Add -vet-explicit-allocators

[Lperlind]

This vet flag will make it so that allocators must be explicitly used in places where context.allocator and context.temp_allocator are a procedure parameter.

The goal of this flag is to prevent using the context.allocator in cases where a different allocator was meant to be used. Some code bases default context.allocator to nil/panic allocator to catch this at runtime. This effectively makes it a compile time error instead.

This change intentionally just targets context.temp_allocator and context.allocator rather than all runtime.Allocator default values as I feel that if an explicit value is set that is not context then some much more intentional default value was intended.

Example code:

#+vet explicit-allocators
package alloc

import "core:fmt"

foo :: proc(allocator := context.allocator) {
}

foo_temp :: proc(allocator := context.temp_allocator) {
}

main :: proc() {
    foo(context.allocator)
    foo_temp(context.allocator)
    result := fmt.aprintf("hello %v", "world", allocator = context.allocator)

    foo() // Error: Parameter 'allocator' of type 'Allocator' must be explicitly provided in procedure call
    foo_temp() // Error: Parameter 'allocator' of type 'Allocator' must be explicitly provided in procedure call
    result := fmt.aprintf("hello %v", "world") // Error: Parameter 'allocator' of type 'Allocator' must be explicitly provided in procedure call
}

[gingerBill]

The idea and implementation is good.

My issue is that -vet-explicit-allocators is pretty much never going to be a good thing in practice since loads of core library will break. So #+vet explicit-allocators is probably one of the main use cases of it.

[dozn]

The idea and implementation is good.

My issue is that -vet-explicit-allocators is pretty much never going to be a good thing in practice since loads of core library will break. So #+vet explicit-allocators is probably one of the main use cases of it.

Could it use -vet-packages:?