Use of undefined value but not undefined

[digital vault]

I'm currently working on code gen for GDExtension. I have this function

pub var variant_from_string: interface.VariantFromTypeConstructorFunc = null;

const std = @import("std");
pub fn init(p_get_proc_address: interface.InterfaceGetProcAddress) !void {
    fns.init(p_get_proc_address);
    init_type_api(fns);
    init_singletons(fns);
    init_util_func(fns);
    variant_from_string = fns.get_variant_from_type_constructor.?(interface.VariantTypes.STRING);
    var string: types.String = undefined;
    var variant: types.Variant = .{ .no_touch = std.mem.zeroes([24]u8) };
    fns.string_new_with_utf8_chars.?(&string, "ZIG IS FULLY INITILIZED!!!\n");
    variant_from_string.?(
        &variant,
        &string,
    );
    @setRuntimeSafety(false);
    util_fns.general.@"print 2648703342"(variant);
    @setRuntimeSafety(true);
}

with the error

gdextension/api.zig:28:41: error: use of undefined value here causes undefined behavior
    util_fns.general.@"print 2648703342"(variant);
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~
referenced by:
    initalize: src/extension.zig:14:12
    hello_extension_entry: src/extension.zig:31:25
    remaining reference traces hidden; use '-freference-trace' to see all reference traces
error: the following command failed with 1 compilation errors:

I don't understand why the compiler believes the variant is undefined.
I was hoping I could just disable the check(setRuntimeSafety), but

1. It didn't work
2. I should probably fix the underlying issue

[honest harness]

what type is fns?

[digital vault]

hopefully an initlized version of

get_godot_version: interface.InterfaceGetGodotVersion = undefined, // p_get_proc_address("get_godot_version"),
mem_alloc: interface.InterfaceMemAlloc = undefined, // p_get_proc_address("mem_alloc"),
mem_realloc: interface.InterfaceMemRealloc = undefined, // p_get_proc_address("mem_realloc"),
mem_free: interface.InterfaceMemFree = undefined, // p_get_proc_address("mem_free"),
print_error: interface.InterfacePrintError = undefined, // p_get_proc_address("print_error"),
print_error_with_message: interface.InterfacePrintErrorWithMessage = undefined, // 
...

[plush swift]

passing undefined is not ub, maybe you are calling undefined?

[digital vault]

```
pub fn init(self: *@This(), p_get_proc_address: interface.InterfaceGetProcAddress) void {
    const t: std.builtin.Type = @typeInfo(@This());
    inline for (t.Struct.fields) |field| {
        @field(self, field.name) = @as(field.type, @ptrCast(p_get_proc_address.?(field.name)));
    }
}
```~~~
No wait

[honest harness]

is it a pointer? i'm dubious of init_type_api etc. being able to actually initialize it

[plush swift]

you can check with @compileLog(util_fns.general.@"print 2648703342");

[digital vault]

unfortunatly it's initlized at runtime

init_type_api doesn't init the fns. it uses the functions to init

https://gitlab.com/biom4st3r/zig-GDExtension/-/blob/default/gdextension/api.zig?ref_type=heads

[plush swift]

I was correct, there's no way for an undefined const to become not undefined at runtime https://gitlab.com/biom4st3r/zig-GDExtension/-/blob/default/gdextension/gdextension_utility_functions.zig?ref_type=heads#L103

[digital vault]

I did I make it const? oops

Lol damn. that'll do it

Shouldn't have complained that I assigned to a const?

[plush swift]

where do you think you assigned to it?

[digital vault]

init_util_func

[plush swift]

That iterates over fields, const and var create global constant and global variable decls

Since there are no fields, the inline for never loops, so the loop body is never analyzed by the compiler.