Merge commit '7b28fcd2b182' from llvm.org/main into next

Author: git apple-llvm automerger

clang/lib/Sema/SemaTemplateDeduction.cpp

@@ -483,7 +483,7 @@ DeduceNonTypeTemplateArgument(Sema &S, TemplateParameterList *TemplateParams,
     return TemplateDeductionResult::Inconsistent;
   }
   Deduced[NTTP.getIndex()] = Result;
-  if (!S.getLangOpts().CPlusPlus17)
+  if (!S.getLangOpts().CPlusPlus17 && !PartialOrdering)
     return TemplateDeductionResult::Success;
 
   if (NTTP.isExpandedParameterPack())
@@ -2652,28 +2652,11 @@ DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
             getDeducedNTTParameterFromExpr(Info, P.getAsExpr())) {
       switch (A.getKind()) {
       case TemplateArgument::Expression: {
-        const Expr *E = A.getAsExpr();
-        // When checking NTTP, if either the parameter or the argument is
-        // dependent, as there would be otherwise nothing to deduce, we force
-        // the argument to the parameter type using this dependent implicit
-        // cast, in order to maintain invariants. Now we can deduce the
-        // resulting type from the original type, and deduce the original type
-        // against the parameter we are checking.
-        if (const auto *ICE = dyn_cast<ImplicitCastExpr>(E);
-            ICE && ICE->getCastKind() == clang::CK_Dependent) {
-          E = ICE->getSubExpr();
-          if (auto Result = DeduceTemplateArgumentsByTypeMatch(
-                  S, TemplateParams, ICE->getType(), E->getType(), Info,
-                  Deduced, TDF_SkipNonDependent,
-                  PartialOrdering ? PartialOrderingKind::NonCall
-                                  : PartialOrderingKind::None,
-                  /*DeducedFromArrayBound=*/false, HasDeducedAnyParam);
-              Result != TemplateDeductionResult::Success)
-            return Result;
-        }
+        // The type of the value is the type of the expression as written.
         return DeduceNonTypeTemplateArgument(
-            S, TemplateParams, NTTP, DeducedTemplateArgument(A), E->getType(),
-            Info, PartialOrdering, Deduced, HasDeducedAnyParam);
+            S, TemplateParams, NTTP, DeducedTemplateArgument(A),
+            A.getAsExpr()->IgnoreImplicitAsWritten()->getType(), Info,
+            PartialOrdering, Deduced, HasDeducedAnyParam);
       }
       case TemplateArgument::Integral:
       case TemplateArgument::StructuralValue: