diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs index d32180525bf70..3b21f00a001bd 100644 --- a/compiler/rustc_passes/src/dead.rs +++ b/compiler/rustc_passes/src/dead.rs @@ -3,6 +3,7 @@ // from live codes are live, and everything else is dead. use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_errors::Applicability; use rustc_hir as hir; use rustc_hir::def::{CtorOf, DefKind, Res}; use rustc_hir::def_id::{DefId, LOCAL_CRATE}; @@ -15,7 +16,7 @@ use rustc_middle::middle::privacy; use rustc_middle::ty::{self, DefIdTree, TyCtxt}; use rustc_session::lint; -use rustc_span::symbol::{sym, Symbol}; +use rustc_span::symbol::{sym, Ident, Symbol}; // Any local node that may call something in its body block should be // explored. For example, if it's a live Node::Item that is a @@ -507,6 +508,13 @@ fn find_live<'tcx>( symbol_visitor.live_symbols } +#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)] +enum ExtraNote { + /// Use this to provide some examples in the diagnostic of potential other purposes for a value + /// or field that is dead code + OtherPurposeExamples, +} + struct DeadVisitor<'tcx> { tcx: TyCtxt<'tcx>, live_symbols: FxHashSet, @@ -572,14 +580,42 @@ impl DeadVisitor<'tcx> { &mut self, id: hir::HirId, span: rustc_span::Span, - name: Symbol, + name: Ident, participle: &str, + extra_note: Option, ) { if !name.as_str().starts_with('_') { self.tcx.struct_span_lint_hir(lint::builtin::DEAD_CODE, id, span, |lint| { let def_id = self.tcx.hir().local_def_id(id); let descr = self.tcx.def_kind(def_id).descr(def_id.to_def_id()); - lint.build(&format!("{} is never {}: `{}`", descr, participle, name)).emit() + + let prefixed = vec![(name.span, format!("_{}", name))]; + + let mut diag = + lint.build(&format!("{} is never {}: `{}`", descr, participle, name)); + + diag.multipart_suggestion( + "if this is intentional, prefix it with an underscore", + prefixed, + Applicability::MachineApplicable, + ); + + let mut note = format!( + "the leading underscore signals that this {} serves some other \ + purpose even if it isn't used in a way that we can detect.", + descr, + ); + if matches!(extra_note, Some(ExtraNote::OtherPurposeExamples)) { + note += " (e.g. for its effect when dropped or in foreign code)"; + } + + diag.note(¬e); + + // Force the note we added to the front, before any other subdiagnostics + // added in lint.build(...) + diag.children.rotate_right(1); + + diag.emit() }); } } @@ -625,7 +661,7 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> { hir::ItemKind::Struct(..) => "constructed", // Issue #52325 _ => "used", }; - self.warn_dead_code(item.hir_id(), span, item.ident.name, participle); + self.warn_dead_code(item.hir_id(), span, item.ident, participle, None); } else { // Only continue if we didn't warn intravisit::walk_item(self, item); @@ -639,7 +675,7 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> { id: hir::HirId, ) { if self.should_warn_about_variant(&variant) { - self.warn_dead_code(variant.id, variant.span, variant.ident.name, "constructed"); + self.warn_dead_code(variant.id, variant.span, variant.ident, "constructed", None); } else { intravisit::walk_variant(self, variant, g, id); } @@ -647,14 +683,20 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> { fn visit_foreign_item(&mut self, fi: &'tcx hir::ForeignItem<'tcx>) { if self.should_warn_about_foreign_item(fi) { - self.warn_dead_code(fi.hir_id(), fi.span, fi.ident.name, "used"); + self.warn_dead_code(fi.hir_id(), fi.span, fi.ident, "used", None); } intravisit::walk_foreign_item(self, fi); } fn visit_field_def(&mut self, field: &'tcx hir::FieldDef<'tcx>) { if self.should_warn_about_field(&field) { - self.warn_dead_code(field.hir_id, field.span, field.ident.name, "read"); + self.warn_dead_code( + field.hir_id, + field.span, + field.ident, + "read", + Some(ExtraNote::OtherPurposeExamples), + ); } intravisit::walk_field_def(self, field); } @@ -666,8 +708,9 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> { self.warn_dead_code( impl_item.hir_id(), impl_item.span, - impl_item.ident.name, + impl_item.ident, "used", + None, ); } self.visit_nested_body(body_id) @@ -685,7 +728,7 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> { } else { impl_item.ident.span }; - self.warn_dead_code(impl_item.hir_id(), span, impl_item.ident.name, "used"); + self.warn_dead_code(impl_item.hir_id(), span, impl_item.ident, "used", None); } self.visit_nested_body(body_id) } diff --git a/src/test/ui/associated-consts/associated-const-dead-code.stderr b/src/test/ui/associated-consts/associated-const-dead-code.stderr index 9b6bbb68a71f7..e9915ba9e96a5 100644 --- a/src/test/ui/associated-consts/associated-const-dead-code.stderr +++ b/src/test/ui/associated-consts/associated-const-dead-code.stderr @@ -2,8 +2,11 @@ error: associated constant is never used: `BAR` --> $DIR/associated-const-dead-code.rs:6:5 | LL | const BAR: u32 = 1; - | ^^^^^^^^^^^^^^^^^^^ + | ^^^^^^---^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_BAR` | + = note: the leading underscore signals that this associated constant serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/associated-const-dead-code.rs:1:9 | diff --git a/src/test/ui/derive-uninhabited-enum-38885.stderr b/src/test/ui/derive-uninhabited-enum-38885.stderr index 72607629d3c10..ff8fb9953fb53 100644 --- a/src/test/ui/derive-uninhabited-enum-38885.stderr +++ b/src/test/ui/derive-uninhabited-enum-38885.stderr @@ -2,8 +2,11 @@ warning: variant is never constructed: `Void` --> $DIR/derive-uninhabited-enum-38885.rs:13:5 | LL | Void(Void), - | ^^^^^^^^^^ + | ----^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Void` | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. = note: `-W dead-code` implied by `-W unused` warning: 1 warning emitted diff --git a/src/test/ui/issues/issue-37515.stderr b/src/test/ui/issues/issue-37515.stderr index 204a39bc8e8e9..3223554a5b778 100644 --- a/src/test/ui/issues/issue-37515.stderr +++ b/src/test/ui/issues/issue-37515.stderr @@ -2,8 +2,11 @@ warning: type alias is never used: `Z` --> $DIR/issue-37515.rs:5:1 | LL | type Z = dyn for<'x> Send; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + | ^^^^^-^^^^^^^^^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Z` | + = note: the leading underscore signals that this type alias serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/issue-37515.rs:3:9 | diff --git a/src/test/ui/lint/dead-code/basic.stderr b/src/test/ui/lint/dead-code/basic.stderr index f7b9b9c613ae0..8264d0736e03e 100644 --- a/src/test/ui/lint/dead-code/basic.stderr +++ b/src/test/ui/lint/dead-code/basic.stderr @@ -2,8 +2,9 @@ error: function is never used: `foo` --> $DIR/basic.rs:4:4 | LL | fn foo() { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_foo` | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/basic.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/const-and-self.stderr b/src/test/ui/lint/dead-code/const-and-self.stderr index c0e406189e8ab..e7233f386cc68 100644 --- a/src/test/ui/lint/dead-code/const-and-self.stderr +++ b/src/test/ui/lint/dead-code/const-and-self.stderr @@ -2,8 +2,9 @@ warning: variant is never constructed: `B` --> $DIR/const-and-self.rs:33:5 | LL | B, - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_B` | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/const-and-self.rs:3:9 | @@ -14,7 +15,9 @@ warning: variant is never constructed: `C` --> $DIR/const-and-self.rs:34:5 | LL | C, - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_C` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. warning: 2 warnings emitted diff --git a/src/test/ui/lint/dead-code/drop-only-field-issue-81658.rs b/src/test/ui/lint/dead-code/drop-only-field-issue-81658.rs new file mode 100644 index 0000000000000..d28b6430bc587 --- /dev/null +++ b/src/test/ui/lint/dead-code/drop-only-field-issue-81658.rs @@ -0,0 +1,42 @@ +//! The field `guard` is never used directly, but it is still useful for its side effect when +//! dropped. Since rustc doesn't consider a `Drop` impl as a use, we want to make sure we at least +//! produce a helpful diagnostic that points the user to what they can do if they indeed intended to +//! have a field that is only used for its `Drop` side effect. +//! +//! Issue: https://github.com/rust-lang/rust/issues/81658 + +#![deny(dead_code)] + +use std::sync::{Mutex, MutexGuard}; + +/// Holds a locked value until it is dropped +pub struct Locked<'a, T> { + // Field is kept for its affect when dropped, but otherwise unused + guard: MutexGuard<'a, T>, //~ ERROR field is never read +} + +impl<'a, T> Locked<'a, T> { + pub fn new(value: &'a Mutex) -> Self { + Self { + guard: value.lock().unwrap(), + } + } +} + +fn main() { + let items = Mutex::new(vec![1, 2, 3]); + + // Hold a lock on items while doing something else + let result = { + // The lock will be released at the end of this scope + let _lock = Locked::new(&items); + + do_something_else() + }; + + println!