Wrong C code generated on operations on sets

[lscrd]

The C compiler issues an error when compiling a program which contains operations (for instance, +) on sets with different types.

Example

var s1: set[char]
var s2: set['a'..'z']
s1 = s1 + s2

Current Output

C compiler error encountered on line:

s1__etK2abcqxo7K0et3U5RHIg[T1_] = s1__etK2abcqxo7K0et3U5RHIg[T1_] | s2__vKC9bTRzNfAnygP9bmyHDlDg[T1_];

Expected Output

Program compiles without error.

Possible Solution

Do not use operations between a set of a type and a set of a subtype.

Additional Information

$ nim -v
Nim Compiler Version 1.4.2 [Linux: amd64]
Compiled at 2020-11-30
Copyright (c) 2006-2020 by Andreas Rumpf

git hash: 3fb5157ab1b666a5a5c34efde0f357a82d433d04
active boot switches: -d:release

Doesn’t work with development version either.

[metagn]

Same as #15435?

[lscrd]

This issues are likely related but the error detected by the C compiler is not the same. As my system is localized, the message is in French.

For #15435 the first error is:

erreur: le transtypage spécifie un type de tableau
180 |   T4_ = ((TM__6x2C9bN0rvuU6HnSvx4zF9aQ_2[T3_] & ~ ((tySet_tyUInt8__k3HXouOuhqAKq0dx450lXQ) (x__9bvrpNC9cbtMYpvjyjwnjxZA))[T3_]) == 0);

With my example, this is:

erreur: la valeur de l'indice n'est ni un tableau ni un pointeur ni un vecteur
131 |   s1__q5c6FUUkqcJ2oGYGGyNlCQ[T1_] = s1__q5c6FUUkqcJ2oGYGGyNlCQ[T1_] | s2__LDX8PQmqIiTZpeAWmW9cQoA[T1_];

[metagn]

For #15435 the first error is

The first error is for the < operation. I added the + operation at the end after you made this issue, and the error for the + codegen in that issue is similar. In the title, you wrote that it happens on "operations on sets" so you would know that it'll error regardless of the operation

[lscrd]

I searched similar issues but was unable to find the #15435 issue :-(. But I agree: this is the same error and #16270 is probably also the same with a different behavior.

[kaushalmodi]

@lscrd

Expected Output
Program compiles without error.

I am getting this error on the latest devel, which makes sense.

t16269.nim(6, 9) Error: type mismatch: got <set[char], set[range 97..122(char)]>
but expected one of:
func `+`[T](x, y: set[T]): set[T]
  first type mismatch at position: 2
  required type for y: set[T]
  but expression 's2' is of type: set[range 97..122(char)]

[lscrd]

@kaushalmodi

We get this error with version 1.6.0 too.

When I wrote that I expected the program to compile without error, I meant that I expected no error when compiling the generated C program. One way to solve this was to introduce some restrictions on types for certain operations, which I understand.

So, for me this error makes sense too.

[kaushalmodi]

Thanks for confirming. It then looks like this issue is a duplicate of #15435; can you review the test added for that issue in this PR: https://github.com/nim-lang/Nim/pull/19079/files ?

This issue can then be closed if it's a duplicate.

[lscrd]

Yes. It’s a duplicate of #15435. For the test added in the PR, I think that last line is useless as this is line 5 which causes a compilation error. Of course, if we comment lines 5 and 6, this last line will also cause a compilation error.

I close the present issue.

[kaushalmodi]

For the test added in the PR, I think that last line is useless as this is line 5 which causes a compilation error.

You're right :) I have removed that unnecessary line from that test as it will never be reached.