Fix C++20 concept detection#4653
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vitaut merged 1 commit intofmtlib:masterfrom Jan 16, 2026
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Jan 15, 2026
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Thanks for the PR but I think we should only support C++20 concepts.
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Jan 16, 2026
| @@ -2805,7 +2814,7 @@ using is_formattable = bool_constant<!std::is_same< | |||
| void>::value>; | |||
| #ifdef __cpp_concepts | |||
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To elaborate: we should only check __cpp_concepts >= 201907L here.
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9ab39ba Updated again to fix -Wundef warning.
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Merged, thanks for the fix! |
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Fix compilation on GCC < 8.4 with
-fconcepts.From GCC 8.4 onwards, ISO-19217 conceptsEdit: Irrelevant-fconceptsare compatible with C++20 concepts thanks to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88075.Repro of what I'm trying to fix: https://godbolt.org/z/vv179vWGe