From 2271376fb224661fd8b7e5e5788217e8fe9e5ecc Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 4 Sep 2021 19:36:51 -0700
Subject: [PATCH 1/9] must_not_suspend impl
---
compiler/rustc_feature/src/active.rs | 4 +
compiler/rustc_feature/src/builtin_attrs.rs | 4 +
compiler/rustc_lint/src/lib.rs | 1 +
compiler/rustc_lint_defs/src/builtin.rs | 8 +
compiler/rustc_passes/src/check_attr.rs | 16 +
compiler/rustc_span/src/symbol.rs | 1 +
.../src/check/generator_interior.rs | 309 +++++++++++++++++-
src/test/ui/lint/must_not_suspend/boxed.rs | 25 ++
.../ui/lint/must_not_suspend/boxed.stderr | 23 ++
.../feature-gate-must_not_suspend.rs | 9 +
.../feature-gate-must_not_suspend.stderr | 12 +
src/test/ui/lint/must_not_suspend/return.rs | 9 +
.../ui/lint/must_not_suspend/return.stderr | 12 +
src/test/ui/lint/must_not_suspend/trait.rs | 28 ++
.../ui/lint/must_not_suspend/trait.stderr | 39 +++
src/test/ui/lint/must_not_suspend/unit.rs | 25 ++
src/test/ui/lint/must_not_suspend/unit.stderr | 23 ++
src/test/ui/lint/must_not_suspend/warn.rs | 25 ++
src/test/ui/lint/must_not_suspend/warn.stderr | 19 ++
19 files changed, 587 insertions(+), 5 deletions(-)
create mode 100644 src/test/ui/lint/must_not_suspend/boxed.rs
create mode 100644 src/test/ui/lint/must_not_suspend/boxed.stderr
create mode 100644 src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs
create mode 100644 src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.stderr
create mode 100644 src/test/ui/lint/must_not_suspend/return.rs
create mode 100644 src/test/ui/lint/must_not_suspend/return.stderr
create mode 100644 src/test/ui/lint/must_not_suspend/trait.rs
create mode 100644 src/test/ui/lint/must_not_suspend/trait.stderr
create mode 100644 src/test/ui/lint/must_not_suspend/unit.rs
create mode 100644 src/test/ui/lint/must_not_suspend/unit.stderr
create mode 100644 src/test/ui/lint/must_not_suspend/warn.rs
create mode 100644 src/test/ui/lint/must_not_suspend/warn.stderr
diff --git a/compiler/rustc_feature/src/active.rs b/compiler/rustc_feature/src/active.rs
index a3807a2bb9fde..66569270bd21e 100644
--- a/compiler/rustc_feature/src/active.rs
+++ b/compiler/rustc_feature/src/active.rs
@@ -679,6 +679,10 @@ declare_features! (
/// Allows `let...else` statements.
(active, let_else, "1.56.0", Some(87335), None),
+ /// Allows `#[must_not_suspend]`.
+ (active, must_not_suspend, "1.56.0", Some(83310), None),
+
+
// -------------------------------------------------------------------------
// feature-group-end: actual feature gates
// -------------------------------------------------------------------------
diff --git a/compiler/rustc_feature/src/builtin_attrs.rs b/compiler/rustc_feature/src/builtin_attrs.rs
index e2aa54a59b202..928a7eb794bd1 100644
--- a/compiler/rustc_feature/src/builtin_attrs.rs
+++ b/compiler/rustc_feature/src/builtin_attrs.rs
@@ -202,6 +202,10 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
ungated!(forbid, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
ungated!(deny, Normal, template!(List: r#"lint1, lint2, ..., /*opt*/ reason = "...""#)),
ungated!(must_use, Normal, template!(Word, NameValueStr: "reason")),
+ gated!(
+ must_not_suspend, Normal, template!(Word, NameValueStr: "reason"), must_not_suspend,
+ experimental!(must_not_suspend)
+ ),
// FIXME(#14407)
ungated!(
deprecated, Normal,
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index ef4bda666ba06..10285272130cc 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -298,6 +298,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
UNUSED_LABELS,
UNUSED_PARENS,
UNUSED_BRACES,
+ MUST_NOT_SUSPEND,
REDUNDANT_SEMICOLONS
);
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 8fb678e2d20fb..386435034b6ac 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -314,6 +314,13 @@ declare_lint! {
"imports that are never used"
}
+declare_lint! {
+ /// [the reference]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
+ pub MUST_NOT_SUSPEND,
+ Warn,
+ "Use of a `#[must_not_suspend]` value across a yield point",
+}
+
declare_lint! {
/// The `unused_extern_crates` lint guards against `extern crate` items
/// that are never used.
@@ -2993,6 +3000,7 @@ declare_lint_pass! {
CENUM_IMPL_DROP_CAST,
CONST_EVALUATABLE_UNCHECKED,
INEFFECTIVE_UNSTABLE_TRAIT_IMPL,
+ MUST_NOT_SUSPEND,
UNINHABITED_STATIC,
FUNCTION_ITEM_REFERENCES,
USELESS_DEPRECATED,
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index fd438bdc9005a..a31f3fe281ee9 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -104,6 +104,7 @@ impl CheckAttrVisitor<'tcx> {
sym::default_method_body_is_const => {
self.check_default_method_body_is_const(attr, span, target)
}
+ sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target),
sym::rustc_const_unstable
| sym::rustc_const_stable
| sym::unstable
@@ -1014,6 +1015,21 @@ impl CheckAttrVisitor<'tcx> {
is_valid
}
+ /// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
+ fn check_must_not_suspend(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
+ match target {
+ Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {
+ self.tcx
+ .sess
+ .struct_span_err(attr.span, "`must_not_suspend` attribute should be applied to a struct, enum, `impl Trait`, or `dyn Trait`")
+ .span_label(*span, "is a function")
+ .emit();
+ false
+ }
+ _ => true,
+ }
+ }
+
/// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) {
match target {
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 24023163cc30e..eecbb9a9cfadc 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -836,6 +836,7 @@ symbols! {
mul,
mul_assign,
mul_with_overflow,
+ must_not_suspend,
must_use,
mut_ptr,
mut_slice_ptr,
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index 5f26e701c0ab7..c5efc30a7c2d4 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -5,6 +5,7 @@
use super::FnCtxt;
use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
+use rustc_errors::pluralize;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, DefKind, Res};
use rustc_hir::def_id::DefId;
@@ -12,9 +13,11 @@ use rustc_hir::hir_id::HirIdSet;
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind};
use rustc_middle::middle::region::{self, YieldData};
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_span::symbol::sym;
use rustc_span::Span;
use smallvec::SmallVec;
+use tracing::debug;
struct InteriorVisitor<'a, 'tcx> {
fcx: &'a FnCtxt<'a, 'tcx>,
@@ -36,6 +39,7 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
fn record(
&mut self,
ty: Ty<'tcx>,
+ hir_id: HirId,
scope: Option<region::Scope>,
expr: Option<&'tcx Expr<'tcx>>,
source_span: Span,
@@ -117,6 +121,20 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
} else {
// Insert the type into the ordered set.
let scope_span = scope.map(|s| s.span(self.fcx.tcx, self.region_scope_tree));
+
+ check_must_not_suspend_ty(
+ self.fcx,
+ ty::ParamEnv::empty(),
+ ty,
+ hir_id,
+ expr,
+ source_span,
+ yield_data.span,
+ "",
+ "",
+ 1,
+ );
+
self.types.insert(ty::GeneratorInteriorTypeCause {
span: source_span,
ty: &ty,
@@ -290,7 +308,7 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
if let PatKind::Binding(..) = pat.kind {
let scope = self.region_scope_tree.var_scope(pat.hir_id.local_id);
let ty = self.fcx.typeck_results.borrow().pat_ty(pat);
- self.record(ty, Some(scope), None, pat.span, false);
+ self.record(ty, pat.hir_id, Some(scope), None, pat.span, false);
}
}
@@ -342,7 +360,14 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
// If there are adjustments, then record the final type --
// this is the actual value that is being produced.
