Auto merge of #10886 - lochetti:fix_10832, r=Centri3,xFrednet

Adding configuration to allow safety comment above stmt containing unsafe block

Adding a new configuration, `accept-comment-above-statement`, to allow a safety comment to be placed before the statement that has the `unsafe` block. It affects the `undocumented_unsafe_blocks` lint.

The default value for this configuration will be `false`. So the user has to opt-in for the change.

This PR fixes https://github.com/rust-lang/rust-clippy/issues/10832

---

changelog: Enhancement [`undocumented_unsafe_blocks`]: Added `accept-comment-above-statement` configuration.
[#10886](https://github.com/rust-lang/rust-clippy/pull/10886)

CHANGELOG.md

@@ -5383,4 +5383,5 @@ Released 2018-09-13
 [`allow-private-module-inception`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allow-private-module-inception
 [`allowed-idents-below-min-chars`]: https://doc.rust-lang.org/clippy/lint_configuration.html#allowed-idents-below-min-chars
 [`min-ident-chars-threshold`]: https://doc.rust-lang.org/clippy/lint_configuration.html#min-ident-chars-threshold
+[`accept-comment-above-statement`]: https://doc.rust-lang.org/clippy/lint_configuration.html#accept-comment-above-statement
 <!-- end autogenerated links to configuration documentation -->

book/src/lint_configuration.md

@@ -695,3 +695,13 @@ Minimum chars an ident can have, anything below or equal to this will be linted.
 * [`min_ident_chars`](https://rust-lang.github.io/rust-clippy/master/index.html#min_ident_chars)
 
 
+## `accept-comment-above-statement`
+Whether to accept a safety comment to be placed above the statement containing the `unsafe` block
+
+**Default Value:** `false` (`bool`)
+
+---
+**Affected lints:**
+* [`undocumented_unsafe_blocks`](https://rust-lang.github.io/rust-clippy/master/index.html#undocumented_unsafe_blocks)
+
+

clippy_lints/src/lib.rs

@@ -929,7 +929,12 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
             enable_raw_pointer_heuristic_for_send,
         ))
     });
-    store.register_late_pass(move |_| Box::new(undocumented_unsafe_blocks::UndocumentedUnsafeBlocks));
+    let accept_comment_above_statement = conf.accept_comment_above_statement;
+    store.register_late_pass(move |_| {
+        Box::new(undocumented_unsafe_blocks::UndocumentedUnsafeBlocks::new(
+            accept_comment_above_statement,
+        ))
+    });
     let allow_mixed_uninlined = conf.allow_mixed_uninlined_format_args;
     store.register_late_pass(move |_| Box::new(format_args::FormatArgs::new(msrv(), allow_mixed_uninlined)));
     store.register_late_pass(|_| Box::new(trailing_empty_array::TrailingEmptyArray));

clippy_lints/src/undocumented_unsafe_blocks.rs

@@ -11,7 +11,7 @@ use rustc_hir::{Block, BlockCheckMode, ItemKind, Node, UnsafeSource};
 use rustc_lexer::{tokenize, TokenKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
-use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::{BytePos, Pos, Span, SyntaxContext};
 
 declare_clippy_lint! {
@@ -92,7 +92,20 @@ declare_clippy_lint! {
     "annotating safe code with a safety comment"
 }
 
-declare_lint_pass!(UndocumentedUnsafeBlocks => [UNDOCUMENTED_UNSAFE_BLOCKS, UNNECESSARY_SAFETY_COMMENT]);
+#[derive(Copy, Clone)]
+pub struct UndocumentedUnsafeBlocks {
+    accept_comment_above_statement: bool,
+}
+
+impl UndocumentedUnsafeBlocks {
+    pub fn new(accept_comment_above_statement: bool) -> Self {
+        Self {
+            accept_comment_above_statement,
+        }
+    }
+}
+
+impl_lint_pass!(UndocumentedUnsafeBlocks => [UNDOCUMENTED_UNSAFE_BLOCKS, UNNECESSARY_SAFETY_COMMENT]);
 
 impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks {
     fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) {
@@ -101,7 +114,7 @@ impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks {
             && !is_lint_allowed(cx, UNDOCUMENTED_UNSAFE_BLOCKS, block.hir_id)
             && !is_unsafe_from_proc_macro(cx, block.span)
             && !block_has_safety_comment(cx, block.span)
-            && !block_parents_have_safety_comment(cx, block.hir_id)
+            && !block_parents_have_safety_comment(self.accept_comment_above_statement, cx, block.hir_id)
         {
             let source_map = cx.tcx.sess.source_map();
             let span = if source_map.is_multiline(block.span) {
@@ -313,10 +326,31 @@ fn is_unsafe_from_proc_macro(cx: &LateContext<'_>, span: Span) -> bool {
 
 // Checks if any parent {expression, statement, block, local, const, static}
 // has a safety comment
-fn block_parents_have_safety_comment(cx: &LateContext<'_>, id: hir::HirId) -> bool {
+fn block_parents_have_safety_comment(
+    accept_comment_above_statement: bool,
+    cx: &LateContext<'_>,
+    id: hir::HirId,
+) -> bool {
     if let Some(node) = get_parent_node(cx.tcx, id) {
         return match node {
-            Node::Expr(expr) => !is_branchy(expr) && span_in_body_has_safety_comment(cx, expr.span),
+            Node::Expr(expr) => {
+                if let Some(
+                    Node::Local(hir::Local { span, .. })
+                    | Node::Item(hir::Item {
+                        kind: hir::ItemKind::Const(..) | ItemKind::Static(..),
+                        span,
+                        ..
+                    }),
+                ) = get_parent_node(cx.tcx, expr.hir_id)
+                {
+                    // if unsafe block is part of a let/const/static statement,
+                    // and accept_comment_above_statement is set to true
+                    // we accept the safety comment in the line the precedes this statement.
+                    accept_comment_above_statement && span_in_body_has_safety_comment(cx, *span)
+                } else {
+                    !is_branchy(expr) && span_in_body_has_safety_comment(cx, expr.span)
+                }
+            },
             Node::Stmt(hir::Stmt {
                 kind:
                     hir::StmtKind::Local(hir::Local { span, .. })
@@ -546,7 +580,14 @@ fn get_body_search_span(cx: &LateContext<'_>) -> Option<Span> {
     for (_, node) in map.parent_iter(body.hir_id) {
         match node {
             Node::Expr(e) => span = e.span,
-            Node::Block(_) | Node::Arm(_) | Node::Stmt(_) | Node::Local(_) => (),
+            Node::Block(_)
+            | Node::Arm(_)
+            | Node::Stmt(_)
+            | Node::Local(_)
+            | Node::Item(hir::Item {
+                kind: hir::ItemKind::Const(..) | ItemKind::Static(..),
+                ..
+            }) => (),
             _ => break,
         }
     }

clippy_lints/src/utils/conf.rs

@@ -538,6 +538,10 @@ define_Conf! {
     ///
     /// Minimum chars an ident can have, anything below or equal to this will be linted.
     (min_ident_chars_threshold: u64 = 1),
+    /// Lint: UNDOCUMENTED_UNSAFE_BLOCKS.
+    ///
+    /// Whether to accept a safety comment to be placed above the statement containing the `unsafe` block
+    (accept_comment_above_statement: bool = false),
 }
 
 /// Search for the configuration file.

tests/ui-toml/toml_unknown_key/conf_unknown_key.stderr

@@ -1,4 +1,5 @@
 error: error reading Clippy's configuration file: unknown field `foobar`, expected one of
+           accept-comment-above-statement
            allow-dbg-in-tests
            allow-expect-in-tests
            allow-mixed-uninlined-format-args
@@ -65,6 +66,7 @@ LL | foobar = 42
    | ^^^^^^
 
 error: error reading Clippy's configuration file: unknown field `barfoo`, expected one of
+           accept-comment-above-statement
            allow-dbg-in-tests
            allow-expect-in-tests
            allow-mixed-uninlined-format-args

