ignore multiline cases

Author: nyurik

clippy_lints/src/format_args.rs

@@ -337,11 +337,12 @@ impl<'tcx> FormatArgsExpr<'_, 'tcx> {
     fn check_trailing_comma(&self) {
         let span = self.macro_call.span;
         if let Some(src) = span.get_source_text(self.cx)
+            && !src.contains('\n')
             && let Some(src) = src.strip_suffix([')', ']', '}'])
-            && let src = src.trim_end_matches(|c: char| c.is_whitespace() && c != '\n')
+            && let src = src.trim_end_matches(|c: char| c.is_whitespace())
             && let Some(src) = src.strip_suffix(',')
         {
-            let src = src.trim_end_matches(|c: char| c.is_whitespace() && c != '\n');
+            let src = src.trim_end_matches(|c: char| c.is_whitespace());
             span_lint_and_sugg(
                 self.cx,
                 UNNECESSARY_TRAILING_COMMA,

tests/ui/unnecessary_trailing_comma.fixed

@@ -62,6 +62,10 @@ fn simple() {
         "very long string to prevent fmt from making it into a single line: {}",
         1,
     );
+
+    print!("{}"
+        , 1
+        ,);
 }
 
 // The macro invocation itself should never be fixed

tests/ui/unnecessary_trailing_comma.rs

@@ -62,6 +62,10 @@ fn simple() {
         "very long string to prevent fmt from making it into a single line: {}",
         1,
     );
+
+    print!("{}"
+        , 1
+        ,);
 }
 
 // The macro invocation itself should never be fixed