[Concepts] Constrained partial specializations and function overloads.

Added support for constraint satisfaction checking and partial ordering of constraints in constrained partial specialization and function template overloads.
Re-commit after fixing some crashes and warnings.

Differential Revision: https://reviews.llvm.org/D41910

1 files changed, 20 insertions, 10 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 699895568b7..ade8a5a6ac1 100644..100755
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1120,11 +1120,11 @@ NamedDecl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
   // Check that we have valid decl-specifiers specified.
   auto CheckValidDeclSpecifiers = [this, &D] {
     // C++ [temp.param]
-    // p1
+    // p1 
     //   template-parameter:
     //     ...
     //     parameter-declaration
-    // p2
+    // p2 
     //   ... A storage class shall not be specified in a template-parameter
     //   declaration.
     // [dcl.typedef]p1:
@@ -3900,7 +3900,9 @@ DeclResult Sema::ActOnVarTemplateSpecialization(
     }
 
     if (isSameAsPrimaryTemplate(VarTemplate->getTemplateParameters(),
-                                Converted)) {
+                                Converted) &&
+        (!Context.getLangOpts().ConceptsTS ||
+         !TemplateParams->hasAssociatedConstraints())) {
       // C++ [temp.class.spec]p9b3:
       //
       //   -- The argument list of the specialization shall not be identical
@@ -3919,8 +3921,8 @@ DeclResult Sema::ActOnVarTemplateSpecialization(
   VarTemplateSpecializationDecl *PrevDecl = nullptr;
 
   if (IsPartialSpecialization)
-    // FIXME: Template parameter list matters too
-    PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
+    PrevDecl = VarTemplate->findPartialSpecialization(Converted, TemplateParams,
+                                                      InsertPos);
   else
     PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
 
@@ -5273,12 +5275,16 @@ bool Sema::CheckTemplateArgumentList(
       bool PackExpansionIntoNonPack =
           NewArgs[ArgIdx].getArgument().isPackExpansion() &&
           (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
-      if (PackExpansionIntoNonPack && isa<TypeAliasTemplateDecl>(Template)) {
+      if (PackExpansionIntoNonPack && (isa<TypeAliasTemplateDecl>(Template) ||
+                                       isa<ConceptDecl>(Template))) {
         // Core issue 1430: we have a pack expansion as an argument to an
         // alias template, and it's not part of a parameter pack. This
         // can't be canonicalized, so reject it now.
+        // As for concepts - we cannot normalize constraints where this
+        // situation exists.
         Diag(NewArgs[ArgIdx].getLocation(),
-             diag::err_alias_template_expansion_into_fixed_list)
+             diag::err_template_expansion_into_fixed_list)
+          << (isa<ConceptDecl>(Template) ? 1 : 0)
           << NewArgs[ArgIdx].getSourceRange();
         Diag((*Param)->getLocation(), diag::note_template_param_here);
         return true;
@@ -7112,6 +7118,7 @@ static bool MatchTemplateParameterKind(Sema &S, NamedDecl *New, NamedDecl *Old,
                                        bool Complain,
                                      Sema::TemplateParameterListEqualKind Kind,
                                        SourceLocation TemplateArgLoc) {
+  // TODO: Concepts: Check constrained-parameter constraints here.
   // Check the actual kind (type, non-type, template).
   if (Old->getKind() != New->getKind()) {
     if (Complain) {
@@ -7813,8 +7820,9 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
   ClassTemplateSpecializationDecl *PrevDecl = nullptr;
 
   if (isPartialSpecialization)
-    // FIXME: Template parameter list matters, too
-    PrevDecl = ClassTemplate->findPartialSpecialization(Converted, InsertPos);
+    PrevDecl = ClassTemplate->findPartialSpecialization(Converted,
+                                                        TemplateParams,
+                                                        InsertPos);
   else
     PrevDecl = ClassTemplate->findSpecialization(Converted, InsertPos);
 
@@ -7838,7 +7846,9 @@ DeclResult Sema::ActOnClassTemplateSpecialization(
                                                       Converted);
 
     if (Context.hasSameType(CanonType,
-                        ClassTemplate->getInjectedClassNameSpecialization())) {
+                        ClassTemplate->getInjectedClassNameSpecialization()) &&
+        (!Context.getLangOpts().ConceptsTS ||
+         !TemplateParams->hasAssociatedConstraints())) {
       // C++ [temp.class.spec]p9b3:
       //
       //   -- The argument list of the specialization shall not be identical