static assertions

[YashasSamaga]

Is this a BUG REPORT, FEATURE REQUEST or QUESTION?:

• Bug Report
• Feature Request
• Question

Design concept:
static_assert takes a constant expression as the first parameter which must evaluate to true (non-zero number) for successful compilation and an optional error string as the second parameter.

static_assert(cond, errstr="")

The compiler would trigger a fatal error if cond evaluates to false. If an error string was given, the error string would be shown to the user; otherwise, the expression will be shown.

The compiler should allow static_assert to be embedded inside other constant expressions. For example,

new arr[(static_assert(sz % 32 == 0, "array size must be a multiple of 32"), sz)];
const expr = 10 + !static_assert(size > 0);

This can be achieved by making static_assert always return a value (say 1).

Error messages:

test.pwn (123): fatal error 123: assertion failed: [expression]
test.pwn (123): fatal error 123: assertion failed: array size must be a multiple of 32
test.pwn (123): error 195: static_assert can evaluate constant expressions only

Why is it needed?

• allows libraries to place assertions in the user's code (where #error isn't of much use)
• allows descriptive error messages

Issues:

• Macro replacement for the old compiler

[YashasSamaga]

Could also allow warning messages:

static_assert(cond, errstr="", errwarn = ERROR)

[Zeex]

What's the advantage of this over:

#define x 33

#if x % 32 != 0
    #error Array size must be a multiple of 32
#endif

?

[Southclaws]

Cleaner, less explicit/terse syntax - I'm usually the one to avoid new syntax but I do prefer the static_assert proposal over the explicit directives.

[Y-Less]

I too am frequently against new syntax, but this would be useful, especially if there was a warning version too. I tend to use variables if I need a custom error/warning in user code, for example the warning for the old foreach syntax is actually a variable shadowing warning for a variable called dont_use_the old foreach or something similar. And errors simply by referencing a non-existent variable.

[YashasSamaga]

@Zeex (or anyone) are you working on this?

[Zeex]

No, I am not

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.