Rollup merge of #129493 - cjgillot:early-opaque-def, r=petrochenkov

Create opaque definitions in resolver.

Implementing https://github.com/rust-lang/rust/issues/129023#issuecomment-2306079532

That was easier than I expected.

r? `@petrochenkov`

compiler/rustc_ast/src/visit.rs

@@ -69,14 +69,14 @@ pub enum FnKind<'a> {
     Fn(FnCtxt, Ident, &'a FnSig, &'a Visibility, &'a Generics, Option<&'a Block>),
 
     /// E.g., `|x, y| body`.
-    Closure(&'a ClosureBinder, &'a FnDecl, &'a Expr),
+    Closure(&'a ClosureBinder, &'a Option<CoroutineKind>, &'a FnDecl, &'a Expr),
 }
 
 impl<'a> FnKind<'a> {
     pub fn header(&self) -> Option<&'a FnHeader> {
         match *self {
             FnKind::Fn(_, _, sig, _, _, _) => Some(&sig.header),
-            FnKind::Closure(_, _, _) => None,
+            FnKind::Closure(..) => None,
         }
     }
 
@@ -90,7 +90,7 @@ impl<'a> FnKind<'a> {
     pub fn decl(&self) -> &'a FnDecl {
         match self {
             FnKind::Fn(_, _, sig, _, _, _) => &sig.decl,
-            FnKind::Closure(_, decl, _) => decl,
+            FnKind::Closure(_, _, decl, _) => decl,
         }
     }
 
@@ -839,7 +839,7 @@ pub fn walk_fn<'a, V: Visitor<'a>>(visitor: &mut V, kind: FnKind<'a>) -> V::Resu
             try_visit!(walk_fn_decl(visitor, decl));
             visit_opt!(visitor, visit_block, body);
         }
-        FnKind::Closure(binder, decl, body) => {
+        FnKind::Closure(binder, _coroutine_kind, decl, body) => {
             try_visit!(visitor.visit_closure_binder(binder));
             try_visit!(walk_fn_decl(visitor, decl));
             try_visit!(visitor.visit_expr(body));
@@ -1107,7 +1107,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) -> V
         ExprKind::Closure(box Closure {
             binder,
             capture_clause,
-            coroutine_kind: _,
+            coroutine_kind,
             constness: _,
             movability: _,
             fn_decl,
@@ -1116,7 +1116,11 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) -> V
             fn_arg_span: _,
         }) => {
             try_visit!(visitor.visit_capture_by(capture_clause));
-            try_visit!(visitor.visit_fn(FnKind::Closure(binder, fn_decl, body), *span, *id))
+            try_visit!(visitor.visit_fn(
+                FnKind::Closure(binder, coroutine_kind, fn_decl, body),
+                *span,
+                *id
+            ))
         }
         ExprKind::Block(block, opt_label) => {
             visit_opt!(visitor, visit_label, opt_label);

compiler/rustc_ast_lowering/src/lib.rs

@@ -45,7 +45,6 @@ use std::collections::hash_map::Entry;
 use rustc_ast::node_id::NodeMap;
 use rustc_ast::ptr::P;
 use rustc_ast::{self as ast, *};
-use rustc_ast_pretty::pprust;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxIndexSet;
@@ -1399,24 +1398,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             self.tcx.dcx().emit_err(errors::NoPreciseCapturesOnApit { span });
                         }
 
-                        let span = t.span;
-
-                        // HACK: pprust breaks strings with newlines when the type
-                        // gets too long. We don't want these to show up in compiler
-                        // output or built artifacts, so replace them here...
-                        // Perhaps we should instead format APITs more robustly.
-                        let ident = Ident::from_str_and_span(
-                            &pprust::ty_to_string(t).replace('\n', " "),
-                            span,
-                        );
-
-                        self.create_def(
-                            self.current_hir_id_owner.def_id, // FIXME: should this use self.current_def_id_parent?
-                            *def_node_id,
-                            ident.name,
-                            DefKind::TyParam,
-                            span,
-                        );
+                        let def_id = self.local_def_id(*def_node_id);
+                        let name = self.tcx.item_name(def_id.to_def_id());
+                        let ident = Ident::new(name, span);
                         let (param, bounds, path) = self.lower_universal_param_and_bounds(
                             *def_node_id,
                             span,
@@ -1618,13 +1602,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         opaque_ty_span: Span,
         lower_item_bounds: impl FnOnce(&mut Self) -> &'hir [hir::GenericBound<'hir>],
     ) -> hir::TyKind<'hir> {
-        let opaque_ty_def_id = self.create_def(
-            self.current_hir_id_owner.def_id, // FIXME: should this use self.current_def_id_parent?
-            opaque_ty_node_id,
-            kw::Empty,
-            DefKind::OpaqueTy,
-            opaque_ty_span,
-        );
+        let opaque_ty_def_id = self.local_def_id(opaque_ty_node_id);
         debug!(?opaque_ty_def_id);
 
         // Map from captured (old) lifetime to synthetic (new) lifetime.