if let Some(adjusted_ty) = self.fcx.typeck_results.borrow().expr_ty_adjusted_opt(expr) {
- self.record(adjusted_ty, scope, Some(expr), expr.span, guard_borrowing_from_pattern);
+ self.record(
+ adjusted_ty,
+ expr.hir_id,
+ scope,
+ Some(expr),
+ expr.span,
+ guard_borrowing_from_pattern,
+ );
}
// Also record the unadjusted type (which is the only type if
@@ -380,9 +405,23 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
tcx.mk_region(ty::RegionKind::ReErased),
ty::TypeAndMut { ty, mutbl: hir::Mutability::Not },
);
- self.record(ref_ty, scope, Some(expr), expr.span, guard_borrowing_from_pattern);
+ self.record(
+ ref_ty,
+ expr.hir_id,
+ scope,
+ Some(expr),
+ expr.span,
+ guard_borrowing_from_pattern,
+ );
}
- self.record(ty, scope, Some(expr), expr.span, guard_borrowing_from_pattern);
+ self.record(
+ ty,
+ expr.hir_id,
+ scope,
+ Some(expr),
+ expr.span,
+ guard_borrowing_from_pattern,
+ );
} else {
self.fcx.tcx.sess.delay_span_bug(expr.span, "no type for node");
}
@@ -409,3 +448,263 @@ impl<'a, 'tcx> Visitor<'tcx> for ArmPatCollector<'a> {
}
}
}
+
+// 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
+pub fn check_must_not_suspend_ty<'tcx>(
+ fcx: &FnCtxt<'_, 'tcx>,
+ param_env: ty::ParamEnv<'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,
+) -> bool {
+ if ty.is_unit()
+ || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, param_env)
+ {
+ return true;
+ }
+
+ let plural_suffix = pluralize!(plural_len);
+
+ let emitted = 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,
+ param_env,
+ boxed_ty,
+ hir_id,
+ expr,
+ source_span,
+ yield_span,
+ descr_pre,
+ descr_post,
+ plural_len,
+ )
+ }
+ ty::Adt(def, _) => check_must_not_suspend_def(
+ fcx.tcx,
+ def.did,
+ hir_id,
+ source_span,
+ yield_span,
+ descr_pre,
+ descr_post,
+ ),
+ ty::Opaque(def, _) => {
+ let mut has_emitted = false;
+ for &(predicate, _) in fcx.tcx.explicit_item_bounds(def) {
+ // We only look at the `DefId`, so it is safe to skip the binder here.
+ if let ty::PredicateKind::Trait(ref poly_trait_predicate) =
+ predicate.kind().skip_binder()
+ {
+ let def_id = poly_trait_predicate.trait_ref.def_id;
+ let descr_pre = &format!("{}implementer{} of ", descr_pre, plural_suffix,);
+ if check_must_not_suspend_def(
+ fcx.tcx,
+ def_id,
+ hir_id,
+ source_span,
+ yield_span,
+ descr_pre,
+ descr_post,
+ ) {
+ has_emitted = true;
+ break;
+ }
+ }
+ }
+ has_emitted
+ }
+ ty::Dynamic(binder, _) => {
+ let mut has_emitted = false;
+ 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,);
+ if check_must_not_suspend_def(
+ fcx.tcx,
+ def_id,
+ hir_id,
+ source_span,
+ yield_span,
+ descr_pre,
+ descr_post,
+ ) {
+ has_emitted = true;
+ break;
+ }
+ }
+ }
+ has_emitted
+ }
+ ty::Tuple(ref tys) => {
+ let mut has_emitted = false;
+ /*
+ let spans = if let hir::ExprKind::Tup(comps) = &expr.kind {
+ debug_assert_eq!(comps.len(), tys.len());
+ comps.iter().map(|e| e.span).collect()
+ } else {
+ vec![]
+ };
+ */
+ let spans = vec![];
+ 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);
+ if check_must_not_suspend_ty(
+ fcx, param_env, ty, hir_id, expr, span, yield_span, descr_pre, descr_post,
+ plural_len,
+ ) {
+ has_emitted = true;
+ }
+ }
+ has_emitted
+ }
+ ty::Array(ty, len) => match len.try_eval_usize(fcx.tcx, param_env) {
+ // If the array is empty we don't lint, to avoid false positives
+ Some(0) | None => false,
+ // If the array is definitely non-empty, we can do `#[must_use]` checking.
+ Some(n) => {
+ let descr_pre = &format!("{}array{} of ", descr_pre, plural_suffix,);
+ check_must_not_suspend_ty(
+ fcx,
+ param_env,
+ ty,
+ hir_id,
+ expr,
+ source_span,
+ yield_span,
+ descr_pre,
+ descr_post,
+ n as usize + 1,
+ )
+ }
+ },
+ _ => false,
+ };
+
+ // Don't move onto the "return value" path if we already sent a diagnostic
+ if emitted {
+ return true;
+ }
+
+ match expr {
+ Some(expr) => match expr.kind {
+ hir::ExprKind::Call(ref callee, _) => {
+ match callee.kind {
+ hir::ExprKind::Path(ref qpath) => {
+ match fcx.typeck_results.borrow().qpath_res(qpath, callee.hir_id) {
+ Res::Def(DefKind::Fn | DefKind::AssocFn, def_id) => {
+ check_must_not_suspend_def(
+ fcx.tcx,
+ def_id,
+ hir_id,
+ source_span,
+ yield_span,
+ "return value of ",
+ "",
+ )
+ }
+
+ // `Res::Local` if it was a closure, for which we
+ // do not currently support must-not-suspend linting
+ _ => false,
+ }
+ }
+ _ => false,
+ }
+ }
+ hir::ExprKind::MethodCall(..) => {
+ if let Some(def_id) = fcx.typeck_results.borrow().type_dependent_def_id(expr.hir_id)
+ {
+ check_must_not_suspend_def(
+ fcx.tcx,
+ def_id,
+ hir_id,
+ source_span,
+ yield_span,
+ "return value of ",
+ "",
+ )
+ } else {
+ false
+ }
+ }
+ _ => false,
+ },
+ None => false,
+ }
+}
+
+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,
+) -> 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,
+ |lint| {
+ let msg = format!(
+ "{}`{}`{} held across a yield point, but should not be",
+ descr_pre_path,
+ tcx.def_path_str(def_id),
+ descr_post_path
+ );
+ let mut err = lint.build(&msg);
+
+ // Add optional reason note
+ if let Some(note) = attr.value_str() {
+ err.note(¬e.as_str());
+ }
+
+ // add span pointing to the offending yield/await)
+ err.span_label(yield_span, "The value is held across this yield point");
+
+ // Add some quick suggestions on what to do
+ err.span_help(
+ source_span,
+ "`drop` this value before the yield point, or use a block (`{ ... }`) \"
+ to shrink its scope",
+ );
+
+ err.emit();
+ },
+ );
+
+ /*
+ cx.struct_span_lint(UNUSED_MUST_USE, span, |lint| {
+ let msg = format!(
+ "unused {}`{}`{} that must be used",
+ descr_pre_path,
+ cx.tcx.def_path_str(def_id),
+ descr_post_path
+ );
+ let mut err = lint.build(&msg);
+ // check for #[must_use = "..."]
+ if let Some(note) = attr.value_str() {
+ err.note(¬e.as_str());
+ }
+ err.emit();
+ });
+ */
+ return true;
+ }
+ }
+ false
+}
diff --git a/src/test/ui/lint/must_not_suspend/boxed.rs b/src/test/ui/lint/must_not_suspend/boxed.rs
new file mode 100644
index 0000000000000..d64d07e5e0df6
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/boxed.rs
@@ -0,0 +1,25 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend = "You gotta use Umm's, ya know?"]
