Unexpected error when using if / else if in return expression.

[dgottner]

Trying to test this code:

const assert = @import("std").debug.assert;

inline fn sgn(n: i64) i8 {
    return if (n < 0)
        -1
    else if (n == 0)
        0
    else
        1;
}

test "sign function" {
    assert(sgn(49) == 1);
    assert(sgn(-49) == -1);
    assert(sgn(0) == 0);
}

results in a compilation error:

$ zig test bug.zig
./bug.zig:6:10: error: values of type 'comptime_int' must be comptime known
    else if (n == 0)

Note that rewriting the above to not use an expression-based if statement does not provoke an error:

const assert = @import("std").debug.assert;

inline fn sgn(n: i64) i8 {
    if (n < 0)
        return -1
    else if (n == 0)
        return 0
    else
        return 1;
}

test "sign function" {
    assert(sgn(49) == 1);
    assert(sgn(-49) == -1);
    assert(sgn(0) == 0);
}

zig test nobug.zig
All 1 tests passed.

[Vexu]

Duplicate of #5557, #3750, #4255 and. #4629