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factor into struct, and comments

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This commit is contained in:
Gus Wynn 2021-09-15 11:48:34 -07:00
parent 2af1ebfbdf
commit 110aecd23e
8 changed files with 104 additions and 92 deletions
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6
compiler/rustc_lint_defs/src/builtin.rs
View File

@ -315,7 +315,7 @@
}
declare_lint! {
/// The `must_not_suspend` lint guards against values that shouldn't be held across yield points
/// The `must_not_suspend` lint guards against values that shouldn't be held across suspend points
/// (`.await`)
///
/// ### Example
@ -339,10 +339,10 @@
/// ### Explanation
///
/// The `must_not_suspend` lint detects values that are marked with the `#[must_not_suspend]`
/// attribute being held across yield points. A "yield" point is usually a `.await` in an async
/// attribute being held across suspend points. A "suspend" point is usually a `.await` in an async
/// function.
///
/// This attribute can be used to mark values that are semantically incorrect across yields
/// This attribute can be used to mark values that are semantically incorrect across suspends
/// (like certain types of timers), values that have async alternatives, and values that
/// regularly cause problems with the `Send`-ness of async fn's returned futures (like
/// `MutexGuard`'s)

120
compiler/rustc_typeck/src/check/generator_interior.rs
View File

@ -126,12 +126,13 @@ fn record(
self.fcx,
ty,
hir_id,
expr,
source_span,
yield_data.span,
"",
"",
1,
SuspendCheckData {
expr,
source_span,
yield_span: yield_data.span,
plural_len: 1,
..Default::default()
},
);
self.types.insert(ty::GeneratorInteriorTypeCause {
@ -448,6 +449,16 @@ fn visit_pat(&mut self, pat: &'tcx Pat<'tcx>) {
}
}
#[derive(Default)]
pub struct SuspendCheckData<'a, 'tcx> {
expr: Option<&'tcx Expr<'tcx>>,
source_span: Span,
yield_span: Span,
descr_pre: &'a str,
descr_post: &'a str,
plural_len: usize,
}
// Returns whether it emitted a diagnostic or not
// Note that this fn and the proceding one are based on the code
// for creating must_use diagnostics
@ -455,12 +466,7 @@ pub fn check_must_not_suspend_ty<'tcx>(
fcx: &FnCtxt<'_, 'tcx>,
ty: Ty<'tcx>,
hir_id: HirId,
expr: Option<&'tcx Expr<'tcx>>,
source_span: Span,
yield_span: Span,
descr_pre: &str,
descr_post: &str,
plural_len: usize,
data: SuspendCheckData<'_, 'tcx>,
) -> bool {
if ty.is_unit()
// FIXME: should this check `is_ty_uninhabited_from`. This query is not available in this stage
@ -468,36 +474,18 @@ pub fn check_must_not_suspend_ty<'tcx>(
// `must_use`
// || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, fcx.param_env)
{
return true;
return false;
}
let plural_suffix = pluralize!(plural_len);
let plural_suffix = pluralize!(data.plural_len);
match *ty.kind() {
ty::Adt(..) if ty.is_box() => {
let boxed_ty = ty.boxed_ty();
let descr_pre = &format!("{}boxed ", descr_pre);
check_must_not_suspend_ty(
fcx,
boxed_ty,
hir_id,
expr,
source_span,
yield_span,
descr_pre,
descr_post,
plural_len,
)
let descr_pre = &format!("{}boxed ", data.descr_pre);
check_must_not_suspend_ty(fcx, boxed_ty, hir_id, SuspendCheckData { descr_pre, ..data })
}
ty::Adt(def, _) => check_must_not_suspend_def(
fcx.tcx,
def.did,
hir_id,
source_span,
yield_span,
descr_pre,
descr_post,
),
ty::Adt(def, _) => check_must_not_suspend_def(fcx.tcx, def.did, hir_id, data),
// FIXME: support adding the attribute to TAITs
ty::Opaque(def, _) => {
let mut has_emitted = false;
@ -507,15 +495,12 @@ pub fn check_must_not_suspend_ty<'tcx>(
predicate.kind().skip_binder()
{
let def_id = poly_trait_predicate.trait_ref.def_id;
let descr_pre = &format!("{}implementer{} of ", descr_pre, plural_suffix,);
