diff --git a/tests/ui/excessive_precision.fixed b/tests/ui/excessive_precision.fixed
new file mode 100644
index 00000000000..1646dff9064
--- /dev/null
+++ b/tests/ui/excessive_precision.fixed
@@ -0,0 +1,63 @@
+// run-rustfix
+#![warn(clippy::excessive_precision)]
+#![allow(dead_code, unused_variables, clippy::print_literal)]
+
+fn main() {
+    // Consts
+    const GOOD32: f32 = 0.123_456;
+    const GOOD32_SM: f32 = 0.000_000_000_1;
+    const GOOD32_DOT: f32 = 10_000_000_000.0;
+    const GOOD32_EDGE: f32 = 1.000_000_8;
+    const GOOD64: f64 = 0.123_456_789_012;
+    const GOOD64_SM: f32 = 0.000_000_000_000_000_1;
+    const GOOD64_DOT: f32 = 10_000_000_000_000_000.0;
+
+    const BAD32_1: f32 = 0.123_456_79;
+    const BAD32_2: f32 = 0.123_456_79;
+    const BAD32_3: f32 = 0.1;
+    const BAD32_EDGE: f32 = 1.000_001;
+
+    const BAD64_1: f64 = 0.123_456_789_012_345_66;
+    const BAD64_2: f64 = 0.123_456_789_012_345_66;
+    const BAD64_3: f64 = 0.1;
+
+    // Literal as param
+    println!("{:?}", 8.888_888_888_888_89);
+
+    // // TODO add inferred type tests for f32
+    // Locals
+    let good32: f32 = 0.123_456_f32;
+    let good32_2: f32 = 0.123_456;
+
+    let good64: f64 = 0.123_456_789_012;
+    let good64_suf: f64 = 0.123_456_789_012f64;
+    let good64_inf = 0.123_456_789_012;
+
+    let bad32: f32 = 1.123_456_8;
+    let bad32_suf: f32 = 1.123_456_8;
+    let bad32_inf = 1.123_456_8;
+
+    let bad64: f64 = 0.123_456_789_012_345_66;
+    let bad64_suf: f64 = 0.123_456_789_012_345_66;
+    let bad64_inf = 0.123_456_789_012_345_66;
+
+    // Vectors
+    let good_vec32: Vec<f32> = vec![0.123_456];
+    let good_vec64: Vec<f64> = vec![0.123_456_789];
+
+    let bad_vec32: Vec<f32> = vec![0.123_456_79];
+    let bad_vec64: Vec<f64> = vec![0.123_456_789_123_456_78];
+
+    // Exponential float notation
+    let good_e32: f32 = 1e-10;
+    let bad_e32: f32 = 1.123_456_8e-10;
+
+    let good_bige32: f32 = 1E-10;
+    let bad_bige32: f32 = 1.123_456_8E-10;
+
+    // Inferred type
+    let good_inferred: f32 = 1f32 * 1_000_000_000.;
+
+    // issue #2840
+    let num = 0.000_000_000_01e-10f64;
+}
diff --git a/tests/ui/excessive_precision.rs b/tests/ui/excessive_precision.rs
index d5fa903c23f..ce4722a90f9 100644
--- a/tests/ui/excessive_precision.rs
+++ b/tests/ui/excessive_precision.rs
@@ -1,5 +1,6 @@
+// run-rustfix
 #![warn(clippy::excessive_precision)]
-#![allow(clippy::print_literal)]
+#![allow(dead_code, unused_variables, clippy::print_literal)]
 
 fn main() {
     // Consts
diff --git a/tests/ui/excessive_precision.stderr b/tests/ui/excessive_precision.stderr
index da8d9471bcc..12f8a61b75c 100644
--- a/tests/ui/excessive_precision.stderr
+++ b/tests/ui/excessive_precision.stderr
@@ -1,5 +1,5 @@
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:14:26
+  --> $DIR/excessive_precision.rs:15:26
    |
 LL |     const BAD32_1: f32 = 0.123_456_789_f32;
    |                          ^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_79`
@@ -7,103 +7,103 @@ LL |     const BAD32_1: f32 = 0.123_456_789_f32;
    = note: `-D clippy::excessive-precision` implied by `-D warnings`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:15:26
+  --> $DIR/excessive_precision.rs:16:26
    |
 LL |     const BAD32_2: f32 = 0.123_456_789;
    |                          ^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_79`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:16:26
+  --> $DIR/excessive_precision.rs:17:26
    |
 LL |     const BAD32_3: f32 = 0.100_000_000_000_1;
    |                          ^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.1`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:17:29
+  --> $DIR/excessive_precision.rs:18:29
    |
 LL |     const BAD32_EDGE: f32 = 1.000_000_9;
    |                             ^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.000_001`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:19:26
+  --> $DIR/excessive_precision.rs:20:26
    |
 LL |     const BAD64_1: f64 = 0.123_456_789_012_345_67f64;
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:20:26
+  --> $DIR/excessive_precision.rs:21:26
    |
 LL |     const BAD64_2: f64 = 0.123_456_789_012_345_67;
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:21:26
+  --> $DIR/excessive_precision.rs:22:26
    |
 LL |     const BAD64_3: f64 = 0.100_000_000_000_000_000_1;
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.1`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:24:22
+  --> $DIR/excessive_precision.rs:25:22
    |
 LL |     println!("{:?}", 8.888_888_888_888_888_888_888);
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `8.888_888_888_888_89`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:35:22
+  --> $DIR/excessive_precision.rs:36:22
    |
 LL |     let bad32: f32 = 1.123_456_789;
    |                      ^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:36:26
+  --> $DIR/excessive_precision.rs:37:26
    |
 LL |     let bad32_suf: f32 = 1.123_456_789_f32;
    |                          ^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:37:21
+  --> $DIR/excessive_precision.rs:38:21
    |
 LL |     let bad32_inf = 1.123_456_789_f32;
    |                     ^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:39:22
+  --> $DIR/excessive_precision.rs:40:22
    |
 LL |     let bad64: f64 = 0.123_456_789_012_345_67;
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:40:26
+  --> $DIR/excessive_precision.rs:41:26
    |
 LL |     let bad64_suf: f64 = 0.123_456_789_012_345_67f64;
    |                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:41:21
+  --> $DIR/excessive_precision.rs:42:21
    |
 LL |     let bad64_inf = 0.123_456_789_012_345_67;
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_012_345_66`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:47:36
+  --> $DIR/excessive_precision.rs:48:36
    |
 LL |     let bad_vec32: Vec<f32> = vec![0.123_456_789];
    |                                    ^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_79`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:48:36
+  --> $DIR/excessive_precision.rs:49:36
    |
 LL |     let bad_vec64: Vec<f64> = vec![0.123_456_789_123_456_789];
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `0.123_456_789_123_456_78`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:52:24
+  --> $DIR/excessive_precision.rs:53:24
    |
 LL |     let bad_e32: f32 = 1.123_456_788_888e-10;
    |                        ^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8e-10`
 
 error: float has excessive precision
-  --> $DIR/excessive_precision.rs:55:27
+  --> $DIR/excessive_precision.rs:56:27
    |
 LL |     let bad_bige32: f32 = 1.123_456_788_888E-10;
    |                           ^^^^^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8E-10`