1 files changed, 25 insertions, 3 deletions
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 64500d0a26d54..fbbab8f007039 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -1848,6 +1848,8 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(
   // FIXME: Concepts: Do not substitute into constraint expressions
   Expr *TrailingRequiresClause = D->getTrailingRequiresClause();
   if (TrailingRequiresClause) {
+    EnterExpressionEvaluationContext ConstantEvaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     ExprResult SubstRC = SemaRef.SubstExpr(TrailingRequiresClause,
                                            TemplateArgs);
     if (SubstRC.isInvalid())
@@ -2186,6 +2188,8 @@ Decl *TemplateDeclInstantiator::VisitCXXMethodDecl(
   // FIXME: Concepts: Do not substitute into constraint expressions
   Expr *TrailingRequiresClause = D->getTrailingRequiresClause();
   if (TrailingRequiresClause) {
+    EnterExpressionEvaluationContext ConstantEvaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     ExprResult SubstRC = SemaRef.SubstExpr(TrailingRequiresClause,
                                            TemplateArgs);
     if (SubstRC.isInvalid())
@@ -2685,6 +2689,16 @@ Decl *TemplateDeclInstantiator::VisitNonTypeTemplateParmDecl(
         D->getDepth() - TemplateArgs.getNumSubstitutedLevels(),
         D->getPosition(), D->getIdentifier(), T, D->isParameterPack(), DI);
 
+  if (AutoTypeLoc AutoLoc = DI->getTypeLoc().getContainedAutoTypeLoc())
+    if (AutoLoc.isConstrained())
+      if (SemaRef.AttachTypeConstraint(
+              AutoLoc, Param,
+              IsExpandedParameterPack
+                ? DI->getTypeLoc().getAs<PackExpansionTypeLoc>()
+                    .getEllipsisLoc()
+                : SourceLocation()))
+        Invalid = true;
+
   Param->setAccess(AS_public);
   Param->setImplicit(D->isImplicit());
   if (Invalid)
@@ -3600,6 +3614,12 @@ Decl *TemplateDeclInstantiator::VisitConceptDecl(ConceptDecl *D) {
   llvm_unreachable("Concept definitions cannot reside inside a template");
 }
 
+Decl *
+TemplateDeclInstantiator::VisitRequiresExprBodyDecl(RequiresExprBodyDecl *D) {
+  return RequiresExprBodyDecl::Create(SemaRef.Context, D->getDeclContext(),
+                                      D->getBeginLoc());
+}
+
 Decl *TemplateDeclInstantiator::VisitDecl(Decl *D) {
   llvm_unreachable("Unexpected decl");
 }
@@ -3713,6 +3733,8 @@ TemplateDeclInstantiator::SubstTemplateParams(TemplateParameterList *L) {
   // checking satisfaction.
   Expr *InstRequiresClause = nullptr;
   if (Expr *E = L->getRequiresClause()) {
+    EnterExpressionEvaluationContext ConstantEvaluated(
+        SemaRef, Sema::ExpressionEvaluationContext::Unevaluated);
     ExprResult Res = SemaRef.SubstExpr(E, TemplateArgs);
     if (Res.isInvalid() || !Res.isUsable()) {
       return nullptr;
@@ -4236,9 +4258,9 @@ bool Sema::CheckInstantiatedFunctionTemplateConstraints(
         MLTAL.getInnermost(), SourceRange());
     if (Inst.isInvalid())
       return true;
-    if (addInstantiatedParametersToScope(*this, Decl,
-                                        Decl->getTemplateInstantiationPattern(),
-                                         Scope, MLTAL))
+    if (addInstantiatedParametersToScope(
+            *this, Decl, Decl->getPrimaryTemplate()->getTemplatedDecl(),
+            Scope, MLTAL))
       return true;
   }