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73 lines
3.6 KiB
73 lines
3.6 KiB
4 months ago
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// RUN: %clang_cc1 -std=c++1z %s -verify
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// The same restrictions apply to the parameter-declaration-clause of a
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// deduction guide as in a function declaration.
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template<typename T> struct A {};
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A(void) -> A<int>; // expected-note {{previous}}
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A(void, int) -> A<int>; // expected-error {{'void' must be the first and only parameter if specified}}
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A() -> A<int>; // expected-error {{redeclaration of deduction guide}}
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// expected-note@-1 {{previous}}
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A() -> A<int>; // expected-note {{previous}}
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// expected-error@-1 {{redeclaration of deduction guide}}
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A() -> A<float>; // FIXME: "functions" is a poor term. expected-error {{functions that differ only in their return type cannot be overloaded}}
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template<typename T> A(T) -> A<typename T::foo>;
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template<typename T> A(T) -> A<typename T::bar>; // ok, can overload on return type (SFINAE applies)
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A(long) -> A<int>;
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template<typename T = int> A(long) -> A<char>; // ok, non-template beats template as usual
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// (Pending DR) The template-name shall name a class template.
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template<typename T> using B = A<T>; // expected-note {{template}}
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B() -> B<int>; // expected-error {{cannot specify deduction guide for alias template 'B'}}
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// FIXME: expected-error@-1 {{declarator requires an identifier}}
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template<typename T> int C;
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C() -> int; // expected-error {{requires a type specifier}}
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template<typename T> void D();
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D() -> int; // expected-error {{requires a type specifier}}
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template<template<typename> typename TT> struct E { // expected-note 2{{template}}
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// FIXME: Should only diagnose this once!
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TT(int) -> TT<int>; // expected-error 2{{cannot specify deduction guide for template template parameter 'TT'}} expected-error {{requires an identifier}}
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};
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A(int) -> int; // expected-error {{deduced type 'int' of deduction guide is not a specialization of template 'A'}}
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template<typename T> A(T) -> B<T>; // expected-error {{deduced type 'B<T>' (aka 'A<type-parameter-0-0>') of deduction guide is not written as a specialization of template 'A'}}
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template<typename T> A(T*) -> const A<T>; // expected-error {{deduced type 'const A<T>' of deduction guide is not a specialization of template 'A'}}
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// A deduction-guide shall be declared in the same scope as the corresponding
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// class template.
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namespace WrongScope {
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namespace {
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template<typename T> struct AnonNS1 {}; // expected-note {{here}}
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AnonNS1(float) -> AnonNS1<float>; // ok
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}
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AnonNS1(int) -> AnonNS1<int>; // expected-error {{deduction guide must be declared in the same scope as template 'WrongScope::}}
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template<typename T> struct AnonNS2 {}; // expected-note {{here}}
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namespace {
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AnonNS1(char) -> AnonNS1<char>; // ok
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AnonNS2(int) -> AnonNS2<int>; // expected-error {{deduction guide must be declared in the same scope as template 'WrongScope::AnonNS2'}}
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}
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namespace N {
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template<typename T> struct NamedNS1 {}; // expected-note {{here}}
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template<typename T> struct NamedNS2 {}; // expected-note {{here}}
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}
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using N::NamedNS1;
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NamedNS1(int) -> NamedNS1<int>; // expected-error {{deduction guide must be declared in the same scope as template}}
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using namespace N;
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NamedNS2(int) -> NamedNS2<int>; // expected-error {{deduction guide must be declared in the same scope as template}}
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struct ClassMemberA {
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template<typename T> struct X {}; // expected-note {{here}}
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};
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struct ClassMemberB : ClassMemberA {
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X(int) -> X<int>; // expected-error {{deduction guide must be declared in the same scope as template 'WrongScope::ClassMemberA::X'}}
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};
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template<typename T> struct Local {};
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void f() {
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Local(int) -> Local<int>; // expected-error {{expected}}
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using WrongScope::Local;
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Local(int) -> Local<int>; // expected-error {{expected}}
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}
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}
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