Propagate accept-comment-above-attributes to statements (rust-lang#15213)

Turns out that things like `#[attr]return unsafe { func(); }` didn't
work because we weren't checking above attributes on statements, only on
blocks!

fixes rust-lang/rust-clippy#13189

Useful for Rust-For-Linux

changelog:[`undocumented_unsafe_blocks`]: Make sure to propagate
`accept-comment-above-attributes` to **all** statements.

Author: samueltardieu

clippy_lints/src/undocumented_unsafe_blocks.rs

@@ -143,7 +143,8 @@ impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks {
         if let Some(tail) = block.expr
             && !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, tail.hir_id)
             && !tail.span.in_external_macro(cx.tcx.sess.source_map())
-            && let HasSafetyComment::Yes(pos) = stmt_has_safety_comment(cx, tail.span, tail.hir_id)
+            && let HasSafetyComment::Yes(pos) =
+                stmt_has_safety_comment(cx, tail.span, tail.hir_id, self.accept_comment_above_attributes)
             && let Some(help_span) = expr_has_unnecessary_safety_comment(cx, tail, pos)
         {
             span_lint_and_then(
@@ -167,7 +168,8 @@ impl<'tcx> LateLintPass<'tcx> for UndocumentedUnsafeBlocks {
         };
         if !is_lint_allowed(cx, UNNECESSARY_SAFETY_COMMENT, stmt.hir_id)
             && !stmt.span.in_external_macro(cx.tcx.sess.source_map())
-            && let HasSafetyComment::Yes(pos) = stmt_has_safety_comment(cx, stmt.span, stmt.hir_id)
+            && let HasSafetyComment::Yes(pos) =
+                stmt_has_safety_comment(cx, stmt.span, stmt.hir_id, self.accept_comment_above_attributes)
             && let Some(help_span) = expr_has_unnecessary_safety_comment(cx, expr, pos)
         {
             span_lint_and_then(
@@ -534,7 +536,12 @@ fn item_has_safety_comment(cx: &LateContext<'_>, item: &hir::Item<'_>) -> HasSaf
 
 /// Checks if the lines immediately preceding the item contain a safety comment.
 #[allow(clippy::collapsible_match)]
-fn stmt_has_safety_comment(cx: &LateContext<'_>, span: Span, hir_id: HirId) -> HasSafetyComment {
+fn stmt_has_safety_comment(
+    cx: &LateContext<'_>,
+    span: Span,
+    hir_id: HirId,
+    accept_comment_above_attributes: bool,
+) -> HasSafetyComment {
     match span_from_macro_expansion_has_safety_comment(cx, span) {
         HasSafetyComment::Maybe => (),
         has_safety_comment => return has_safety_comment,
@@ -549,6 +556,13 @@ fn stmt_has_safety_comment(cx: &LateContext<'_>, span: Span, hir_id: HirId) -> H
         _ => return HasSafetyComment::Maybe,
     };
 
+    // if span_with_attrs_has_safety_comment(cx, span, hir_id, accept_comment_above_attrib
+    // }
+    let mut span = span;
+    if accept_comment_above_attributes {
+        span = include_attrs_in_span(cx, hir_id, span);
+    }
+
     let source_map = cx.sess().source_map();
     if let Some(comment_start) = comment_start
         && let Ok(unsafe_line) = source_map.lookup_line(span.lo())

tests/ui-toml/undocumented_unsafe_blocks/undocumented_unsafe_blocks.disabled.stderr

@@ -450,5 +450,13 @@ help: consider removing the safety comment
 LL |     // SAFETY: unnecessary_safety_comment triggers here
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 52 previous errors
+error: unsafe block missing a safety comment
+  --> tests/ui-toml/undocumented_unsafe_blocks/undocumented_unsafe_blocks.rs:733:12
+   |
+LL |     return unsafe { h() };
+   |            ^^^^^^^^^^^^^^
+   |
+   = help: consider adding a safety comment on the preceding line
+
+error: aborting due to 53 previous errors
 

tests/ui-toml/undocumented_unsafe_blocks/undocumented_unsafe_blocks.rs

@@ -723,4 +723,15 @@ fn issue_13039() {
     _ = unsafe { foo() }
 }
 
+fn rfl_issue15034() -> i32 {
+    unsafe fn h() -> i32 {
+        1i32
+    }
+    // This shouldn't lint with accept-comment-above-attributes! Thus fixing a false positive!
+    // SAFETY: My safety comment!
+    #[allow(clippy::unnecessary_cast)]
+    return unsafe { h() };
+    //~[disabled]^ ERROR: unsafe block missing a safety comment
+}
+
 fn main() {}