Add a couple of examples to undocumented_unsafe_blocks

Author: Jarcho

clippy_lints/src/undocumented_unsafe_blocks.rs

@@ -15,6 +15,24 @@ declare_clippy_lint! {
     /// explaining why the unsafe operations performed inside
     /// the block are safe.
     ///
+    /// Note the comment must appear on the line(s) preceding the unsafe block
+    /// with nothing appearing in between. The following is ok:
+    /// ```ignore
+    /// foo(
+    ///     // SAFETY:
+    ///     // This is a valid safety comment
+    ///     unsafe { *x }
+    /// )
+    /// ```
+    /// But neither of these are:
+    /// ```ignore
+    /// // SAFETY:
+    /// // This is not a valid safety comment
+    /// foo(
+    ///     /* SAFETY: Neither is this */ unsafe { *x },
+    /// );
+    /// ```
+    ///
     /// ### Why is this bad?
     /// Undocumented unsafe blocks can make it difficult to
     /// read and maintain code, as well as uncover unsoundness

tests/ui/undocumented_unsafe_blocks.rs

@@ -251,6 +251,11 @@ fn from_proc_macro() {
 
 // Invalid comments
 
+#[rustfmt::skip]
+fn inline_block_comment() {
+    /* Safety: */ unsafe {}
+}
+
 fn no_comment() {
     unsafe {}
 }

tests/ui/undocumented_unsafe_blocks.stderr

@@ -1,102 +1,110 @@
 error: unsafe block missing a safety comment
-  --> $DIR/undocumented_unsafe_blocks.rs:255:5
+  --> $DIR/undocumented_unsafe_blocks.rs:256:19
+   |
+LL |     /* Safety: */ unsafe {}
+   |                   ^^^^^^^^^
+   |
+   = note: `-D clippy::undocumented-unsafe-blocks` implied by `-D warnings`
+   = help: consider adding a safety comment on the preceding line
+
+error: unsafe block missing a safety comment
+  --> $DIR/undocumented_unsafe_blocks.rs:260:5
    |
 LL |     unsafe {}
    |     ^^^^^^^^^
    |
-   = note: `-D clippy::undocumented-unsafe-blocks` implied by `-D warnings`
    = help: consider adding a safety comment on the preceding line
 
 error: unsafe block missing a safety comment
-  --> $DIR/undocumented_unsafe_blocks.rs:259:14
+  --> $DIR/undocumented_unsafe_blocks.rs:264:14
    |
 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:259:29
+  --> $DIR/undocumented_unsafe_blocks.rs:264:29
    |
 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:259:48
+  --> $DIR/undocumented_unsafe_blocks.rs:264:48
    |
 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:263:18
+  --> $DIR/undocumented_unsafe_blocks.rs:268:18
    |
 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:263:37
+  --> $DIR/undocumented_unsafe_blocks.rs:268:37
    |
 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:267:14
+  --> $DIR/undocumented_unsafe_blocks.rs:272:14
    |
 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:272:19
+  --> $DIR/undocumented_unsafe_blocks.rs:277:19
    |
 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:278:14
+  --> $DIR/undocumented_unsafe_blocks.rs:283:14
    |
 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:282:14
+  --> $DIR/undocumented_unsafe_blocks.rs:287:14
    |
 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:286:13
+  --> $DIR/undocumented_unsafe_blocks.rs:291:13
    |
 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:296:8
+  --> $DIR/undocumented_unsafe_blocks.rs:301:8
    |
 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:302:13
+  --> $DIR/undocumented_unsafe_blocks.rs:307:13
    |
 LL |             unsafe {}
    |             ^^^^^^^^^
@@ -108,36 +116,36 @@ LL |     t!();
    = 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:310:5
+  --> $DIR/undocumented_unsafe_blocks.rs:315:5
    |
 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:314:5
+  --> $DIR/undocumented_unsafe_blocks.rs:319:5
    |
 LL |     unsafe {
    |     ^^^^^^^^
    |
    = help: consider adding a safety comment on the preceding line
 
 error: unsafe block missing a safety comment
-  --> $DIR/undocumented_unsafe_blocks.rs:324:5
+  --> $DIR/undocumented_unsafe_blocks.rs:329:5
    |
 LL |     unsafe {};
    |     ^^^^^^^^^
    |
    = help: consider adding a safety comment on the preceding line
 
 error: unsafe block missing a safety comment
-  --> $DIR/undocumented_unsafe_blocks.rs:328:20
+  --> $DIR/undocumented_unsafe_blocks.rs:333:20
    |
 LL |     println!("{}", unsafe { String::from_utf8_unchecked(vec![]) });
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding a safety comment on the preceding line
 
-error: aborting due to 17 previous errors
+error: aborting due to 18 previous errors