+struct Umm {
+ i: i64
+}
+
+
+fn bar() -> Box<Umm> {
+ Box::new(Umm {
+ i: 1
+ })
+}
+
+async fn other() {}
+
+pub async fn uhoh() {
+ let _guard = bar(); //~ boxed `Umm` held across
+ other().await;
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/boxed.stderr b/src/test/ui/lint/must_not_suspend/boxed.stderr
new file mode 100644
index 0000000000000..c3c23db7d72f7
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/boxed.stderr
@@ -0,0 +1,23 @@
+error: boxed `Umm` held across a yield 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
+ |
+note: the lint level is defined here
+ --> $DIR/boxed.rs:3:9
+ |
+LL | #![deny(must_not_suspend)]
+ | ^^^^^^^^^^^^^^^^
+ = note: You gotta use Umm's, ya know?
+help: `drop` this value before the yield point, or use a block (`{ ... }`) "
+ to shrink its scope
+ --> $DIR/boxed.rs:20:9
+ |
+LL | let _guard = bar();
+ | ^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs b/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs
new file mode 100644
index 0000000000000..aff8ff33b65a8
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs
@@ -0,0 +1,9 @@
+// edition:2018
+
+#[must_not_suspend = "You gotta use Umm's, ya know?"] //~ the `#[must_not_suspend]`
+struct Umm {
+ _i: i64
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.stderr b/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.stderr
new file mode 100644
index 0000000000000..ab20a8be8747d
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.stderr
@@ -0,0 +1,12 @@
+error[E0658]: the `#[must_not_suspend]` attribute is an experimental feature
+ --> $DIR/feature-gate-must_not_suspend.rs:3:1
+ |
+LL | #[must_not_suspend = "You gotta use Umm's, ya know?"]
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: see issue #83310 <https://github.com/rust-lang/rust/issues/83310> for more information
+ = help: add `#![feature(must_not_suspend)]` to the crate attributes to enable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/lint/must_not_suspend/return.rs b/src/test/ui/lint/must_not_suspend/return.rs
new file mode 100644
index 0000000000000..5f80e78937628
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/return.rs
@@ -0,0 +1,9 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend] //~ attribute should be
+fn foo() -> i32 {
+ 0
+}
+fn main() {}
diff --git a/src/test/ui/lint/must_not_suspend/return.stderr b/src/test/ui/lint/must_not_suspend/return.stderr
new file mode 100644
index 0000000000000..ff1798320cf8e
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/return.stderr
@@ -0,0 +1,12 @@
+error: `must_not_suspend` attribute should be applied to a struct, enum, `impl Trait`, or `dyn Trait`
+ --> $DIR/return.rs:5:1
+ |
+LL | #[must_not_suspend]
+ | ^^^^^^^^^^^^^^^^^^^
+LL | / fn foo() -> i32 {
+LL | | 0
+LL | | }
+ | |_- is a function
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/must_not_suspend/trait.rs b/src/test/ui/lint/must_not_suspend/trait.rs
new file mode 100644
index 0000000000000..0438e072ce67e
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/trait.rs
@@ -0,0 +1,28 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend]
+trait Wow {}
+
+impl Wow for i32 {}
+
+fn r#impl() -> impl Wow {
+ 1
+}
+
+fn r#dyn() -> Box<dyn Wow> {
+ Box::new(1)
+}
+
+async fn other() {}
+
+pub async fn uhoh() {
+ let _guard1 = r#impl(); //~ implementer of `Wow` held across
+ let _guard2 = r#dyn(); //~ boxed `Wow` trait object held across
+
+ other().await;
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/trait.stderr b/src/test/ui/lint/must_not_suspend/trait.stderr
new file mode 100644
index 0000000000000..1175cbb919208
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/trait.stderr
@@ -0,0 +1,39 @@
+error: implementer of `Wow` held across a yield 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
+ |
+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
+ --> $DIR/trait.rs:21:9
+ |
+LL | let _guard1 = r#impl();
+ | ^^^^^^^
+
+error: boxed `Wow` trait object held across a yield 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
+ |
+help: `drop` this value before the yield point, or use a block (`{ ... }`) "
+ to shrink its scope
+ --> $DIR/trait.rs:22:9
+ |
+LL | let _guard2 = r#dyn();
+ | ^^^^^^^
+
+error: aborting due to 2 previous errors
+
diff --git a/src/test/ui/lint/must_not_suspend/unit.rs b/src/test/ui/lint/must_not_suspend/unit.rs
new file mode 100644
index 0000000000000..4e87b801114e9
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/unit.rs
@@ -0,0 +1,25 @@
+// edition:2018
+#![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(); //~ `Umm` held across
+ other().await;
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/unit.stderr b/src/test/ui/lint/must_not_suspend/unit.stderr
new file mode 100644
index 0000000000000..cff00dd8ca409
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/unit.stderr
@@ -0,0 +1,23 @@
+error: `Umm` held across a yield 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
+ |
+note: the lint level is defined here
+ --> $DIR/unit.rs:3:9
+ |
+LL | #![deny(must_not_suspend)]
+ | ^^^^^^^^^^^^^^^^
+ = note: You gotta use Umm's, ya know?
+help: `drop` this value before the yield point, or use a block (`{ ... }`) "
+ to shrink its scope
+ --> $DIR/unit.rs:20:9
+ |
+LL | let _guard = bar();
+ | ^^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/must_not_suspend/warn.rs b/src/test/ui/lint/must_not_suspend/warn.rs
new file mode 100644
index 0000000000000..d0d7238480759
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/warn.rs
@@ -0,0 +1,25 @@
+// edition:2018
+// run-pass
+#![feature(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(); //~ `Umm` held across
+ other().await;
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/warn.stderr b/src/test/ui/lint/must_not_suspend/warn.stderr
new file mode 100644
index 0000000000000..bda44d051ee7c
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/warn.stderr
@@ -0,0 +1,19 @@
+warning: `Umm` held across a yield 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
+ |
+ = note: `#[warn(must_not_suspend)]` on by default
+ = note: You gotta use Umm's, ya know?
+help: `drop` this value before the yield point, or use a block (`{ ... }`) "
+ to shrink its scope
+ --> $DIR/warn.rs:20:9
+ |
+LL | let _guard = bar();
+ | ^^^^^^
+
+warning: 1 warning emitted
+
From 67ee91e77e8106357df63fc2d4b6f04f36ccd2da Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 11 Sep 2021 10:50:09 -0700
Subject: [PATCH 2/9] remove attempt at fn call
---
.../src/check/generator_interior.rs | 70 +------------------
1 file changed, 1 insertion(+), 69 deletions(-)
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index c5efc30a7c2d4..118c6e9a27363 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -472,7 +472,7 @@ pub fn check_must_not_suspend_ty<'tcx>(
let plural_suffix = pluralize!(plural_len);
- let emitted = match *ty.kind() {
+ match *ty.kind() {
ty::Adt(..) if ty.is_box() => {
let boxed_ty = ty.boxed_ty();
let descr_pre = &format!("{}boxed ", descr_pre);
@@ -589,58 +589,6 @@ pub fn check_must_not_suspend_ty<'tcx>(
}
},
_ => false,
- };
-
- // Don't move onto the "return value" path if we already sent a diagnostic
- if emitted {
- return true;
- }
-
- match expr {
- Some(expr) => match expr.kind {
- hir::ExprKind::Call(ref callee, _) => {
- match callee.kind {
- hir::ExprKind::Path(ref qpath) => {
- match fcx.typeck_results.borrow().qpath_res(qpath, callee.hir_id) {
- Res::Def(DefKind::Fn | DefKind::AssocFn, def_id) => {
- check_must_not_suspend_def(
- fcx.tcx,
- def_id,
- hir_id,
- source_span,
- yield_span,
- "return value of ",
- "",
- )
- }
-
- // `Res::Local` if it was a closure, for which we
- // do not currently support must-not-suspend linting
- _ => false,
- }
- }
- _ => false,
- }
- }
- hir::ExprKind::MethodCall(..) => {
- if let Some(def_id) = fcx.typeck_results.borrow().type_dependent_def_id(expr.hir_id)
- {
- check_must_not_suspend_def(
- fcx.tcx,
- def_id,
- hir_id,
- source_span,
- yield_span,
- "return value of ",
- "",
- )
- } else {
- false
- }
- }
- _ => false,
- },
- None => false,
}
}
@@ -687,22 +635,6 @@ fn check_must_not_suspend_def(
},
);
- /*
- cx.struct_span_lint(UNUSED_MUST_USE, span, |lint| {
- let msg = format!(
- "unused {}`{}`{} that must be used",
- descr_pre_path,
- cx.tcx.def_path_str(def_id),
- descr_post_path
- );
- let mut err = lint.build(&msg);
- // check for #[must_use = "..."]