tests/ui-toml/undocumented_unsafe_blocks/auxiliary/proc_macro_unsafe.rs

@@ -0,0 +1,18 @@
+//@compile-flags: --emit=link
+//@no-prefer-dynamic
+
+#![crate_type = "proc-macro"]
+
+extern crate proc_macro;
+
+use proc_macro::{Delimiter, Group, Ident, TokenStream, TokenTree};
+
+#[proc_macro]
+pub fn unsafe_block(input: TokenStream) -> TokenStream {
+    let span = input.into_iter().next().unwrap().span();
+    TokenStream::from_iter([TokenTree::Ident(Ident::new("unsafe", span)), {
+        let mut group = Group::new(Delimiter::Brace, TokenStream::new());
+        group.set_span(span);
+        TokenTree::Group(group)
+    }])
+}

tests/ui-toml/undocumented_unsafe_blocks/clippy.toml

@@ -0,0 +1 @@
+accept-comment-above-statement = true

tests/ui-toml/undocumented_unsafe_blocks/undocumented_unsafe_blocks.rs

@@ -0,0 +1,534 @@
+//@aux-build:proc_macro_unsafe.rs
+
+#![warn(clippy::undocumented_unsafe_blocks, clippy::unnecessary_safety_comment)]
+#![allow(clippy::let_unit_value, clippy::missing_safety_doc)]
+
+extern crate proc_macro_unsafe;
+
+// Valid comments
+
+fn nested_local() {
+    let _ = {
+        let _ = {
+            // SAFETY:
+            let _ = unsafe {};
+        };
+    };
+}
+
+fn deep_nest() {
+    let _ = {
+        let _ = {
+            // SAFETY:
+            let _ = unsafe {};
+
+            // Safety:
+            unsafe {};
+
+            let _ = {
+                let _ = {
+                    let _ = {
+                        let _ = {
+                            let _ = {
+                                // Safety:
+                                let _ = unsafe {};
+
+                                // SAFETY:
+                                unsafe {};
+                            };
+                        };
+                    };
+
+                    // Safety:
+                    unsafe {};
+                };
+            };
+        };
+
+        // Safety:
+        unsafe {};
+    };
+
+    // SAFETY:
+    unsafe {};
+}
+
+fn local_tuple_expression() {
+    // Safety:
+    let _ = (42, unsafe {});
+}
+
+fn line_comment() {
+    // Safety:
+    unsafe {}
+}
+
+fn line_comment_newlines() {
+    // SAFETY:
+
+    unsafe {}
+}
+
+fn line_comment_empty() {
+    // Safety:
+    //
+    //
+    //
+    unsafe {}
+}
+
+fn line_comment_with_extras() {
+    // This is a description
+    // Safety:
+    unsafe {}
+}
+
+fn block_comment() {
+    /* Safety: */
+    unsafe {}
+}
+
+fn block_comment_newlines() {
+    /* SAFETY: */
+
+    unsafe {}
+}
+
+fn block_comment_with_extras() {
+    /* This is a description
+     * SAFETY:
+     */
+    unsafe {}
+}
+
+fn block_comment_terminator_same_line() {
+    /* This is a description
+     * Safety: */
+    unsafe {}
+}
+
+fn buried_safety() {
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor
+    // incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+    // ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+    // reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint
+    // occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est
+    // laborum. Safety:
+    // Tellus elementum sagittis vitae et leo duis ut diam quam. Sit amet nulla facilisi
+    // morbi tempus iaculis urna. Amet luctus venenatis lectus magna. At quis risus sed vulputate odio
+    // ut. Luctus venenatis lectus magna fringilla urna. Tortor id aliquet lectus proin nibh nisl
+    // condimentum id venenatis. Vulputate dignissim suspendisse in est ante in nibh mauris cursus.
+    unsafe {}
+}
+
+fn safety_with_prepended_text() {
+    // This is a test. safety:
+    unsafe {}
+}
+
+fn local_line_comment() {
+    // Safety:
+    let _ = unsafe {};
+}
+
+fn local_block_comment() {
+    /* SAFETY: */
+    let _ = unsafe {};
+}
+
+fn comment_array() {
+    // Safety:
+    let _ = [unsafe { 14 }, unsafe { 15 }, 42, unsafe { 16 }];
+}
+
+fn comment_tuple() {
