Casting int to array backed bit_fields can crash the compiler

[hitchh1k3r]

Context

I was trying to set constant values for a 24bit bit_field.

Odin: dev-2024-06:96c06185d
OS: Windows 10 Professional (version: 22H2), build 19045.4412
CPU: Intel(R) Core(TM) i7-4771 CPU @ 3.50GHz
RAM: 16311 MiB
Backend: LLVM 17.0.1

Expected Behavior

The compiler should not crash.

Current Behavior

The compiler crashes with something like:

[DEBUG] 256
u8 -> 1
[...]\Odin\src\llvm_backend_const.cpp(414): Assertion Failure: `sz >= max_count` max_count: 2, sz: 1, written: 0, type u8

Failure Information

The compiler crashes when casting an integer to an array backed bit_field if the integer is larger than the array's individual elements can hold.

Here is a minimal reproduction:

package main

import "core:fmt"

main :: proc() {
  BitField :: bit_field [2]u8 {}
  fmt.println(BitField(256))
}

[hitchh1k3r]

While playing around with the crash, I found a second one that is probably related. If you cast a variable to an array backed bit_field:

BitField :: bit_field [2]u8 {}
i := u8(0)
fmt.println(BitField(i)) // Crash

this assert fails:

[...]Odin\src\llvm_backend_utility.cpp(1459): Assertion Failure: `is_type_array(st) || is_type_enumerated_array(st) || is_type_matrix(st)` bit_field [2]u8 { }

It's okay if you cast an array though:

BitField :: bit_field [2]u8 {}
i := [2]u8{ 0, 0 }
fmt.println(BitField(i)) // Okay

Which makes me think the int -> array backed bit_field is not supposed to be allowed, but there is just no error message that an array is expected.

[gingerBill]

This bug is caused by the array-programming cast but it should not be allowed.