- if let Some(note) = attr.value_str() {
- err.note(¬e.as_str());
- }
- err.emit();
- });
- */
return true;
}
}
From 74ea16301e2e6fb96ac8414761cf227775e64dfd Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 11 Sep 2021 12:06:05 -0700
Subject: [PATCH 3/9] skip the uninhabitated check and comments
---
compiler/rustc_lint_defs/src/builtin.rs | 23 ++++++++++++++++++-
compiler/rustc_passes/src/check_attr.rs | 8 +++----
.../src/check/generator_interior.rs | 18 +++++----------
src/test/ui/lint/must_not_suspend/boxed.rs | 2 +-
.../feature-gate-must_not_suspend.rs | 2 +-
.../ui/lint/must_not_suspend/other_items.rs | 8 +++++++
.../lint/must_not_suspend/other_items.stderr | 10 ++++++++
src/test/ui/lint/must_not_suspend/return.rs | 2 +-
.../ui/lint/must_not_suspend/return.stderr | 4 ++--
src/test/ui/lint/must_not_suspend/trait.rs | 4 ++--
src/test/ui/lint/must_not_suspend/unit.rs | 2 +-
src/test/ui/lint/must_not_suspend/warn.rs | 2 +-
12 files changed, 59 insertions(+), 26 deletions(-)
create mode 100644 src/test/ui/lint/must_not_suspend/other_items.rs
create mode 100644 src/test/ui/lint/must_not_suspend/other_items.stderr
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 386435034b6ac..0463cb2b76553 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -315,7 +315,28 @@ declare_lint! {
}
declare_lint! {
- /// [the reference]: https://doc.rust-lang.org/reference/attributes/diagnostics.html#the-must_use-attribute
+ /// 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
+ /// function.
+ ///
+ /// This attribute can be used to mark values that are semantically incorrect across yields
+ /// (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)
+ ///
+ /// ### Example
+ ///
+ /// ```rust
+ /// #[must_not_suspend]
+ /// struct SyncThing {}
+ ///
+ /// async fn yield() {}
+ ///
+ /// pub async fn uhoh() {
+ /// let guard = SyncThing {};
+ /// yield().await;
+ /// }
+ /// ```
pub MUST_NOT_SUSPEND,
Warn,
"Use of a `#[must_not_suspend]` value across a yield point",
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index a31f3fe281ee9..3e59fc4f55159 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -1018,15 +1018,15 @@ impl CheckAttrVisitor<'tcx> {
/// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
fn check_must_not_suspend(&self, attr: &Attribute, span: &Span, target: Target) -> bool {
match target {
- Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {
+ Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
+ _ => {
self.tcx
.sess
- .struct_span_err(attr.span, "`must_not_suspend` attribute should be applied to a struct, enum, `impl Trait`, or `dyn Trait`")
- .span_label(*span, "is a function")
+ .struct_span_err(attr.span, "`must_not_suspend` attribute should be applied to a struct, enum, or trait")
+ .span_label(*span, "is not a struct, enum, or trait")
.emit();
false
}
- _ => true,
}
}
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index 118c6e9a27363..c4c09a55a6e00 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -124,7 +124,6 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
check_must_not_suspend_ty(
self.fcx,
- ty::ParamEnv::empty(),
ty,
hir_id,
expr,
@@ -454,7 +453,6 @@ impl<'a, 'tcx> Visitor<'tcx> for ArmPatCollector<'a> {
// for creating must_use diagnostics
pub fn check_must_not_suspend_ty<'tcx>(
fcx: &FnCtxt<'_, 'tcx>,
- param_env: ty::ParamEnv<'tcx>,
ty: Ty<'tcx>,
hir_id: HirId,
expr: Option<&'tcx Expr<'tcx>>,
@@ -464,8 +462,10 @@ pub fn check_must_not_suspend_ty<'tcx>(
descr_post: &str,
plural_len: usize,
) -> bool {
+ debug!("FOUND TYPE: {:?}", ty);
if ty.is_unit()
- || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, param_env)
+ // || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, fcx.param_env)
+ // FIXME: should this check is_ty_uninhabited_from
{
return true;
}
@@ -478,7 +478,6 @@ pub fn check_must_not_suspend_ty<'tcx>(
let descr_pre = &format!("{}boxed ", descr_pre);
check_must_not_suspend_ty(
fcx,
- param_env,
boxed_ty,
hir_id,
expr,
@@ -547,28 +546,24 @@ pub fn check_must_not_suspend_ty<'tcx>(
}
ty::Tuple(ref tys) => {
let mut has_emitted = false;
- /*
- let spans = if let hir::ExprKind::Tup(comps) = &expr.kind {
+ let spans = if let Some(hir::ExprKind::Tup(comps)) = expr.map(|e| &e.kind) {
debug_assert_eq!(comps.len(), tys.len());
comps.iter().map(|e| e.span).collect()
} else {
vec![]
};
- */
- let spans = vec![];
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);
if check_must_not_suspend_ty(
- fcx, param_env, ty, hir_id, expr, span, yield_span, descr_pre, descr_post,
- plural_len,
+ fcx, ty, hir_id, expr, span, yield_span, descr_pre, descr_post, plural_len,
) {
has_emitted = true;
}
}
has_emitted
}
- ty::Array(ty, len) => match len.try_eval_usize(fcx.tcx, param_env) {
+ ty::Array(ty, len) => match len.try_eval_usize(fcx.tcx, fcx.param_env) {
// If the array is empty we don't lint, to avoid false positives
Some(0) | None => false,
// If the array is definitely non-empty, we can do `#[must_use]` checking.