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -1485,7 +1485,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
 
         let disallowed = (!tilde_const_allowed).then(|| match fk {
             FnKind::Fn(_, ident, _, _, _, _) => TildeConstReason::Function { ident: ident.span },
-            FnKind::Closure(_, _, _) => TildeConstReason::Closure,
+            FnKind::Closure(..) => TildeConstReason::Closure,
         });
         self.with_tilde_const(disallowed, |this| visit::walk_fn(this, fk));
     }

compiler/rustc_resolve/src/def_collector.rs

@@ -2,6 +2,7 @@ use std::mem;
 
 use rustc_ast::visit::FnKind;
 use rustc_ast::*;
+use rustc_ast_pretty::pprust;
 use rustc_expand::expand::AstFragment;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind};
@@ -120,8 +121,6 @@ impl<'a, 'b, 'tcx> DefCollector<'a, 'b, 'tcx> {
 
 impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
     fn visit_item(&mut self, i: &'a Item) {
-        debug!("visit_item: {:?}", i);
-
         // Pick the def data. This need not be unique, but the more
         // information we encapsulate into, the better
         let mut opt_macro_data = None;
@@ -183,38 +182,51 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
     }
 
     fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
-        if let FnKind::Fn(_, _, sig, _, generics, body) = fn_kind {
-            match sig.header.coroutine_kind {
-                Some(coroutine_kind) => {
-                    self.visit_generics(generics);
+        match fn_kind {
+            FnKind::Fn(_ctxt, _ident, FnSig { header, decl, span: _ }, _vis, generics, body)
+                if let Some(coroutine_kind) = header.coroutine_kind =>
+            {
+                self.visit_fn_header(header);
+                self.visit_generics(generics);
 
-                    // For async functions, we need to create their inner defs inside of a
-                    // closure to match their desugared representation. Besides that,
-                    // we must mirror everything that `visit::walk_fn` below does.
-                    self.visit_fn_header(&sig.header);
-                    for param in &sig.decl.inputs {
-                        self.visit_param(param);
-                    }
-                    self.visit_fn_ret_ty(&sig.decl.output);
-                    // If this async fn has no body (i.e. it's an async fn signature in a trait)
-                    // then the closure_def will never be used, and we should avoid generating a
-                    // def-id for it.
-                    if let Some(body) = body {
-                        let closure_def = self.create_def(
-                            coroutine_kind.closure_id(),
-                            kw::Empty,
-                            DefKind::Closure,
-                            span,
-                        );
-                        self.with_parent(closure_def, |this| this.visit_block(body));
-                    }
-                    return;
+                // For async functions, we need to create their inner defs inside of a
+                // closure to match their desugared representation. Besides that,
+                // we must mirror everything that `visit::walk_fn` below does.
+                let FnDecl { inputs, output } = &**decl;
+                for param in inputs {
+                    self.visit_param(param);
                 }
-                None => {}
-            }
-        }
 
-        visit::walk_fn(self, fn_kind);
+                let (return_id, return_span) = coroutine_kind.return_id();
+                let return_def =
+                    self.create_def(return_id, kw::Empty, DefKind::OpaqueTy, return_span);
+                self.with_parent(return_def, |this| this.visit_fn_ret_ty(output));
+
+                // If this async fn has no body (i.e. it's an async fn signature in a trait)
+                // then the closure_def will never be used, and we should avoid generating a
+                // def-id for it.
+                if let Some(body) = body {
+                    let closure_def = self.create_def(
+                        coroutine_kind.closure_id(),
+                        kw::Empty,
+                        DefKind::Closure,
+                        span,
+                    );
+                    self.with_parent(closure_def, |this| this.visit_block(body));
+                }
+            }
+            FnKind::Closure(binder, Some(coroutine_kind), decl, body) => {
+                self.visit_closure_binder(binder);
+                visit::walk_fn_decl(self, decl);
+
+                // Async closures desugar to closures inside of closures, so
+                // we must create two defs.
+                let coroutine_def =
+                    self.create_def(coroutine_kind.closure_id(), kw::Empty, DefKind::Closure, span);
+                self.with_parent(coroutine_def, |this| visit::walk_expr(this, body));
+            }
+            _ => visit::walk_fn(self, fn_kind),
+        }
     }
 
