Map operation fails with "Error 4089: Can't get real value of map"

[f-ishikawa]

Description

The domain restriction operation for a map fails with an error.

Steps to Reproduce

Using 2.7.4, the following operations lead to
Error 4089: Can't get real value of map in 'Test2'

public test1a : () ==> ()
test1a() == (
dcl m : map token to int := { mk_token(1) |-> 1 };
m := {mk_token(1)} <:- m;
);

public test1b : () ==> ()
test1b() == (
dcl m : map int to int := { 1 |-> 2 };
m := {1} <:- m;
);

[nickbattle]

Thanks for reporting this. There is definitely something strange here, but the domain restriction operator is <-: rather than <:-. If you change that, it appears to work correctly(?). So I need to look at why or how <:- parses without an error. I'll investigate.

[nickbattle]

So setval <:- mapval parses as setval <: (-mapval). But for some reason, the type check of a unary minus is not checking that the argument is numeric. So for example -"Hello" does not cause a type checking error (it causes a runtime error, of course).

So in your case, it was trying to "cast" a map to a numeric value, which in the general case is real. Hence the error, cannot get real value of map.

The fix looks relatively simple. Just checking it now.

[nickbattle]

Now fixed in ncb/development.