diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs index 85692e109be..4595cf6e270 100644 --- a/compiler/rustc_infer/src/infer/mod.rs +++ b/compiler/rustc_infer/src/infer/mod.rs @@ -21,7 +21,7 @@ use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind, ToType}; use rustc_middle::mir::interpret::{ErrorHandled, EvalToValTreeResult}; use rustc_middle::traits::select; -use rustc_middle::ty::abstract_const::AbstractConst; +use rustc_middle::ty::abstract_const::{AbstractConst, FailureKind}; use rustc_middle::ty::error::{ExpectedFound, TypeError}; use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable}; use rustc_middle::ty::relate::RelateResult; @@ -1683,7 +1683,7 @@ pub fn try_const_eval_resolve( #[instrument(skip(self), level = "debug")] pub fn const_eval_resolve( &self, - param_env: ty::ParamEnv<'tcx>, + mut param_env: ty::ParamEnv<'tcx>, unevaluated: ty::Unevaluated<'tcx>, span: Option, ) -> EvalToValTreeResult<'tcx> { @@ -1694,10 +1694,45 @@ pub fn const_eval_resolve( // variables if substs.has_infer_types_or_consts() { let ac = AbstractConst::new(self.tcx, unevaluated.shrink()); - if let Ok(None) = ac { - substs = InternalSubsts::identity_for_item(self.tcx, unevaluated.def.did); - } else { - return Err(ErrorHandled::TooGeneric); + match ac { + Ok(None) => { + substs = InternalSubsts::identity_for_item(self.tcx, unevaluated.def.did); + param_env = self.tcx.param_env(unevaluated.def.did); + } + Ok(Some(ct)) => { + if ct.unify_failure_kind(self.tcx) == FailureKind::Concrete { + substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(idx, arg)| { + let needs_replacement = + arg.has_param_types_or_consts() || arg.has_infer_types_or_consts(); + match arg.unpack() { + GenericArgKind::Type(_) if needs_replacement => self + .tcx + .mk_ty(ty::Placeholder(ty::PlaceholderType { + universe: ty::UniverseIndex::ROOT, + name: ty::BoundVar::from_usize(idx), + })) + .into(), + GenericArgKind::Const(ct) if needs_replacement => self + .tcx + .mk_const(ty::ConstS { + ty: ct.ty(), + kind: ty::ConstKind::Placeholder(ty::PlaceholderConst { + universe: ty::UniverseIndex::ROOT, + name: ty::BoundConst { + var: ty::BoundVar::from_usize(idx), + ty: ct.ty(), + }, + }), + }) + .into(), + _ => arg, + } + })); + } else { + return Err(ErrorHandled::TooGeneric); + } + } + Err(guar) => return Err(ErrorHandled::Reported(guar)), } } diff --git a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs index decbf013311..254bc4ab663 100644 --- a/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs +++ b/compiler/rustc_trait_selection/src/traits/const_evaluatable.rs @@ -185,21 +185,12 @@ pub fn is_const_evaluatable<'cx, 'tcx>( } let concrete = infcx.const_eval_resolve(param_env, uv.expand(), Some(span)); match concrete { - Err(ErrorHandled::TooGeneric) => Err(if uv.has_infer_types_or_consts() { - NotConstEvaluatable::MentionsInfer - } else if uv.has_param_types_or_consts() { - infcx - .tcx - .sess - .delay_span_bug(span, &format!("unexpected `TooGeneric` for {:?}", uv)); - NotConstEvaluatable::MentionsParam - } else { - let guar = infcx.tcx.sess.delay_span_bug( + Err(ErrorHandled::TooGeneric) => { + Err(NotConstEvaluatable::Error(infcx.tcx.sess.delay_span_bug( span, format!("Missing value for constant, but no error reported?"), - ); - NotConstEvaluatable::Error(guar) - }), + ))) + } Err(ErrorHandled::Linted) => { let reported = infcx .tcx diff --git a/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.rs b/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.rs index 18f33acaabb..5874625adff 100644 --- a/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.rs +++ b/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.rs @@ -1,3 +1,5 @@ +// check-pass + #![feature(generic_const_exprs)] #![allow(incomplete_features)] @@ -21,11 +23,6 @@ fn foo(_: T) -> <() as Foo<{ N + 1 }>>::Assoc } fn main() { - // FIXME(generic_const_exprs): We can't correctly infer `T` which requires - // evaluating `{ N + 1 }` which has substs containing an inference var let mut _q = Default::default(); - //~^ ERROR type annotations needed - _q = foo::<_, 2>(_q); - //~^ ERROR type annotations needed } diff --git a/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.stderr b/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.stderr deleted file mode 100644 index 9e8328d3701..00000000000 --- a/src/test/ui/const-generics/generic_const_exprs/const_eval_resolve_canonical.stderr +++ /dev/null @@ -1,38 +0,0 @@ -error[E0282]: type annotations needed - --> $DIR/const_eval_resolve_canonical.rs:26:9 - | -LL | let mut _q = Default::default(); - | ^^^^^^ - | -help: consider giving `_q` an explicit type - | -LL | let mut _q: _ = Default::default(); - | +++ - -error[E0283]: type annotations needed - --> $DIR/const_eval_resolve_canonical.rs:29:10 - | -LL | _q = foo::<_, 2>(_q); - | ^^^^^^^^^^^ cannot infer the value of the constant `{ N + 1 }` - | -note: multiple `impl`s satisfying `(): Foo<{ N + 1 }>` found - --> $DIR/const_eval_resolve_canonical.rs:8:1 - | -LL | impl Foo<0> for () { - | ^^^^^^^^^^^^^^^^^^ -... -LL | impl Foo<3> for () { - | ^^^^^^^^^^^^^^^^^^ -note: required by a bound in `foo` - --> $DIR/const_eval_resolve_canonical.rs:18:9 - | -LL | fn foo(_: T) -> <() as Foo<{ N + 1 }>>::Assoc - | --- required by a bound in this -LL | where -LL | (): Foo<{ N + 1 }>, - | ^^^^^^^^^^^^^^ required by this bound in `foo` - -error: aborting due to 2 previous errors - -Some errors have detailed explanations: E0282, E0283. -For more information about an error, try `rustc --explain E0282`.