let descr_pre = &format!("{}implementer{} of ", data.descr_pre, plural_suffix);
if check_must_not_suspend_def(
fcx.tcx,
def_id,
hir_id,
source_span,
yield_span,
descr_pre,
descr_post,
SuspendCheckData { descr_pre, ..data },
) {
has_emitted = true;
break;
@ -529,15 +514,12 @@ pub fn check_must_not_suspend_ty<'tcx>(
for predicate in binder.iter() {
if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate.skip_binder() {
let def_id = trait_ref.def_id;
let descr_post = &format!(" trait object{}{}", plural_suffix, descr_post,);
let descr_post = &format!(" trait object{}{}", plural_suffix, data.descr_post);
if check_must_not_suspend_def(
fcx.tcx,
def_id,
hir_id,
source_span,
yield_span,
descr_pre,
descr_post,
SuspendCheckData { descr_post, ..data },
) {
has_emitted = true;
break;
@ -548,7 +530,7 @@ pub fn check_must_not_suspend_ty<'tcx>(
}
ty::Tuple(ref tys) => {
let mut has_emitted = false;
let spans = if let Some(hir::ExprKind::Tup(comps)) = expr.map(|e| &e.kind) {
let spans = if let Some(hir::ExprKind::Tup(comps)) = data.expr.map(|e| &e.kind) {
debug_assert_eq!(comps.len(), tys.len());
comps.iter().map(|e| e.span).collect()
} else {
@ -556,9 +538,12 @@ pub fn check_must_not_suspend_ty<'tcx>(
};
for (i, ty) in tys.iter().map(|k| k.expect_ty()).enumerate() {
let descr_post = &format!(" in tuple element {}", i);
let span = *spans.get(i).unwrap_or(&source_span);
let span = *spans.get(i).unwrap_or(&data.source_span);
if check_must_not_suspend_ty(
fcx, ty, hir_id, expr, span, yield_span, descr_pre, descr_post, plural_len,
fcx,
ty,
hir_id,
SuspendCheckData { descr_post, source_span: span, ..data },
) {
has_emitted = true;
}
@ -566,17 +551,17 @@ pub fn check_must_not_suspend_ty<'tcx>(
has_emitted
}
ty::Array(ty, len) => {
let descr_pre = &format!("{}array{} of ", descr_pre, plural_suffix,);
let descr_pre = &format!("{}array{} of ", data.descr_pre, plural_suffix);
check_must_not_suspend_ty(
fcx,
ty,
hir_id,
expr,
source_span,
yield_span,
descr_pre,
descr_post,
len.try_eval_usize(fcx.tcx, fcx.param_env).unwrap_or(0) as usize + 1,
SuspendCheckData {
descr_pre,
plural_len: len.try_eval_usize(fcx.tcx, fcx.param_env).unwrap_or(0) as usize
+ 1,
..data
},
)
}
_ => false,
@ -587,39 +572,38 @@ fn check_must_not_suspend_def(
tcx: TyCtxt<'_>,
def_id: DefId,
hir_id: HirId,
source_span: Span,
yield_span: Span,
descr_pre_path: &str,
descr_post_path: &str,
data: SuspendCheckData<'_, '_>,
) -> bool {
for attr in tcx.get_attrs(def_id).iter() {
if attr.has_name(sym::must_not_suspend) {
tcx.struct_span_lint_hir(
rustc_session::lint::builtin::MUST_NOT_SUSPEND,
hir_id,
source_span,
data.source_span,
|lint| {
let msg = format!(
"{}`{}`{} held across a yield point, but should not be",
descr_pre_path,
"{}`{}`{} held across a suspend point, but should not be",
data.descr_pre,
tcx.def_path_str(def_id),
descr_post_path
data.descr_post,
);
let mut err = lint.build(&msg);
// add span pointing to the offending yield/await
err.span_label(yield_span, "the value is held across this yield point");
err.span_label(data.yield_span, "the value is held across this suspend point");
// Add optional reason note
if let Some(note) = attr.value_str() {
err.span_note(source_span, &note.as_str());
// FIXME(guswynn): consider formatting this better
err.span_note(data.source_span, &note.as_str());
}
// Add some quick suggestions on what to do
// FIXME: can `drop` work as a suggestion here as well?
err.span_help(
source_span,
"`drop` this value before the yield point, or use a block (`{ ... }`) \
to shrink its scope",
data.source_span,
"consider using a block (`{ ... }`) \
to shrink the value's scope, ending before the suspend point",
);
err.emit();