     fn visit_use_tree(&mut self, use_tree: &'a UseTree, id: NodeId, _nested: bool) {
@@ -334,27 +346,7 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
     fn visit_expr(&mut self, expr: &'a Expr) {
         let parent_def = match expr.kind {
             ExprKind::MacCall(..) => return self.visit_macro_invoc(expr.id),
-            ExprKind::Closure(ref closure) => {
-                // Async closures desugar to closures inside of closures, so
-                // we must create two defs.
-                let closure_def = self.create_def(expr.id, kw::Empty, DefKind::Closure, expr.span);
-                match closure.coroutine_kind {
-                    Some(coroutine_kind) => {
-                        self.with_parent(closure_def, |this| {
-                            let coroutine_def = this.create_def(
-                                coroutine_kind.closure_id(),
-                                kw::Empty,
-                                DefKind::Closure,
-                                expr.span,
-                            );
-                            this.with_parent(coroutine_def, |this| visit::walk_expr(this, expr));
-                        });
-                        return;
-                    }
-                    None => closure_def,
-                }
-            }
-            ExprKind::Gen(_, _, _, _) => {
+            ExprKind::Closure(..) | ExprKind::Gen(..) => {
                 self.create_def(expr.id, kw::Empty, DefKind::Closure, expr.span)
             }
             ExprKind::ConstBlock(ref constant) => {
@@ -381,6 +373,26 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
             TyKind::MacCall(..) => self.visit_macro_invoc(ty.id),
             // Anonymous structs or unions are visited later after defined.
             TyKind::AnonStruct(..) | TyKind::AnonUnion(..) => {}
+            TyKind::ImplTrait(id, _) => {
+                // HACK: pprust breaks strings with newlines when the type
+                // gets too long. We don't want these to show up in compiler
+                // output or built artifacts, so replace them here...
+                // Perhaps we should instead format APITs more robustly.
+                let name = Symbol::intern(&pprust::ty_to_string(ty).replace('\n', " "));
+                let kind = match self.impl_trait_context {
+                    ImplTraitContext::Universal => DefKind::TyParam,
+                    ImplTraitContext::Existential => DefKind::OpaqueTy,
+                };
+                let id = self.create_def(*id, name, kind, ty.span);
+                match self.impl_trait_context {
+                    // Do not nest APIT, as we desugar them as `impl_trait: bounds`,
+                    // so the `impl_trait` node is not a parent to `bounds`.
+                    ImplTraitContext::Universal => visit::walk_ty(self, ty),
+                    ImplTraitContext::Existential => {
+                        self.with_parent(id, |this| visit::walk_ty(this, ty))
+                    }
+                };
+            }
             _ => visit::walk_ty(self, ty),
         }
     }

compiler/rustc_resolve/src/late.rs

@@ -1010,7 +1010,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
                             this.in_func_body = previous_state;
                         }
                     }
-                    FnKind::Closure(binder, declaration, body) => {
+                    FnKind::Closure(binder, _, declaration, body) => {
                         this.visit_closure_binder(binder);
 
                         this.with_lifetime_rib(

tests/mir-opt/building/async_await.b-{closure#0}.coroutine_resume.0.mir

@@ -3,14 +3,14 @@
     field_tys: {
         _0: CoroutineSavedTy {
             ty: Coroutine(
-                DefId(0:4 ~ async_await[ccf8]::a::{closure#0}),
+                DefId(0:5 ~ async_await[ccf8]::a::{closure#0}),
                 [
                     (),
                     std::future::ResumeTy,
                     (),
                     (),
                     CoroutineWitness(
-                        DefId(0:4 ~ async_await[ccf8]::a::{closure#0}),
+                        DefId(0:5 ~ async_await[ccf8]::a::{closure#0}),
                         [],
                     ),
                     (),
@@ -24,14 +24,14 @@
         },
         _1: CoroutineSavedTy {
             ty: Coroutine(
-                DefId(0:4 ~ async_await[ccf8]::a::{closure#0}),
+                DefId(0:5 ~ async_await[ccf8]::a::{closure#0}),
                 [
                     (),
                     std::future::ResumeTy,
                     (),
                     (),
                     CoroutineWitness(
-                        DefId(0:4 ~ async_await[ccf8]::a::{closure#0}),
+                        DefId(0:5 ~ async_await[ccf8]::a::{closure#0}),
                         [],
                     ),
                     (),

