move check_opaque_type_parameter_valid

Author: lcnr

compiler/rustc_borrowck/messages.ftl

@@ -162,13 +162,6 @@ borrowck_opaque_type_lifetime_mismatch =
     .prev_lifetime_label = lifetime `{$prev}` previously used here
     .note = if all non-lifetime generic parameters are the same, but the lifetime parameters differ, it is not possible to differentiate the opaque types
 
-borrowck_opaque_type_non_generic_param =
-    expected generic {$kind} parameter, found `{$ty}`
-    .label = {STREQ($ty, "'static") ->
-        [true] cannot use static lifetime; use a bound lifetime instead or remove the lifetime parameter from the opaque type
-        *[other] this generic parameter must be used with a generic {$kind} parameter
-    }
-
 borrowck_partial_var_move_by_use_in_closure =
     variable {$is_partial ->
         [true] partially moved

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -1,22 +1,16 @@
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_errors::ErrorGuaranteed;
-use rustc_hir::OpaqueTyOrigin;
-use rustc_hir::def_id::LocalDefId;
-use rustc_infer::infer::outlives::env::OutlivesEnvironment;
-use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, TyCtxtInferExt as _};
+use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin};
 use rustc_macros::extension;
 use rustc_middle::ty::{
-    self, GenericArgKind, GenericArgs, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable,
-    TypeVisitableExt, TypingMode, fold_regions,
+    self, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, fold_regions,
 };
 use rustc_span::Span;
-use rustc_trait_selection::regions::OutlivesEnvironmentBuildExt;
-use rustc_trait_selection::traits::ObligationCtxt;
+use rustc_trait_selection::opaque_types::check_opaque_type_parameter_valid;
 use tracing::{debug, instrument};
 
 use super::RegionInferenceContext;
 use crate::opaque_types::ConcreteOpaqueTypes;
-use crate::session_diagnostics::{LifetimeMismatchOpaqueParam, NonGenericOpaqueTypeParam};
+use crate::session_diagnostics::LifetimeMismatchOpaqueParam;
 use crate::universal_regions::RegionClassification;
 