+    // sAFETY:
+    let _ = (42, unsafe {}, "test", unsafe {});
+}
+
+fn comment_unary() {
+    // SAFETY:
+    let _ = *unsafe { &42 };
+}
+
+#[allow(clippy::match_single_binding)]
+fn comment_match() {
+    // SAFETY:
+    let _ = match unsafe {} {
+        _ => {},
+    };
+}
+
+fn comment_addr_of() {
+    // Safety:
+    let _ = &unsafe {};
+}
+
+fn comment_repeat() {
+    // Safety:
+    let _ = [unsafe {}; 5];
+}
+
+fn comment_macro_call() {
+    macro_rules! t {
+        ($b:expr) => {
+            $b
+        };
+    }
+
+    t!(
+        // SAFETY:
+        unsafe {}
+    );
+}
+
+fn comment_macro_def() {
+    macro_rules! t {
+        () => {
+            // Safety:
+            unsafe {}
+        };
+    }
+
+    t!();
+}
+
+fn non_ascii_comment() {
+    // ॐ᧻໒ SaFeTy: ௵∰
+    unsafe {};
+}
+
+fn local_commented_block() {
+    let _ =
+        // safety:
+        unsafe {};
+}
+
+fn local_nest() {
+    // safety:
+    let _ = [(42, unsafe {}, unsafe {}), (52, unsafe {}, unsafe {})];
+}
+
+fn in_fn_call(x: *const u32) {
+    fn f(x: u32) {}
+
+    // Safety: reason
+    f(unsafe { *x });
+}
+
+fn multi_in_fn_call(x: *const u32) {
+    fn f(x: u32, y: u32) {}
+
+    // Safety: reason
+    f(unsafe { *x }, unsafe { *x });
+}
+
+fn in_multiline_fn_call(x: *const u32) {
+    fn f(x: u32, y: u32) {}
+
+    f(
+        // Safety: reason
+        unsafe { *x },
+        0,
+    );
+}
+
+fn in_macro_call(x: *const u32) {
+    // Safety: reason
+    println!("{}", unsafe { *x });
+}
+
+fn in_multiline_macro_call(x: *const u32) {
+    println!(
+        "{}",
+        // Safety: reason
+        unsafe { *x },
+    );
+}
+
+fn from_proc_macro() {
+    proc_macro_unsafe::unsafe_block!(token);
+}
+
+fn in_closure(x: *const u32) {
+    // Safety: reason
+    let _ = || unsafe { *x };
+}
+
+// Invalid comments
+
+#[rustfmt::skip]
+fn inline_block_comment() {
+    /* Safety: */ unsafe {}
+}
+
+fn no_comment() {
+    unsafe {}
+}
+
+fn no_comment_array() {
+    let _ = [unsafe { 14 }, unsafe { 15 }, 42, unsafe { 16 }];
+}
+
+fn no_comment_tuple() {
+    let _ = (42, unsafe {}, "test", unsafe {});
+}
+
+fn no_comment_unary() {
+    let _ = *unsafe { &42 };
+}
+
+#[allow(clippy::match_single_binding)]
+fn no_comment_match() {
+    let _ = match unsafe {} {
+        _ => {},
+    };
+}
+
+fn no_comment_addr_of() {
+    let _ = &unsafe {};
+}
+
+fn no_comment_repeat() {
+    let _ = [unsafe {}; 5];
+}
+
+fn local_no_comment() {
+    let _ = unsafe {};
+}
+
+fn no_comment_macro_call() {
+    macro_rules! t {
+        ($b:expr) => {
+            $b
+        };
+    }
+
+    t!(unsafe {});
+}
+
+fn no_comment_macro_def() {
+    macro_rules! t {
+        () => {
+            unsafe {}
+        };
+    }
+
+    t!();
+}
+
+fn trailing_comment() {
+    unsafe {} // SAFETY:
+}
+
+fn internal_comment() {
+    unsafe {
+        // SAFETY:
+    }
+}
+
+fn interference() {
+    // SAFETY
+
+    let _ = 42;
+
+    unsafe {};
+}
+
+pub fn print_binary_tree() {
+    println!("{}", unsafe { String::from_utf8_unchecked(vec![]) });
+}
+
+mod unsafe_impl_smoke_test {
+    unsafe trait A {}
+
+    // error: no safety comment
+    unsafe impl A for () {}
+
+    // Safety: ok
+    unsafe impl A for (i32) {}
+
+    mod sub_mod {
+        // error:
+        unsafe impl B for (u32) {}
+        unsafe trait B {}
+    }
+
+    #[rustfmt::skip]
+    mod sub_mod2 {
+        //
+        // SAFETY: ok
+        //
+
+        unsafe impl B for (u32) {}
+        unsafe trait B {}
+    }
+}
+
+mod unsafe_impl_from_macro {
+    unsafe trait T {}
+
+    // error
+    macro_rules! no_safety_comment {
+        ($t:ty) => {
+            unsafe impl T for $t {}
+        };
+    }
+
+    // ok
+    no_safety_comment!(());
+
+    // ok
+    macro_rules! with_safety_comment {
+        ($t:ty) => {
+            // SAFETY:
+            unsafe impl T for $t {}
