addFunctionAssumeCapacity

pub fn addFunctionAssumeCapacity(
    self: *Builder,
    ty: Type,
    name: StrtabString,
    addr_space: AddrSpace,
) Function.Index {
    assert(ty.isFunction(self));
    const function_index: Function.Index = @enumFromInt(self.functions.items.len);
    self.functions.appendAssumeCapacity(.{
        .global = self.addGlobalAssumeCapacity(name, .{
            .addr_space = addr_space,
            .type = ty,
            .kind = .{ .function = function_index },
        }),
        .strip = undefined,
    });
    return function_index;
}