11// This file was taken from the compiler:
2- // https://raw.githubusercontent.com/rust-lang/rust/949b98cab8a186b98bf87e64374b8d0848c55271 /compiler/rustc_trait_selection/src/traits/codegen.rs
2+ // https://raw.githubusercontent.com/rust-lang/rust/03d488b48af9f66b91e9400387f781b82411fa82 /compiler/rustc_trait_selection/src/traits/codegen.rs
33// This file is licensed under Apache 2.0
4- // (https://github.com/rust-lang/rust/blob/949b98cab8a186b98bf87e64374b8d0848c55271 /LICENSE-APACHE)
4+ // (https://github.com/rust-lang/rust/blob/03d488b48af9f66b91e9400387f781b82411fa82 /LICENSE-APACHE)
55// and MIT
6- // (https://github.com/rust-lang/rust/blob/949b98cab8a186b98bf87e64374b8d0848c55271 /LICENSE-MIT).
6+ // (https://github.com/rust-lang/rust/blob/03d488b48af9f66b91e9400387f781b82411fa82 /LICENSE-MIT).
77
88// Changes:
99// + Fix compilation errors.
1010// + Remove all diagnostics (this is the main motivation for duplication).
11- // + `ErrorGuaranteed` changed to `()` (private constructor).
11+ // + Remove all `instrument`ation.
12+ // + Replace `crate::*` imports with `prusti_rustc_interface::*` imports.
1213
1314
1415// This file contains various trait resolution methods used by codegen.
1718// general routines.
1819
1920use log:: debug;
20- use prusti_rustc_interface:: trait_selection:: infer:: { InferCtxt , TyCtxtInferExt } ;
21+ use prusti_rustc_interface:: trait_selection:: infer:: { TyCtxtInferExt } ;
2122use prusti_rustc_interface:: trait_selection:: traits:: {
2223 FulfillmentContext , ImplSource , Obligation , ObligationCause , SelectionContext , TraitEngine ,
2324 Unimplemented ,
2425} ;
25- use prusti_rustc_interface:: middle:: ty :: fold :: TypeFoldable ;
26+ use prusti_rustc_interface:: middle:: traits :: CodegenObligationError ;
2627use prusti_rustc_interface:: middle:: ty:: { self , TyCtxt } ;
2728
2829/// Attempts to resolve an obligation to an `ImplSource`. The result is
@@ -32,10 +33,10 @@ use prusti_rustc_interface::middle::ty::{self, TyCtxt};
3233/// obligations *could be* resolved if we wanted to.
3334///
3435/// This also expects that `trait_ref` is fully normalized.
35- pub fn codegen_fulfill_obligation < ' tcx > (
36+ pub ( super ) fn codegen_fulfill_obligation < ' tcx > (
3637 tcx : TyCtxt < ' tcx > ,
3738 ( param_env, trait_ref) : ( ty:: ParamEnv < ' tcx > , ty:: PolyTraitRef < ' tcx > ) ,
38- ) -> Result < & ' tcx ImplSource < ' tcx , ( ) > , ( ) > {
39+ ) -> Result < & ' tcx ImplSource < ' tcx , ( ) > , CodegenObligationError > {
3940 // Remove any references to regions; this helps improve caching.
4041 let trait_ref = tcx. erase_regions ( trait_ref) ;
4142 // We expect the input to be fully normalized.
@@ -57,37 +58,8 @@ pub fn codegen_fulfill_obligation<'tcx>(
5758
5859 let selection = match selcx. select ( & obligation) {
5960 Ok ( Some ( selection) ) => selection,
60- Ok ( None ) => {
61- // // Ambiguity can happen when monomorphizing during trans
62- // // expands to some humongo type that never occurred
63- // // statically -- this humongo type can then overflow,
64- // // leading to an ambiguous result. So report this as an
65- // // overflow bug, since I believe this is the only case
66- // // where ambiguity can result.
67- // let reported = infcx.tcx.sess.delay_span_bug(
68- // prusti_rustc_interface::span::DUMMY_SP,
69- // &format!(
70- // "encountered ambiguity selecting `{:?}` during codegen, presuming due to \
71- // overflow or prior type error",
72- // trait_ref
73- // ),
74- // );
75- return Err ( ( ) ) ;
76- }
77- Err ( Unimplemented ) => {
78- // // This can trigger when we probe for the source of a `'static` lifetime requirement
79- // // on a trait object: `impl Foo for dyn Trait {}` has an implicit `'static` bound.
