Fatal error in ENFORCE rule at compile time.

[stefjoosten]

What happened

I was experimenting with enforcement rules in RAP4, when suddenly I got a fatal error. Since the script was without type errors, I expected it to pass fluently through the compiler.

The screenshot tells the entire story: This is a fatal error, so this clearly is a bug.

Reproducing the error

1. Log in to https://rap.tarski.nl
2. Create a new script with the following contents:

    CONTEXT Issue1419
   
    CLASSIFY Ss ISA S
    CLASSIFY Uu ISA U
   
    RELATION r[S*T]
    RELATION s[T*U]
    RELATION t[Ss*Uu]
   
    ENFORCE t >: r;s
   
    ENDCONTEXT
   

3. Compile this script Lo and behold, the fatal error appears.

Symptoms

In a first attempt to analyze this error, I noticed that the following script compiles without errors:

CONTEXT Issue1419

CLASSIFY Ss ISA S
CLASSIFY Uu ISA U

RELATION r[S*T]
RELATION s[T*U]
RELATION t[Ss*Uu]

ENFORCE t >: I[Ss];r;s;I[Uu]

ENDCONTEXT