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Add deprecated_safe lint
It warns about usages of `std::env::{set_var, remove_var}` with an automatic fix wrapping the call in an `unsafe` block.
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10 files changed

+172
-11
lines changed

10 files changed

+172
-11
lines changed

‎compiler/rustc_lint_defs/src/builtin.rs

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@@ -37,6 +37,7 @@ declare_lint_pass! {
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DEPRECATED,
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DEPRECATED_CFG_ATTR_CRATE_TYPE_NAME,
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DEPRECATED_IN_FUTURE,
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DEPRECATED_SAFE,
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DEPRECATED_WHERE_CLAUSE_LOCATION,
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DUPLICATE_MACRO_ATTRIBUTES,
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ELIDED_LIFETIMES_IN_ASSOCIATED_CONSTANT,
@@ -4844,3 +4845,51 @@ declare_lint! {
48444845
reference: "issue #124559 <https://github.com/rust-lang/rust/issues/124559>",
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};
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}
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declare_lint! {
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/// The `deprecated_safe` lint detects unsafe functions being used as safe
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/// functions.
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///
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/// ### Example
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///
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/// ```rust,edition2021,compile_fail
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/// #![deny(deprecated_safe)]
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/// // edition 2021
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/// use std::env;
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/// fn enable_backtrace() {
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/// env::set_var("RUST_BACKTRACE", "1");
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/// }
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/// ```
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///
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/// {{produces}}
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///
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/// ### Explanation
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///
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/// Rust [editions] allow the language to evolve without breaking backward
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/// compatibility. This lint catches code that uses `unsafe` functions that
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/// were declared as safe (non-`unsafe`) in earlier editions. If you switch
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/// the compiler to a new edition without updating the code, then it
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/// will fail to compile if you are using a function previously marked as
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/// safe.
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///
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/// You can audit the code to see if it suffices the preconditions of the
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/// `unsafe` code, and if it does, you can wrap it in an `unsafe` block. If
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/// you can't fulfill the preconditions, you probably need to switch to a
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/// different way of doing what you want to achieve.
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///
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/// This lint can automatically wrap the calls in `unsafe` blocks, but this
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/// obviously cannot verify that the preconditions of the `unsafe`
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/// functions are fulfilled, so that is still up to the user.
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///
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/// The lint is currently "allow" by default, but that might change in the
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/// future.
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///
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/// [editions]: https://doc.rust-lang.org/edition-guide/
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pub DEPRECATED_SAFE,
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Allow,
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"detects unsafe functions being used as safe functions",
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@future_incompatible = FutureIncompatibleInfo {
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reason: FutureIncompatibilityReason::EditionError(Edition::Edition2024),
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reference: "issue #27970 <https://github.com/rust-lang/rust/issues/27970>",
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};
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}

‎compiler/rustc_mir_build/messages.ftl

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Original file line numberDiff line numberDiff line change
@@ -28,6 +28,12 @@ mir_build_borrow_of_moved_value = borrow of moved value
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.value_borrowed_label = value borrowed here after move
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.suggestion = borrow this binding in the pattern to avoid moving the value
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mir_build_call_to_deprecated_safe_fn_requires_unsafe =
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call to deprecated safe function `{$function}` is unsafe and requires unsafe block
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.note = consult the function's documentation for information on how to avoid undefined behavior
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.label = call to unsafe function
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.suggestion = you can wrap the call in an `unsafe` block if you can guarantee the code is only ever called from single-threaded code
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mir_build_call_to_fn_with_requires_unsafe =
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call to function `{$function}` with `#[target_feature]` is unsafe and requires unsafe block
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.help = in order for the call to be safe, the context requires the following additional target {$missing_target_features_count ->

