Commit d42d5eb8 authored by Saar Raz's avatar Saar Raz
Browse files

[Concepts] Implement P1616R1 - Using unconstrained template template... 

[Concepts] Implement P1616R1 - Using unconstrained template template parameters with constrained templates

Summary: Allow unconstrained template template parameters to accept constrainted templates as arguments.

Reviewers: rsmith

Subscribers: cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D73155
parent c77bbea9

clang/lib/Sema/SemaTemplate.cpp

+5 −0
Original line number Diff line number Diff line
@@ -7164,6 +7164,11 @@ bool Sema::CheckTemplateTemplateArgument(TemplateTemplateParmDecl *Param, 
      //   [temp.constr.order].

      SmallVector<const Expr *, 3> ParamsAC, TemplateAC;

      Params->getAssociatedConstraints(ParamsAC);

      // C++2a[temp.arg.template]p3

      //   [...] In this comparison, if P is unconstrained, the constraints on A

      //   are not considered.

      if (ParamsAC.empty())

        return false;

      Template->getAssociatedConstraints(TemplateAC);

      bool IsParamAtLeastAsConstrained;

      if (IsAtLeastAsConstrained(Param, ParamsAC, Template, TemplateAC,

clang/test/CXX/temp/temp.arg/temp.arg.template/p3-2a.cpp

+5 −5
Original line number Diff line number Diff line
@@ -7,9 +7,9 @@ template<typename T> concept F = T::f(); 
// expected-note@-1{{similar constraint expressions not considered equivalent}}

template<template<C> class P> struct S1 { }; // expected-note 2{{'P' declared here}}



template<C> struct X { }; // expected-note{{'X' declared here}}

template<C> struct X { };



template<D> struct Y { }; // expected-note 2{{'Y' declared here}}

template<D> struct Y { }; // expected-note{{'Y' declared here}}

template<typename T> struct Z { };

template<F> struct W { }; // expected-note{{'W' declared here}}
@@ -18,10 +18,10 @@ S1<Y> s12; // expected-error{{template template argument 'Y' is more constrained 
S1<Z> s13;

S1<W> s14; // expected-error{{template template argument 'W' is more constrained than template template parameter 'P'}}



template<template<typename> class P> struct S2 { }; // expected-note 2{{'P' declared here}}

template<template<typename> class P> struct S2 { };



S2<X> s21; // expected-error{{template template argument 'X' is more constrained than template template parameter 'P'}}

S2<Y> s22; // expected-error{{template template argument 'Y' is more constrained than template template parameter 'P'}}

S2<X> s21;

S2<Y> s22;

S2<Z> s23;



template <template <typename...> class C>