Attribute rustc_dump_clauses 

Dumps the list of ty::Clauses as computed by the clauses_of query.

See AttributeKind::RustcDumpClauses for the internal representation of this attribute.

Example

//@ dont-require-annotations: ERROR
//@ compile-flags: --crate-type lib -Z ui-testing=no
//@ normalize-stderr: "DefId\((\d+):(\d+)" -> "DefId(..:.."
//@ normalize-stderr: "\[[A-Fa-f0-9]{4}\]" -> "[....]"

#![feature(negative_impls)]
#![feature(rustc_attrs)]

#[rustc_dump_clauses]
fn function<T: Send>(_t: T) {}

#[rustc_dump_clauses]
trait Trait: Sync {
    #[rustc_dump_clauses]
    type Assoc;
}

#[rustc_dump_clauses]
struct X<'a, T: ?Sized, I: Iterator> {
    x: &'a T,
    y: &'a I::Item,
}

#[rustc_dump_clauses]
impl<T: ?Sized, I> !Sync for X<'_, T, I> {}

produces:

error: rustc_dump_clauses
 --> $DIR/rustc_dump_clauses.rs:10:1
  |
10 | fn function<T: Send>(_t: T) {}
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: Binder { value: TraitClause(<T as std::marker::Sized>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<T as std::marker::Send>, polarity:Positive), bound_vars: [] }

error: rustc_dump_clauses
 --> $DIR/rustc_dump_clauses.rs:13:1
  |
13 | trait Trait: Sync {
  | ^^^^^^^^^^^^^^^^^
  |
  = note: Binder { value: TraitClause(<Self as std::marker::MetaSized>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<Self as std::marker::Sync>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<Self as Trait>, polarity:Positive), bound_vars: [] }

error: rustc_dump_clauses
 --> $DIR/rustc_dump_clauses.rs:19:1
  |
19 | struct X<'a, T: ?Sized, I: Iterator> {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: Binder { value: TraitClause(<T as std::marker::MetaSized>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<I as std::marker::Sized>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<I as std::iter::Iterator>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: OutlivesClause(T/#1, 'a/#0), bound_vars: [] }
  = note: Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(..:.. ~ core[....]::iter::traits::iterator::Iterator::Item) }, args: [I/#2], .. }), 'a/#0), bound_vars: [] }

error: rustc_dump_clauses
 --> $DIR/rustc_dump_clauses.rs:25:1
  |
25 | impl<T: ?Sized, I> !Sync for X<'_, T, I> {}
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: Binder { value: TraitClause(<T as std::marker::MetaSized>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<I as std::marker::Sized>, polarity:Positive), bound_vars: [] }

error: rustc_dump_clauses
 --> $DIR/rustc_dump_clauses.rs:15:5
  |
15 |     type Assoc;
  |     ^^^^^^^^^^
  |
  = note: Binder { value: TraitClause(<Self as std::marker::MetaSized>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<Self as std::marker::Sync>, polarity:Positive), bound_vars: [] }
  = note: Binder { value: TraitClause(<Self as Trait>, polarity:Positive), bound_vars: [] }

error: aborting due to 5 previous errors

Example: super trait bounds are not elaborated

//@ dont-require-annotations: ERROR
//@ compile-flags: --crate-type lib -Z ui-testing=no

#![feature(rustc_attrs)]

#[rustc_dump_clauses]
fn foo<T: Copy>(t: &T) -> T {
    *t
}

produces:

error: rustc_dump_clauses
--> $DIR/rustc_dump_clauses_super_trait.rs:7:1
 |
7 | fn foo<T: Copy>(t: &T) -> T {
 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 |
 = note: Binder { value: TraitClause(<T as std::marker::Sized>, polarity:Positive), bound_vars: [] }
 = note: Binder { value: TraitClause(<T as std::marker::Copy>, polarity:Positive), bound_vars: [] }

error: aborting due to 1 previous error