Escaping keyword in concrete pattern yields undeclared variable

[kevinvandervlist]

As far as I could see this has not been reported yet.

module Weird

extend lang::std::Layout;
extend lang::std::Id;

import IO;

syntax C = c: Id type;

str a((C)`<Id tpe>`) = "<tpe>";

// Syntax error, unescaped keyword
// str b((C)`<Id type>`) = "<\type>";

// Syntax error, unescaped keyword
//str c((C)`<Id \type>`) = "<type>";

str d((C)`<Id \type>`) = "<\type>";

void main() {
    x = parse(#C, "foo");
    // This works as expected
    println(a(x));
    // this yields a runtime error
    println(d(x));
}

will produce:

rascal>import Weird;
ok
rascal>main();
foo
|project://Minos/src/Weird.rsc|(306,5,<18,27>,<18,32>): Undeclared variable: type
Advice: |http://tutor.rascal-mpl.org/Errors/Static/UndeclaredVariable/UndeclaredVariable.html|
ok

Shouldn't you be able to escape type like I do in d?

[jurgenvinju]

Good report. Thanks!

• type or \type is always implicitly declared as a constructor for the reified type representation: type(Symbol, map[Symbol,Production]). So in principle its use as in your example should always lead to a static "redeclaration" error.
• However, one might allow shadowing the name, like in your example it could be ok if \type shadowed the generic type constructor.
• The current "undeclared variable" error is definitely misleading; either the shadowing should work correctly, or the error should be "redeclaration".
• I wonder what the new type checker has to say about this one. @PaulKlint

[PaulKlint]

Well ... the new type checker only complaints that an import ParseTree; is missing (the interpreter is a bit more permissive). Apart from that the above code is fine, the variable \type just shadows the built-in one.

The commented out versions give a syntax error because type is a reserved word.

The line println(d(x)); indeed gives runtime error (in the interpreter).