80- // // This can also trigger when we have a global bound that is not actually satisfied,
81- // // but was included during typeck due to the trivial_bounds feature.
82- // let guar = infcx.tcx.sess.delay_span_bug(
83- // prusti_rustc_interface::span::DUMMY_SP,
84- // &format!(
85- // "Encountered error `Unimplemented` selecting `{:?}` during codegen",
86- // trait_ref
87- // ),
88- // );
89- return Err ( ( ) ) ;
90- }
61+ Ok ( None ) => return Err ( CodegenObligationError :: Ambiguity ) ,
62+ Err ( Unimplemented ) => return Err ( CodegenObligationError :: Unimplemented ) ,
9163 Err ( e) => {
9264 panic ! ( "Encountered error `{:?}` selecting `{:?}` during codegen" , e, trait_ref)
9365 }
@@ -103,52 +75,23 @@ pub fn codegen_fulfill_obligation<'tcx>(
10375 debug ! ( "fulfill_obligation: register_predicate_obligation {:?}" , predicate) ;
10476 fulfill_cx. register_predicate_obligation ( & infcx, predicate) ;
10577 } ) ;
106- let impl_source = drain_fulfillment_cx_or_panic ( & infcx, & mut fulfill_cx, impl_source) ;
78+
79+ // In principle, we only need to do this so long as `impl_source`
80+ // contains unbound type parameters. It could be a slight
81+ // optimization to stop iterating early.
82+ let errors = fulfill_cx. select_all_or_error ( & infcx) ;
83+ if !errors. is_empty ( ) {
84+ return Err ( CodegenObligationError :: FulfillmentError ) ;
85+ }
86+
87+ let impl_source = infcx. resolve_vars_if_possible ( impl_source) ;
88+ let impl_source = infcx. tcx . erase_regions ( impl_source) ;
10789
10890 // Opaque types may have gotten their hidden types constrained, but we can ignore them safely
10991 // as they will get constrained elsewhere, too.
11092 let _opaque_types = infcx. inner . borrow_mut ( ) . opaque_type_storage . take_opaque_types ( ) ;
11193
112- debug ! ( "Cache miss: {:?} => {:?}" , trait_ref , impl_source ) ;
94+ debug ! ( "Cache miss: {trait_ref :?} => {impl_source :?}" ) ;
11395 Ok ( & * tcx. arena . alloc ( impl_source) )
11496 } )
11597}
116-
117- // # Global Cache
118-
119- /// Finishes processes any obligations that remain in the
120- /// fulfillment context, and then returns the result with all type
121- /// variables removed and regions erased. Because this is intended
122- /// for use outside of type inference, if any errors occur,
123- /// it will panic. It is used during normalization and other cases
124- /// where processing the obligations in `fulfill_cx` may cause
125- /// type inference variables that appear in `result` to be
126- /// unified, and hence we need to process those obligations to get
127- /// the complete picture of the type.
128- fn drain_fulfillment_cx_or_panic < ' tcx , T > (
129- infcx : & InferCtxt < ' _ , ' tcx > ,
130- fulfill_cx : & mut FulfillmentContext < ' tcx > ,
131- result : T ,
132- ) -> T
133- where
134- T : TypeFoldable < ' tcx > ,
135- {
136- debug ! ( "drain_fulfillment_cx_or_panic()" ) ;
137-
138- // In principle, we only need to do this so long as `result`
139- // contains unbound type parameters. It could be a slight
140- // optimization to stop iterating early.
141- let errors = fulfill_cx. select_all_or_error ( infcx) ;
142- if !errors. is_empty ( ) {
143- // infcx.tcx.sess.delay_span_bug(
144- // prusti_rustc_interface::span::DUMMY_SP,
145- // &format!(
146- // "Encountered errors `{:?}` resolving bounds outside of type inference",
147- // errors
148- // ),
149- // );
150- }
151-
152- let result = infcx. resolve_vars_if_possible ( result) ;
153- infcx. tcx . erase_regions ( result)
154- }
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