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Separate complex multispan into some notes
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@JohnTitor
JohnTitor committed Nov 2, 2020
1 parent c269525 commit ad978e5
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Showing 3 changed files with 144 additions and 54 deletions.
143 changes: 114 additions & 29 deletions compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file
Expand Up @@ -1570,36 +1570,121 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
format!("does not implement `{}`", trait_ref.print_only_trait_path())
};

let mut explain_yield = |interior_span: Span,
yield_span: Span,
scope_span: Option<Span>| {
let mut span = MultiSpan::from_span(yield_span);
if let Ok(snippet) = source_map.span_to_snippet(interior_span) {
span.push_span_label(
yield_span,
format!("{} occurs here, with `{}` maybe used later", await_or_yield, snippet),
);
// If available, use the scope span to annotate the drop location.
if let Some(scope_span) = scope_span {
span.push_span_label(
source_map.end_point(scope_span),
format!("`{}` is later dropped here", snippet),
);
let mut explain_yield =
|interior_span: Span, yield_span: Span, scope_span: Option<Span>| {
let mut span = MultiSpan::from_span(yield_span);
if let Ok(snippet) = source_map.span_to_snippet(interior_span) {
// #70935: If snippet contains newlines, display "the value" instead
// so that we do not emit complex diagnostics.
let snippet = &format!("`{}`", snippet);
let snippet = if snippet.contains('\n') { "the value" } else { snippet };
// The multispan can be complex here, like:
// note: future is not `Send` as this value is used across an await
// --> $DIR/issue-70935-complex-spans.rs:13:9
// |
// LL | baz(|| async{
// | __________^___-
// | | _________|
// | ||
// LL | || foo(tx.clone());
// LL | || }).await;
// | || - ^- value is later dropped here
// | ||_________|______|
// | |__________| await occurs here, with value maybe used later
// | has type `closure` which is not `Send`
// = note: the return type of a function must have a statically known size
// So, detect it and separate into some notes, like:
// note: future is not `Send` as this value is used across an await
// --> $DIR/issue-70935-complex-spans.rs:13:9
// |
// LL | / baz(|| async{
// LL | | foo(tx.clone());
// LL | | }).await;
// | |________________^
// note: first, await occurs here, with the value maybe used later
// --> $DIR/issue-70935-complex-spans.rs:13:9
// |
// LL | / baz(|| async{
// LL | | foo(tx.clone());
// LL | | }).await;
// | |________________^
// note: ...but, the value is later dropped here
// --> $DIR/issue-70935-complex-spans.rs:15:17
// |
// LL | }).await;
// | ^
// = note: the return type of a function must have a statically known size

// If available, use the scope span to annotate the drop location.
if let Some(scope_span) = scope_span {
let scope_span = source_map.end_point(scope_span);
let is_overlapped =
yield_span.overlaps(scope_span) || yield_span.overlaps(interior_span);
if is_overlapped {
err.span_note(
span,
&format!(
"{} {} as this value is used across {}",
future_or_generator, trait_explanation, an_await_or_yield
),
);
err.span_note(
yield_span,
&format!(
"first, {} occurs here, with {} maybe used later",
await_or_yield, snippet
),
);
err.span_note(
scope_span,
&format!("...but, {} is later dropped here", snippet),
);
} else {
span.push_span_label(
yield_span,
format!(
"{} occurs here, with {} maybe used later",
await_or_yield, snippet
),
);
span.push_span_label(
scope_span,
format!("{} is later dropped here", snippet),
);
span.push_span_label(
interior_span,
format!("has type `{}` which {}", target_ty, trait_explanation),
);
err.span_note(
span,
&format!(
"{} {} as this value is used across {}",
future_or_generator, trait_explanation, an_await_or_yield
),
);
}
} else {
span.push_span_label(
yield_span,
format!(
"{} occurs here, with {} maybe used later",
await_or_yield, snippet
),
);
span.push_span_label(
interior_span,
format!("has type `{}` which {}", target_ty, trait_explanation),
);
err.span_note(
span,
&format!(
"{} {} as this value is used across {}",
future_or_generator, trait_explanation, an_await_or_yield
),
);
}
}
}
span.push_span_label(
interior_span,
format!("has type `{}` which {}", target_ty, trait_explanation),
);

