method-resolution: emit error for method calls with illegal Sized b…#22372
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ChayimFriedman2 merged 1 commit intoMay 15, 2026
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Resolves a FIXME at hir-ty/src/method_resolution.rs:151 in lookup_method_including_private that previously allowed calls like `x.cant_call()` on a `&dyn Foo` receiver to type-check without diagnostic when `cant_call(&self) where Self: Sized`, even though the `Self: Sized` predicate cannot be satisfied by the trait object. The existing predicates_require_illegal_sized_bound check in confirm.rs already correctly identifies this case (it iterates elaborated predicates and looks for `Self: Sized` clauses with a `TyKind::Dynamic` self type). Adds an InferenceDiagnostic::MethodCallIllegalSizedBound variant, plumbs the cooked diagnostic through hir, and renders it as RustcHardError E0277. Tests: trait-object call with Sized-bounded method errors; trait-object call to dyn-safe method does not; concrete-type call to a Sized-bounded method does not. Part of rust-lang#22140. Signed-off-by: Onyeka Obi <softwareengineerasaservant@isurvivable.cv>
ChayimFriedman2
approved these changes
May 15, 2026
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Resolves a FIXME at hir-ty/src/method_resolution.rs:151 in
lookup_method_including_private that previously allowed calls
like
x.cant_call()on a&dyn Fooreceiver to type-checkwithout diagnostic when
cant_call(&self) where Self: Sized,even though the
Self: Sizedpredicate cannot be satisfiedby the trait object.
The existing predicates_require_illegal_sized_bound check in
confirm.rs already correctly identifies this case (it iterates
elaborated predicates and looks for
Self: Sizedclauses witha
TyKind::Dynamicself type). Adds anInferenceDiagnostic::MethodCallIllegalSizedBound variant,
plumbs the cooked diagnostic through hir, and renders it as
RustcHardError E0277.
Tests: trait-object call with Sized-bounded method errors;
trait-object call to dyn-safe method does not; concrete-type
call to a Sized-bounded method does not.
Part of #22140.