+        };
+    }
+
+    // ok
+    with_safety_comment!((i32));
+}
+
+mod unsafe_impl_macro_and_not_macro {
+    unsafe trait T {}
+
+    // error
+    macro_rules! no_safety_comment {
+        ($t:ty) => {
+            unsafe impl T for $t {}
+        };
+    }
+
+    // ok
+    no_safety_comment!(());
+
+    // error
+    unsafe impl T for (i32) {}
+
+    // ok
+    no_safety_comment!(u32);
+
+    // error
+    unsafe impl T for (bool) {}
+}
+
+#[rustfmt::skip]
+mod unsafe_impl_valid_comment {
+    unsafe trait SaFety {}
+    // SaFety:
+    unsafe impl SaFety for () {}
+
+    unsafe trait MultiLineComment {}
+    // The following impl is safe
+    // ...
+    // Safety: reason
+    unsafe impl MultiLineComment for () {}
+
+    unsafe trait NoAscii {}
+    // 安全 SAFETY: 以下のコードは安全です
+    unsafe impl NoAscii for () {}
+
+    unsafe trait InlineAndPrecedingComment {}
+    // SAFETY:
+    /* comment */ unsafe impl InlineAndPrecedingComment for () {}
+
+    unsafe trait BuriedSafety {}
+    // Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor
+    // incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation
+    // ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in
+    // reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint
+    // occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est
+    // laborum. Safety:
+    // Tellus elementum sagittis vitae et leo duis ut diam quam. Sit amet nulla facilisi
+    // morbi tempus iaculis urna. Amet luctus venenatis lectus magna. At quis risus sed vulputate odio
+    // ut. Luctus venenatis lectus magna fringilla urna. Tortor id aliquet lectus proin nibh nisl
+    // condimentum id venenatis. Vulputate dignissim suspendisse in est ante in nibh mauris cursus.
+    unsafe impl BuriedSafety for () {}
+
+    unsafe trait MultiLineBlockComment {}
+    /* This is a description
+     * Safety: */
+    unsafe impl MultiLineBlockComment for () {}
+}
+
+#[rustfmt::skip]
+mod unsafe_impl_invalid_comment {
+    unsafe trait NoComment {}
+
+    unsafe impl NoComment for () {}
+
+    unsafe trait InlineComment {}
+
+    /* SAFETY: */ unsafe impl InlineComment for () {}
+
+    unsafe trait TrailingComment {}
+
+    unsafe impl TrailingComment for () {} // SAFETY:
+
+    unsafe trait Interference {}
+    // SAFETY:
+    const BIG_NUMBER: i32 = 1000000;
+    unsafe impl Interference for () {}
+}
+
+unsafe trait ImplInFn {}
+
+fn impl_in_fn() {
+    // error
+    unsafe impl ImplInFn for () {}
+
+    // SAFETY: ok
+    unsafe impl ImplInFn for (i32) {}
+}
+
+unsafe trait CrateRoot {}
+
+// error
+unsafe impl CrateRoot for () {}
+
+// SAFETY: ok
+unsafe impl CrateRoot for (i32) {}
+
+fn issue_9142() {
+    // SAFETY: ok
+    let _ =
+        // we need this comment to avoid rustfmt putting
+        // it all on one line
+        unsafe {};
+
+    // SAFETY: this is more than one level away, so it should warn
+    let _ = {
+        if unsafe { true } {
+            todo!();
+        } else {
+            let bar = unsafe {};
+            todo!();
+            bar
+        }
+    };
+}
+
+pub unsafe fn a_function_with_a_very_long_name_to_break_the_line() -> u32 {
+    1
+}
+
+pub const unsafe fn a_const_function_with_a_very_long_name_to_break_the_line() -> u32 {
+    2
+}
+
+fn issue_10832() {
+    // Safety: A safety comment
+    let _some_variable_with_a_very_long_name_to_break_the_line =
+        unsafe { a_function_with_a_very_long_name_to_break_the_line() };
+
+    // Safety: Another safety comment
+    const _SOME_CONST_WITH_A_VERY_LONG_NAME_TO_BREAK_THE_LINE: u32 =
+        unsafe { a_const_function_with_a_very_long_name_to_break_the_line() };
+
+    // Safety: Yet another safety comment
+    static _SOME_STATIC_WITH_A_VERY_LONG_NAME_TO_BREAK_THE_LINE: u32 =
+        unsafe { a_const_function_with_a_very_long_name_to_break_the_line() };
+}
+
+fn main() {}