@@ -576,7 +571,6 @@ pub fn check_must_not_suspend_ty<'tcx>(
let descr_pre = &format!("{}array{} of ", descr_pre, plural_suffix,);
check_must_not_suspend_ty(
fcx,
- param_env,
ty,
hir_id,
expr,
diff --git a/src/test/ui/lint/must_not_suspend/boxed.rs b/src/test/ui/lint/must_not_suspend/boxed.rs
index d64d07e5e0df6..1f823fc559d40 100644
--- a/src/test/ui/lint/must_not_suspend/boxed.rs
+++ b/src/test/ui/lint/must_not_suspend/boxed.rs
@@ -17,7 +17,7 @@ fn bar() -> Box<Umm> {
async fn other() {}
pub async fn uhoh() {
- let _guard = bar(); //~ boxed `Umm` held across
+ let _guard = bar(); //~ ERROR boxed `Umm` held across
other().await;
}
diff --git a/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs b/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs
index aff8ff33b65a8..1554408c174ce 100644
--- a/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs
+++ b/src/test/ui/lint/must_not_suspend/feature-gate-must_not_suspend.rs
@@ -1,6 +1,6 @@
// edition:2018
-#[must_not_suspend = "You gotta use Umm's, ya know?"] //~ the `#[must_not_suspend]`
+#[must_not_suspend = "You gotta use Umm's, ya know?"] //~ ERROR the `#[must_not_suspend]`
struct Umm {
_i: i64
}
diff --git a/src/test/ui/lint/must_not_suspend/other_items.rs b/src/test/ui/lint/must_not_suspend/other_items.rs
new file mode 100644
index 0000000000000..5aa1abb14d3fa
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/other_items.rs
@@ -0,0 +1,8 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend] //~ ERROR attribute should be
+mod inner {}
+
+fn main() {}
diff --git a/src/test/ui/lint/must_not_suspend/other_items.stderr b/src/test/ui/lint/must_not_suspend/other_items.stderr
new file mode 100644
index 0000000000000..41c8896921b0f
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/other_items.stderr
@@ -0,0 +1,10 @@
+error: `must_not_suspend` attribute should be applied to a struct, enum, or trait
+ --> $DIR/other_items.rs:5:1
+ |
+LL | #[must_not_suspend]
+ | ^^^^^^^^^^^^^^^^^^^
+LL | mod inner {}
+ | ------------ is not a struct, enum, or trait
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/must_not_suspend/return.rs b/src/test/ui/lint/must_not_suspend/return.rs
index 5f80e78937628..5b1fa5e272118 100644
--- a/src/test/ui/lint/must_not_suspend/return.rs
+++ b/src/test/ui/lint/must_not_suspend/return.rs
@@ -2,7 +2,7 @@
#![feature(must_not_suspend)]
#![deny(must_not_suspend)]
-#[must_not_suspend] //~ attribute should be
+#[must_not_suspend] //~ ERROR attribute should be
fn foo() -> i32 {
0
}
diff --git a/src/test/ui/lint/must_not_suspend/return.stderr b/src/test/ui/lint/must_not_suspend/return.stderr
index ff1798320cf8e..fdada85eb4d1c 100644
--- a/src/test/ui/lint/must_not_suspend/return.stderr
+++ b/src/test/ui/lint/must_not_suspend/return.stderr
@@ -1,4 +1,4 @@
-error: `must_not_suspend` attribute should be applied to a struct, enum, `impl Trait`, or `dyn Trait`
+error: `must_not_suspend` attribute should be applied to a struct, enum, or trait
--> $DIR/return.rs:5:1
|
LL | #[must_not_suspend]
@@ -6,7 +6,7 @@ LL | #[must_not_suspend]
LL | / fn foo() -> i32 {
LL | | 0
LL | | }
- | |_- is a function
+ | |_- is not a struct, enum, or trait
error: aborting due to previous error
diff --git a/src/test/ui/lint/must_not_suspend/trait.rs b/src/test/ui/lint/must_not_suspend/trait.rs
index 0438e072ce67e..6c911cb4b0f09 100644
--- a/src/test/ui/lint/must_not_suspend/trait.rs
+++ b/src/test/ui/lint/must_not_suspend/trait.rs
@@ -18,8 +18,8 @@ fn r#dyn() -> Box<dyn Wow> {
async fn other() {}
pub async fn uhoh() {
- let _guard1 = r#impl(); //~ implementer of `Wow` held across
- let _guard2 = r#dyn(); //~ boxed `Wow` trait object held across
+ let _guard1 = r#impl(); //~ ERROR implementer of `Wow` held across
+ let _guard2 = r#dyn(); //~ ERROR boxed `Wow` trait object held across
other().await;
}
diff --git a/src/test/ui/lint/must_not_suspend/unit.rs b/src/test/ui/lint/must_not_suspend/unit.rs
index 4e87b801114e9..d3a19f704324d 100644
--- a/src/test/ui/lint/must_not_suspend/unit.rs
+++ b/src/test/ui/lint/must_not_suspend/unit.rs
@@ -17,7 +17,7 @@ fn bar() -> Umm {
async fn other() {}
pub async fn uhoh() {
- let _guard = bar(); //~ `Umm` held across
+ let _guard = bar(); //~ ERROR `Umm` held across
other().await;
}
diff --git a/src/test/ui/lint/must_not_suspend/warn.rs b/src/test/ui/lint/must_not_suspend/warn.rs
index d0d7238480759..50a696ba52322 100644
--- a/src/test/ui/lint/must_not_suspend/warn.rs
+++ b/src/test/ui/lint/must_not_suspend/warn.rs
@@ -17,7 +17,7 @@ fn bar() -> Umm {
async fn other() {}
pub async fn uhoh() {
- let _guard = bar(); //~ `Umm` held across
+ let _guard = bar(); //~ WARNING `Umm` held across
other().await;
}
From 461a0f3da4acd6dfea31b9f12c1e14405b055438 Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 11 Sep 2021 12:24:40 -0700
Subject: [PATCH 4/9] array comment + test for references
---
.../src/check/generator_interior.rs | 34 +++++++--------
src/test/ui/lint/must_not_suspend/ref.rs | 30 ++++++++++++++
src/test/ui/lint/must_not_suspend/ref.stderr | 41 +++++++++++++++++++
3 files changed, 85 insertions(+), 20 deletions(-)
create mode 100644 src/test/ui/lint/must_not_suspend/ref.rs
create mode 100644 src/test/ui/lint/must_not_suspend/ref.stderr
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index c4c09a55a6e00..1b63d6d974148 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -462,7 +462,6 @@ pub fn check_must_not_suspend_ty<'tcx>(
descr_post: &str,
plural_len: usize,
) -> bool {
- debug!("FOUND TYPE: {:?}", ty);
if ty.is_unit()
// || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, fcx.param_env)
// FIXME: should this check is_ty_uninhabited_from
@@ -563,25 +562,20 @@ pub fn check_must_not_suspend_ty<'tcx>(
}
has_emitted
}
- ty::Array(ty, len) => match len.try_eval_usize(fcx.tcx, fcx.param_env) {
- // If the array is empty we don't lint, to avoid false positives
- Some(0) | None => false,
- // If the array is definitely non-empty, we can do `#[must_use]` checking.
- Some(n) => {
- let descr_pre = &format!("{}array{} of ", descr_pre, plural_suffix,);
- check_must_not_suspend_ty(
- fcx,
- ty,
- hir_id,
- expr,
- source_span,
- yield_span,
- descr_pre,
- descr_post,
- n as usize + 1,
- )
- }
- },
+ ty::Array(ty, len) => {
+ let descr_pre = &format!("{}array{} of ", 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,
+ )
+ }
_ => false,
}
}
diff --git a/src/test/ui/lint/must_not_suspend/ref.rs b/src/test/ui/lint/must_not_suspend/ref.rs
new file mode 100644
index 0000000000000..89fd73c187e90
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/ref.rs
@@ -0,0 +1,30 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend = "You gotta use Umm's, ya know?"]
+struct Umm {
+ i: i64
+}
+
+struct Bar {
+ u: Umm,
+}
+
+async fn other() {}
+
+impl Bar {
+ async fn uhoh(&mut self) {
+ let guard = &mut self.u; //~ ERROR `Umm` held across
+ //~^ ERROR `Umm` held across
+
+ other().await;
+
+ *guard = Umm {
+ i: 2
+ }
+ }
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/ref.stderr b/src/test/ui/lint/must_not_suspend/ref.stderr
new file mode 100644
index 0000000000000..91c91a4b545f8
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/ref.stderr
@@ -0,0 +1,41 @@
+error: `Umm` held across a yield 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
+ |
+note: the lint level is defined here
+ --> $DIR/ref.rs:3:9
+ |
+LL | #![deny(must_not_suspend)]
+ | ^^^^^^^^^^^^^^^^
+ = note: You gotta use Umm's, ya know?
+help: `drop` this value before the yield point, or use a block (`{ ... }`) "
+ to shrink its scope
+ --> $DIR/ref.rs:18:26
+ |
+LL | let guard = &mut self.u;
+ | ^^^^^^
+
+error: `Umm` held across a yield 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
+ |
+ = note: You gotta use Umm's, ya know?
