fix suggestion error with attr macros

Author: J-ZhengLi

clippy_lints/src/semicolon_if_nothing_returned.rs

@@ -5,6 +5,7 @@ use rustc_errors::Applicability;
 use rustc_hir::{Block, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
+use rustc_span::{ExpnKind, MacroKind, Span};
 
 declare_clippy_lint! {
     /// ### What it does
@@ -39,6 +40,7 @@ impl<'tcx> LateLintPass<'tcx> for SemicolonIfNothingReturned {
     fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) {
         if !block.span.from_expansion()
             && let Some(expr) = block.expr
+            && !from_attr_macro(expr.span)
             && let t_expr = cx.typeck_results().expr_ty(expr)
             && t_expr.is_unit()
             && let mut app = Applicability::MachineApplicable
@@ -63,3 +65,7 @@ impl<'tcx> LateLintPass<'tcx> for SemicolonIfNothingReturned {
         }
     }
 }
+
+fn from_attr_macro(span: Span) -> bool {
+    matches!(span.ctxt().outer_expn_data().kind, ExpnKind::Macro(MacroKind::Attr, _))
+}

tests/ui/semicolon_if_nothing_returned.fixed

@@ -129,19 +129,26 @@ fn let_else_stmts() {
 mod issue12123 {
     #[rustfmt::skip]
     mod this_triggers {
-        #[fake_main];
+        #[fake_main]
         async fn main() {
-            
+
         }
     }
 
     mod and_this {
-        #[fake_main];
+        #[fake_main]
         async fn main() {
             println!("hello");
         }
     }
 
+    #[rustfmt::skip]
+    mod maybe_this {
+        /** */ #[fake_main]
+        async fn main() {
+        }
+    }
+
     mod but_this_does_not {
         #[fake_main]
         async fn main() {}

tests/ui/semicolon_if_nothing_returned.rs

@@ -131,7 +131,7 @@ mod issue12123 {
     mod this_triggers {
         #[fake_main]
         async fn main() {
-            
+
         }
     }
 
@@ -142,6 +142,13 @@ mod issue12123 {
         }
     }
 
+    #[rustfmt::skip]
+    mod maybe_this {
+        /** */ #[fake_main]
+        async fn main() {
+        }
+    }
+
     mod but_this_does_not {
         #[fake_main]
         async fn main() {}

tests/ui/semicolon_if_nothing_returned.stderr

@@ -31,17 +31,5 @@ error: consider adding a `;` to the last statement for consistent formatting
 LL |         ptr::drop_in_place(s.as_mut_ptr())
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: add a `;` here: `ptr::drop_in_place(s.as_mut_ptr());`
 
-error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:132:9
-   |
-LL |         #[fake_main]
-   |         ^^^^^^^^^^^^ help: add a `;` here: `#[fake_main];`
-
-error: consider adding a `;` to the last statement for consistent formatting
-  --> $DIR/semicolon_if_nothing_returned.rs:139:9
-   |
-LL |         #[fake_main]
-   |         ^^^^^^^^^^^^ help: add a `;` here: `#[fake_main];`
-
-error: aborting due to 7 previous errors
+error: aborting due to 5 previous errors