From e63d69244e6f0d1463cea210445cb46f59cd9f83 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sat, 25 Sep 2021 22:54:08 -0700
Subject: [PATCH] Stop suggesting a float truncation that is not shorter

---
 clippy_lints/src/float_literal.rs   |  2 +-
 tests/ui/excessive_precision.fixed  | 10 ++++-----
 tests/ui/excessive_precision.stderr | 32 +----------------------------
 3 files changed, 7 insertions(+), 37 deletions(-)

diff --git a/clippy_lints/src/float_literal.rs b/clippy_lints/src/float_literal.rs
index a3d70f31f00..1e8a5bd7d34 100644
--- a/clippy_lints/src/float_literal.rs
+++ b/clippy_lints/src/float_literal.rs
@@ -111,7 +111,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
                             Applicability::MachineApplicable,
                         );
                     }
-                } else if digits > max as usize && sym_str != float_str {
+                } else if digits > max as usize && float_str.len() < sym_str.len() {
                     span_lint_and_sugg(
                         cx,
                         EXCESSIVE_PRECISION,
diff --git a/tests/ui/excessive_precision.fixed b/tests/ui/excessive_precision.fixed
index bf0325fec79..90376620a9f 100644
--- a/tests/ui/excessive_precision.fixed
+++ b/tests/ui/excessive_precision.fixed
@@ -17,8 +17,8 @@ fn main() {
     const BAD32_3: f32 = 0.1;
     const BAD32_EDGE: f32 = 1.000_001;
 
-    const BAD64_1: f64 = 0.123_456_789_012_345_66_f64;
-    const BAD64_2: f64 = 0.123_456_789_012_345_66;
+    const BAD64_1: f64 = 0.123_456_789_012_345_67f64;
+    const BAD64_2: f64 = 0.123_456_789_012_345_67;
     const BAD64_3: f64 = 0.1;
 
     // Literal as param
@@ -37,9 +37,9 @@ fn main() {
     let bad32_suf: f32 = 1.123_456_8_f32;
     let bad32_inf = 1.123_456_8_f32;
 
-    let bad64: f64 = 0.123_456_789_012_345_66;
-    let bad64_suf: f64 = 0.123_456_789_012_345_66_f64;
-    let bad64_inf = 0.123_456_789_012_345_66;
+    let bad64: f64 = 0.123_456_789_012_345_67;
+    let bad64_suf: f64 = 0.123_456_789_012_345_67f64;
+    let bad64_inf = 0.123_456_789_012_345_67;
 
     // Vectors
     let good_vec32: Vec<f32> = vec![0.123_456];
diff --git a/tests/ui/excessive_precision.stderr b/tests/ui/excessive_precision.stderr
index 599773f2f70..e59c20c30b4 100644
--- a/tests/ui/excessive_precision.stderr
+++ b/tests/ui/excessive_precision.stderr
@@ -24,18 +24,6 @@ error: float has excessive precision
 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: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_f64`
-
-error: float has excessive precision
-  --> $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:22:26
    |
@@ -66,24 +54,6 @@ error: float has excessive precision
 LL |     let bad32_inf = 1.123_456_789_f32;
    |                     ^^^^^^^^^^^^^^^^^ help: consider changing the type or truncating it to: `1.123_456_8_f32`
 
-error: float has excessive precision
-  --> $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: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_f64`
-
-error: float has excessive precision
-  --> $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:48:36
    |
@@ -108,5 +78,5 @@ error: float has excessive precision
 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`
 
-error: aborting due to 18 previous errors
+error: aborting due to 13 previous errors