Chalk writer integration

[detrumi]

This adds a rust-analyzer dump-chalk command, similar to analysis-stats, which writes out the whole chalk progam (see chalk#365 for more info about the .chalk writer)

Write out chalk programs in debug output if chalk debugging is active (using CHALK_DEBUG).

Example output:

[DEBUG ra_hir_ty::traits] solve(UCanonical { canonical: Canonical { value: InEnvironment { environment: Env([]), goal: Implemented(SeparatorTraitRef(?)) }, binders: [] }, universes: 1 }) => None
[INFO  ra_hir_ty::traits] trait_solve_query(Implements(fn min<?0.0>(?0.0, ?0.0) -> ?0.0: Deref))
[DEBUG ra_hir_ty::traits] solve goal: UCanonical { canonical: Canonical { value: InEnvironment { environment: Env([]), goal: Implemented(SeparatorTraitRef(?)) }, binders: [U0 with kind type] }, universes: 1 }
[DEBUG ra_hir_ty::traits::chalk] impls_for_trait Deref
[DEBUG ra_hir_ty::traits::chalk] impls_for_trait returned 0 impls
[DEBUG ra_hir_ty::traits::chalk] trait_datum Ord
[DEBUG ra_hir_ty::traits::chalk] trait Ord = Name(Text("Ord"))
[DEBUG ra_hir_ty::traits] chalk program:
    #[upstream]
    #[non_enumerable]
    #[object_safe]
    trait Ord {}
    #[upstream]
    #[non_enumerable]
    #[object_safe]
    #[lang(sized)]
    trait Sized {}
    fn fn_0<_1_0>(arg_0: _1_0, arg_1: _1_0) -> _1_0
    where
      _1_0: Ord;
    #[upstream]
    #[non_enumerable]
    #[object_safe]
    trait Deref {
      type Assoc_1829: Sized;
    }
    
[DEBUG ra_hir_ty::traits] solve(UCanonical { canonical: Canonical { value: InEnvironment { environment: Env([]), goal: Implemented(SeparatorTraitRef(?)) }, binders: [U0 with kind type] }, universes: 1 }) => None
[INFO  ra_hir_ty::traits] trait_solve_query(Implements(?0.0: Ord))

[flodiebold]

I'm not sure we should do this whenever CHALK_DEBUG is set. Maybe we could use another env variable?

[detrumi]

I'm not sure we should do this whenever CHALK_DEBUG is set. Maybe we could use another env variable?

So only print programs if both CHALK_DEBUG and that env var is set? How about PRINT_CHALK?

[flodiebold]

Yeah, that'd be fine! Maybe CHALK_PRINT fits better with CHALK_DEBUG, but either way is ok.

[flodiebold]

bors r+

[bors]

Build succeeded:

• Rust (ubuntu-latest)
• Rust (windows-latest)
• TypeScript (ubuntu-latest)
• TypeScript (windows-latest)