295 lines
12 KiB
C++
295 lines
12 KiB
C++
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// RUN: %clang_cc1 -fcxx-exceptions -verify=expected,beforecxx14,beforecxx20,beforecxx23 -std=c++11 %s
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// RUN: %clang_cc1 -fcxx-exceptions -verify=expected,aftercxx14,beforecxx20,beforecxx23 -std=c++14 %s
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// RUN: %clang_cc1 -fcxx-exceptions -verify=expected,aftercxx14,aftercxx20,beforecxx23 -std=c++20 %s
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// RUN: %clang_cc1 -fcxx-exceptions -verify=expected,aftercxx14,aftercxx20 -std=c++23 %s
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namespace N {
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typedef char C;
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}
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namespace M {
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typedef double D;
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}
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struct NonLiteral { // expected-note 2{{no constexpr constructors}}
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NonLiteral() {}
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NonLiteral(int) {}
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};
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struct Literal {
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constexpr Literal() {}
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operator int() const { return 0; }
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};
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struct S {
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virtual int ImplicitlyVirtual() const = 0; // beforecxx20-note {{overridden virtual function}}
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};
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struct SS : S {
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int ImplicitlyVirtual() const;
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};
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// The definition of a constexpr function shall satisfy the following
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// constraints:
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struct T : SS, NonLiteral {
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constexpr T();
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constexpr int f() const;
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// - it shall not be virtual; [until C++20]
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virtual constexpr int ExplicitlyVirtual() const { return 0; } // beforecxx20-error {{virtual function cannot be constexpr}}
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constexpr int ImplicitlyVirtual() const { return 0; } // beforecxx20-error {{virtual function cannot be constexpr}}
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virtual constexpr int OutOfLineVirtual() const; // beforecxx20-error {{virtual function cannot be constexpr}}
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// - its return type shall be a literal type;
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// Once we support P2448R2 constexpr functions will be allowd to return non-literal types
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// The destructor will also be allowed
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constexpr NonLiteral NonLiteralReturn() const { return {}; } // expected-error {{constexpr function's return type 'NonLiteral' is not a literal type}}
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constexpr void VoidReturn() const { return; } // beforecxx14-error {{constexpr function's return type 'void' is not a literal type}}
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constexpr ~T(); // beforecxx20-error {{destructor cannot be declared constexpr}}
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typedef NonLiteral F() const;
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constexpr F NonLiteralReturn2; // ok until definition
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// - each of its parameter types shall be a literal type;
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// Once we support P2448R2 constexpr functions will be allowd to have parameters of non-literal types
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constexpr int NonLiteralParam(NonLiteral) const { return 0; } // expected-error {{constexpr function's 1st parameter type 'NonLiteral' is not a literal type}}
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typedef int G(NonLiteral) const;
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constexpr G NonLiteralParam2; // ok until definition
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// - its function-body shall be = delete, = default,
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constexpr int Deleted() const = delete;
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// It's not possible for the function-body to legally be "= default" here
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// (that is, for a non-constructor function) in C++11.
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// Other than constructors, only the copy- and move-assignment operators and
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// destructor can be defaulted. Destructors can't be constexpr since they
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// don't have a literal return type. Defaulted assignment operators can't be
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// constexpr since they can't be const.