err.span_note(
span,
&format!(
"{} {} as this value is used across {}",
future_or_generator, trait_explanation, an_await_or_yield
),
);
};
};
match interior_or_upvar_span {
GeneratorInteriorOrUpvar::Interior(interior_span) => {
if let Some((scope_span, yield_span, expr, from_awaited_ty)) = interior_extra_info {
Expand Down
40 changes: 19 additions & 21 deletions src/test/ui/async-await/issue-70935-complex-spans.stderr
View file
@@ -1,31 +1,29 @@
error: future cannot be sent between threads safely
--> $DIR/issue-70935-complex-spans.rs:10:45
|
LL | fn foo(tx: std::sync::mpsc::Sender<i32>) -> impl Future + Send {
| ^^^^^^^^^^^^^^^^^^ future created by async block is not `Send`
LL |
LL | / async move {
LL | | baz(|| async{
LL | | foo(tx.clone());
LL | | }).await;
LL | | }
| |_____- this returned value is of type `impl std::future::Future`
LL | fn foo(tx: std::sync::mpsc::Sender<i32>) -> impl Future + Send {
| ^^^^^^^^^^^^^^^^^^ future created by async block is not `Send`
|
= help: the trait `std::marker::Sync` is not implemented for `std::sync::mpsc::Sender<i32>`
= help: the trait `Sync` is not implemented for `Sender<i32>`
note: future is not `Send` as this value is used across an await
--> $DIR/issue-70935-complex-spans.rs:13:9
|
LL | baz(|| async{
| __________^___-
| | _________|
| ||
LL | || foo(tx.clone());
LL | || }).await;
| || - ^- value is later dropped here
| ||_________|______|
| |__________| await occurs here, with value maybe used later
| has type `[closure@$DIR/issue-70935-complex-spans.rs:13:13: 15:10 tx:&std::sync::mpsc::Sender<i32>]` which is not `Send`
= note: the return type of a function must have a statically known size
LL | / baz(|| async{
LL | | foo(tx.clone());
LL | | }).await;
| |________________^
note: first, await occurs here, with the value maybe used later
--> $DIR/issue-70935-complex-spans.rs:13:9
|
LL | / baz(|| async{
LL | | foo(tx.clone());
LL | | }).await;
| |________________^
note: ...but, the value is later dropped here
--> $DIR/issue-70935-complex-spans.rs:15:17
|
LL | }).await;
| ^

error: aborting due to previous error

15 changes: 11 additions & 4 deletions src/test/ui/async-await/issues/issue-65436-raw-ptr-not-send.stderr
View file
Expand Up @@ -12,10 +12,17 @@ note: future is not `Send` as this value is used across an await
--> $DIR/issue-65436-raw-ptr-not-send.rs:14:9
|
LL | bar(Foo(std::ptr::null())).await;
| ^^^^^^^^----------------^^^^^^^^- `std::ptr::null()` is later dropped here
| | |
| | has type `*const u8` which is not `Send`
| await occurs here, with `std::ptr::null()` maybe used later
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: first, await occurs here, with `std::ptr::null()` maybe used later
--> $DIR/issue-65436-raw-ptr-not-send.rs:14:9
|
LL | bar(Foo(std::ptr::null())).await;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: ...but, `std::ptr::null()` is later dropped here
--> $DIR/issue-65436-raw-ptr-not-send.rs:14:41
|
LL | bar(Foo(std::ptr::null())).await;
| ^
help: consider moving this into a `let` binding to create a shorter lived borrow
--> $DIR/issue-65436-raw-ptr-not-send.rs:14:13
|
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