This commit modifies polymorphization's handling of predicates so that
if any generic parameter is used in a predicate then all parameters in
that predicate are used.
Signed-off-by: David Wood <david@davidtw.co>
This commit adjusts polymorphization's handling of predicates so that
after ensuring that `T` is used in `I: Foo<T>` if `I` is used, it now
ensures that `I` is used if `T` is used in `I: Foo<T>`. This is
necessary to mark generic parameters that only exist in impl parameters
as used - thereby avoiding symbol clashes when using the new mangling
scheme.
Signed-off-by: David Wood <david@davidtw.co>
This commit constrains the support added for handling unevaluated consts
in polymorphization (introduced in #75260) by:
- Skipping associated constants as this causes cycle errors.
- Skipping promoted constants when they contain `Self` as this ensures
`T` is used in constants of the form `<Self as Foo<T>>`.
Signed-off-by: David Wood <david@davidtw.co>
polymorphize: unevaluated constants
This PR makes polymorphization visit the promoted MIR of unevaluated constants with available promoted MIR instead of visiting the substitutions of that constant - which will mark all of the generic parameters as used; in addition polymorphization will now visit non-promoted unevaluated constants rather than visit their substs.
r? @lcnr
This commit modifies how instances are polymorphized so that closures
and generators have any closures or generators captured within their
upvars also polymorphized - this avoids symbol clashes with the new
symbol mangling scheme.
Signed-off-by: David Wood <david@davidtw.co>
This commit makes polymorphization visit non-promoted unevaluated
constants rather than visit their substs directly.
Signed-off-by: David Wood <david@davidtw.co>
This commit makes polymorphization visited the MIR of unevaluated
constants with available promoted MIR instead of visiting the
substitutions of that constant - which will mark all of the generic
parameters as used.
Signed-off-by: David Wood <david@davidtw.co>
mir: add `used_generic_parameters_needs_subst`
Fixes#74636.
This PR adds a `used_generic_parameters_needs_subst` helper function which checks whether a type needs substitution, but only for parameters that the `unused_generic_params` query considers used. This is used in the MIR interpreter to make the check for some pointer casts and for reflection intrinsics more precise.
I've opened this as a draft PR because this might not be the approach we want to fix this issue and we have to decide what to do about the reflection case.
r? @eddyb
cc @lcnr @wesleywiser
This commit adds a `ensure_monomorphic_enough` utility function which
checks whether a type needs substitution, but only for parameters
that the `unused_generic_params` query considers used.
`ensure_monomorphic_enough` is then used throughout interpret where
`needs_subst` checks previously existed (in particular, for some
pointer casts and for reflection intrinsics more precise).
Signed-off-by: David Wood <david@davidtw.co>
This commit disables polymorphisation to resolve regressions related to
closures which inherit unused generic parameters and are then used in
casts or reflection.
Signed-off-by: David Wood <david@davidtw.co>
This commit introduces a `FiniteBitSet` type which replaces the manual
bit manipulation which was being performed in polymorphization.
Signed-off-by: David Wood <david@davidtw.co>
This commit replaces the `-Z polymorphize-errors` debugging flag with a
`#[rustc_polymorphize_error]` attribute for use on functions.
Signed-off-by: David Wood <david@davidtw.co>
This commit normalizes function signatures for instances before
substituting, a workaround for polymorphization considering
parameters unused when they show up in the signature, but not the
body (due to being normalized).
Unfortunately, this causes test output to change with the parallel
compiler only.
Signed-off-by: David Wood <david@davidtw.co>
This commit implements the `unused_generic_params` query, an initial
version of polymorphization which detects when an item does not use
generic parameters and is being needlessly monomorphized as a result.
Signed-off-by: David Wood <david@davidtw.co>
