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FMT_STRING("{:.{}f}") works in v80102 but not in v90000 #3006

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SanderBouwhuis opened this issue Jul 28, 2022 · 6 comments

SanderBouwhuis commented Jul 28, 2022 •

edited

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I have had this pattern for well over a year now and it always worked correctly. I updated to the latest master, and now I get errors:

...
wchar_t pwcValue[1024];
...
fmt::format_to_n(pwcValue, _countof(pwcValue)-1, FMT_STRING("{:.{}f}"), dValue, u8TotDecimals)
...

This is the error I get:

CDataCube.cpp(4653,97): error C3615: constexpr function 'fmt::v9::basic_format_parse_context<char,fmt::v9::detail::error_handler>::on_error' cannot result in a constant expression
Fmt\core.h(717,27): message : failure was caused by call of undefined function or one not declared 'constexpr' (compiling source file CDataCube.cpp)
Fmt\core.h(717,27): message : see usage of 'fmt::v9::detail::error_handler::on_error' (compiling source file CDataCube.cpp)

Why doesn't this work anymore?
Is there something I can change to make it working with the latest master?

The text was updated successfully, but these errors were encountered:

Contributor

vitaut commented Jul 28, 2022

Please provide a godbolt repro.

Author

SanderBouwhuis commented Jul 28, 2022 •

edited

Loading

I figured out the problem. If I change the FMT_STRING to wchar_t it does work:
Fails:
FMT_STRING("{:.{}f}"), dValue, u8TotDecimals)
Works:
FMT_STRING(L"{:.{}f}"), dValue, u8TotDecimals)

Previously it worked. So, something must have changed. What is the reason you can't use char strings as input in combination with wchar_t output anymore since last month?
Why is the error message completely wrong/confusing?

Contributor

vitaut commented Jul 28, 2022

In general mixing char and wchar_t strings is not recommended (and if possible disallowed). I was not able to repro the issue in https://godbolt.org/z/x6cGqKnsa though.

Author

SanderBouwhuis commented Jul 29, 2022

Ok, it doesn't matter. I changed my source code to not mix char with wchar_t anymore.

SanderBouwhuis closed this as completed

Contributor

vitaut commented Aug 9, 2022

Could be related to #3015.

Author

SanderBouwhuis commented Aug 10, 2022

@vitaut
Not sure whether the commit related to #3015 fixed it, but I just checked and it works again.

Thanks for fixing this regression!