("{}", result); +} + +fn do_something_else() -> i32 { + 1 + 1 +} diff --git a/src/test/ui/lint/dead-code/drop-only-field-issue-81658.stderr b/src/test/ui/lint/dead-code/drop-only-field-issue-81658.stderr new file mode 100644 index 0000000000000..f379a0941166f --- /dev/null +++ b/src/test/ui/lint/dead-code/drop-only-field-issue-81658.stderr @@ -0,0 +1,17 @@ +error: field is never read: `guard` + --> $DIR/drop-only-field-issue-81658.rs:15:5 + | +LL | guard: MutexGuard<'a, T>, + | -----^^^^^^^^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_guard` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) +note: the lint level is defined here + --> $DIR/drop-only-field-issue-81658.rs:8:9 + | +LL | #![deny(dead_code)] + | ^^^^^^^^^ + +error: aborting due to previous error + diff --git a/src/test/ui/lint/dead-code/empty-unused-enum.stderr b/src/test/ui/lint/dead-code/empty-unused-enum.stderr index ed9a7ccd14b21..5c06cd5a6a0b2 100644 --- a/src/test/ui/lint/dead-code/empty-unused-enum.stderr +++ b/src/test/ui/lint/dead-code/empty-unused-enum.stderr @@ -2,8 +2,9 @@ error: enum is never used: `E` --> $DIR/empty-unused-enum.rs:3:6 | LL | enum E {} - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_E` | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/empty-unused-enum.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/field-used-in-ffi-issue-81658.rs b/src/test/ui/lint/dead-code/field-used-in-ffi-issue-81658.rs new file mode 100644 index 0000000000000..12eafe6ae4958 --- /dev/null +++ b/src/test/ui/lint/dead-code/field-used-in-ffi-issue-81658.rs @@ -0,0 +1,50 @@ +//! The field `items` is being "used" by FFI (implicitly through pointers). However, since rustc +//! doesn't know how to detect that, we produce a message that says the field is unused. This can +//! cause some confusion and we want to make sure our diagnostics help as much as they can. +//! +//! Issue: https://github.com/rust-lang/rust/issues/81658 + +#![deny(dead_code)] + +/// A struct for holding on to data while it is being used in our FFI code +pub struct FFIData { + /// These values cannot be dropped while the pointers to each item + /// are still in use + items: Option>, //~ ERROR field is never read +} + +impl FFIData { + pub fn new() -> Self { + Self {items: None} + } + + /// Load items into this type and return pointers to each item that can + /// be passed to FFI + pub fn load(&mut self, items: Vec) -> Vec<*const T> { + let ptrs = items.iter().map(|item| item as *const _).collect(); + + self.items = Some(items); + + ptrs + } +} + +extern { + /// The FFI code that uses items + fn process_item(item: *const i32); +} + +fn main() { + // Data cannot be dropped until the end of this scope or else the items + // will be dropped before they are processed + let mut data = FFIData::new(); + + let ptrs = data.load(vec![1, 2, 3, 4, 5]); + + for ptr in ptrs { + // Safety: This pointer is valid as long as the arena is in scope + unsafe { process_item(ptr); } + } + + // Items will be safely freed at the end of this scope +} diff --git a/src/test/ui/lint/dead-code/field-used-in-ffi-issue-81658.stderr b/src/test/ui/lint/dead-code/field-used-in-ffi-issue-81658.stderr new file mode 100644 index 0000000000000..d6a247d98e292 --- /dev/null +++ b/src/test/ui/lint/dead-code/field-used-in-ffi-issue-81658.stderr @@ -0,0 +1,17 @@ +error: field is never read: `items` + --> $DIR/field-used-in-ffi-issue-81658.rs:13:5 + | +LL | items: Option>, + | -----^^^^^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_items` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) +note: the lint level is defined here + --> $DIR/field-used-in-ffi-issue-81658.rs:7:9 + | +LL | #![deny(dead_code)] + | ^^^^^^^^^ + +error: aborting due to previous error + diff --git a/src/test/ui/lint/dead-code/impl-trait.stderr b/src/test/ui/lint/dead-code/impl-trait.stderr index 09b6d08eb8fb8..fb18eb2819f76 100644 --- a/src/test/ui/lint/dead-code/impl-trait.stderr +++ b/src/test/ui/lint/dead-code/impl-trait.stderr @@ -2,8 +2,11 @@ error: type alias is never used: `Unused` --> $DIR/impl-trait.rs:12:1 | LL | type Unused = (); - | ^^^^^^^^^^^^^^^^^ + | ^^^^^------^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Unused` | + = note: the leading underscore signals that this type alias serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/impl-trait.