Keep original literal notation in suggestion

clippy_lints/src/unused_rounding.rs

@@ -36,7 +36,7 @@ fn is_useless_rounding(expr: &Expr) -> Option<(&str, String)> {
         && let ExprKind::Lit(spanned) = &receiver.kind
         && let LitKind::Float(symbol, ty) = spanned.kind {
             let f = symbol.as_str().parse::<f64>().unwrap();
-            let f_str = symbol.to_string() + if let LitFloatType::Suffixed(ty) = ty {
+            let f_str = spanned.token_lit.symbol.to_string() + if let LitFloatType::Suffixed(ty) = ty {
                 ty.name_str()
             } else {
                 ""

tests/ui/unused_rounding.fixed

@@ -6,4 +6,9 @@ fn main() {
     let _ = 1.0f64;
     let _ = 1.00f32;
     let _ = 2e-54f64.floor();
+
+    // issue9866
+    let _ = 3.3_f32.round();
+    let _ = 3.3_f64.round();
+    let _ = 3.0_f32;
 }

tests/ui/unused_rounding.rs

@@ -6,4 +6,9 @@ fn main() {
     let _ = 1.0f64.floor();
     let _ = 1.00f32.round();
     let _ = 2e-54f64.floor();
+
+    // issue9866
+    let _ = 3.3_f32.round();
+    let _ = 3.3_f64.round();
+    let _ = 3.0_f32.round();
 }

tests/ui/unused_rounding.stderr

@@ -18,5 +18,11 @@ error: used the `round` method with a whole number float
 LL |     let _ = 1.00f32.round();
    |             ^^^^^^^^^^^^^^^ help: remove the `round` method call: `1.00f32`
 
-error: aborting due to 3 previous errors
+error: used the `round` method with a whole number float
+  --> $DIR/unused_rounding.rs:13:13
+   |
+LL |     let _ = 3.0_f32.round();
+   |             ^^^^^^^^^^^^^^^ help: remove the `round` method call: `3.0_f32`
+
+error: aborting due to 4 previous errors