+help: `drop` this value before the yield point, or use a block (`{ ... }`) "
+ to shrink its scope
+ --> $DIR/ref.rs:18:26
+ |
+LL | let guard = &mut self.u;
+ | ^^^^^^
+
+error: aborting due to 2 previous errors
+
From ee1d2ea3b73d07d95d5c22ccd1e884e3674fcec6 Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 11 Sep 2021 12:39:33 -0700
Subject: [PATCH 5/9] fix doctests
---
compiler/rustc_lint_defs/src/builtin.rs | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 0463cb2b76553..781ac6a14a4b3 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -327,14 +327,16 @@ declare_lint! {
/// ### Example
///
/// ```rust
+ /// #![feature(must_not_suspend)]
+ ///
/// #[must_not_suspend]
/// struct SyncThing {}
///
- /// async fn yield() {}
+ /// async fn yield_now() {}
///
/// pub async fn uhoh() {
/// let guard = SyncThing {};
- /// yield().await;
+ /// yield_now().await;
/// }
/// ```
pub MUST_NOT_SUSPEND,
From 2af1ebfbdf01e4aa43fd9b1b5af602b545101e1f Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Mon, 13 Sep 2021 08:19:40 -0700
Subject: [PATCH 6/9] error formatting and fix build
---
compiler/rustc_feature/src/active.rs | 4 +--
compiler/rustc_lint_defs/src/builtin.rs | 26 ++++++++++++-------
.../src/check/generator_interior.rs | 15 ++++++-----
.../ui/lint/must_not_suspend/boxed.stderr | 11 +++++---
src/test/ui/lint/must_not_suspend/ref.stderr | 22 ++++++++++------
.../ui/lint/must_not_suspend/trait.stderr | 10 +++----
src/test/ui/lint/must_not_suspend/unit.stderr | 11 +++++---
src/test/ui/lint/must_not_suspend/warn.stderr | 11 +++++---
8 files changed, 67 insertions(+), 43 deletions(-)
diff --git a/compiler/rustc_feature/src/active.rs b/compiler/rustc_feature/src/active.rs
index 66569270bd21e..6ab925cfa9b7f 100644
--- a/compiler/rustc_feature/src/active.rs
+++ b/compiler/rustc_feature/src/active.rs
@@ -679,8 +679,8 @@ declare_features! (
/// Allows `let...else` statements.
(active, let_else, "1.56.0", Some(87335), None),
- /// Allows `#[must_not_suspend]`.
- (active, must_not_suspend, "1.56.0", Some(83310), None),
+ /// Allows the `#[must_not_suspend]` attribute.
+ (active, must_not_suspend, "1.57.0", Some(83310), None),
// -------------------------------------------------------------------------
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index 781ac6a14a4b3..a192056e244bd 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -315,14 +315,8 @@ declare_lint! {
}
declare_lint! {
- /// 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
- /// function.
- ///
- /// This attribute can be used to mark values that are semantically incorrect across yields
- /// (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)
+ /// The `must_not_suspend` lint guards against values that shouldn't be held across yield points
+ /// (`.await`)
///
/// ### Example
///
@@ -339,9 +333,23 @@ declare_lint! {
/// yield_now().await;
/// }
/// ```
+ ///
+ /// {{produces}}
+ ///
+ /// ### 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
+ /// function.
+ ///
+ /// This attribute can be used to mark values that are semantically incorrect across yields
+ /// (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)
+ ///
pub MUST_NOT_SUSPEND,
Warn,
- "Use of a `#[must_not_suspend]` value across a yield point",
+ "use of a `#[must_not_suspend]` value across a yield point",
}
declare_lint! {
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index 1b63d6d974148..7e4bc08c1723c 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -463,8 +463,10 @@ pub fn check_must_not_suspend_ty<'tcx>(
plural_len: usize,
) -> bool {
if ty.is_unit()
+ // FIXME: should this check `is_ty_uninhabited_from`. This query is not available in this stage
+ // of typeck (before ReVar and RePlaceholder are removed), but may remove noise, like in
+ // `must_use`
// || fcx.tcx.is_ty_uninhabited_from(fcx.tcx.parent_module(hir_id).to_def_id(), ty, fcx.param_env)
- // FIXME: should this check is_ty_uninhabited_from
{
return true;
}
@@ -496,6 +498,7 @@ pub fn check_must_not_suspend_ty<'tcx>(
descr_pre,
descr_post,
),
+ // FIXME: support adding the attribute to TAITs
ty::Opaque(def, _) => {
let mut has_emitted = false;
for &(predicate, _) in fcx.tcx.explicit_item_bounds(def) {
@@ -604,18 +607,18 @@ fn check_must_not_suspend_def(
);
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");
+
// Add optional reason note
if let Some(note) = attr.value_str() {
- err.note(¬e.as_str());
+ err.span_note(source_span, ¬e.as_str());
}
- // add span pointing to the offending yield/await)
- err.span_label(yield_span, "The value is held across this yield point");
-
// Add some quick suggestions on what to do
err.span_help(
source_span,
- "`drop` this value before the yield point, or use a block (`{ ... }`) \"
+ "`drop` this value before the yield point, or use a block (`{ ... }`) \
to shrink its scope",
);
diff --git a/src/test/ui/lint/must_not_suspend/boxed.stderr b/src/test/ui/lint/must_not_suspend/boxed.stderr
index c3c23db7d72f7..7bd80405b5de6 100644
--- a/src/test/ui/lint/must_not_suspend/boxed.stderr
+++ b/src/test/ui/lint/must_not_suspend/boxed.stderr
@@ -4,16 +4,19 @@ error: boxed `Umm` held across a yield point, but should not be
LL | let _guard = bar();
| ^^^^^^
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield point
|
note: the lint level is defined here
--> $DIR/boxed.rs:3:9
|
LL | #![deny(must_not_suspend)]
| ^^^^^^^^^^^^^^^^
- = note: You gotta use Umm's, ya know?
-help: `drop` this value before the yield point, or use a block (`{ ... }`) "
- to shrink its scope
+note: You gotta use Umm's, ya know?
+ --> $DIR/boxed.rs:20:9
+ |
+LL | let _guard = bar();
+ | ^^^^^^
+help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
--> $DIR/boxed.rs:20:9
|
LL | let _guard = bar();
diff --git a/src/test/ui/lint/must_not_suspend/ref.stderr b/src/test/ui/lint/must_not_suspend/ref.stderr
index 91c91a4b545f8..d2a550d7b45d4 100644
--- a/src/test/ui/lint/must_not_suspend/ref.stderr
+++ b/src/test/ui/lint/must_not_suspend/ref.stderr
@@ -5,16 +5,19 @@ LL | let guard = &mut self.u;
| ^^^^^^
...
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield point
|
note: the lint level is defined here
--> $DIR/ref.rs:3:9
|
LL | #![deny(must_not_suspend)]
| ^^^^^^^^^^^^^^^^
- = note: You gotta use Umm's, ya know?
-help: `drop` this value before the yield point, or use a block (`{ ... }`) "
- to shrink its scope
+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
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;
@@ -27,11 +30,14 @@ LL | let guard = &mut self.u;
| ^^^^^^
...
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield point
|
- = note: You gotta use Umm's, ya know?
-help: `drop` this value before the yield point, or use a block (`{ ... }`) "
- to shrink its scope
+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
--> $DIR/ref.rs:18:26
|
LL | let guard = &mut self.u;
diff --git a/src/test/ui/lint/must_not_suspend/trait.stderr b/src/test/ui/lint/must_not_suspend/trait.stderr
index 1175cbb919208..8d7bb80876440 100644
--- a/src/test/ui/lint/must_not_suspend/trait.stderr
+++ b/src/test/ui/lint/must_not_suspend/trait.stderr
@@ -5,15 +5,14 @@ LL | let _guard1 = r#impl();
| ^^^^^^^
...
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield 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: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
--> $DIR/trait.rs:21:9
|
LL | let _guard1 = r#impl();
@@ -26,10 +25,9 @@ LL | let _guard2 = r#dyn();
| ^^^^^^^
LL |
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield point
|
-help: `drop` this value before the yield point, or use a block (`{ ... }`) "
- to shrink its scope
+help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
--> $DIR/trait.rs:22:9
|
LL | let _guard2 = r#dyn();
diff --git a/src/test/ui/lint/must_not_suspend/unit.stderr b/src/test/ui/lint/must_not_suspend/unit.stderr
index cff00dd8ca409..87e0fd27e70f2 100644
--- a/src/test/ui/lint/must_not_suspend/unit.stderr
+++ b/src/test/ui/lint/must_not_suspend/unit.stderr
@@ -4,16 +4,19 @@ error: `Umm` held across a yield point, but should not be
LL | let _guard = bar();
| ^^^^^^
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield point
|
note: the lint level is defined here
--> $DIR/unit.rs:3:9
|
LL | #![deny(must_not_suspend)]
| ^^^^^^^^^^^^^^^^
- = note: You gotta use Umm's, ya know?
