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introduce predicates_defined_on for traits

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This new query returns only the predicates *directly defined* on an
item (in contrast to the more common `predicates_of`, which returns
the predicates that must be proven to reference an item). These two
sets are almost always identical except for traits, where
`predicates_of` includes an artificial `Self: Trait<...>` predicate
(basically saying that you cannot use a trait item without proving
that the trait is implemented for the type parameters).

This new query is only used in chalk lowering, where this artificial
`Self: Trait` predicate is problematic. We encode it in metadata but
only where needed since it is kind of repetitive with existing
information.

Co-authored-by: Tyler Mandry <tmandry@gmail.com>
This commit is contained in:
Niko Matsakis 2018-07-02 10:35:30 -04:00
parent 327093007a
commit 90ea49b891
10 changed files with 109 additions and 21 deletions
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4
src/test/ui/chalkify/lower_env1.stderr
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@ -4,7 +4,7 @@ error: program clause dump
LL | #[rustc_dump_program_clauses] //~ ERROR program clause dump
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: FromEnv(Self: Bar) :- FromEnv(Self: Bar).
= note: FromEnv(Self: Foo) :- FromEnv(Self: Bar).
= note: FromEnv(Self: Foo) :- FromEnv(Self: Bar).
= note: Implemented(Self: Bar) :- FromEnv(Self: Bar).
@ -14,7 +14,7 @@ error: program clause dump
LL | #[rustc_dump_env_program_clauses] //~ ERROR program clause dump
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: FromEnv(Self: Bar) :- FromEnv(Self: Bar).
= note: FromEnv(Self: Foo) :- FromEnv(Self: Bar).
= note: FromEnv(Self: Foo) :- FromEnv(Self: Bar).
= note: Implemented(Self: Bar) :- FromEnv(Self: Bar).
= note: Implemented(Self: Foo) :- FromEnv(Self: Foo).