diff options
4 files changed, 224 insertions, 5 deletions
diff --git a/compiler/rustc_pattern_analysis/src/rustc.rs b/compiler/rustc_pattern_analysis/src/rustc.rs index 88d45ead295..7c12f69f14c 100644 --- a/compiler/rustc_pattern_analysis/src/rustc.rs +++ b/compiler/rustc_pattern_analysis/src/rustc.rs @@ -1,5 +1,6 @@ use std::fmt; use std::iter::once; +use std::ops::ControlFlow; use rustc_abi::{FIRST_VARIANT, FieldIdx, Integer, VariantIdx}; use rustc_arena::DroplessArena; @@ -11,7 +12,8 @@ use rustc_middle::mir::{self, Const}; use rustc_middle::thir::{self, Pat, PatKind, PatRange, PatRangeBoundary}; use rustc_middle::ty::layout::IntegerExt; use rustc_middle::ty::{ - self, FieldDef, OpaqueTypeKey, ScalarInt, Ty, TyCtxt, TypeVisitableExt, VariantDef, + self, FieldDef, OpaqueTypeKey, ScalarInt, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, + TypeVisitableExt, TypeVisitor, VariantDef, }; use rustc_middle::{bug, span_bug}; use rustc_session::lint; @@ -135,11 +137,22 @@ impl<'p, 'tcx: 'p> RustcPatCtxt<'p, 'tcx> { /// Returns the hidden type corresponding to this key if the body under analysis is allowed to /// know it. fn reveal_opaque_key(&self, key: OpaqueTypeKey<'tcx>) -> Option<Ty<'tcx>> { - self.typeck_results - .concrete_opaque_types - .get(&key.def_id) - .map(|x| ty::EarlyBinder::bind(x.ty).instantiate(self.tcx, key.args)) + if let Some(hidden_ty) = self.typeck_results.concrete_opaque_types.get(&key.def_id) { + let ty = ty::EarlyBinder::bind(hidden_ty.ty).instantiate(self.tcx, key.args); + if ty.visit_with(&mut RecursiveOpaque { def_id: key.def_id.into() }).is_continue() { + Some(ty) + } else { + // HACK: We skip revealing opaque types which recursively expand + // to themselves. This is because we may infer hidden types like + // `Opaque<T> = Opaque<Opaque<T>>` or `Opaque<T> = Opaque<(T,)>` + // in hir typeck. + None + } + } else { + None + } } + // This can take a non-revealed `Ty` because it reveals opaques itself. pub fn is_uninhabited(&self, ty: Ty<'tcx>) -> bool { !ty.inhabited_predicate(self.tcx).apply_revealing_opaque( @@ -1105,3 +1118,20 @@ pub fn analyze_match<'p, 'tcx>( Ok(report) } + +struct RecursiveOpaque { + def_id: DefId, +} +impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for RecursiveOpaque { + type Result = ControlFlow<()>; + + fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result { + if let ty::Alias(ty::Opaque, alias_ty) = t.kind() { + if alias_ty.def_id == self.def_id { + return ControlFlow::Break(()); + } + } + + if t.has_opaque_types() { t.super_visit_with(self) } else { ControlFlow::Continue(()) } + } +} diff --git a/tests/ui/impl-trait/recursive-in-exhaustiveness.current.stderr b/tests/ui/impl-trait/recursive-in-exhaustiveness.current.stderr new file mode 100644 index 00000000000..42dbc7c9160 --- /dev/null +++ b/tests/ui/impl-trait/recursive-in-exhaustiveness.current.stderr @@ -0,0 +1,56 @@ +warning: function cannot return without recursing + --> $DIR/recursive-in-exhaustiveness.rs:17:1 + | +LL | fn build<T>(x: T) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing +LL | +LL | let (x,) = (build(x),); + | -------- recursive call site + | + = help: a `loop` may express intention better if this is on purpose + = note: `#[warn(unconditional_recursion)]` on by default + +warning: function cannot return without recursing + --> $DIR/recursive-in-exhaustiveness.rs:27:1 + | +LL | fn build2<T>(x: T) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing +... +LL | let (x,) = (build2(x),); + | --------- recursive call site + | + = help: a `loop` may express intention better if this is on purpose + +error[E0720]: cannot resolve opaque type + --> $DIR/recursive-in-exhaustiveness.rs:27:23 + | +LL | fn build2<T>(x: T) -> impl Sized { + | ^^^^^^^^^^ recursive opaque type +... +LL | (build2(x),) + | ------------ returning here with type `(impl Sized,)` + +warning: function cannot return without recursing + --> $DIR/recursive-in-exhaustiveness.rs:40:1 + | +LL | fn build3<T>(x: T) -> impl Sized { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing +LL | +LL | let (x,) = (build3((x,)),); + | ------------ recursive call site + | + = help: a `loop` may express intention better if this is on purpose + +error[E0792]: expected generic type parameter, found `(T,)` + --> $DIR/recursive-in-exhaustiveness.rs:49:5 + | +LL | fn build3<T>(x: T) -> impl Sized { + | - this generic parameter must be used with a generic type parameter +... +LL | build3(x) + | ^^^^^^^^^ + +error: aborting due to 2 previous errors; 3 warnings emitted + +Some errors have detailed explanations: E0720, E0792. +For more information about an error, try `rustc --explain E0720`. diff --git a/tests/ui/impl-trait/recursive-in-exhaustiveness.next.stderr b/tests/ui/impl-trait/recursive-in-exhaustiveness.next.stderr new file mode 100644 index 00000000000..4c3d5aa8fb8 --- /dev/null +++ b/tests/ui/impl-trait/recursive-in-exhaustiveness.next.stderr @@ -0,0 +1,80 @@ +error[E0284]: type annotations needed: cannot satisfy `impl Sized == _` + --> $DIR/recursive-in-exhaustiveness.rs:19:17 + | +LL | let (x,) = (build(x),); + | ^^^^^^^^ cannot satisfy `impl Sized == _` + +error[E0271]: type mismatch resolving `build2<(_,)>::{opaque#0} normalizes-to _` + --> $DIR/recursive-in-exhaustiveness.rs:31:6 + | +LL | (build2(x),) + | ^^^^^^^^^ types differ + +error[E0271]: type mismatch resolving `build2<(_,)>::{opaque#0} normalizes-to _` + --> $DIR/recursive-in-exhaustiveness.rs:31:5 + | +LL | (build2(x),) + | ^^^^^^^^^^^^ types differ + +error[E0277]: the size for values of type `(impl Sized,)` cannot be known at compilation time + --> $DIR/recursive-in-exhaustiveness.rs:31:5 + | +LL | (build2(x),) + | ^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `(impl Sized,)` + = note: tuples must have a statically known size to be initialized + +error[E0271]: type mismatch resolving `build3<(T,)>::{opaque#0} normalizes-to _` + --> $DIR/recursive-in-exhaustiveness.rs:42:17 + | +LL | let (x,) = (build3((x,)),); + | ^^^^^^^^^^^^ types differ + +error[E0277]: the size for values of type `(impl Sized,)` cannot be known at compilation time + --> $DIR/recursive-in-exhaustiveness.rs:42:16 + | +LL | let (x,) = (build3((x,)),); + | ^^^^^^^^^^^^^^^ doesn't have a size known at compile-time + | + = help: the trait `Sized` is not implemented for `(impl Sized,)` + = note: tuples must have a statically known size to be initialized + +error[E0308]: mismatched types + --> $DIR/recursive-in-exhaustiveness.rs:42:16 + | +LL | fn build3<T>(x: T) -> impl Sized { + | ---------- the found opaque type +LL | +LL | let (x,) = (build3((x,)),); + | ^^^^^^^^^^^^^^^ types differ + | + = note: expected type `_` + found tuple `(impl Sized,)` + +error[E0271]: type mismatch resolving `build3<(T,)>::{opaque#0} normalizes-to _` + --> $DIR/recursive-in-exhaustiveness.rs:42:17 + | +LL | let (x,) = (build3((x,)),); + | ^^^^^^^^^^^^ types differ + | + = note: the return type of a function must have a statically known size + +error[E0271]: type mismatch resolving `build3<(T,)>::{opaque#0} normalizes-to _` + --> $DIR/recursive-in-exhaustiveness.rs:42:16 + | +LL | let (x,) = (build3((x,)),); + | ^^^^^^^^^^^^^^^ types differ + +error[E0271]: type mismatch resolving `build3<(T,)>::{opaque#0} normalizes-to _` + --> $DIR/recursive-in-exhaustiveness.rs:42:17 + | +LL | let (x,) = (build3((x,)),); + | ^^^^^^^^^^^^ types differ + | + = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no` + +error: aborting due to 10 previous errors + +Some errors have detailed explanations: E0271, E0277, E0284, E0308. +For more information about an error, try `rustc --explain E0271`. diff --git a/tests/ui/impl-trait/recursive-in-exhaustiveness.rs b/tests/ui/impl-trait/recursive-in-exhaustiveness.rs new file mode 100644 index 00000000000..58944533686 --- /dev/null +++ b/tests/ui/impl-trait/recursive-in-exhaustiveness.rs @@ -0,0 +1,53 @@ +//@ revisions: current next +//@ ignore-compare-mode-next-solver (explicit revisions) +//@[next] compile-flags: -Znext-solver + +// Test several spicy non-trivial recursive opaque definitions inferred from HIR typeck +// don't cause stack overflows in exhaustiveness code, which currently reveals opaques +// manually in a way that is not overflow aware. +// +// These should eventually be outright rejected, but today (some) non-trivial recursive +// opaque definitions are accepted, and changing that requires an FCP, so for now just +// make sure we don't stack overflow :^) + +// Opaque<T> = Opaque<Opaque<T>> +// +// We unfortunately accept this today, and due to how opaque type relating is implemented +// in the NLL type relation, this defines `Opaque<T> = T`. +fn build<T>(x: T) -> impl Sized { + //[current]~^ WARN function cannot return without recursing + let (x,) = (build(x),); + //[next]~^ ERROR type annotations needed + build(x) +} + +// Opaque<T> = (Opaque<T>,) +// +// Not allowed today. Detected as recursive. +fn build2<T>(x: T) -> impl Sized { + //[current]~^ ERROR cannot resolve opaque type + //[current]~| WARN function cannot return without recursing + let (x,) = (build2(x),); + (build2(x),) + //[next]~^ ERROR type mismatch resolving + //[next]~| ERROR type mismatch resolving + //[next]~| ERROR the size for values of type +} + +// Opaque<T> = Opaque<(T,)> +// +// Not allowed today. Detected as not defining. +fn build3<T>(x: T) -> impl Sized { + //[current]~^ WARN function cannot return without recursing + let (x,) = (build3((x,)),); + //[next]~^ ERROR type mismatch resolving + //[next]~| ERROR type mismatch resolving + //[next]~| ERROR type mismatch resolving + //[next]~| ERROR type mismatch resolving + //[next]~| ERROR the size for values of type + //[next]~| ERROR mismatched types + build3(x) + //[current]~^ ERROR expected generic type parameter, found `(T,)` +} + +fn main() {} |