diff options
4 files changed, 49 insertions, 23 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs index b1ac02d9fed..8a1be7ea172 100644 --- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs +++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs @@ -72,17 +72,16 @@ pub fn is_const_evaluatable<'cx, 'tcx>( // We were unable to unify the abstract constant with // a constant found in the caller bounds, there are // now three possible cases here. - // - // - The substs are concrete enough that we can simply - // try and evaluate the given constant. - // - The abstract const still references an inference - // variable, in this case we return `TooGeneric`. - // - The abstract const references a generic parameter, - // this means that we emit an error here. #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)] enum FailureKind { + /// The abstract const still references an inference + /// variable, in this case we return `TooGeneric`. MentionsInfer, + /// The abstract const references a generic parameter, + /// this means that we emit an error here. MentionsParam, + /// The substs are concrete enough that we can simply + /// try and evaluate the given constant. Concrete, } let mut failure_kind = FailureKind::Concrete; diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs index 69f66f6e6b1..e6a1cf58fe3 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/on_unimplemented.rs @@ -200,22 +200,15 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> { if let Some(def) = aty.ty_adt_def() { // We also want to be able to select the array's type's original // signature with no type arguments resolved - flags.push(( - sym::_Self, - Some(format!("[{}]", self.tcx.type_of(def.did).to_string())), - )); - let tcx = self.tcx; - if let Some(len) = len.try_eval_usize(tcx, ty::ParamEnv::empty()) { - flags.push(( - sym::_Self, - Some(format!("[{}; {}]", self.tcx.type_of(def.did).to_string(), len)), - )); - } else { - flags.push(( - sym::_Self, - Some(format!("[{}; _]", self.tcx.type_of(def.did).to_string())), - )); - } + let type_string = self.tcx.type_of(def.did).to_string(); + flags.push((sym::_Self, Some(format!("[{}]", type_string)))); + + let len = len.val.try_to_value().and_then(|v| v.try_to_machine_usize(self.tcx)); + let string = match len { + Some(n) => format!("[{}; {}]", type_string, n), + None => format!("[{}; _]", type_string), + }; + flags.push((sym::_Self, Some(string))); } } if let ty::Dynamic(traits, _) = self_ty.kind() { diff --git a/src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.rs b/src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.rs new file mode 100644 index 00000000000..afef748ff46 --- /dev/null +++ b/src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.rs @@ -0,0 +1,22 @@ +#![feature(const_generics, const_evaluatable_checked)] +#![allow(incomplete_features)] + +// This tests that during error handling for the "trait not implemented" error +// we dont try to evaluate std::mem::size_of::<Self::Assoc> causing an ICE + +struct Adt; + +trait Foo { + type Assoc; + fn foo() + where + [Adt; std::mem::size_of::<Self::Assoc>()]: , + { + <[Adt; std::mem::size_of::<Self::Assoc>()] as Foo>::bar() + //~^ Error: the trait bound + } + + fn bar() {} +} + +fn main() {} diff --git a/src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.stderr b/src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.stderr new file mode 100644 index 00000000000..d894fa90ba9 --- /dev/null +++ b/src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.stderr @@ -0,0 +1,12 @@ +error[E0277]: the trait bound `[Adt; _]: Foo` is not satisfied + --> $DIR/dont-evaluate-array-len-on-err-1.rs:15:9 + | +LL | <[Adt; std::mem::size_of::<Self::Assoc>()] as Foo>::bar() + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `[Adt; _]` +... +LL | fn bar() {} + | -------- required by `Foo::bar` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0277`. |