[clang] Don't wrap immediate invocations in ConstantExprs within constexpr initializers (PR #89565)

[via cfe-commits]

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@@ -16548,11 +16548,10 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
         std::string PrettySourceValue = toString(Value, 10);
         std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
 
-        S.DiagRuntimeBehavior(
-            E->getExprLoc(), E,
-            S.PDiag(diag::warn_impcast_integer_precision_constant)
-                << PrettySourceValue << PrettyTargetValue << E->getType() << T
-                << E->getSourceRange() << SourceRange(CC));
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cor3ntin wrote:

This seems unrelated - We do not want to emit this diag during constant evaluation, because we know the source value and that it does not lose precision.

https://github.com/llvm/llvm-project/pull/89565