‎compiler/rustc_mir_build/src/check_unsafety.rs

Lines changed: 17 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@ use rustc_middle::thir::visit::Visitor;
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use rustc_middle::thir::*;
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use rustc_middle::ty::print::with_no_trimmed_paths;
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use rustc_middle::ty::{self, ParamEnv, Ty, TyCtxt};
12-
use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
12+
use rustc_session::lint::builtin::{DEPRECATED_SAFE, UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
1313
use rustc_session::lint::Level;
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use rustc_span::def_id::{DefId, LocalDefId};
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use rustc_span::symbol::Symbol;
@@ -115,7 +115,22 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
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// caller is from an edition before 2024.
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UnsafeOpKind::CallToUnsafeFunction(Some(id))
117117
if !span.at_least_rust_2024()
118-
&& self.tcx.has_attr(id, sym::rustc_deprecated_safe_2024) => {}
118+
&& self.tcx.has_attr(id, sym::rustc_deprecated_safe_2024) =>
119+
{
120+
self.tcx.emit_node_span_lint(
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DEPRECATED_SAFE,
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self.hir_context,
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span,
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CallToDeprecatedSafeFnRequiresUnsafe {
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span,
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function: with_no_trimmed_paths!(self.tcx.def_path_str(id)),
127+
sub: CallToDeprecatedSafeFnRequiresUnsafeSub {
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left: span.shrink_to_lo(),
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right: span.shrink_to_hi(),
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},
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},
132+
)
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}
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_ => kind.emit_requires_unsafe_err(
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self.tcx,
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span,

‎compiler/rustc_mir_build/src/errors.rs

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Original file line numberDiff line numberDiff line change
@@ -20,6 +20,25 @@ pub struct UnconditionalRecursion {
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pub call_sites: Vec<Span>,
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}
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#[derive(LintDiagnostic)]
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#[diag(mir_build_call_to_deprecated_safe_fn_requires_unsafe)]
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pub struct CallToDeprecatedSafeFnRequiresUnsafe {
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#[label]
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pub span: Span,
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pub function: String,
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#[subdiagnostic]
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pub sub: CallToDeprecatedSafeFnRequiresUnsafeSub,
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}
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#[derive(Subdiagnostic)]
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#[multipart_suggestion(mir_build_suggestion, applicability = "machine-applicable")]
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pub struct CallToDeprecatedSafeFnRequiresUnsafeSub {
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#[suggestion_part(code = "unsafe {{ ")]
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pub left: Span,
38+
#[suggestion_part(code = " }}")]
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pub right: Span,
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}
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#[derive(LintDiagnostic)]
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#[diag(mir_build_unsafe_op_in_unsafe_fn_call_to_unsafe_fn_requires_unsafe, code = E0133)]
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#[note]

‎tests/ui/rust-2024/unsafe-env-suggestion.fixed

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@@ -0,0 +1,20 @@
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//@ run-rustfix
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#![deny(deprecated_safe)]
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use std::env;
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7+
#[deny(unused_unsafe)]
8+
fn main() {
9+
unsafe { env::set_var("FOO", "BAR") };
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//~^ ERROR call to deprecated safe function
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//~| WARN this is accepted in the current edition
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unsafe { env::remove_var("FOO") };
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//~^ ERROR call to deprecated safe function
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//~| WARN this is accepted in the current edition
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16+
unsafe {
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env::set_var("FOO", "BAR");
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env::remove_var("FOO");
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}
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}

‎tests/ui/rust-2024/unsafe-env-suggestion.rs

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@@ -0,0 +1,20 @@
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//@ run-rustfix
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#![deny(deprecated_safe)]
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5+
use std::env;
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7+
#[deny(unused_unsafe)]
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fn main() {
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env::set_var("FOO", "BAR");
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//~^ ERROR call to deprecated safe function
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//~| WARN this is accepted in the current edition
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env::remove_var("FOO");
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//~^ ERROR call to deprecated safe function
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//~| WARN this is accepted in the current edition
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16+
unsafe {
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env::set_var("FOO", "BAR");
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env::remove_var("FOO");
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}
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}

