The consteval specifier declares a function or function template to be an immediate function, that is, every potentially-evaluated call to the function must (directly or indirectly) produce a compile time constant expression.
An immediate function is a constexpr function, subject to its requirements as the case may be.
Its return type is a literal type.
Each of its parameters must be of a literal type.
When initializing the return value, each constructor call and implicit conversion is valid in a constant expression.
A constexpr function must accept and return only literal types.
A constexpr function can be recursive.
Before C++20, a constexpr function can't be virtual, and a constructor can't be defined as constexpr when the enclosing class has any virtual base classes.21 fév. 2023
Literal types are the types of constexpr variables and they can be constructed, manipulated, and returned from constexpr functions.
Note: the standard doesn't define a named requirement with this name.
This is a type category defined by the core language.
It is included here as a named requirement only for consistency.
Constexpr consternation
8 sept. 2011 [temp.dep.constexpr]p2 identifies constants with literal type ... a class with a non-constant in-class initializer cannot have any constexpr ... |
Class Types in Non-Type Template Parameters
30 mars 2018 Non-type template parameters are one of the few places in C++ ... of the constexpr keyword leaving us in a situation where we have a great. |
Generalized Constant Expressions — Revision 3
24 avr. 2006 In current C++ a variable or static data member declared const can be used in ... it returns a value (i.e. |
Constexpr Lambda
28 avr. 2015 constructors can not be evaluated as core constant expressions (since closure objects are non-literal types). |
Wording for Constexpr Lambda
1 mars 2016 type be considered a literal type if the type of each of its ... constexpr non-virtual non-explicit const conversion function template to ... |
Generalized Constant Expressions — Revision 2
26 févr. 2006 7 A user-defined literal is a constexpr variable or static data member of user-defined type or an rvalue of user-defined type constructed with ... |
General Constant Expressions for System Programming Languages
a name that denotes a global variable of literal type defined with the keyword constexpr or const and initialized with a constant expression. 3. an object |
Class Types in Non-Type Template Parameters
30 mars 2018 Non-type template parameters are one of the few places in C++ ... of the constexpr keyword leaving us in a situation where we have a great. |
Constexpr Introduction - Scott Schurr - CppCon 2015.key
constexpr objects can't change at runtime Static data member of literal type static constexpr char who[] ... static constexpr const char* a = &who[1];. |
ARM® Compiler Errors and Warnings Reference Guide
3659: a function cannot be both constexpr and virtual. 3660: a constexpr function cannot have a nonliteral return type %t. 1 C and C++ Compiler Errors and |
Constexpr Lambda - Standard C++
28 avr 2015 · literal type if the type of each of its data-members is a literal type; expressions; either because those functions can not be specified autooperator()(inti)const{ returni;} }L{}; I'm confident we'll have a good answer for lambdas + constexpr in goto; static, thread_local, non-literal and uninitialized variable |
Generalized Constant Expressions - Bjarne Stroustrups Homepage
26 fév 2006 · the proposal for Literals for user-defined types [Str03], Generalized initializer lists [DRS03] A constant-expression function cannot be called before it is defined As for other const variables, storage need not be allocated for a constant- expression datum constexpr complex I(0, 1); // OK -- literal complex |
General Constant Expressions for System Programming Languages
It has been implemented for C++ in the GNU Compiler Collection, and is part of the next stream system programming languages, such as C and C++ do not have the notion of literal types, constexpr functions, and discusses some of the pitfalls The name of global variables defined with the const keyword and initialized |
Constexpr Introduction - Scott Schurr - CppCon 2015key
constexpr objects can't change at runtime Constant static constexpr const char * a = &who[1]; static_assert calculations might not have the same results as Not virtual • Returns • Literal type or • Reference to literal type • Parameters must be • Literal error: constexpr variable 'mask' must be initialized by a constant |
Permitting trivial default initialization in constexpr contexts - Open-std
15 juil 2019 · default initialization does not compile in constexpr by making Example1::f( const TrivialType&) valid in constexpr, the need for this proposed change As always, undefined behavior cannot be invoked in constexpr (3 4 4) - a definition of a variable of non-literal type or of static or thread storage |
N2235 - Open-std
17 avr 2007 · the proposal for Literals for user-defined types [Str03], Generalized initializer lists [DRS03] A constant-expression function cannot be called before it is defined As for other const variables, storage need not be allocated for a constant- expression datum constexpr complex I(0, 1); // OK -- literal complex |
Extern template constexpr - Squarespace
Today I have Daniele Parastrelli's guest post about extern templates for you in object declarations or non-static member functions (up to C++14) means const It was thought to start in (C++20 or later) If the constexpr variable is not the following requirements: the return type of c++20 (up to C++20) must be literal in its |
Михаил Матросов
non-volatile non-template non-inline const-qualified variables (including constexpr) that aren't declared extern and aren't previously declared to have external linkage; 11 #define n 42 // Cannot contain expressions; simply evil const int n = 42; const std::string s4 = "4"; // If not a literal type; implicitly static // Anywhere |
ARM® Compiler Errors and Warnings Reference Guide
144: a value of type cannot be used to initialize an entity of type The initializing string for a 332: class has no copy constructor to copy a const object 1 C and C++ 976: a compound literal is not allowed in an integral constant expression 3646: a constexpr variable declaration must be a definition |
[PDF] Constexpr Lambda - Standard C++
Apr 28, 2015 · literal type if the type of each of its data members is a literal type; are verboten inside constant expressions; either because those functions can not be specified I'm confident we'll have a good answer for lambdas + constexpr in C++17 a definition of a variable of nonliteral type or of static or thread |
[PDF] constexpr consternation - open-std
Sep 8, 2011 · constexpr variables and static data members are required to be of The type of a constexpr static data member is required to be a literal because a class with a non constant in class initializer cannot have any constexpr |
[PDF] Dont constexpr All The Things - open-std
Jan 13, 2020 · consteval functions [P1073R3], and consteval variables [P0596R1] came as well Some C++ functions can be marked as constexpr and others cannot It doesn 't include calls to non constexpr functions or inappropriately marked have parameter types and a result type that is are constexpr friendly |
[PDF] General Constant Expressions for System Programming Languages
evaluation to functions and variables of user defined types, thereby including formerly It has been implemented for C++ in the GNU Compiler Collection, and is part of stream system programming languages, such as C and C++ do not have standard the notion of literal types, constexpr functions, and discusses some |
[PDF] Observation: static const member variables of class templates are
“Integer” only (almost) through non type template parameters 4 •if a constexpr member function (in a literal type) is const, you •can have local variables of “ literal” type •loops static assert(num < 1000, "can not handle large numbers"); |
[PDF] Compile-time Computations in C++14 - HSR-Wiki
•(static) const variables in namespace scope of built in types initialized with constant •Literal Types like Trivial structs classes + constexpr constructor initialization and trivial you need to specify it •Quiz Does it make sense to have non const constexpr member ASSERTM("can not compare tuples",false); endif |
[PDF] I predict this note will be quite badly ordered 1 - NUS Computing
Jan 30, 2019 · A decimal literal has the smallest type of int, long, or long long (ie, the first Note, objects of class type that we do not explicitly initialize will have a A const pointer is in the format of type *const variableName is a constexpr function Do note the C style string cannot use relational operators to |
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