[clang] [libcxx] [Clang] Implement CWG2369 "Ordering between constraints and substitution" (PR #102857)

[via cfe-commits]

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@@ -1144,6 +1164,46 @@ bool Sema::CheckInstantiatedFunctionTemplateConstraints(
                                      PointOfInstantiation, Satisfaction);
 }
 
+bool Sema::CheckFunctionConstraintsWithoutInstantiation(
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cor3ntin wrote:

This is very similar to `CheckInstantiatedFunctionTemplateConstraints` can you either reuse that or share some code?

https://github.com/llvm/llvm-project/pull/102857