-help: `drop` this value before the yield point, or use a block (`{ ... }`) "
- to shrink its scope
+note: You gotta use Umm's, ya know?
+ --> $DIR/unit.rs:20:9
+ |
+LL | let _guard = bar();
+ | ^^^^^^
+help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
--> $DIR/unit.rs:20:9
|
LL | let _guard = bar();
diff --git a/src/test/ui/lint/must_not_suspend/warn.stderr b/src/test/ui/lint/must_not_suspend/warn.stderr
index bda44d051ee7c..03b77520c9f9f 100644
--- a/src/test/ui/lint/must_not_suspend/warn.stderr
+++ b/src/test/ui/lint/must_not_suspend/warn.stderr
@@ -4,12 +4,15 @@ warning: `Umm` held across a yield point, but should not be
LL | let _guard = bar();
| ^^^^^^
LL | other().await;
- | ------------- The value is held across this yield point
+ | ------------- the value is held across this yield point
|
= note: `#[warn(must_not_suspend)]` on by default
- = note: You gotta use Umm's, ya know?
-help: `drop` this value before the yield point, or use a block (`{ ... }`) "
- to shrink its scope
+note: You gotta use Umm's, ya know?
+ --> $DIR/warn.rs:20:9
+ |
+LL | let _guard = bar();
+ | ^^^^^^
+help: `drop` this value before the yield point, or use a block (`{ ... }`) to shrink its scope
--> $DIR/warn.rs:20:9
|
LL | let _guard = bar();
From 110aecd23eefa603ffd1b5d8f64832230d42b435 Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Wed, 15 Sep 2021 11:48:34 -0700
Subject: [PATCH 7/9] factor into struct, and comments
---
compiler/rustc_lint_defs/src/builtin.rs | 6 +-
.../src/check/generator_interior.rs | 120 ++++++++----------
.../ui/lint/must_not_suspend/boxed.stderr | 6 +-
src/test/ui/lint/must_not_suspend/handled.rs | 28 ++++
src/test/ui/lint/must_not_suspend/ref.stderr | 12 +-
.../ui/lint/must_not_suspend/trait.stderr | 12 +-
src/test/ui/lint/must_not_suspend/unit.stderr | 6 +-
src/test/ui/lint/must_not_suspend/warn.stderr | 6 +-
8 files changed, 104 insertions(+), 92 deletions(-)
create mode 100644 src/test/ui/lint/must_not_suspend/handled.rs
diff --git a/compiler/rustc_lint_defs/src/builtin.rs b/compiler/rustc_lint_defs/src/builtin.rs
index a192056e244bd..649ad21385e5e 100644
--- a/compiler/rustc_lint_defs/src/builtin.rs
+++ b/compiler/rustc_lint_defs/src/builtin.rs
@@ -315,7 +315,7 @@ declare_lint! {
}
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 @@ declare_lint! {
/// ### 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)
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index 7e4bc08c1723c..e8a24f01b7563 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -126,12 +126,13 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
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 @@ impl<'a, 'tcx> Visitor<'tcx> for ArmPatCollector<'a> {
}
}
+#[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, ¬e.as_str());
+ // FIXME(guswynn): consider formatting this better
+ err.span_note(data.source_span, ¬e.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();
diff --git a/src/test/ui/lint/must_not_suspend/boxed.stderr b/src/test/ui/lint/must_not_suspend/boxed.stderr
index 7bd80405b5de6..edc62b6d687ad 100644
--- a/src/test/ui/lint/must_not_suspend/boxed.stderr
+++ b/src/test/ui/lint/must_not_suspend/boxed.stderr
@@ -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();
diff --git a/src/test/ui/lint/must_not_suspend/handled.rs b/src/test/ui/lint/must_not_suspend/handled.rs
new file mode 100644
index 0000000000000..8714be6449f92
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/handled.rs
@@ -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() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/ref.stderr b/src/test/ui/lint/must_not_suspend/ref.stderr
index d2a550d7b45d4..d4c58bcbcd280 100644
--- a/src/test/ui/lint/must_not_suspend/ref.stderr
+++ b/src/test/ui/lint/must_not_suspend/ref.stderr
@@ -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;
diff --git a/src/test/ui/lint/must_not_suspend/trait.stderr b/src/test/ui/lint/must_not_suspend/trait.stderr
index 8d7bb80876440..d19ffddd482e0 100644
--- a/src/test/ui/lint/must_not_suspend/trait.stderr
+++ b/src/test/ui/lint/must_not_suspend/trait.stderr
@@ -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();
diff --git a/src/test/ui/lint/must_not_suspend/unit.stderr b/src/test/ui/lint/must_not_suspend/unit.stderr
index 87e0fd27e70f2..425c076823d2f 100644
--- a/src/test/ui/lint/must_not_suspend/unit.stderr
+++ b/src/test/ui/lint/must_not_suspend/unit.stderr
@@ -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();
diff --git a/src/test/ui/lint/must_not_suspend/warn.stderr b/src/test/ui/lint/must_not_suspend/warn.stderr
index 03b77520c9f9f..24f52275b430a 100644
--- a/src/test/ui/lint/must_not_suspend/warn.stderr
+++ b/src/test/ui/lint/must_not_suspend/warn.stderr
@@ -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();
From f1021bf05459ca5e84a580895565cab9663ed839 Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 18 Sep 2021 12:23:16 -0700
Subject: [PATCH 8/9] generic test
---
.../src/check/generator_interior.rs | 3 ++
src/test/ui/lint/must_not_suspend/generic.rs | 21 +++++++++++++
.../ui/lint/must_not_suspend/generic.stderr | 31 +++++++++++++++++++
3 files changed, 55 insertions(+)
create mode 100644 src/test/ui/lint/must_not_suspend/generic.rs
create mode 100644 src/test/ui/lint/must_not_suspend/generic.stderr
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index e8a24f01b7563..ac67d2b93c57b 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -462,6 +462,9 @@ pub struct SuspendCheckData<'a, 'tcx> {
// 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
+//
+// Note that this technique was chosen over things like a `Suspend` marker trait
+// as it is simpler and has precendent in the compiler
pub fn check_must_not_suspend_ty<'tcx>(
fcx: &FnCtxt<'_, 'tcx>,
ty: Ty<'tcx>,
diff --git a/src/test/ui/lint/must_not_suspend/generic.rs b/src/test/ui/lint/must_not_suspend/generic.rs
new file mode 100644
index 0000000000000..94457e375400e
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/generic.rs
@@ -0,0 +1,21 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend]
+struct No {}
+
+async fn shushspend() {}
+
+async fn wheeee<T>(t: T) {
+ shushspend().await;
+ drop(t);
+}
+
+async fn yes() {
+ wheeee(No {}).await; //~ ERROR `No` held across
+ //~^ ERROR `No` held across
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/generic.stderr b/src/test/ui/lint/must_not_suspend/generic.stderr
new file mode 100644
index 0000000000000..d853ba720a3ad
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/generic.stderr
@@ -0,0 +1,31 @@
+error: `No` held across a suspend point, but should not be
+ --> $DIR/generic.rs:16:12
+ |
+LL | wheeee(No {}).await;
+ | -------^^^^^------- the value is held across this suspend point
+ |
+note: the lint level is defined here
+ --> $DIR/generic.rs:3:9
+ |
+LL | #![deny(must_not_suspend)]
+ | ^^^^^^^^^^^^^^^^
+help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
+ --> $DIR/generic.rs:16:12
+ |
+LL | wheeee(No {}).await;
+ | ^^^^^
+
+error: `No` held across a suspend point, but should not be
+ --> $DIR/generic.rs:16:12
+ |
+LL | wheeee(No {}).await;
+ | -------^^^^^------- the value is held across this suspend point
+ |
+help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
+ --> $DIR/generic.rs:16:12
+ |
+LL | wheeee(No {}).await;
+ | ^^^^^
+
+error: aborting due to 2 previous errors
+
From 08e026675ee38bb4ca81106e766a6456c8b7382e Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Sat, 18 Sep 2021 13:00:36 -0700
Subject: [PATCH 9/9] deduplication
---
.../src/check/generator_interior.rs | 29 ++++++++++-------
src/test/ui/lint/must_not_suspend/dedup.rs | 20 ++++++++++++
.../ui/lint/must_not_suspend/dedup.stderr | 19 ++++++++++++
src/test/ui/lint/must_not_suspend/generic.rs | 9 +++---
.../ui/lint/must_not_suspend/generic.stderr | 31 -------------------
src/test/ui/lint/must_not_suspend/ref.rs | 1 -
src/test/ui/lint/must_not_suspend/ref.stderr | 24 ++------------
7 files changed, 62 insertions(+), 71 deletions(-)
create mode 100644 src/test/ui/lint/must_not_suspend/dedup.rs
create mode 100644 src/test/ui/lint/must_not_suspend/dedup.stderr
delete mode 100644 src/test/ui/lint/must_not_suspend/generic.stderr
diff --git a/compiler/rustc_typeck/src/check/generator_interior.rs b/compiler/rustc_typeck/src/check/generator_interior.rs
index ac67d2b93c57b..5ad9bdbe68db0 100644
--- a/compiler/rustc_typeck/src/check/generator_interior.rs
+++ b/compiler/rustc_typeck/src/check/generator_interior.rs
@@ -33,6 +33,7 @@ struct InteriorVisitor<'a, 'tcx> {
/// that they may succeed the said yield point in the post-order.