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constexpr T &operator=(const T &) = default; // beforecxx14-error {{an explicitly-defaulted copy assignment operator may not have 'const', 'constexpr' or 'volatile' qualifiers}} \
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// beforecxx14-warning {{C++14}} \
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// aftercxx14-error{{defaulted definition of copy assignment operator is not constexpr}}
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};
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constexpr int T::OutOfLineVirtual() const { return 0; }
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#if __cplusplus >= 201402L
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struct T2 {
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int n = 0;
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constexpr T2 &operator=(const T2&) = default; // ok
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};
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struct T3 {
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constexpr T3 &operator=(const T3 &) const = default; // beforecxx20-error {{an explicitly-defaulted copy assignment operator may not have 'const' or 'volatile' qualifiers}} \
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// aftercxx20-warning {{explicitly defaulted copy assignment operator is implicitly deleted}} \
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// aftercxx20-note {{function is implicitly deleted because its declared type does not match the type of an implicit copy assignment operator}}
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};
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#endif
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struct U {
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constexpr U SelfReturn() const;
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constexpr int SelfParam(U) const;
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};
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struct V : virtual U { // expected-note {{here}}
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constexpr int F() const { return 0; } // expected-error {{constexpr member function not allowed in struct with virtual base class}}
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};
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// or a compound-statememt that contains only [CXX11]
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constexpr int AllowedStmtsCXX11() {
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// - null statements
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;
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// - static_assert-declarations
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static_assert(true, "the impossible happened!");
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// - typedef declarations and alias-declarations that do not define classes
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// or enumerations
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typedef int I;
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typedef struct S T;
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using J = int;
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using K = int[sizeof(I) + sizeof(J)];
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// Note, the standard requires we reject this.
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struct U;
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// - using-declarations
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using N::C;
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// - using-directives
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using namespace N;
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// - and exactly one return statement
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return sizeof(K) + sizeof(C) + sizeof(K);
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}
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// or a compound-statement that does not contain [C++14]
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constexpr int DisallowedStmtsCXX14_1(bool b) {
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// - an asm-definition
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if (b)
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asm("int3"); // beforecxx20-warning {{use of this statement in a constexpr function is a C++20 extension}}
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return 0;
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}
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constexpr int DisallowedStmtsCXX14_2() {
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return 0; // beforecxx14-note {{previous}}
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// - a goto statement
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goto x; // beforecxx23-warning {{use of this statement in a constexpr function is a C++23 extension}}
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x:;
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return 0; // beforecxx14-warning {{multiple return}}
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}
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constexpr int DisallowedStmtsCXX14_2_1() {
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merp: // beforecxx23-warning {{use of this statement in a constexpr function is a C++23 extension}}
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return 0;
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}
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constexpr int DisallowedStmtsCXX14_3() {
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// - a try-block,
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try { } // beforecxx20-warning {{use of this statement in a constexpr function is a C++20 extension}}
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catch (...) {}
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return 0;
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}
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constexpr int DisallowedStmtsCXX14_4() {
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// - a definition of a variable of non-literal type
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return 0;
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NonLiteral nl; // beforecxx23-error {{variable of non-literal type 'NonLiteral' cannot be defined in a constexpr function before C++23}} \
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// beforecxx23-note@14 {{'NonLiteral' is not literal}}
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}
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constexpr int DisallowedStmtsCXX14_5() {
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return 0;
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// - a definition of a variable of static storage duration
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static constexpr int n = 123; // beforecxx23-warning {{definition of a static variable in a constexpr function is a C++23 extension}} \
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// beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}}
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}
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constexpr int DisallowedStmtsCXX14_6() {
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// - a definition of a variable of thread storage duration
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return 0;
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thread_local constexpr int n = 123; // beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}} \
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// beforecxx23-warning {{definition of a thread_local variable in a constexpr function is a C++23 extension}}
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}
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constexpr int DisallowedStmtsCXX14_7() {
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// - a definition of a variable for which no initialization is performed
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return 0;
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int n; // beforecxx20-warning {{uninitialized variable in a constexpr function}}
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}
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constexpr int ForStmt() {
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for (int n = 0; n < 10; ++n) {} // beforecxx14-error {{statement not allowed in constexpr function}}
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return 0;
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}
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constexpr int VarDecl() {
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int a = 0; // beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}}
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return 0;
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}
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constexpr int ConstexprVarDecl() {
