Make attr template suggestions preserve attribute safety.

Author: ariagivens

compiler/rustc_feature/src/builtin_attrs.rs

@@ -135,23 +135,23 @@ impl AttributeTemplate {
 
         if self.word {
             debug_assert!(macro_call.is_empty(), "Macro suggestions use list style");
-            suggestions.push(format!("{maybe_unsafe_start}{start}{name}{end}{maybe_unsafe_end}"));
+            suggestions.push(format!("{start}{maybe_unsafe_start}{name}{maybe_unsafe_end}{end}"));
         }
         if let Some(descr) = self.list {
             for descr in descr {
                 suggestions.push(format!(
-                    "{maybe_unsafe_start}{start}{name}{macro_call}({descr}){end}{maybe_unsafe_end}"
+                    "{start}{maybe_unsafe_start}{name}{macro_call}({descr}){maybe_unsafe_end}{end}"
                 ));
             }
         }
         suggestions.extend(self.one_of.iter().map(|&word| {
-            format!("{maybe_unsafe_start}{start}{name}({word}){end}{maybe_unsafe_end}")
+            format!("{start}{maybe_unsafe_start}{name}({word}){maybe_unsafe_end}{end}")
         }));
         if let Some(descr) = self.name_value_str {
             debug_assert!(macro_call.is_empty(), "Macro suggestions use list style");
             for descr in descr {
                 suggestions.push(format!(
-                    "{maybe_unsafe_start}{start}{name} = \"{descr}\"{end}{maybe_unsafe_end}"
+                    "{start}{maybe_unsafe_start}{name} = \"{descr}\"{maybe_unsafe_end}{end}"
                 ));
             }
         }

tests/ui/attributes/malformed-attrs.stderr

@@ -159,9 +159,8 @@ LL | #[unsafe(export_name)]
    |
 help: must be of the form
    |
-LL - #[unsafe(export_name)]
-LL + #[export_name = "name"]
-   |
+LL | #[unsafe(export_name = "name")]
+   |                      ++++++++
 
 error: `rustc_allow_const_fn_unstable` expects a list of feature names
   --> $DIR/malformed-attrs.rs:31:1
@@ -330,7 +329,7 @@ LL | #[unsafe(naked())]
 help: must be of the form
    |
 LL - #[unsafe(naked())]
-LL + #[naked]
+LL + #[unsafe(naked)]
    |
 
 error[E0565]: malformed `track_caller` attribute input
@@ -651,7 +650,7 @@ LL |     #[unsafe(ffi_pure = 1)]
 help: must be of the form
    |
 LL -     #[unsafe(ffi_pure = 1)]
-LL +     #[ffi_pure]
+LL +     #[unsafe(ffi_pure)]
    |
 
 error[E0539]: malformed `link_ordinal` attribute input
@@ -677,7 +676,7 @@ LL |     #[unsafe(ffi_const = 1)]
 help: must be of the form
    |
 LL -     #[unsafe(ffi_const = 1)]
-LL +     #[ffi_const]
+LL +     #[unsafe(ffi_const)]
    |
 
 error[E0539]: malformed `linkage` attribute input