‎tests/ui/rust-2024/unsafe-env-suggestion.stderr

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@@ -0,0 +1,33 @@
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error: call to deprecated safe function `std::env::set_var` is unsafe and requires unsafe block
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--> $DIR/unsafe-env-suggestion.rs:9:5
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|
4+
LL | env::set_var("FOO", "BAR");
5+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
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|
7+
= warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
8+
= note: for more information, see issue #27970 <https://github.com/rust-lang/rust/issues/27970>
9+
note: the lint level is defined here
10+
--> $DIR/unsafe-env-suggestion.rs:3:9
11+
|
12+
LL | #![deny(deprecated_safe)]
13+
| ^^^^^^^^^^^^^^^
14+
help: you can wrap the call in an `unsafe` block if you can guarantee the code is only ever called from single-threaded code
15+
|
16+
LL | unsafe { env::set_var("FOO", "BAR") };
17+
| ++++++++ +
18+
19+
error: call to deprecated safe function `std::env::remove_var` is unsafe and requires unsafe block
20+
--> $DIR/unsafe-env-suggestion.rs:12:5
21+
|
22+
LL | env::remove_var("FOO");
23+
| ^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
24+
|
25+
= warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2024!
26+
= note: for more information, see issue #27970 <https://github.com/rust-lang/rust/issues/27970>
27+
help: you can wrap the call in an `unsafe` block if you can guarantee the code is only ever called from single-threaded code
28+
|
29+
LL | unsafe { env::remove_var("FOO") };
30+
| ++++++++ +
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32+
error: aborting due to 2 previous errors
33+

‎tests/ui/rust-2024/unsafe-env.e2021.stderr

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@@ -1,19 +1,19 @@
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error[E0133]: call to unsafe function `unsafe_fn` is unsafe and requires unsafe function or block
2-
--> $DIR/unsafe-env.rs:24:5
2+
--> $DIR/unsafe-env.rs:23:5
33
|
44
LL | unsafe_fn();
55
| ^^^^^^^^^^^ call to unsafe function
66
|
77
= note: consult the function's documentation for information on how to avoid undefined behavior
88

99
error: unnecessary `unsafe` block
10-
--> $DIR/unsafe-env.rs:27:5
10+
--> $DIR/unsafe-env.rs:26:5
1111
|
1212
LL | unsafe {
1313
| ^^^^^^ unnecessary `unsafe` block
1414
|
1515
note: the lint level is defined here
16-
--> $DIR/unsafe-env.rs:12:8
16+
--> $DIR/unsafe-env.rs:11:8
1717
|
1818
LL | #[deny(unused_unsafe)]
1919
| ^^^^^^^^^^^^^

‎tests/ui/rust-2024/unsafe-env.e2024.stderr

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@@ -1,35 +1,35 @@
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error[E0133]: call to unsafe function `set_var` is unsafe and requires unsafe block
2-
--> $DIR/unsafe-env.rs:14:5
2+
--> $DIR/unsafe-env.rs:13:5
33
|
44
LL | env::set_var("FOO", "BAR");
55
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
66
|
77
= note: consult the function's documentation for information on how to avoid undefined behavior
88

99
error[E0133]: call to unsafe function `remove_var` is unsafe and requires unsafe block
10-
--> $DIR/unsafe-env.rs:16:5
10+
--> $DIR/unsafe-env.rs:15:5
1111
|
1212
LL | env::remove_var("FOO");
1313
| ^^^^^^^^^^^^^^^^^^^^^^ call to unsafe function
1414
|
1515
= note: consult the function's documentation for information on how to avoid undefined behavior
1616

1717
error[E0133]: call to unsafe function `unsafe_fn` is unsafe and requires unsafe block
18-
--> $DIR/unsafe-env.rs:24:5
18+
--> $DIR/unsafe-env.rs:23:5
1919
|
2020
LL | unsafe_fn();
2121
| ^^^^^^^^^^^ call to unsafe function
2222
|
2323
= note: consult the function's documentation for information on how to avoid undefined behavior
2424

2525
error: unnecessary `unsafe` block
26-
--> $DIR/unsafe-env.rs:27:5
26+
--> $DIR/unsafe-env.rs:26:5
2727
|
2828
LL | unsafe {
2929
| ^^^^^^ unnecessary `unsafe` block
3030
|
3131
note: the lint level is defined here
32-
--> $DIR/unsafe-env.rs:12:8
32+
--> $DIR/unsafe-env.rs:11:8
3333
|
3434
LL | #[deny(unused_unsafe)]
3535
| ^^^^^^^^^^^^^

‎tests/ui/rust-2024/unsafe-env.rs

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@@ -4,7 +4,6 @@
44
//@[e2024] compile-flags: -Zunstable-options
55

66
use std::env;
7-
use std::mem;
87

98
unsafe fn unsafe_fn() {}
109
fn safe_fn() {}

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