155 lines
7.0 KiB
C++
155 lines
7.0 KiB
C++
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// RUN: %clang_cc1 -std=c++17 %s -verify -fcxx-exceptions
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// RUN: not %clang_cc1 -std=c++17 %s -emit-llvm-only -fcxx-exceptions
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struct S { int a, b, c; };
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// A simple-declaration can be a decompsition declaration.
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namespace SimpleDecl {
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auto [a_x, b_x, c_x] = S();
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void f(S s) {
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auto [a, b, c] = S();
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{
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for (auto [a, b, c] = S();;) {}
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if (auto [a, b, c] = S(); true) {}
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switch (auto [a, b, c] = S(); 0) { case 0:; }
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}
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}
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}
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// A for-range-declaration can be a decomposition declaration.
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namespace ForRangeDecl {
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extern S arr[10];
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void h() {
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for (auto [a, b, c] : arr) {
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}
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}
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}
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// Other kinds of declaration cannot.
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namespace OtherDecl {
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// A parameter-declaration is not a simple-declaration.
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// This parses as an array declaration.
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void f(auto [a, b, c]); // expected-error {{'auto' not allowed in function prototype}} expected-error {{'a'}}
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void g() {
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// A condition is allowed as a Clang extension.
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// See commentary in test/Parser/decomposed-condition.cpp
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for (; auto [a, b, c] = S(); ) {} // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'S' is not contextually convertible to 'bool'}}
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if (auto [a, b, c] = S()) {} // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'S' is not contextually convertible to 'bool'}}
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if (int n; auto [a, b, c] = S()) {} // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'S' is not contextually convertible to 'bool'}}
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switch (auto [a, b, c] = S()) {} // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{statement requires expression of integer type ('S' invalid)}}
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switch (int n; auto [a, b, c] = S()) {} // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{statement requires expression of integer type ('S' invalid)}}
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while (auto [a, b, c] = S()) {} // expected-warning {{ISO C++17 does not permit structured binding declaration in a condition}} expected-error {{value of type 'S' is not contextually convertible to 'bool'}}
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// An exception-declaration is not a simple-declaration.
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try {}
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catch (auto [a, b, c]) {} // expected-error {{'auto' not allowed in exception declaration}} expected-error {{'a'}}
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}
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// A member-declaration is not a simple-declaration.
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class A {
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auto [a, b, c] = S(); // expected-error {{not permitted in this context}}
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static auto [a, b, c] = S(); // expected-error {{not permitted in this context}}
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};
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}
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namespace GoodSpecifiers {
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void f() {
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int n[1];
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const volatile auto &[a] = n;
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}
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}
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namespace BadSpecifiers {
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typedef int I1[1];
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I1 n;
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struct S { int n; } s;
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void f() {
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// storage-class-specifiers
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static auto &[a] = n; // expected-warning {{declared 'static' is a C++20 extension}}
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thread_local auto &[b] = n; // expected-warning {{declared 'thread_local' is a C++20 extension}}
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extern auto &[c] = n; // expected-error {{cannot be declared 'extern'}} expected-error {{cannot have an initializer}}
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struct S {
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mutable auto &[d] = n; // expected-error {{not permitted in this context}}
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// function-specifiers
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virtual auto &[e] = n; // expected-error {{not permitted in this context}}
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explicit auto &[f] = n; // expected-error {{not permitted in this context}}
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// misc decl-specifiers
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friend auto &[g] = n; // expected-error {{'auto' not allowed}} expected-error {{friends can only be classes or functions}}
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};
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typedef auto &[h] = n; // expected-error {{cannot be declared 'typedef'}}
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constexpr auto &[i] = n; // expected-error {{cannot be declared 'constexpr'}}
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}
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static constexpr inline thread_local auto &[j1] = n; // expected-error {{cannot be declared with 'constexpr inline' specifiers}}
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static thread_local auto &[j2] = n; // expected-warning {{declared with 'static thread_local' specifiers is a C++20 extension}}
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inline auto &[k] = n; // expected-error {{cannot be declared 'inline'}}
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const int K = 5;
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void g() {
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// defining-type-specifiers other than cv-qualifiers and 'auto'
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S [a] = s; // expected-error {{cannot be declared with type 'BadSpecifiers::S'}}
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decltype(auto) [b] = s; // expected-error {{cannot be declared with type 'decltype(auto)'}}
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auto ([c]) = s; // expected-error {{cannot be declared with parentheses}}
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// FIXME: This error is not very good.
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auto [d]() = s; // expected-error {{expected ';'}} expected-error {{expected expression}}
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auto [e][1] = s; // expected-error {{expected ';'}} expected-error {{requires an initializer}}
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// FIXME: This should fire the 'misplaced array declarator' diagnostic.
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int [K] arr = {0}; // expected-error {{expected ';'}} expected-error {{cannot be declared with type 'int'}} expected-error {{decomposition declaration '[K]' requires an initializer}}
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int [5] arr = {0}; // expected-error {{place the brackets after the name}}
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auto *[f] = s; // expected-error {{cannot be declared with type 'auto *'}} expected-error {{incompatible initializer}}
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auto S::*[g] = s; // expected-error {{cannot be declared with type 'auto BadSpecifiers::S::*'}} expected-error {{incompatible initializer}}
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// ref-qualifiers are OK.
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auto &&[ok_1] = S();
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auto &[ok_2] = s;
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// attributes are OK.
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[[]] auto [ok_3] = s;
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alignas(S) auto [ok_4] = s;
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// ... but not after the identifier or declarator.
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// FIXME: These errors are not very good.
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auto [bad_attr_1 [[]]] = s; // expected-error {{attribute list cannot appear here}} expected-error 2{{}}
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auto [bad_attr_2] [[]] = s; // expected-error {{expected ';'}} expected-error {{}}
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}
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}
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namespace MultiDeclarator {
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struct S { int n; };
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void f(S s) {
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auto [a] = s, [b] = s; // expected-error {{must be the only declaration}}
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auto [c] = s, d = s; // expected-error {{must be the only declaration}}
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auto e = s, [f] = s; // expected-error {{must be the only declaration}}
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auto g = s, h = s, i = s, [j] = s; // expected-error {{must be the only declaration}}
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}
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}
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namespace Template {
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int n[3];
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// FIXME: There's no actual rule against this...
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template<typename T> auto [a, b, c] = n; // expected-error {{decomposition declaration template not supported}}
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}
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namespace Init {
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void f() {
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int arr[1];
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struct S { int n; };
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auto &[bad1]; // expected-error {{decomposition declaration '[bad1]' requires an initializer}}
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const auto &[bad2](S{}, S{}); // expected-error {{initializer for variable '[bad2]' with type 'const auto &' contains multiple expressions}}
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const auto &[bad3](); // expected-error {{expected expression}}
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auto &[good1] = arr;
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auto &&[good2] = S{};
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const auto &[good3](S{});
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S [goodish3] = { 4 }; // expected-error {{cannot be declared with type 'S'}}
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S [goodish4] { 4 }; // expected-error {{cannot be declared with type 'S'}}
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}
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}
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