guard_bindings: SmallVec<[SmallVec<[HirId; 4]>; 1]>,
guard_bindings_set: HirIdSet,
+ linted_values: HirIdSet,
}
impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
@@ -122,18 +123,21 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
// Insert the type into the ordered set.
let scope_span = scope.map(|s| s.span(self.fcx.tcx, self.region_scope_tree));
- check_must_not_suspend_ty(
- self.fcx,
- ty,
- hir_id,
- SuspendCheckData {
- expr,
- source_span,
- yield_span: yield_data.span,
- plural_len: 1,
- ..Default::default()
- },
- );
+ if !self.linted_values.contains(&hir_id) {
+ check_must_not_suspend_ty(
+ self.fcx,
+ ty,
+ hir_id,
+ SuspendCheckData {
+ expr,
+ source_span,
+ yield_span: yield_data.span,
+ plural_len: 1,
+ ..Default::default()
+ },
+ );
+ self.linted_values.insert(hir_id);
+ }
self.types.insert(ty::GeneratorInteriorTypeCause {
span: source_span,
@@ -181,6 +185,7 @@ pub fn resolve_interior<'a, 'tcx>(
prev_unresolved_span: None,
guard_bindings: <_>::default(),
guard_bindings_set: <_>::default(),
+ linted_values: <_>::default(),
};
intravisit::walk_body(&mut visitor, body);
diff --git a/src/test/ui/lint/must_not_suspend/dedup.rs b/src/test/ui/lint/must_not_suspend/dedup.rs
new file mode 100644
index 0000000000000..040fff5a5a5a8
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/dedup.rs
@@ -0,0 +1,20 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+#[must_not_suspend]
+struct No {}
+
+async fn shushspend() {}
+
+async fn wheeee<T>(t: T) {
+ shushspend().await;
+ drop(t);
+}
+
+async fn yes() {
+ wheeee(No {}).await; //~ ERROR `No` held across
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/dedup.stderr b/src/test/ui/lint/must_not_suspend/dedup.stderr
new file mode 100644
index 0000000000000..542b7a3bc7e98
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/dedup.stderr
@@ -0,0 +1,19 @@
+error: `No` held across a suspend point, but should not be
+ --> $DIR/dedup.rs:16:12
+ |
+LL | wheeee(No {}).await;
+ | -------^^^^^------- the value is held across this suspend point
+ |
+note: the lint level is defined here
+ --> $DIR/dedup.rs:3:9
+ |
+LL | #![deny(must_not_suspend)]
+ | ^^^^^^^^^^^^^^^^
+help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
+ --> $DIR/dedup.rs:16:12
+ |
+LL | wheeee(No {}).await;
+ | ^^^^^
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/lint/must_not_suspend/generic.rs b/src/test/ui/lint/must_not_suspend/generic.rs
index 94457e375400e..b3effa020c48f 100644
--- a/src/test/ui/lint/must_not_suspend/generic.rs
+++ b/src/test/ui/lint/must_not_suspend/generic.rs
@@ -1,4 +1,7 @@
// edition:2018
+// run-pass
+//
+// this test shows a case where the lint doesn't fire in generic code
#![feature(must_not_suspend)]
#![deny(must_not_suspend)]
@@ -12,10 +15,6 @@ async fn wheeee<T>(t: T) {
drop(t);
}
-async fn yes() {
- wheeee(No {}).await; //~ ERROR `No` held across
- //~^ ERROR `No` held across
-}
-
fn main() {
+ let _fut = wheeee(No {});
}
diff --git a/src/test/ui/lint/must_not_suspend/generic.stderr b/src/test/ui/lint/must_not_suspend/generic.stderr
deleted file mode 100644
index d853ba720a3ad..0000000000000
--- a/src/test/ui/lint/must_not_suspend/generic.stderr
+++ /dev/null
@@ -1,31 +0,0 @@
-error: `No` held across a suspend point, but should not be
- --> $DIR/generic.rs:16:12
- |
-LL | wheeee(No {}).await;
- | -------^^^^^------- the value is held across this suspend point
- |
-note: the lint level is defined here
- --> $DIR/generic.rs:3:9
- |
-LL | #![deny(must_not_suspend)]
- | ^^^^^^^^^^^^^^^^
-help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
- --> $DIR/generic.rs:16:12
- |
-LL | wheeee(No {}).await;
- | ^^^^^
-
-error: `No` held across a suspend point, but should not be
- --> $DIR/generic.rs:16:12
- |
-LL | wheeee(No {}).await;
- | -------^^^^^------- the value is held across this suspend point
- |
-help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
- --> $DIR/generic.rs:16:12
- |
-LL | wheeee(No {}).await;
- | ^^^^^
-
-error: aborting due to 2 previous errors
-
diff --git a/src/test/ui/lint/must_not_suspend/ref.rs b/src/test/ui/lint/must_not_suspend/ref.rs
index 89fd73c187e90..738dd9e04655c 100644
--- a/src/test/ui/lint/must_not_suspend/ref.rs
+++ b/src/test/ui/lint/must_not_suspend/ref.rs
@@ -16,7 +16,6 @@ async fn other() {}
impl Bar {
async fn uhoh(&mut self) {
let guard = &mut self.u; //~ ERROR `Umm` held across
- //~^ ERROR `Umm` held across
other().await;
diff --git a/src/test/ui/lint/must_not_suspend/ref.stderr b/src/test/ui/lint/must_not_suspend/ref.stderr
index d4c58bcbcd280..78b44b00625d1 100644
--- a/src/test/ui/lint/must_not_suspend/ref.stderr
+++ b/src/test/ui/lint/must_not_suspend/ref.stderr
@@ -3,7 +3,7 @@ error: `Umm` held across a suspend point, but should not be
|
LL | let guard = &mut self.u;
| ^^^^^^
-...
+LL |
LL | other().await;
| ------------- the value is held across this suspend point
|
@@ -23,25 +23,5 @@ help: consider using a block (`{ ... }`) to shrink the value's scope, ending bef
LL | let guard = &mut self.u;
| ^^^^^^
-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 suspend point
- |
-note: You gotta use Umm's, ya know?
- --> $DIR/ref.rs:18:26
- |
-LL | let guard = &mut self.u;
- | ^^^^^^
-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: aborting due to 2 previous errors
+error: aborting due to previous error