[clang] [Clang] Fix crash on non-parameter NTTP arguments during partial ordering (PR #231599)

[Corentin Jabot via cfe-commits]

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@@ -257,9 +257,10 @@ getNTTParameterFromExpr(const Expr *E, UnsignedOrNone Depth) {
 }
 
 QualType Sema::getTypeOfConstantTemplateParameter(const TemplateArgument &Arg) {
-  if (NonTypeOrVarTemplateParmDecl NTTP =
-          getNTTParameterFromExpr(Arg.getAsExpr(), std::nullopt))
-    return NTTP.getType();
+  if (Arg.getKind() == TemplateArgument::Expression)
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cor3ntin wrote:

Ugh, actually we should have used getNonTypeTemplateArgumentType() in the non expression case...
I.E, in the expression case we want tohandle declrefs, etc, but in all other cases, we still want the type of the NTTP

@EmmanuelAC1 

https://github.com/llvm/llvm-project/pull/231599