Print unsafety of attribute in AST pretty print

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -627,6 +627,13 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
 
     fn print_attr_item(&mut self, item: &ast::AttrItem, span: Span) {
         self.ibox(0);
+        match item.unsafety {
+            ast::Safety::Unsafe(_) => {
+                self.word("unsafe");
+                self.popen();
+            }
+            ast::Safety::Default | ast::Safety::Safe(_) => {}
+        }
         match &item.args {
             AttrArgs::Delimited(DelimArgs { dspan: _, delim, tokens }) => self.print_mac_common(
                 Some(MacHeader::Path(&item.path)),
@@ -655,6 +662,10 @@ pub trait PrintState<'a>: std::ops::Deref<Target = pp::Printer> + std::ops::Dere
                 self.word(token_str);
             }
         }
+        match item.unsafety {
+            ast::Safety::Unsafe(_) => self.pclose(),
+            ast::Safety::Default | ast::Safety::Safe(_) => {}
+        }
         self.end();
     }
 

tests/ui/unpretty/unsafe-attr.rs

@@ -0,0 +1,11 @@
+//@ compile-flags: -Zunpretty=normal
+//@ check-pass
+
+#[no_mangle]
+extern "C" fn foo() {}
+
+#[unsafe(no_mangle)]
+extern "C" fn bar() {}
+
+#[cfg_attr(FALSE, unsafe(no_mangle))]
+extern "C" fn zoo() {}

tests/ui/unpretty/unsafe-attr.stdout

@@ -0,0 +1,11 @@
+//@ compile-flags: -Zunpretty=normal
+//@ check-pass
+
+#[no_mangle]
+extern "C" fn foo() {}
+
+#[unsafe(no_mangle)]
+extern "C" fn bar() {}
+
+#[cfg_attr(FALSE, unsafe(no_mangle))]
+extern "C" fn zoo() {}