Usman Akinyemi b31dc4ab49 diagnostics: avoid ICE for undeclared generic parameter in impl ...

Avoid an ICE for:

    struct A;
    impl A<B> {}

The compiler no longer panics and can proceed to emit existing diagnostics.

Adds `tests/ui/missing/undeclared-generic-parameter.rs`.

Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>

2026-03-21 21:54:46 +05:30

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auxiliary

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missing-items

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missing-allocator.rs

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missing-allocator.stderr

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missing-block-hint.rs

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missing-block-hint.stderr

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missing-comma-in-match.fixed

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missing-comma-in-match.rs

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missing-comma-in-match.stderr

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missing-derivable-attr.rs

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missing-derivable-attr.stderr

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missing-fields-in-struct-pattern.rs

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missing-fields-in-struct-pattern.stderr

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missing-let.rs

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missing-let.stderr

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missing-macro-use.rs

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missing-macro-use.stderr

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missing-main.rs

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missing-main.stderr

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missing-return.rs

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missing-return.stderr

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missing-stability.rs

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missing-stability.stderr

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undeclared-generic-parameter.rs

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undeclared-generic-parameter.stderr

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