Rollup merge of #65743 - eddyb:generator-on-call, r=matthewjasper

rustc_typeck: don't record direct callees in generator_interior.

For expressions like `f(g().await)` we were recording `f` as needing to be kept in a temporary (and therefore be tracked by the generator type) across the suspend, even if a function/method path.
However, this is never needed, and can cause issues with complex function types (see #65244).

cc @Zoxc @nikomatsakis

Author: Centril

src/librustc_typeck/check/generator_interior.rs

@@ -3,9 +3,10 @@
 //! is calculated in `rustc_mir::transform::generator` and may be a subset of the
 //! types computed here.
 
+use rustc::hir::def::{CtorKind, DefKind, Res};
 use rustc::hir::def_id::DefId;
 use rustc::hir::intravisit::{self, Visitor, NestedVisitorMap};
-use rustc::hir::{self, Pat, PatKind, Expr};
+use rustc::hir::{self, Pat, PatKind, Expr, ExprKind};
 use rustc::middle::region::{self, YieldData};
 use rustc::ty::{self, Ty};
 use syntax_pos::Span;
@@ -184,7 +185,33 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
     }
 
     fn visit_expr(&mut self, expr: &'tcx Expr) {
-        intravisit::walk_expr(self, expr);
+        match &expr.kind {
+            ExprKind::Call(callee, args) => match &callee.kind {
+                ExprKind::Path(qpath) => {
+                    let res = self.fcx.tables.borrow().qpath_res(qpath, callee.hir_id);
+                    match res {
+                        // Direct calls never need to keep the callee `ty::FnDef`
+                        // ZST in a temporary, so skip its type, just in case it
+                        // can significantly complicate the generator type.
+                        Res::Def(DefKind::Fn, _) |
+                        Res::Def(DefKind::Method, _) |
+                        Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) => {
+                            // NOTE(eddyb) this assumes a path expression has
+                            // no nested expressions to keep track of.
+                            self.expr_count += 1;
+
+                            // Record the rest of the call expression normally.
+                            for arg in args {
+                                self.visit_expr(arg);
+                            }
+                        }
+                        _ => intravisit::walk_expr(self, expr),
+                    }
+                }
+                _ => intravisit::walk_expr(self, expr),
+            }
+            _ => intravisit::walk_expr(self, expr),
+        }
 
         self.expr_count += 1;
 

src/test/ui/async-await/async-fn-nonsend.stderr

@@ -9,9 +9,9 @@ LL |     assert_send(local_dropped_before_await());
    |
    = help: within `impl std::future::Future`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<()>`
    = note: required because it appears within the type `impl std::fmt::Debug`
-   = note: required because it appears within the type `{impl std::fmt::Debug, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}`
-   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:21:39: 26:2 {impl std::fmt::Debug, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]`
-   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:21:39: 26:2 {impl std::fmt::Debug, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]>`
+   = note: required because it appears within the type `{impl std::fmt::Debug, impl std::future::Future, impl std::future::Future, ()}`
+   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:21:39: 26:2 {impl std::fmt::Debug, impl std::future::Future, impl std::future::Future, ()}]`
+   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:21:39: 26:2 {impl std::fmt::Debug, impl std::future::Future, impl std::future::Future, ()}]>`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `impl std::future::Future`
 
@@ -26,9 +26,9 @@ LL |     assert_send(non_send_temporary_in_match());
    |
    = help: within `impl std::future::Future`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<()>`
    = note: required because it appears within the type `impl std::fmt::Debug`
-   = note: required because it appears within the type `{fn(impl std::fmt::Debug) -> std::option::Option<impl std::fmt::Debug> {std::option::Option::<impl std::fmt::Debug>::Some}, fn() -> impl std::fmt::Debug {non_send}, impl std::fmt::Debug, std::option::Option<impl std::fmt::Debug>, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}`
-   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:28:40: 37:2 {fn(impl std::fmt::Debug) -> std::option::Option<impl std::fmt::Debug> {std::option::Option::<impl std::fmt::Debug>::Some}, fn() -> impl std::fmt::Debug {non_send}, impl std::fmt::Debug, std::option::Option<impl std::fmt::Debug>, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]`
-   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:28:40: 37:2 {fn(impl std::fmt::Debug) -> std::option::Option<impl std::fmt::Debug> {std::option::Option::<impl std::fmt::Debug>::Some}, fn() -> impl std::fmt::Debug {non_send}, impl std::fmt::Debug, std::option::Option<impl std::fmt::Debug>, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]>`
+   = note: required because it appears within the type `{impl std::fmt::Debug, std::option::Option<impl std::fmt::Debug>, impl std::future::Future, impl std::future::Future, ()}`
+   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:28:40: 37:2 {impl std::fmt::Debug, std::option::Option<impl std::fmt::Debug>, impl std::future::Future, impl std::future::Future, ()}]`
+   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:28:40: 37:2 {impl std::fmt::Debug, std::option::Option<impl std::fmt::Debug>, impl std::future::Future, impl std::future::Future, ()}]>`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `impl std::future::Future`
 
@@ -45,9 +45,9 @@ LL |     assert_send(non_sync_with_method_call());
    = note: required because of the requirements on the impl of `std::marker::Send` for `&mut dyn std::fmt::Write`
    = note: required because it appears within the type `std::fmt::Formatter<'_>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&mut std::fmt::Formatter<'_>`
-   = note: required because it appears within the type `for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}`
-   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]`
-   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]>`
+   = note: required because it appears within the type `for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, impl std::future::Future, impl std::future::Future, ()}`
+   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, impl std::future::Future, impl std::future::Future, ()}]`
+   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, impl std::future::Future, impl std::future::Future, ()}]>`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `impl std::future::Future`
 
@@ -68,9 +68,9 @@ LL |     assert_send(non_sync_with_method_call());
    = note: required because of the requirements on the impl of `std::marker::Send` for `std::slice::Iter<'_, std::fmt::ArgumentV1<'_>>`
    = note: required because it appears within the type `std::fmt::Formatter<'_>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&mut std::fmt::Formatter<'_>`
-   = note: required because it appears within the type `for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}`
-   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]`
-   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, fn() -> impl std::future::Future {fut}, impl std::future::Future, impl std::future::Future, ()}]>`
+   = note: required because it appears within the type `for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, impl std::future::Future, impl std::future::Future, ()}`
+   = note: required because it appears within the type `[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, impl std::future::Future, impl std::future::Future, ()}]`
+   = note: required because it appears within the type `std::future::GenFuture<[static generator@$DIR/async-fn-nonsend.rs:39:38: 45:2 for<'r, 's> {&'r mut std::fmt::Formatter<'s>, bool, bool, impl std::future::Future, impl std::future::Future, ()}]>`
    = note: required because it appears within the type `impl std::future::Future`
    = note: required because it appears within the type `impl std::future::Future`