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/lint-dead-code-1.stderr b/src/test/ui/lint/dead-code/lint-dead-code-1.stderr index af97ea98b2b6d..15448448e1169 100644 --- a/src/test/ui/lint/dead-code/lint-dead-code-1.stderr +++ b/src/test/ui/lint/dead-code/lint-dead-code-1.stderr @@ -2,8 +2,9 @@ error: struct is never constructed: `Bar` --> $DIR/lint-dead-code-1.rs:12:16 | LL | pub struct Bar; - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_Bar` | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/lint-dead-code-1.rs:5:9 | @@ -14,55 +15,77 @@ error: static is never used: `priv_static` --> $DIR/lint-dead-code-1.rs:20:1 | LL | static priv_static: isize = 0; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | ^^^^^^^-----------^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_priv_static` + | + = note: the leading underscore signals that this static serves some other purpose even if it isn't used in a way that we can detect. error: constant is never used: `priv_const` --> $DIR/lint-dead-code-1.rs:27:1 | LL | const priv_const: isize = 0; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | ^^^^^^----------^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_priv_const` + | + = note: the leading underscore signals that this constant serves some other purpose even if it isn't used in a way that we can detect. error: struct is never constructed: `PrivStruct` --> $DIR/lint-dead-code-1.rs:35:8 | LL | struct PrivStruct; - | ^^^^^^^^^^ + | ^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_PrivStruct` + | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. error: enum is never used: `priv_enum` --> $DIR/lint-dead-code-1.rs:64:6 | LL | enum priv_enum { foo2, bar2 } - | ^^^^^^^^^ + | ^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_priv_enum` + | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. error: variant is never constructed: `bar3` --> $DIR/lint-dead-code-1.rs:67:5 | LL | bar3 - | ^^^^ + | ^^^^ help: if this is intentional, prefix it with an underscore: `_bar3` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `priv_fn` --> $DIR/lint-dead-code-1.rs:88:4 | LL | fn priv_fn() { - | ^^^^^^^ + | ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_priv_fn` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `foo` --> $DIR/lint-dead-code-1.rs:93:4 | LL | fn foo() { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_foo` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `bar` --> $DIR/lint-dead-code-1.rs:98:4 | LL | fn bar() { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_bar` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `baz` --> $DIR/lint-dead-code-1.rs:102:4 | LL | fn baz() -> impl Copy { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_baz` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 10 previous errors diff --git a/src/test/ui/lint/dead-code/lint-dead-code-2.stderr b/src/test/ui/lint/dead-code/lint-dead-code-2.stderr index b01ba57f98580..5e19c7d02ffd3 100644 --- a/src/test/ui/lint/dead-code/lint-dead-code-2.stderr +++ b/src/test/ui/lint/dead-code/lint-dead-code-2.stderr @@ -2,8 +2,9 @@ error: function is never used: `dead_fn` --> $DIR/lint-dead-code-2.rs:22:4 | LL | fn dead_fn() {} - | ^^^^^^^ + | ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_dead_fn` | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/lint-dead-code-2.rs:2:9 | @@ -14,13 +15,17 @@ error: function is never used: `dead_fn2` --> $DIR/lint-dead-code-2.rs:25:4 | LL | fn dead_fn2() {} - | ^^^^^^^^ + | ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_dead_fn2` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `main` --> $DIR/lint-dead-code-2.rs:38:4 | LL | fn main() { - | ^^^^ + | ^^^^ help: if this is intentional, prefix it with an underscore: `_main` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 3 previous errors diff --git a/src/test/ui/lint/dead-code/lint-dead-code-3.stderr b/src/test/ui/lint/dead-code/lint-dead-code-3.stderr index cf8f01ea19f0c..d32fde5872d99 100644 --- a/src/test/ui/lint/dead-code/lint-dead-code-3.stderr +++ b/src/test/ui/lint/dead-code/lint-dead-code-3.stderr @@ -2,8 +2,9 @@ error: struct is never constructed: `Foo` --> $DIR/lint-dead-code-3.rs:14:8 | LL | struct Foo; - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_Foo` | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/lint-dead-code-3.rs:4:9 | @@ -14,25 +15,35 @@ error: associated function is never used: `foo` --> $DIR/lint-dead-code-3.rs:16:8 | LL | fn foo(&self) { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_foo` + | + = note: the leading underscore signals that this associated function serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `bar` --> $DIR/lint-dead-code-3.rs:21:4 | LL | fn bar() { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_bar` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: enum is never used: `c_void` --> $DIR/lint-dead-code-3.rs:60:6 | LL | enum c_void {} - | ^^^^^^ + | ^^^^^^ help: if this is intentional, prefix it with an underscore: `_c_void` + | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `free` --> $DIR/lint-dead-code-3.rs:62:5 | LL | fn free(p: *const c_void); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + | ^^^----^^^^^^^^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_free` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 5 previous errors diff --git a/src/test/ui/lint/dead-code/lint-dead-code-4.stderr b/src/test/ui/lint/dead-code/lint-dead-code-4.stderr index 3905d1a06bdfe..2785faa29f5d9 100644 --- a/src/test/ui/lint/dead-code/lint-dead-code-4.stderr +++ b/src/test/ui/lint/dead-code/lint-dead-code-4.stderr @@ -2,8 +2,11 @@ error: field is never read: `b` --> $DIR/lint-dead-code-4.rs:7:5 | LL | b: bool, - | ^^^^^^^ + | -^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_b` | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) note: the lint level is defined here --> $DIR/lint-dead-code-4.rs:3:9 | @@ -14,59 +17,88 @@ error: variant is never constructed: `X` --> $DIR/lint-dead-code-4.rs:15:5 | LL | X, - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_X` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: variant is never constructed: `Y` --> $DIR/lint-dead-code-4.rs:16:5 | -LL | / Y { +LL | Y { + | ^ help: if this is intentional, prefix it with an underscore: `_Y` + | _____| + | | LL | | a: String, LL | | b: i32, LL | | c: i32, LL | | }, | |_____^ + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: enum is never used: `ABC` --> $DIR/lint-dead-code-4.rs:24:6 | LL | enum ABC { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_ABC` + | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. error: variant is never constructed: `I` --> $DIR/lint-dead-code-4.rs:36:5 | LL | I, - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_I` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: field is never read: `b` --> $DIR/lint-dead-code-4.rs:39:9 | LL | b: i32, - | ^^^^^^ + | -^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_b` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `c` --> $DIR/lint-dead-code-4.rs:40:9 | LL | c: i32, - | ^^^^^^ + | -^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_c` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: variant is never constructed: `K` --> $DIR/lint-dead-code-4.rs:42:5 | LL | K - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_K` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: field is never read: `x` --> $DIR/lint-dead-code-4.rs:61:5 | LL | x: usize, - | ^^^^^^^^ + | -^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_x` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `c` --> $DIR/lint-dead-code-4.rs:63:5 | LL | c: bool, - | ^^^^^^^ + | -^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_c` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: aborting due to 10 previous errors diff --git a/src/test/ui/lint/dead-code/lint-dead-code-5.stderr b/src/test/ui/lint/dead-code/lint-dead-code-5.stderr index 519add826273f..6375d98d35cb2 100644 --- a/src/test/ui/lint/dead-code/lint-dead-code-5.stderr +++ b/src/test/ui/lint/dead-code/lint-dead-code-5.stderr @@ -2,8 +2,9 @@ error: variant is never constructed: `Variant2` --> $DIR/lint-dead-code-5.rs:6:5 | LL | Variant2 - | ^^^^^^^^ + | ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_Variant2` | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/lint-dead-code-5.rs:2:9 | @@ -14,19 +15,29 @@ error: variant is never constructed: `Variant5` --> $DIR/lint-dead-code-5.rs:13:5 | LL | Variant5 { _x: isize }, - | ^^^^^^^^^^^^^^^^^^^^^^ + | --------^^^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Variant5` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: variant is never constructed: `Variant6` --> $DIR/lint-dead-code-5.rs:14:5 | LL | Variant6(isize), - | ^^^^^^^^^^^^^^^ + | --------^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Variant6` + | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. error: enum is never used: `Enum3` --> $DIR/lint-dead-code-5.rs:35:6 | LL | enum Enum3 { - | ^^^^^ + | ^^^^^ help: if this is intentional, prefix it with an underscore: `_Enum3` + | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 4 previous errors diff --git a/src/test/ui/lint/dead-code/lint-dead-code-6.stderr b/src/test/ui/lint/dead-code/lint-dead-code-6.stderr index 7dc60730d6aad..ef26fe54ab589 100644 --- a/src/test/ui/lint/dead-code/lint-dead-code-6.stderr +++ b/src/test/ui/lint/dead-code/lint-dead-code-6.stderr @@ -2,8 +2,9 @@ error: struct is never constructed: `UnusedStruct` --> $DIR/lint-dead-code-6.rs:3:8 | LL | struct UnusedStruct; - | ^^^^^^^^^^^^ + | ^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_UnusedStruct` | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/lint-dead-code-6.rs:1:9 | @@ -14,19 +15,25 @@ error: associated function is never used: `unused_impl_fn_1` --> $DIR/lint-dead-code-6.rs:5:8 | LL | fn unused_impl_fn_1() { - | ^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused_impl_fn_1` + | + = note: the leading underscore signals that this associated function serves some other purpose even if it isn't used in a way that we can detect. error: associated function is never used: `unused_impl_fn_2` --> $DIR/lint-dead-code-6.rs:9:8 | LL | fn unused_impl_fn_2(var: i32) { - | ^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused_impl_fn_2` + | + = note: the leading underscore signals that this associated function serves some other purpose even if it isn't used in a way that we can detect. error: associated function is never used: `unused_impl_fn_3` --> $DIR/lint-dead-code-6.rs:13:8 | LL | fn unused_impl_fn_3( - | ^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused_impl_fn_3` + | + = note: the leading underscore signals that this associated function serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 4 previous errors diff --git a/src/test/ui/lint/dead-code/newline-span.stderr b/src/test/ui/lint/dead-code/newline-span.stderr index fd74405f2b648..5bd566be35e01 100644 --- a/src/test/ui/lint/dead-code/newline-span.stderr +++ b/src/test/ui/lint/dead-code/newline-span.stderr @@ -2,8 +2,9 @@ error: function is never used: `unused` --> $DIR/newline-span.rs:3:4 | LL | fn unused() { - | ^^^^^^ + | ^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused` | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/newline-span.rs:1:9 | @@ -14,13 +15,17 @@ error: function is never used: `unused2` --> $DIR/newline-span.rs:7:4 | LL | fn unused2(var: i32) { - | ^^^^^^^ + | ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused2` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: function is never used: `unused3` --> $DIR/newline-span.rs:11:4 | LL | fn unused3( - | ^^^^^^^ + | ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_unused3` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 3 previous errors diff --git a/src/test/ui/lint/dead-code/type-alias.stderr b/src/test/ui/lint/dead-code/type-alias.stderr index b2acd5d4213b3..1e7a030de3aa7 100644 --- a/src/test/ui/lint/dead-code/type-alias.stderr +++ b/src/test/ui/lint/dead-code/type-alias.stderr @@ -2,8 +2,11 @@ error: type alias is never used: `Unused` --> $DIR/type-alias.rs:4:1 | LL | type Unused = u8; - | ^^^^^^^^^^^^^^^^^ + | ^^^^^------^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Unused` | + = note: the leading underscore signals that this type alias serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/type-alias.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/unused-enum.stderr b/src/test/ui/lint/dead-code/unused-enum.stderr index 9f368fdd2f816..d536479c800ae 100644 --- a/src/test/ui/lint/dead-code/unused-enum.stderr +++ b/src/test/ui/lint/dead-code/unused-enum.stderr @@ -2,8 +2,9 @@ error: struct is never constructed: `F` --> $DIR/unused-enum.rs:3:8 | LL | struct F; - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_F` | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/unused-enum.rs:1:9 | @@ -15,13 +16,17 @@ error: struct is never constructed: `B` --> $DIR/unused-enum.rs:4:8 | LL | struct B; - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_B` + | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. error: enum is never used: `E` --> $DIR/unused-enum.rs:6:6 | LL | enum E { - | ^ + | ^ help: if this is intentional, prefix it with