c26498.md

title	description	ms.date	f1_keywords	helpviewer_keywords
Warning C26498	Learn more about: Warning C26498 USE_CONSTEXPR_FOR_FUNCTIONCALL	08/18/2020	C26498 USE_CONSTEXPR_FOR_FUNCTIONCALL	C26498

Warning C26498

The function 'function' is constexpr, mark variable 'variable' constexpr if compile-time evaluation is desired (con.5)

This rule helps to enforce Con.5 from the C++ Core Guidelines: use constexpr for values that can be computed at compile time.

Remarks

The warning is triggered by assigning the result of a constexpr function to any non-constexpr variable whose value doesn't change after the initial assignment.

Code analysis name: USE_CONSTEXPR_FOR_FUNCTIONCALL

Example

This sample code shows where C26498 may appear:

constexpr int getMyValue()
{
    return 1;
}

void foo()
{
    constexpr int val0 = getMyValue(); // no C26498
    const int val1 = getMyValue();     // C26498, C26814
    int val2 = getMyValue();           // C26498, value is never modified
    int val3 = getMyValue();           // no C26498, val3 is assigned to below.
    val3 = val3 * val2;
}

To fix the issues, mark val1 and val2 constexpr:

constexpr int getMyValue()
{
    return 1;
}

void foo()
{
    constexpr int val0 = getMyValue(); // OK
    constexpr int val1 = getMyValue(); // OK
    constexpr int val2 = getMyValue(); // OK
    int val3 = getMyValue();           // OK
    val3 = val3 * val2;
}

See also

C26497
C26814
Con.5