1 files changed, 28 insertions, 3 deletions
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 64ef819e30d..327447746c3 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -2591,6 +2591,23 @@ ConvertDeducedTemplateArgument(Sema &S, NamedDecl *Param,
   return ConvertArg(Arg, 0);
 }
 
+template<typename TemplateDeclT>
+static Sema::TemplateDeductionResult
+CheckDeducedArgumentConstraints(Sema& S, TemplateDeclT *Template,
+                                ArrayRef<TemplateArgument> DeducedArgs,
+                                TemplateDeductionInfo &Info) {
+  llvm::SmallVector<const Expr *, 3> AssociatedConstraints;
+  Template->getAssociatedConstraints(AssociatedConstraints);
+  if (S.CheckConstraintSatisfaction(Template, AssociatedConstraints,
+                                    DeducedArgs, Info.getLocation(),
+                                    Info.AssociatedConstraintsSatisfaction) ||
+      !Info.AssociatedConstraintsSatisfaction.IsSatisfied) {
+    Info.reset(TemplateArgumentList::CreateCopy(S.Context, DeducedArgs));
+    return Sema::TDK_ConstraintsNotSatisfied;
+  }
+  return Sema::TDK_Success;
+}
+
 // FIXME: This should not be a template, but
 // ClassTemplatePartialSpecializationDecl sadly does not derive from
 // TemplateDecl.
@@ -2688,6 +2705,10 @@ static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
     // If we get here, we successfully used the default template argument.
   }
 
+  if (Sema::TemplateDeductionResult Result
+        = CheckDeducedArgumentConstraints(S, Template, Builder, Info))
+    return Result;
+
   return Sema::TDK_Success;
 }
 
@@ -2767,10 +2788,14 @@ FinishTemplateArgumentDeduction(
     return Sema::TDK_SubstitutionFailure;
   }
 
+  bool ConstraintsNotSatisfied;
   SmallVector<TemplateArgument, 4> ConvertedInstArgs;
   if (S.CheckTemplateArgumentList(Template, Partial->getLocation(), InstArgs,
-                                  false, ConvertedInstArgs))
-    return Sema::TDK_SubstitutionFailure;
+                                  false, ConvertedInstArgs,
+                                  /*UpdateArgsWithConversions=*/true,
+                                  &ConstraintsNotSatisfied))
+    return ConstraintsNotSatisfied ? Sema::TDK_ConstraintsNotSatisfied :
+                                     Sema::TDK_SubstitutionFailure;
 
   TemplateParameterList *TemplateParams = Template->getTemplateParameters();
   for (unsigned I = 0, E = TemplateParams->size(); I != E; ++I) {
@@ -2831,7 +2856,6 @@ static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
   return Sema::TDK_Success;
 }
 
-
 /// Perform template argument deduction to determine whether
 /// the given template arguments match the given class template
 /// partial specialization per C++ [temp.class.spec.match].
@@ -5049,6 +5073,7 @@ template<typename TemplateLikeDecl>
 static bool isAtLeastAsSpecializedAs(Sema &S, QualType T1, QualType T2,
                                      TemplateLikeDecl *P2,
                                      TemplateDeductionInfo &Info) {
+  // TODO: Concepts: Regard constraints
   // C++ [temp.class.order]p1:
   //   For two class template partial specializations, the first is at least as
   //   specialized as the second if, given the following rewrite to two