constexpr variable cannot have non literal type 'const
What is the difference between constexpr and consteval?
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.
What are the limitations of constexpr?
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
What is a literal type in constexpr?
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.
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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 ... |
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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. |
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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. |
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Constexpr Lambda
28 avr. 2015 constructors can not be evaluated as core constant expressions (since closure objects are non-literal types). |
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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 ... |
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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 ... |
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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 |
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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. |
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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];. |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
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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 |
