diff options
| -rw-r--r-- | compiler/rustc_hir_typeck/src/method/suggest.rs | 68 | ||||
| -rw-r--r-- | tests/ui/async-await/pin-needed-to-poll-3.rs | 25 | ||||
| -rw-r--r-- | tests/ui/async-await/pin-needed-to-poll-3.stderr | 18 |
3 files changed, 103 insertions, 8 deletions
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs index bbe4a8791c6..803d1554324 100644 --- a/compiler/rustc_hir_typeck/src/method/suggest.rs +++ b/compiler/rustc_hir_typeck/src/method/suggest.rs @@ -3360,14 +3360,66 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .source_map() .indentation_before(rcvr.span) .unwrap_or_else(|| " ".to_string()); - err.multipart_suggestion( - "consider pinning the expression", - vec![ - (rcvr.span.shrink_to_lo(), format!("let mut pinned = std::pin::pin!(")), - (rcvr.span.shrink_to_hi(), format!(");\n{indent}pinned.{pin_call}()")), - ], - Applicability::MaybeIncorrect, - ); + let mut expr = rcvr; + while let Node::Expr(call_expr) = self.tcx.parent_hir_node(expr.hir_id) + && let hir::ExprKind::MethodCall(hir::PathSegment { .. }, ..) = + call_expr.kind + { + expr = call_expr; + } + match self.tcx.parent_hir_node(expr.hir_id) { + Node::LetStmt(stmt) + if let Some(init) = stmt.init + && let Ok(code) = + self.tcx.sess.source_map().span_to_snippet(rcvr.span) => + { + // We need to take care to account for the existing binding when we + // suggest the code. + err.multipart_suggestion( + "consider pinning the expression", + vec![ + ( + stmt.span.shrink_to_lo(), + format!( + "let mut pinned = std::pin::pin!({code});\n{indent}" + ), + ), + ( + init.span.until(rcvr.span.shrink_to_hi()), + format!("pinned.{pin_call}()"), + ), + ], + Applicability::MaybeIncorrect, + ); + } + Node::Block(_) | Node::Stmt(_) => { + // There's no binding, so we can provide a slightly nicer looking + // suggestion. + err.multipart_suggestion( + "consider pinning the expression", + vec![ + ( + rcvr.span.shrink_to_lo(), + format!("let mut pinned = std::pin::pin!("), + ), + ( + rcvr.span.shrink_to_hi(), + format!(");\n{indent}pinned.{pin_call}()"), + ), + ], + Applicability::MaybeIncorrect, + ); + } + _ => { + // We don't quite know what the users' code looks like, so we don't + // provide a pinning suggestion. + err.span_help( + rcvr.span, + "consider pinning the expression with `std::pin::pin!()` and \ + assigning that to a new binding", + ); + } + } // We don't care about the other suggestions. alt_rcvr_sugg = true; } diff --git a/tests/ui/async-await/pin-needed-to-poll-3.rs b/tests/ui/async-await/pin-needed-to-poll-3.rs new file mode 100644 index 00000000000..11ba7d29aba --- /dev/null +++ b/tests/ui/async-await/pin-needed-to-poll-3.rs @@ -0,0 +1,25 @@ +use std::{ + future::Future, + pin::Pin, + task::{Context, Poll}, +}; + + +struct FutureWrapper<F> { + fut: F, +} + +impl<F> Future for FutureWrapper<F> +where + F: Future, +{ + type Output = F::Output; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let res = self.fut.poll(cx); + //~^ ERROR no method named `poll` found for type parameter `F` in the current scope + res + } +} + +fn main() {} diff --git a/tests/ui/async-await/pin-needed-to-poll-3.stderr b/tests/ui/async-await/pin-needed-to-poll-3.stderr new file mode 100644 index 00000000000..e4fbef69bac --- /dev/null +++ b/tests/ui/async-await/pin-needed-to-poll-3.stderr @@ -0,0 +1,18 @@ +error[E0599]: no method named `poll` found for type parameter `F` in the current scope + --> $DIR/pin-needed-to-poll-3.rs:19:28 + | +LL | impl<F> Future for FutureWrapper<F> + | - method `poll` not found for this type parameter +... +LL | let res = self.fut.poll(cx); + | ^^^^ method not found in `F` + | +help: consider pinning the expression + | +LL ~ let mut pinned = std::pin::pin!(self.fut); +LL ~ let res = pinned.as_mut().poll(cx); + | + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0599`. |