fix: Only special case single line item attribute suggestions

Author: Muscraft

compiler/rustc_errors/src/emitter.rs

@@ -2152,6 +2152,7 @@ impl HumanEmitter {
 
             let line_start = sm.lookup_char_pos(parts[0].original_span.lo()).line;
             let mut lines = complete.lines();
+            let lines_len = lines.clone().count();
             if lines.clone().next().is_none() {
                 // Account for a suggestion to completely remove a line(s) with whitespace (#94192).
                 let line_end = sm.lookup_char_pos(parts[0].original_span.hi()).line;
@@ -2192,6 +2193,7 @@ impl HumanEmitter {
                 if highlight_parts.len() == 1
                     && line.trim().starts_with("#[")
                     && line.trim().ends_with(']')
+                    && lines_len == 1
                 {
                     is_item_attribute = true;
                 }

src/tools/clippy/tests/ui/new_without_default.stderr

@@ -191,7 +191,6 @@ LL +     fn default() -> Self {
 LL +         Self::new()
 LL +     }
 LL + }
-LL | impl NewWithCfg {
    |
 
 error: you should consider adding a `Default` implementation for `NewWith2Cfgs`
@@ -212,7 +211,6 @@ LL +     fn default() -> Self {
 LL +         Self::new()
 LL +     }
 LL + }
-LL | impl NewWith2Cfgs {
    |
 
 error: you should consider adding a `Default` implementation for `NewWithExtraneous`
@@ -250,7 +248,6 @@ LL +     fn default() -> Self {
 LL +         Self::new()
 LL +     }
 LL + }
-LL | impl NewWithCfgAndExtraneous {
    |
 
 error: aborting due to 13 previous errors