mtremer referenced this issue in ipfire/ipfire-2.x


          fmt: Update to version 9.1.0

90d43e5

- Update from version 9.0.0 to 9.1.0
- Update of rootfile
- Changelog
    9.1.0 - 2022-08-27
	* ``fmt::formatted_size`` now works at compile time
		  `#3026 <https://github.com/fmtlib/fmt/pull/3026>`_
			  For example (`godbolt <https://godbolt.org/z/1MW5rMdf8>`__):
			   .. code:: c++
			     #include <fmt/compile.h>
			     int main() {
			       using namespace fmt::literals;
			       constexpr size_t n = fmt::formatted_size("{}"_cf, 42);
			       fmt::print("{}\n", n); // prints 2
			     }
	* Fixed handling of invalid UTF-8
		  `#3038 <https://github.com/fmtlib/fmt/pull/3038>`_,
		  `#3044 <https://github.com/fmtlib/fmt/pull/3044>`_,
		  `#3056 <https://github.com/fmtlib/fmt/pull/3056>`_
	* Improved Unicode support in ``ostream`` overloads of ``print``
		  `#2994 <https://github.com/fmtlib/fmt/pull/2994>`_,
		  `#3001 <https://github.com/fmtlib/fmt/pull/3001>`_,
		  `#3025 <https://github.com/fmtlib/fmt/pull/3025>`_
	* Fixed handling of the sign specifier in localized formatting on systems with
	   32-bit ``wchar_t``
		  `#3041 <https://github.com/fmtlib/fmt/issues/3041>`_).
	* Added support for wide streams to ``fmt::streamed``
		  `#2994 <https://github.com/fmtlib/fmt/pull/2994>`_
	* Added the ``n`` specifier that disables the output of delimiters when
	   formatting ranges
		  `#2981 <https://github.com/fmtlib/fmt/pull/2981>`_,
		  `#2983 <https://github.com/fmtlib/fmt/pull/2983>`_
			  For example (`godbolt <https://godbolt.org/z/roKqGdj8c>`__):
			   .. code:: c++
			     #include <fmt/ranges.h>
			     #include <vector>
			     int main() {
			       auto v = std::vector{1, 2, 3};
			       fmt::print("{:n}\n", v); // prints 1, 2, 3
			     }
	* Worked around problematic ``std::string_view`` constructors introduced in C++23
		  `#3030 <https://github.com/fmtlib/fmt/issues/3030>`_,
		  `#3050 <https://github.com/fmtlib/fmt/issues/3050>`_
	* Improve handling (exclusion) of recursive ranges
		  `#2968 <https://github.com/fmtlib/fmt/issues/2968>`_,
		  `#2974 <https://github.com/fmtlib/fmt/pull/2974>`_
	* Improved error reporting in format string compilation
		  `#3055 <https://github.com/fmtlib/fmt/issues/3055>`_
	* Improved the implementation of
		  `Dragonbox <https://github.com/jk-jeon/dragonbox>`_, the algorithm used for
		   the default floating-point formatting
		  `#2984 <https://github.com/fmtlib/fmt/pull/2984>`_
	* Fixed issues with floating-point formatting on exotic platforms.
	* Improved the implementation of chrono formatting
		  `#3010 <https://github.com/fmtlib/fmt/pull/3010>`_
	* Improved documentation
		  `#2966 <https://github.com/fmtlib/fmt/pull/2966>`_,
		  `#3009 <https://github.com/fmtlib/fmt/pull/3009>`_,
		  `#3020 <https://github.com/fmtlib/fmt/issues/3020>`_,
		  `#3037 <https://github.com/fmtlib/fmt/pull/3037>`_
	* Improved build configuration
		  `#2991 <https://github.com/fmtlib/fmt/pull/2991>`_,
		  `#2995 <https://github.com/fmtlib/fmt/pull/2995>`_,
		  `#3004 <https://github.com/fmtlib/fmt/issues/3004>`_,
		  `#3007 <https://github.com/fmtlib/fmt/pull/3007>`_,
		  `#3040 <https://github.com/fmtlib/fmt/pull/3040>`_
	* Fixed various warnings and compilation issues
		  `#2969 <https://github.com/fmtlib/fmt/issues/2969>`_,
		  `#2971 <https://github.com/fmtlib/fmt/pull/2971>`_,
		  `#2975 <https://github.com/fmtlib/fmt/issues/2975>`_,
		  `#2982 <https://github.com/fmtlib/fmt/pull/2982>`_,
		  `#2985 <https://github.com/fmtlib/fmt/pull/2985>`_,
		  `#2988 <https://github.com/fmtlib/fmt/issues/2988>`_,
		  `#3000 <https://github.com/fmtlib/fmt/issues/3000>`_,
		  `#3006 <https://github.com/fmtlib/fmt/issues/3006>`_,
		  `#3014 <https://github.com/fmtlib/fmt/issues/3014>`_,
		  `#3015 <https://github.com/fmtlib/fmt/issues/3015>`_,
		  `#3021 <https://github.com/fmtlib/fmt/pull/3021>`_,
		  `#3023 <https://github.com/fmtlib/fmt/issues/3023>`_,
		  `#3024 <https://github.com/fmtlib/fmt/pull/3024>`_,
		  `#3029 <https://github.com/fmtlib/fmt/pull/3029>`_,
		  `#3043 <https://github.com/fmtlib/fmt/pull/3043>`_,
		  `#3052 <https://github.com/fmtlib/fmt/issues/3052>`_,
		  `#3053 <https://github.com/fmtlib/fmt/pull/3053>`_,
		  `#3054 <https://github.com/fmtlib/fmt/pull/3054>`_

Signed-off-by: Adolf Belka <[email protected]>
Reviewed-by: Michael Tremer <[email protected]>

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