Array access via Enum type fails

[steeve]

Hey, thank you for this great project!

Here is a quick reproducer:

typedef enum {
    one = 1,
    two = 2,
    three = 3,
    four = 4,
} EnumValues;

static inline int dynamic_array_access(EnumValues idx) {
  static const int values[] = {0, 1, 2, 3, 4};
  return values[idx - 1];
}

It will reach the following unreachable at

translate-c/src/Translator.zig

Lines 3108 to 3118 in 0a146cc

	const maybe_bigger_than_usize = switch (index_qt.base(t.comp).type) {
	.bool => {
	break :index try ZigTag.int_from_bool.create(t.arena, index);
	},
	.int => |int| switch (int) {
	.long_long, .ulong_long, .int128, .uint128 => true,
	else => false,
	},
	.bit_int => |bit_int| bit_int.bits > t.comp.target.ptrBitWidth(),
	else => unreachable,
	};

Thank you!

[steeve]

Gemini suggested adding the following cse:

            .@"enum" => |e| blk: {
                const tag = e.tag orelse break :blk false;
                switch (tag.base(t.comp).type) {
                    .int => |int| switch (int) {
                        .long_long, .ulong_long, .int128, .uint128 => break :blk true,
                        else => break :blk false,
                    },
                    .bit_int => |bit_int| break :blk bit_int.bits > t.comp.target.ptrBitWidth(),
                    else => unreachable,
                }
            },

Which generates the following code:

pub fn dynamic_array_access(arg_idx: EnumValues) callconv(.c) c_int {
    var idx = arg_idx;
    _ = &idx;
    const static_local_values = struct {
        const values: [5]c_int = [5]c_int{
            0,
            1,
            2,
            3,
            4,
        };
    };
    _ = &static_local_values;
    return static_local_values.values[idx -% @as(EnumValues, 1)];
}

Since it's AI, I figure I might ask before sending a PR.

[Vexu]

It's not wrong but it'd be better to use continue on the switch instead of repeating it.

[steeve]

You're right, I'll send a PR