 impl<'tcx> RegionInferenceContext<'tcx> {
@@ -289,156 +283,3 @@ impl<'tcx> InferCtxt<'tcx> {
         definition_ty
     }
 }
-
-/// Opaque type parameter validity check as documented in the [rustc-dev-guide chapter].
-///
-/// [rustc-dev-guide chapter]:
-/// https://rustc-dev-guide.rust-lang.org/opaque-types-region-infer-restrictions.html
-fn check_opaque_type_parameter_valid<'tcx>(
-    infcx: &InferCtxt<'tcx>,
-    opaque_type_key: OpaqueTypeKey<'tcx>,
-    span: Span,
-) -> Result<(), ErrorGuaranteed> {
-    let tcx = infcx.tcx;
-    let opaque_generics = tcx.generics_of(opaque_type_key.def_id);
-    let opaque_env = LazyOpaqueTyEnv::new(tcx, opaque_type_key.def_id);
-    let mut seen_params: FxIndexMap<_, Vec<_>> = FxIndexMap::default();
-
-    for (i, arg) in opaque_type_key.iter_captured_args(tcx) {
-        let arg_is_param = match arg.unpack() {
-            GenericArgKind::Type(ty) => matches!(ty.kind(), ty::Param(_)),
-            GenericArgKind::Lifetime(lt) => {
-                matches!(*lt, ty::ReEarlyParam(_) | ty::ReLateParam(_))
-                    || (lt.is_static() && opaque_env.param_equal_static(i))
-            }
-            GenericArgKind::Const(ct) => matches!(ct.kind(), ty::ConstKind::Param(_)),
-        };
-
-        if arg_is_param {
-            // Register if the same lifetime appears multiple times in the generic args.
-            // There is an exception when the opaque type *requires* the lifetimes to be equal.
-            // See [rustc-dev-guide chapter] § "An exception to uniqueness rule".
-            let seen_where = seen_params.entry(arg).or_default();
-            if !seen_where.first().is_some_and(|&prev_i| opaque_env.params_equal(i, prev_i)) {
-                seen_where.push(i);
-            }
-        } else {
-            // Prevent `fn foo() -> Foo<u32>` from being defining.
-            let opaque_param = opaque_generics.param_at(i, tcx);
-            let kind = opaque_param.kind.descr();
-
-            opaque_env.param_is_error(i)?;
-
-            return Err(infcx.dcx().emit_err(NonGenericOpaqueTypeParam {
-                ty: arg,
-                kind,
-                span,
-                param_span: tcx.def_span(opaque_param.def_id),
-            }));
-        }
-    }
-
-    for (_, indices) in seen_params {
-        if indices.len() > 1 {
-            let descr = opaque_generics.param_at(indices[0], tcx).kind.descr();
-            let spans: Vec<_> = indices
-                .into_iter()
-                .map(|i| tcx.def_span(opaque_generics.param_at(i, tcx).def_id))
-                .collect();
-            #[allow(rustc::diagnostic_outside_of_impl)]
-            #[allow(rustc::untranslatable_diagnostic)]
-            return Err(infcx
-                .dcx()
-                .struct_span_err(span, "non-defining opaque type use in defining scope")
-                .with_span_note(spans, format!("{descr} used multiple times"))
-                .emit());
-        }
-    }
-
-    Ok(())
-}
-
-/// Computes if an opaque type requires a lifetime parameter to be equal to
-/// another one or to the `'static` lifetime.
-/// These requirements are derived from the explicit and implied bounds.
-struct LazyOpaqueTyEnv<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    def_id: LocalDefId,
-
-    /// Equal parameters will have the same name. Computed Lazily.
-    /// Example:
-    ///     `type Opaque<'a: 'static, 'b: 'c, 'c: 'b> = impl Sized;`
-    ///     Identity args: `['a, 'b, 'c]`
-    ///     Canonical args: `['static, 'b, 'b]`
-    canonical_args: std::cell::OnceCell<ty::GenericArgsRef<'tcx>>,
-}
-
-impl<'tcx> LazyOpaqueTyEnv<'tcx> {
-    fn new(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Self {
-        Self { tcx, def_id, canonical_args: std::cell::OnceCell::new() }
-    }
-
-    fn param_equal_static(&self, param_index: usize) -> bool {
-        self.get_canonical_args()[param_index].expect_region().is_static()
-    }
-
-    fn params_equal(&self, param1: usize, param2: usize) -> bool {
-        let canonical_args = self.get_canonical_args();
-        canonical_args[param1] == canonical_args[param2]
-    }
-
-    fn param_is_error(&self, param_index: usize) -> Result<(), ErrorGuaranteed> {
-        self.get_canonical_args()[param_index].error_reported()
-    }
-
-    fn get_canonical_args(&self) -> ty::GenericArgsRef<'tcx> {
-        if let Some(&canonical_args) = self.canonical_args.get() {
-            return canonical_args;
-        }
-
-        let &Self { tcx, def_id, .. } = self;
-        let origin = tcx.local_opaque_ty_origin(def_id);
-        let parent = match origin {
-            OpaqueTyOrigin::FnReturn { parent, .. }
-            | OpaqueTyOrigin::AsyncFn { parent, .. }
-            | OpaqueTyOrigin::TyAlias { parent, .. } => parent,
-        };
-        let param_env = tcx.param_env(parent);
-        let args = GenericArgs::identity_for_item(tcx, parent).extend_to(
-            tcx,
-            def_id.to_def_id(),
-            |param, _| {
-                tcx.map_opaque_lifetime_to_parent_lifetime(param.def_id.expect_local()).into()
-            },
-        );
-
-        // FIXME(#132279): It feels wrong to use `non_body_analysis` here given that we're
-        // in a body here.
-        let infcx = tcx.infer_ctxt().build(TypingMode::non_body_analysis());
-        let ocx = ObligationCtxt::new(&infcx);
-
-        let wf_tys = ocx.assumed_wf_types(param_env, parent).unwrap_or_else(|_| {
-            tcx.dcx().span_delayed_bug(tcx.def_span(def_id), "error getting implied bounds");
-            Default::default()
-        });
-        let outlives_env = OutlivesEnvironment::new(&infcx, parent, param_env, wf_tys);
-
-        let mut seen = vec![tcx.lifetimes.re_static];
-        let canonical_args = fold_regions(tcx, args, |r1, _| {
-            if r1.is_error() {
-                r1
-            } else if let Some(&r2) = seen.iter().find(|&&r2| {
-                let free_regions = outlives_env.free_region_map();
-                free_regions.sub_free_regions(tcx, r1, r2)
-                    && free_regions.sub_free_regions(tcx, r2, r1)
-            }) {
-                r2
-            } else {
-                seen.push(r1);
-                r1
-            }
-        });
-        self.canonical_args.set(canonical_args).unwrap();
-        canonical_args
-    }
-}

