[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, 42 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 6db8eb3e5ed..770c07d41b1 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -207,6 +207,8 @@ bool Sema::CodeSynthesisContext::isInstantiationRecord() const {
   case DefiningSynthesizedFunction:
   case ExceptionSpecEvaluation:
   case ConstraintSubstitution:
+  case ParameterMappingSubstitution:
+  case ConstraintNormalization:
   case RewritingOperatorAsSpaceship:
     return false;
 
@@ -380,6 +382,22 @@ Sema::InstantiatingTemplate::InstantiatingTemplate(
           PointOfInstantiation, InstantiationRange, Template, nullptr,
           {}, &DeductionInfo) {}
 
+Sema::InstantiatingTemplate::InstantiatingTemplate(
+    Sema &SemaRef, SourceLocation PointOfInstantiation,
+    ConstraintNormalization, NamedDecl *Template,
+    SourceRange InstantiationRange)
+    : InstantiatingTemplate(
+          SemaRef, CodeSynthesisContext::ConstraintNormalization,
+          PointOfInstantiation, InstantiationRange, Template) {}
+
+Sema::InstantiatingTemplate::InstantiatingTemplate(
+    Sema &SemaRef, SourceLocation PointOfInstantiation,
+    ParameterMappingSubstitution, NamedDecl *Template,
+    SourceRange InstantiationRange)
+    : InstantiatingTemplate(
+          SemaRef, CodeSynthesisContext::ParameterMappingSubstitution,
+          PointOfInstantiation, InstantiationRange, Template) {}
+
 void Sema::pushCodeSynthesisContext(CodeSynthesisContext Ctx) {
   Ctx.SavedInNonInstantiationSFINAEContext = InNonInstantiationSFINAEContext;
   InNonInstantiationSFINAEContext = false;
@@ -733,6 +751,17 @@ void Sema::PrintInstantiationStack() {
                    diag::note_constraint_substitution_here)
           << Active->InstantiationRange;
       break;
+    case CodeSynthesisContext::ConstraintNormalization:
+      Diags.Report(Active->PointOfInstantiation,
+                   diag::note_constraint_normalization_here)
+          << cast<NamedDecl>(Active->Entity)->getName()
+          << Active->InstantiationRange;
+      break;
+    case CodeSynthesisContext::ParameterMappingSubstitution:
+      Diags.Report(Active->PointOfInstantiation,
+                   diag::note_parameter_mapping_substitution_here)
+          << Active->InstantiationRange;
+      break;
     }
   }
 }
@@ -757,6 +786,8 @@ Optional<TemplateDeductionInfo *> Sema::isSFINAEContext() const {
     case CodeSynthesisContext::DefaultFunctionArgumentInstantiation:
     case CodeSynthesisContext::ExceptionSpecInstantiation:
     case CodeSynthesisContext::ConstraintsCheck:
+    case CodeSynthesisContext::ParameterMappingSubstitution:
+    case CodeSynthesisContext::ConstraintNormalization:
       // This is a template instantiation, so there is no SFINAE.
       return None;
 
@@ -2926,6 +2957,17 @@ Sema::SubstStmt(Stmt *S, const MultiLevelTemplateArgumentList &TemplateArgs) {
   return Instantiator.TransformStmt(S);
 }
 
+bool Sema::SubstTemplateArguments(
+    ArrayRef<TemplateArgumentLoc> Args,
+    const MultiLevelTemplateArgumentList &TemplateArgs,
+    TemplateArgumentListInfo &Out) {
+  TemplateInstantiator Instantiator(*this, TemplateArgs,
+                                    SourceLocation(),
+                                    DeclarationName());
+  return Instantiator.TransformTemplateArguments(Args.begin(), Args.end(),
+                                                 Out);
+}
+
 ExprResult
 Sema::SubstExpr(Expr *E, const MultiLevelTemplateArgumentList &TemplateArgs) {
   if (!E)