6
src/test/ui/lint/must_not_suspend/boxed.stderr
View File

@ -1,10 +1,10 @@
error: boxed `Umm` held across a yield point, but should not be
error: boxed `Umm` held across a suspend point, but should not be
--> $DIR/boxed.rs:20:9
|
LL | let _guard = bar();
| ^^^^^^
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
note: the lint level is defined here
--> $DIR/boxed.rs:3:9
@ -16,7 +16,7 @@ note: You gotta use Umm's, ya know?
|
LL | let _guard = bar();
| ^^^^^^
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/boxed.rs:20:9
|
LL | let _guard = bar();

28
src/test/ui/lint/must_not_suspend/handled.rs Normal file
View File

@ -0,0 +1,28 @@
// edition:2018
// run-pass
#![feature(must_not_suspend)]
#![deny(must_not_suspend)]
#[must_not_suspend = "You gotta use Umm's, ya know?"]
struct Umm {
_i: i64
}
fn bar() -> Umm {
Umm {
_i: 1
}
}
async fn other() {}
pub async fn uhoh() {
{
let _guard = bar();
}
other().await;
}
fn main() {
}

12
src/test/ui/lint/must_not_suspend/ref.stderr
View File

@ -1,11 +1,11 @@
error: `Umm` held across a yield point, but should not be
error: `Umm` held across a suspend point, but should not be
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;
| ^^^^^^
...
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
note: the lint level is defined here
--> $DIR/ref.rs:3:9
@ -17,27 +17,27 @@ note: You gotta use Umm's, ya know?
|
LL | let guard = &mut self.u;
| ^^^^^^
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;
| ^^^^^^
error: `Umm` held across a yield point, but should not be
error: `Umm` held across a suspend point, but should not be
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;
| ^^^^^^
...
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
note: You gotta use Umm's, ya know?
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;
| ^^^^^^
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;

12
src/test/ui/lint/must_not_suspend/trait.stderr
View File

@ -1,33 +1,33 @@
error: implementer of `Wow` held across a yield point, but should not be
error: implementer of `Wow` held across a suspend point, but should not be
--> $DIR/trait.rs:21:9
|
LL | let _guard1 = r#impl();
| ^^^^^^^
...
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
note: the lint level is defined here
--> $DIR/trait.rs:3:9
|
LL | #![deny(must_not_suspend)]
| ^^^^^^^^^^^^^^^^
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/trait.rs:21:9
|
LL | let _guard1 = r#impl();
| ^^^^^^^
error: boxed `Wow` trait object held across a yield point, but should not be
error: boxed `Wow` trait object held across a suspend point, but should not be
--> $DIR/trait.rs:22:9
|
LL | let _guard2 = r#dyn();
| ^^^^^^^
LL |
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/trait.rs:22:9
|
LL | let _guard2 = r#dyn();

6
src/test/ui/lint/must_not_suspend/unit.stderr
View File

@ -1,10 +1,10 @@
error: `Umm` held across a yield point, but should not be
error: `Umm` held across a suspend point, but should not be
--> $DIR/unit.rs:20:9
|
LL | let _guard = bar();
| ^^^^^^
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
note: the lint level is defined here
--> $DIR/unit.rs:3:9
@ -16,7 +16,7 @@ note: You gotta use Umm's, ya know?
|
LL | let _guard = bar();
| ^^^^^^
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/unit.rs:20:9
|
LL | let _guard = bar();

6
src/test/ui/lint/must_not_suspend/warn.stderr
View File

@ -1,10 +1,10 @@
warning: `Umm` held across a yield point, but should not be
warning: `Umm` held across a suspend point, but should not be
--> $DIR/warn.rs:20:9
|
LL | let _guard = bar();
| ^^^^^^
LL | other().await;
| ------------- the value is held across this yield point
| ------------- the value is held across this suspend point
|
= note: `#[warn(must_not_suspend)]` on by default
note: You gotta use Umm's, ya know?
@ -12,7 +12,7 @@ note: You gotta use Umm's, ya know?
|
LL | let _guard = bar();
| ^^^^^^
help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
--> $DIR/warn.rs:20:9
|
LL | let _guard = bar();