[Bug] [kompile] - Reporting a requires clause variable as RHS

[ehildenb]

K Version

+ kompile --version
K version:    5.3.0
Build date:   Tue Jun 28 15:38:19 UTC 2022

Actual version: 6f12ca3

Description

A variable on the LHS of the rule is being seen as on teh RHS of the rule for the haskell backend.

Input Files

module TEST
    imports MAP
    imports INT
    imports BOOL

    syntax Pgm ::= "a" | "b"

    rule <k> a => b </k>

    syntax Int ::= f ( Int ) [function, functional, no-evaluators]

    configuration <k> $PGM:Pgm </k>

    rule <k> a => b </k> requires f(_X) ==Int 3

endmodule

Reproduction Steps

+ kompile --backend haskell test.k --main-module TEST --syntax-module TEST
[Error] Compiler: Found variable _X on right hand side of rule, not bound on
left hand side. Did you mean "?_X"?
        Source(/home/dev/src/k/test.k)
        Location(14,37,14,39)
        14 |        rule <k> a => b </k> requires f(_X) ==Int 3
           .                                        ^~
[Error] Compiler: Had 1 structural errors.

Expected Behavior

This should kompile just fine for the haskell backend, variables in the requires clause should be considered as part of LHS for haskell backend.

[ehildenb]

Disabling this line of code fixes this:

k/kernel/src/main/java/org/kframework/compile/checks/CheckRHSVariables.java

Line 111 in 382a862

errors.add(KEMException.compilerError("Found variable " + k.name()