an underscore: `_E` + | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. error: aborting due to 3 previous errors diff --git a/src/test/ui/lint/dead-code/unused-struct-variant.stderr b/src/test/ui/lint/dead-code/unused-struct-variant.stderr index b93d6d4ac1866..394ced3e81001 100644 --- a/src/test/ui/lint/dead-code/unused-struct-variant.stderr +++ b/src/test/ui/lint/dead-code/unused-struct-variant.stderr @@ -2,8 +2,11 @@ error: variant is never constructed: `Bar` --> $DIR/unused-struct-variant.rs:8:5 | LL | Bar(B), - | ^^^^^^ + | ---^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_Bar` | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/unused-struct-variant.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/unused-variant.stderr b/src/test/ui/lint/dead-code/unused-variant.stderr index a547f5af4b082..7dcb79d0490c1 100644 --- a/src/test/ui/lint/dead-code/unused-variant.stderr +++ b/src/test/ui/lint/dead-code/unused-variant.stderr @@ -2,8 +2,9 @@ error: variant is never constructed: `Variant1` --> $DIR/unused-variant.rs:5:5 | LL | Variant1, - | ^^^^^^^^ + | ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_Variant1` | + = note: the leading underscore signals that this variant serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/unused-variant.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/with-core-crate.stderr b/src/test/ui/lint/dead-code/with-core-crate.stderr index 2c63e60d67609..1bde434069ee7 100644 --- a/src/test/ui/lint/dead-code/with-core-crate.stderr +++ b/src/test/ui/lint/dead-code/with-core-crate.stderr @@ -2,8 +2,9 @@ error: function is never used: `foo` --> $DIR/with-core-crate.rs:7:4 | LL | fn foo() { - | ^^^ + | ^^^ help: if this is intentional, prefix it with an underscore: `_foo` | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/with-core-crate.rs:1:9 | diff --git a/src/test/ui/lint/dead-code/write-only-field.stderr b/src/test/ui/lint/dead-code/write-only-field.stderr index a191d22c8b94c..13a21bb1193de 100644 --- a/src/test/ui/lint/dead-code/write-only-field.stderr +++ b/src/test/ui/lint/dead-code/write-only-field.stderr @@ -2,8 +2,11 @@ error: field is never read: `f` --> $DIR/write-only-field.rs:4:5 | LL | f: i32, - | ^^^^^^ + | -^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_f` | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) note: the lint level is defined here --> $DIR/write-only-field.rs:1:9 | @@ -14,31 +17,51 @@ error: field is never read: `sub` --> $DIR/write-only-field.rs:5:5 | LL | sub: Sub, - | ^^^^^^^^ + | ---^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_sub` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `f` --> $DIR/write-only-field.rs:9:5 | LL | f: i32, - | ^^^^^^ + | -^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_f` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `y` --> $DIR/write-only-field.rs:28:9 | LL | y: bool, - | ^^^^^^^ + | -^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_y` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `u` --> $DIR/write-only-field.rs:58:9 | LL | u: u32, - | ^^^^^^ + | -^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_u` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `v` --> $DIR/write-only-field.rs:59:9 | LL | v: u32, - | ^^^^^^ + | -^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_v` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: aborting due to 6 previous errors diff --git a/src/test/ui/lint/issue-17718-const-naming.stderr b/src/test/ui/lint/issue-17718-const-naming.stderr index ce4ebcb5e3ef6..e880006e114c1 100644 --- a/src/test/ui/lint/issue-17718-const-naming.stderr +++ b/src/test/ui/lint/issue-17718-const-naming.stderr @@ -2,8 +2,11 @@ error: constant is never used: `foo` --> $DIR/issue-17718-const-naming.rs:4:1 | LL | const foo: isize = 3; - | ^^^^^^^^^^^^^^^^^^^^^ + | ^^^^^^---^^^^^^^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_foo` | + = note: the leading underscore signals that this constant serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/issue-17718-const-naming.rs:2:9 | diff --git a/src/test/ui/span/macro-span-replacement.stderr b/src/test/ui/span/macro-span-replacement.stderr index 45cf5f8688cd1..f94a9e30a3dfa 100644 --- a/src/test/ui/span/macro-span-replacement.stderr +++ b/src/test/ui/span/macro-span-replacement.stderr @@ -2,11 +2,14 @@ warning: struct is never constructed: `S` --> $DIR/macro-span-replacement.rs:7:14 | LL | $b $a; - | ^ + | --^ + | | + | help: if this is intentional, prefix it with an underscore: `_S` ... LL | m!