now looks like:
In file included from fmt.cc:1:
.../include/c++/15.0.1/format: In instantiation of 'constexpr const auto
std::format_kind<int>':
fmt.cc:3:15: required from here
3 | auto i = std::format_kind<int>;
| ^~~~~~~~~~~~~~~~
.../include/c++/15.0.1/format:5164:31: error: use of 'std::format_kind<int>'
before deduction of 'auto'
5164 | = __no_primary_template(format_kind<_Rg>); // must define
specialization
| ^~~~~~~~~~~~~~~~
.../include/c++/15.0.1/format:5164:30: error: '__no_primary_template' was not
declared in this scope
5164 | = __no_primary_template(format_kind<_Rg>); // must define
specialization
| ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
libstdc++-v3/ChangeLog:
* include/std/format (format_kind): Do not use 'not'
alternative token to make the primary template ill-formed.
Use __no_primary_template as the undefined identifier that will
appear in diagnostics.
---
Testing now on x86_64-linux.
libstdc++-v3/include/std/format | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index b1455977c65..9ce9b3cfed1 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -5160,7 +5160,8 @@ namespace __format
/// @cond undocumented
template<typename _Rg>
- constexpr auto format_kind = not defined(format_kind<_Rg>);
+ constexpr auto format_kind
+ = __no_primary_template(format_kind<_Rg>); // must define specialization
template<typename _Tp>
consteval range_format
--
2.49.0
