1 files changed, 15 insertions, 9 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index bbf1965eef4..766ed944b13 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -5008,9 +5008,15 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
 
   // If the parameter type somehow involves auto, deduce the type now.
   if (getLangOpts().CPlusPlus1z && ParamType->isUndeducedType()) {
+    // When checking a deduced template argument, deduce from its type even if
+    // the type is dependent, in order to check the types of non-type template
+    // arguments line up properly in partial ordering.
+    Optional<unsigned> Depth;
+    if (CTAK != CTAK_Specified)
+      Depth = Param->getDepth() + 1;
     if (DeduceAutoType(
             Context.getTrivialTypeSourceInfo(ParamType, Param->getLocation()),
-                       Arg, ParamType) == DAR_Failed) {
+            Arg, ParamType, Depth) == DAR_Failed) {
       Diag(Arg->getExprLoc(),
            diag::err_non_type_template_parm_type_deduction_failure)
         << Param->getDeclName() << Param->getType() << Arg->getType()
@@ -5029,14 +5035,6 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
     }
   }
 
-  // If either the parameter has a dependent type or the argument is
-  // type-dependent, there's nothing we can check now.
-  if (ParamType->isDependentType() || Arg->isTypeDependent()) {
-    // FIXME: Produce a cloned, canonical expression?
-    Converted = TemplateArgument(Arg);
-    return Arg;
-  }
-
   // We should have already dropped all cv-qualifiers by now.
   assert(!ParamType.hasQualifiers() &&
          "non-type template parameter type cannot be qualified");
@@ -5058,6 +5056,14 @@ ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
     return ExprError();
   }
 
+  // If either the parameter has a dependent type or the argument is
+  // type-dependent, there's nothing we can check now.
+  if (ParamType->isDependentType() || Arg->isTypeDependent()) {
+    // FIXME: Produce a cloned, canonical expression?
+    Converted = TemplateArgument(Arg);
+    return Arg;
+  }
+
   if (getLangOpts().CPlusPlus1z) {
     // C++1z [temp.arg.nontype]p1:
     //   A template-argument for a non-type template parameter shall be