Field name in a syntax definition wrongly associated as redefinition of Rascal grammar field?

[msteindorfer]

When importing my own syntax definition of a language in a compiled Rascal console, then I'm getting the following error:

Error: Field chars already defined as type [34-34]+ on non-terminal type StringConstant, cannot redefine to type MyStringChars? AT |std:///lang/rascal/syntax/Rascal.rsc|(14583,14,<374,8>,<374,22>)

Both my own syntax definition and also the Rascal grammar contain a lexical named StringConstant with a field chars, however it remains unclear to me why the compiler associated my syntax definition's lexical, with the Rascal'l lexical (neither Rascal grammar nor any other module is imported):

// MyLanguage.rsc
lexical StringConstant
  = @category="Constant" "\"": MyStringChars? chars "\"" ;

// Rascal.rsc
lexical StringConstant
  = @category="Constant" "\"" StringCharacter* chars "\"" ;

[DavyLandman]

which modules have you imported? if one of them also (transitively) imports the rascal grammar, that's the cause.

[msteindorfer]

@DavyLandman, no module import, just the syntax definition standalone, thus I don't understand where the Rascal grammar comes from.

[msteindorfer]

What if I indeed would like to include two grammars that have the same names for productions or lexicals (e.g., if I'd like to transform from one language to another)?

I'd assume that names like StringConstant or IntegerLiteral are common in grammars.

[DavyLandman]

That is possible, but mixing them in the same file is a bit painful, as grammars are merged differently than the import works for other stuff. I think @tvdstorm has most experience with that.