metadataConstantAssumeCapacity

fn metadataConstantAssumeCapacity(self: *Builder, constant: Constant) Metadata {
    const Adapter = struct {
        builder: *const Builder,
        pub fn hash(_: @This(), key: Constant) u32 {
            var hasher = comptime std.hash.Wyhash.init(std.hash.int(@backingInt(Metadata.Tag.constant)));
            hasher.update(std.mem.asBytes(&key));
            return @truncate(hasher.final());
        }

        pub fn eql(ctx: @This(), lhs_key: Constant, _: void, rhs_index: usize) bool {
            if (Metadata.Tag.constant != ctx.builder.metadata_items.items(.tag)[rhs_index]) return false;
            const rhs_data: Constant = @fromBackingInt(ctx.builder.metadata_items.items(.data)[rhs_index]);
            return rhs_data == lhs_key;
        }
    };

    const gop = self.metadata_map.getOrPutAssumeCapacityAdapted(
        constant,
        Adapter{ .builder = self },
    );

    if (!gop.found_existing) {
        gop.key_ptr.* = {};
        gop.value_ptr.* = {};
        self.metadata_items.appendAssumeCapacity(.{
            .tag = .constant,
            .data = @backingInt(constant),
        });
    }
    return .{ .index = @intCast(gop.index), .kind = .node };
}