diff --git a/compiler/rustc_traits/src/normalize_projection_ty.rs b/compiler/rustc_traits/src/normalize_projection_ty.rs index 0dbac56b47dd4..01bb1ca70eb4c 100644 --- a/compiler/rustc_traits/src/normalize_projection_ty.rs +++ b/compiler/rustc_traits/src/normalize_projection_ty.rs @@ -3,10 +3,13 @@ use rustc_infer::infer::TyCtxtInferExt; use rustc_middle::query::Providers; use rustc_middle::ty::{ParamEnvAnd, TyCtxt}; use rustc_trait_selection::infer::InferCtxtBuilderExt; +use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt; use rustc_trait_selection::traits::query::{ normalize::NormalizationResult, CanonicalProjectionGoal, NoSolution, }; -use rustc_trait_selection::traits::{self, ObligationCause, SelectionContext}; +use rustc_trait_selection::traits::{ + self, FulfillmentErrorCode, ObligationCause, SelectionContext, +}; use std::sync::atomic::Ordering; pub(crate) fn provide(p: &mut Providers) { @@ -40,6 +43,27 @@ fn normalize_projection_ty<'tcx>( &mut obligations, ); ocx.register_obligations(obligations); + // #112047: With projections and opaques, we are able to create opaques that + // are recursive (given some substitution of the opaque's type variables). + // In that case, we may only realize a cycle error when calling + // `normalize_erasing_regions` in mono. + if !ocx.infcx.next_trait_solver() { + let errors = ocx.select_where_possible(); + if !errors.is_empty() { + // Rustdoc may attempt to normalize type alias types which are not + // well-formed. Rustdoc also normalizes types that are just not + // well-formed, since we don't do as much HIR analysis (checking + // that impl vars are constrained by the signature, for example). + if !tcx.sess.opts.actually_rustdoc { + for error in &errors { + if let FulfillmentErrorCode::CodeCycle(cycle) = &error.code { + ocx.infcx.err_ctxt().report_overflow_obligation_cycle(cycle); + } + } + } + return Err(NoSolution); + } + } // FIXME(associated_const_equality): All users of normalize_projection_ty expected // a type, but there is the possibility it could've been a const now. Maybe change // it to a Term later?