compiler/rustc_borrowck/src/session_diagnostics.rs

@@ -294,17 +294,6 @@ pub(crate) struct MoveBorrow<'a> {
     pub borrow_span: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(borrowck_opaque_type_non_generic_param, code = E0792)]
-pub(crate) struct NonGenericOpaqueTypeParam<'a, 'tcx> {
-    pub ty: GenericArg<'tcx>,
-    pub kind: &'a str,
-    #[primary_span]
-    pub span: Span,
-    #[label]
-    pub param_span: Span,
-}
-
 #[derive(Diagnostic)]
 #[diag(borrowck_opaque_type_lifetime_mismatch)]
 pub(crate) struct LifetimeMismatchOpaqueParam<'tcx> {

compiler/rustc_trait_selection/messages.ftl

@@ -264,8 +264,15 @@ trait_selection_oc_no_diverge = `else` clause of `let...else` does not diverge
 trait_selection_oc_no_else = `if` may be missing an `else` clause
 trait_selection_oc_try_compat = `?` operator has incompatible types
 trait_selection_oc_type_compat = type not compatible with trait
+
 trait_selection_opaque_captures_lifetime = hidden type for `{$opaque_ty}` captures lifetime that does not appear in bounds
     .label = opaque type defined here
+trait_selection_opaque_type_non_generic_param =
+    expected generic {$kind} parameter, found `{$ty}`
+    .label = {STREQ($ty, "'static") ->
+        [true] cannot use static lifetime; use a bound lifetime instead or remove the lifetime parameter from the opaque type
+        *[other] this generic parameter must be used with a generic {$kind} parameter
+    }
 
 trait_selection_outlives_bound = lifetime of the source pointer does not outlive lifetime bound of the object type
 trait_selection_outlives_content = lifetime of reference outlives lifetime of borrowed content...

compiler/rustc_trait_selection/src/errors.rs

@@ -12,7 +12,7 @@ use rustc_hir::intravisit::{Visitor, VisitorExt, walk_ty};
 use rustc_hir::{self as hir, AmbigArg, FnRetTy, GenericParamKind, IsAnonInPath, Node};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_middle::ty::print::{PrintTraitRefExt as _, TraitRefPrintOnlyTraitPath};
-use rustc_middle::ty::{self, Binder, ClosureKind, FnSig, Region, Ty, TyCtxt};
+use rustc_middle::ty::{self, Binder, ClosureKind, FnSig, GenericArg, Region, Ty, TyCtxt};
 use rustc_span::{BytePos, Ident, Span, Symbol, kw};
 
 use crate::error_reporting::infer::ObligationCauseAsDiagArg;
@@ -1922,3 +1922,14 @@ impl Subdiagnostic for AddPreciseCapturingForOvercapture {
         }
     }
 }
+
+#[derive(Diagnostic)]
+#[diag(trait_selection_opaque_type_non_generic_param, code = E0792)]
+pub(crate) struct NonGenericOpaqueTypeParam<'a, 'tcx> {
+    pub ty: GenericArg<'tcx>,
+    pub kind: &'a str,
+    #[primary_span]
+    pub span: Span,
+    #[label]
+    pub param_span: Span,
+}

compiler/rustc_trait_selection/src/lib.rs

@@ -36,6 +36,7 @@
 pub mod error_reporting;
 pub mod errors;
 pub mod infer;
+pub mod opaque_types;
 pub mod regions;
 pub mod solve;
 pub mod traits;