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Should create warning or error for inherited unusable predicates

Open Marcono1234 opened this issue 4 years ago • 0 comments

Currently CodeQL permits writing classes with predicates using database queries, and then subclasses which do not fulfill the requirements for these database types. This renders these inherited predicates unusable and creates pretty cryptic compilation errors when trying to use them. Examples:

  • https://github.com/github/codeql/issues/3705
  • https://github.com/github/codeql/issues/5320
  • https://github.com/github/codeql/issues/7067

It would be good if:

  1. The CodeQL compiler would detect such unusuable inherited predicates and cause a compilation error (or at least a warning) for the subclass. This would avoid exposing such subclasses to the user, causing the cryptic compilation errors when they try to use predicates of the subclass.
  2. The error message would be clearer, ideally pointing to where the requirement for the database types come from, with predicate call hierarchy if possible. For example for CodeQL Java's Array.getQualifiedName() (see https://github.com/github/codeql/issues/7067) it should indicate that RefType.getPackage() only supports @class and @interface.

Marcono1234 avatar Nov 06 '21 13:11 Marcono1234