tests/ui-toml/undocumented_unsafe_blocks/undocumented_unsafe_blocks.stderr

@@ -0,0 +1,314 @@
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:262:19
+   |
+LL |     /* Safety: */ unsafe {}
+   |                   ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+   = note: `-D clippy::undocumented-unsafe-blocks` implied by `-D warnings`
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:266:5
+   |
+LL |     unsafe {}
+   |     ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:270:14
+   |
+LL |     let _ = [unsafe { 14 }, unsafe { 15 }, 42, unsafe { 16 }];
+   |              ^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:270:29
+   |
+LL |     let _ = [unsafe { 14 }, unsafe { 15 }, 42, unsafe { 16 }];
+   |                             ^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:270:48
+   |
+LL |     let _ = [unsafe { 14 }, unsafe { 15 }, 42, unsafe { 16 }];
+   |                                                ^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:274:18
+   |
+LL |     let _ = (42, unsafe {}, "test", unsafe {});
+   |                  ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:274:37
+   |
+LL |     let _ = (42, unsafe {}, "test", unsafe {});
+   |                                     ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:278:14
+   |
+LL |     let _ = *unsafe { &42 };
+   |              ^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:283:19
+   |
+LL |     let _ = match unsafe {} {
+   |                   ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:289:14
+   |
+LL |     let _ = &unsafe {};
+   |              ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:293:14
+   |
+LL |     let _ = [unsafe {}; 5];
+   |              ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:297:13
+   |
+LL |     let _ = unsafe {};
+   |             ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:307:8
+   |
+LL |     t!(unsafe {});
+   |        ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:313:13
+   |
+LL |             unsafe {}
+   |             ^^^^^^^^^
+...
+LL |     t!();
+   |     ---- in this macro invocation
+   |
+   = help: consider adding a safety comment on the preceding line
+   = note: this error originates in the macro `t` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:321:5
+   |
+LL |     unsafe {} // SAFETY:
+   |     ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:325:5
+   |
+LL |     unsafe {
+   |     ^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:335:5
+   |
+LL |     unsafe {};
+   |     ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:339:20
+   |
+LL |     println!("{}", unsafe { String::from_utf8_unchecked(vec![]) });
+   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:346:5
+   |
+LL |     unsafe impl A for () {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:353:9
+   |
+LL |         unsafe impl B for (u32) {}
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:374:13
+   |
+LL |             unsafe impl T for $t {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL |     no_safety_comment!(());
+   |     ---------------------- in this macro invocation
+   |
+   = help: consider adding a safety comment on the preceding line
+   = note: this error originates in the macro `no_safety_comment` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:399:13
+   |
+LL |             unsafe impl T for $t {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL |     no_safety_comment!(());
+   |     ---------------------- in this macro invocation
+   |
+   = help: consider adding a safety comment on the preceding line
+   = note: this error originates in the macro `no_safety_comment` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:407:5
+   |
+LL |     unsafe impl T for (i32) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:399:13
+   |
+LL |             unsafe impl T for $t {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL |     no_safety_comment!(u32);
+   |     ----------------------- in this macro invocation
+   |
+   = help: consider adding a safety comment on the preceding line
+   = note: this error originates in the macro `no_safety_comment` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:413:5
+   |
+LL |     unsafe impl T for (bool) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:459:5
+   |
+LL |     unsafe impl NoComment for () {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:463:19
+   |
+LL |     /* SAFETY: */ unsafe impl InlineComment for () {}
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:467:5
+   |
+LL |     unsafe impl TrailingComment for () {} // SAFETY:
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: constant item has unnecessary safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:471:5
+   |
+LL |     const BIG_NUMBER: i32 = 1000000;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: consider removing the safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:470:5
+   |
+LL |     // SAFETY:
+   |     ^^^^^^^^^^
+   = note: `-D clippy::unnecessary-safety-comment` implied by `-D warnings`
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:472:5
+   |
+LL |     unsafe impl Interference for () {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:479:5
+   |
+LL |     unsafe impl ImplInFn for () {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe impl missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:488:1
+   |
+LL | unsafe impl CrateRoot for () {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: statement has unnecessary safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:501:5
+   |
+LL | /     let _ = {
+LL | |         if unsafe { true } {
+LL | |             todo!();
+LL | |         } else {
+...  |
+LL | |         }
+LL | |     };
+   | |______^
+   |
+help: consider removing the safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:500:5
+   |
+LL |     // SAFETY: this is more than one level away, so it should warn
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:502:12
+   |
+LL |         if unsafe { true } {
+   |            ^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:505:23
+   |
+LL |             let bar = unsafe {};
+   |                       ^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: aborting due to 35 previous errors
+

tests/ui/undocumented_unsafe_blocks.rs

@@ -509,4 +509,26 @@ fn issue_9142() {
     };
 }
 
+pub unsafe fn a_function_with_a_very_long_name_to_break_the_line() -> u32 {
+    1
+}
+
+pub const unsafe fn a_const_function_with_a_very_long_name_to_break_the_line() -> u32 {
+    2
+}
+
+fn issue_10832() {
+    // Safety: A safety comment. But it will warn anyways
+    let _some_variable_with_a_very_long_name_to_break_the_line =
+        unsafe { a_function_with_a_very_long_name_to_break_the_line() };
+
+    // Safety: Another safety comment. But it will warn anyways
+    const _SOME_CONST_WITH_A_VERY_LONG_NAME_TO_BREAK_THE_LINE: u32 =
+        unsafe { a_const_function_with_a_very_long_name_to_break_the_line() };
+
+    // Safety: Yet another safety comment. But it will warn anyways
+    static _SOME_STATIC_WITH_A_VERY_LONG_NAME_TO_BREAK_THE_LINE: u32 =
+        unsafe { a_const_function_with_a_very_long_name_to_break_the_line() };
+}
+
 fn main() {}

tests/ui/undocumented_unsafe_blocks.stderr

@@ -318,5 +318,29 @@ LL |             let bar = unsafe {};
    |
    = help: consider adding a safety comment on the preceding line
 
-error: aborting due to 36 previous errors
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:523:9
+   |
+LL |         unsafe { a_function_with_a_very_long_name_to_break_the_line() };
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:527:9
+   |
+LL |         unsafe { a_const_function_with_a_very_long_name_to_break_the_line() };
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:531:9
+   |
+LL |         unsafe { a_const_function_with_a_very_long_name_to_break_the_line() };
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: aborting due to 39 previous errors