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constexpr int a = 0; // beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}}
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return 0;
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}
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constexpr int VarWithCtorDecl() {
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Literal a; // beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}}
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return 0;
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}
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NonLiteral nl;
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constexpr NonLiteral &ExternNonLiteralVarDecl() {
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extern NonLiteral nl; // beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}}
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return nl;
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}
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static_assert(&ExternNonLiteralVarDecl() == &nl, "");
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constexpr int FuncDecl() {
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constexpr int ForwardDecl(int); // beforecxx14-warning {{use of this statement in a constexpr function is a C++14 extension}}
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return ForwardDecl(42);
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}
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constexpr int ClassDecl1() {
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typedef struct {} S1; // beforecxx14-warning {{type definition in a constexpr function is a C++14 extension}}
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return 0;
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}
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constexpr int ClassDecl2() {
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using S2 = struct {}; // beforecxx14-warning {{type definition in a constexpr function is a C++14 extension}}
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return 0;
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}
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constexpr int ClassDecl3() {
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struct S3 {}; // beforecxx14-warning {{type definition in a constexpr function is a C++14 extension}}
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return 0;
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}
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constexpr int NoReturn() {} // expected-error {{no return statement in constexpr function}}
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constexpr int MultiReturn() {
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return 0; // beforecxx14-note {{return statement}}
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return 0; // beforecxx14-warning {{multiple return statements in constexpr function}}
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}
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// - every constructor call and implicit conversion used in initializing the
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// return value shall be one of those allowed in a constant expression.
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//
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// We implement the proposed resolution of DR1364 and ignore this bullet.
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// However, we implement the spirit of the check as part of the p5 checking that
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// a constexpr function must be able to produce a constant expression.
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namespace DR1364 {
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constexpr int f(int k) {
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return k; // ok, even though lvalue-to-rvalue conversion of a function
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// parameter is not allowed in a constant expression.
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}
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int kGlobal; // expected-note {{here}}
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constexpr int f() { // expected-error {{constexpr function never produces a constant expression}}
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return kGlobal; // expected-note {{read of non-const}}
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}
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}
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namespace rdar13584715 {
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typedef __PTRDIFF_TYPE__ ptrdiff_t;
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template<typename T> struct X {
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static T value() {};
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};
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void foo(ptrdiff_t id) {
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switch (id) {
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case reinterpret_cast<ptrdiff_t>(&X<long>::value): // expected-error{{case value is not a constant expression}} \
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// expected-note{{reinterpret_cast is not allowed in a constant expression}}
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break;
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}
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}
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}
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namespace std_example {
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constexpr int square(int x) {
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return x * x;
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}
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constexpr long long_max() {
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return 2147483647;
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}
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constexpr int abs(int x) {
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if (x < 0) // beforecxx14-warning {{C++14}}
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x = -x;
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return x;
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}
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constexpr int first(int n) {
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return 0;
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static int value = n; // beforecxx23-warning {{definition of a static variable in a constexpr function is a C++23 extension}} \
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// beforecxx14-warning {{variable declaration in a constexpr function is a C++14 extension}}
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}
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constexpr int uninit() {
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int a; // beforecxx20-warning {{uninitialized}}
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return a;
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}
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constexpr int prev(int x) { // beforecxx14-error {{never produces a constant expression}}
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return --x; // beforecxx14-note {{subexpression}}
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}
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constexpr int g(int x, int n) {
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int r = 1; // beforecxx14-warning{{C++14}}
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while (--n > 0) // beforecxx14-error {{statement not allowed in constexpr function}}
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r *= x;
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return r;
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}
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}
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struct Base {
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constexpr Base() = default;
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};
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struct Derived : virtual Base { // expected-note 3{{virtual base class declared here}}
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constexpr Derived() = default; // expected-error {{default constructor cannot be 'constexpr' in a class with virtual base class}}
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constexpr Derived(const Derived&) = default; // expected-error {{copy constructor cannot be 'constexpr' in a class with virtual base class}}
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constexpr Derived(Derived&&) = default; // expected-error {{move constructor cannot be 'constexpr' in a class with virtual base class}}
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};
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