tests/ui/coroutine/print/coroutine-print-verbose-1.stderr

@@ -10,7 +10,7 @@ note: coroutine is not `Send` as this value is used across a yield
   --> $DIR/coroutine-print-verbose-1.rs:35:9
    |
 LL |         let _non_send_gen = make_non_send_coroutine();
-   |             ------------- has type `Opaque(DefId(0:34 ~ coroutine_print_verbose_1[75fb]::make_non_send_coroutine::{opaque#0}), [])` which is not `Send`
+   |             ------------- has type `Opaque(DefId(0:24 ~ coroutine_print_verbose_1[75fb]::make_non_send_coroutine::{opaque#0}), [])` which is not `Send`
 LL |         yield;
    |         ^^^^^ yield occurs here, with `_non_send_gen` maybe used later
 note: required by a bound in `require_send`
@@ -33,12 +33,12 @@ note: required because it's used within this coroutine
    |
 LL |     #[coroutine] || {
    |                  ^^
-note: required because it appears within the type `Opaque(DefId(0:35 ~ coroutine_print_verbose_1[75fb]::make_gen2::{opaque#0}), [Arc<RefCell<i32>>])`
+note: required because it appears within the type `Opaque(DefId(0:29 ~ coroutine_print_verbose_1[75fb]::make_gen2::{opaque#0}), [Arc<RefCell<i32>>])`
   --> $DIR/coroutine-print-verbose-1.rs:41:30
    |
 LL | pub fn make_gen2<T>(t: T) -> impl Coroutine<Return = T> {
    |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: required because it appears within the type `Opaque(DefId(0:36 ~ coroutine_print_verbose_1[75fb]::make_non_send_coroutine2::{opaque#0}), [])`
+note: required because it appears within the type `Opaque(DefId(0:32 ~ coroutine_print_verbose_1[75fb]::make_non_send_coroutine2::{opaque#0}), [])`
   --> $DIR/coroutine-print-verbose-1.rs:47:34
    |
 LL | fn make_non_send_coroutine2() -> impl Coroutine<Return = Arc<RefCell<i32>>> {

tests/ui/nll/ty-outlives/impl-trait-captures.stderr

@@ -1,16 +1,16 @@
-error[E0700]: hidden type for `Opaque(DefId(0:13 ~ impl_trait_captures[aeb9]::foo::{opaque#0}), ['a/#0, T, 'a/#0])` captures lifetime that does not appear in bounds
+error[E0700]: hidden type for `Opaque(DefId(0:11 ~ impl_trait_captures[aeb9]::foo::{opaque#0}), ['a/#0, T, 'a/#0])` captures lifetime that does not appear in bounds
   --> $DIR/impl-trait-captures.rs:11:5
    |
 LL | fn foo<'a, T>(x: &T) -> impl Foo<'a> {
    |                  --     ------------ opaque type defined here
    |                  |
-   |                  hidden type `&ReLateParam(DefId(0:8 ~ impl_trait_captures[aeb9]::foo), BrNamed(DefId(0:12 ~ impl_trait_captures[aeb9]::foo::'_), '_)) T` captures the anonymous lifetime defined here
+   |                  hidden type `&ReLateParam(DefId(0:8 ~ impl_trait_captures[aeb9]::foo), BrNamed(DefId(0:13 ~ impl_trait_captures[aeb9]::foo::'_), '_)) T` captures the anonymous lifetime defined here
 LL |     x
    |     ^
    |
-help: add a `use<...>` bound to explicitly capture `ReLateParam(DefId(0:8 ~ impl_trait_captures[aeb9]::foo), BrNamed(DefId(0:12 ~ impl_trait_captures[aeb9]::foo::'_), '_))`
+help: add a `use<...>` bound to explicitly capture `ReLateParam(DefId(0:8 ~ impl_trait_captures[aeb9]::foo), BrNamed(DefId(0:13 ~ impl_trait_captures[aeb9]::foo::'_), '_))`
    |
-LL | fn foo<'a, T>(x: &T) -> impl Foo<'a> + use<'a, ReLateParam(DefId(0:8 ~ impl_trait_captures[aeb9]::foo), BrNamed(DefId(0:12 ~ impl_trait_captures[aeb9]::foo::'_), '_)), T> {
+LL | fn foo<'a, T>(x: &T) -> impl Foo<'a> + use<'a, ReLateParam(DefId(0:8 ~ impl_trait_captures[aeb9]::foo), BrNamed(DefId(0:13 ~ impl_trait_captures[aeb9]::foo::'_), '_)), T> {
    |                                      +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
 error: aborting due to 1 previous error