why can not i use this rule to validate variable declartion

[zrwsmd]

why can not i use this rule to validate variable declaration
full langium file can be seen below demo.txt
demo.txt

[msujew]

Hey @zrwsmd,

I assume you're using the default lexical scoping mechanism. Since the variables inside of the InputsListSingle object are nested in its local scope, they are not visible to the elements of the surrounding PLC_PRG program. You need to adjust the ScopeComputation (see here for an example) to ensure that elements are visible outside of their parent node.

Note that using the word validate here is incredibly confusing. The issue isn't that you cannot validate, but that the reference cannot correctly link. The validation error is only a consequence of the linker error.

[zrwsmd]

so i should override computeLocalScopes method?
this file actually separated into different files,1-10 lines is at aa.st, below is at main.st

[msujew]

Yes, if the element should be visible to the elements of the same file, you shouls override the computeLocalScopes method.

[zrwsmd]

it works out!very thanks.if i want to reference productId,i guess also should define a class extends DefaultScopeProvider?

[msujew]

if i want to reference productId,i guess also should define a class extends DefaultScopeProvider?

Yes, exactly. The ScopeComputation is in charge of the lexical scope (i.e. which elements are visible on a block-based level), while the ScopeProvider allows you to define arbitrary linking rules for any reference.