(S struct); | ------------- in this macro invocation | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/macro-span-replacement.rs:3:9 | diff --git a/src/test/ui/span/unused-warning-point-at-identifier.stderr b/src/test/ui/span/unused-warning-point-at-identifier.stderr index 6ef877da122f5..3bf342f197252 100644 --- a/src/test/ui/span/unused-warning-point-at-identifier.stderr +++ b/src/test/ui/span/unused-warning-point-at-identifier.stderr @@ -2,8 +2,9 @@ warning: enum is never used: `Enum` --> $DIR/unused-warning-point-at-identifier.rs:5:6 | LL | enum Enum { - | ^^^^ + | ^^^^ help: if this is intentional, prefix it with an underscore: `_Enum` | + = note: the leading underscore signals that this enum serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/unused-warning-point-at-identifier.rs:3:9 | @@ -15,19 +16,25 @@ warning: struct is never constructed: `Struct` --> $DIR/unused-warning-point-at-identifier.rs:12:8 | LL | struct Struct { - | ^^^^^^ + | ^^^^^^ help: if this is intentional, prefix it with an underscore: `_Struct` + | + = note: the leading underscore signals that this struct serves some other purpose even if it isn't used in a way that we can detect. warning: function is never used: `func` --> $DIR/unused-warning-point-at-identifier.rs:19:4 | LL | fn func() -> usize { - | ^^^^ + | ^^^^ help: if this is intentional, prefix it with an underscore: `_func` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. warning: function is never used: `func_complete_span` --> $DIR/unused-warning-point-at-identifier.rs:24:1 | LL | func_complete_span() - | ^^^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_func_complete_span` + | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. warning: 4 warnings emitted diff --git a/src/test/ui/test-attrs/test-warns-dead-code.stderr b/src/test/ui/test-attrs/test-warns-dead-code.stderr index d3bcea2951364..e5a8dee6ccb68 100644 --- a/src/test/ui/test-attrs/test-warns-dead-code.stderr +++ b/src/test/ui/test-attrs/test-warns-dead-code.stderr @@ -2,8 +2,9 @@ error: function is never used: `dead` --> $DIR/test-warns-dead-code.rs:5:4 | LL | fn dead() {} - | ^^^^ + | ^^^^ help: if this is intentional, prefix it with an underscore: `_dead` | + = note: the leading underscore signals that this function serves some other purpose even if it isn't used in a way that we can detect. note: the lint level is defined here --> $DIR/test-warns-dead-code.rs:3:9 | diff --git a/src/test/ui/union/union-fields-1.stderr b/src/test/ui/union/union-fields-1.stderr index 87621cc01b1b9..3595bf6dce688 100644 --- a/src/test/ui/union/union-fields-1.stderr +++ b/src/test/ui/union/union-fields-1.stderr @@ -2,8 +2,11 @@ error: field is never read: `c` --> $DIR/union-fields-1.rs:6:5 | LL | c: u8, - | ^^^^^ + | -^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_c` | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) note: the lint level is defined here --> $DIR/union-fields-1.rs:1:9 | @@ -14,19 +17,31 @@ error: field is never read: `a` --> $DIR/union-fields-1.rs:9:5 | LL | a: u8, - | ^^^^^ + | -^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_a` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `a` --> $DIR/union-fields-1.rs:13:20 | LL | union NoDropLike { a: u8 } - | ^^^^^ + | -^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_a` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: field is never read: `c` --> $DIR/union-fields-1.rs:18:5 | LL | c: u8, - | ^^^^^ + | -^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_c` + | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) error: aborting due to 4 previous errors diff --git a/src/test/ui/union/union-lint-dead-code.stderr b/src/test/ui/union/union-lint-dead-code.stderr index 7de70ec33801f..8ead9cde9b333 100644 --- a/src/test/ui/union/union-lint-dead-code.stderr +++ b/src/test/ui/union/union-lint-dead-code.stderr @@ -2,8 +2,11 @@ error: field is never read: `b` --> $DIR/union-lint-dead-code.rs:5:5 | LL | b: bool, - | ^^^^^^^ + | -^^^^^^ + | | + | help: if this is intentional, prefix it with an underscore: `_b` | + = note: the leading underscore signals that this field serves some other purpose even if it isn't used in a way that we can detect. (e.g. for its effect when dropped or in foreign code) note: the lint level is defined here --> $DIR/union-lint-dead-code.rs:1:9 |