[clang] [Clang] Eagerly instantiate used constexpr function upon definition. (PR #73463)

[Richard Smith via cfe-commits]

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@@ -6481,6 +6481,33 @@ void Sema::PerformPendingInstantiations(bool LocalOnly) {
     PendingInstantiations.swap(delayedPCHInstantiations);
 }
 
+// Instantiate all referenced specializations of the given function template
+// definition. This make sure that function template that are defined after the
+// point of instantiation of their used can be evaluated after they are defined.
+// see CWG2497.
+void Sema::InstantiateFunctionTemplateSpecializations(
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zygoloid wrote:

This name doesn't describe what the function does very well. Maybe something more like `PerformPendingInstantiationsOfConstexprFunction` would be clearer?

https://github.com/llvm/llvm-project/pull/73463