generics: defer constraint checks for implementation-header parameters (fixes upstream#41770) - #50
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…s (fixes upstream#41770)
A Delphi-style implementation of a generic routine does not repeat the
constraints of its declaration. While the implementation header is
parsed, the fresh type parameter is still an undefineddef, and the
constraint check rejected it ("Class type expected, but got T") before
it could be matched with the already validated declaration.
Skip the check only for an undefined generic parameter of an
implementation header when a generic declaration with the same name and
arity exists; complete header matching is still required afterwards.
FPC issue: https://gitlab.com/freepascal.org/fpc/source/-/issues/41770
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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FPC merge request: https://gitlab.com/freepascal.org/fpc/source/-/merge_requests/1555 |
Keep a valid implementation-header/runtime control and reject invalid concrete specialization at the call site, invalid body specialization and a mismatched implementation signature. These cover distinct phases rather than repeating the accepted example.
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Problem. FPC issue #41770: a Delphi-style implementation of a generic routine does not repeat the constraints of its declaration. While the implementation header is parsed, the fresh type parameter is still an
undefineddef, and the constraint check rejected it ("Class type expected, but got T") before it could be matched with the already validated declaration.Fix. In
pgenutil.passkip the check only for an undefined generic parameter of an implementation header when a generic declaration with the same name and arity exists; complete header matching is still required afterwards, so mismatched headers, forwards and standalone unconstrained generics are rejected as before.Test.
tests/webtbs/tw41770.pp: rejected on currentmain, runs after the fix.Validation. Win64 build of
main(a359fc1) with the patch; 405 neighbouring tests fromtests/test(inline, rtti, helpers, generics, opt) give identical results before and after.🤖 Generated with Claude Code