Fix rust-lang/rust#79255 - Incorrect try suggestion for unnecessary float literal cast ending in dot

Author: nico-abram

clippy_lints/src/types.rs

@@ -1711,7 +1711,7 @@ fn show_unnecessary_cast(cx: &LateContext<'_>, expr: &Expr<'_>, literal_str: &st
         expr.span,
         &format!("casting {} literal to `{}` is unnecessary", literal_kind_name, cast_to),
         "try",
-        format!("{}_{}", literal_str, cast_to),
+        format!("{}_{}", literal_str.trim_end_matches('.'), cast_to),
         Applicability::MachineApplicable,
     );
 }

tests/ui/unnecessary_cast_fixable.fixed

@@ -11,6 +11,8 @@ fn main() {
     let _ = -100_f32;
     let _ = -100_f64;
     let _ = -100_f64;
+    100_f32;
+    100_f64;
     // Should not trigger
     #[rustfmt::skip]
     let v = vec!(1);

tests/ui/unnecessary_cast_fixable.rs

@@ -11,6 +11,8 @@ fn main() {
     let _ = -100 as f32;
     let _ = -100 as f64;
     let _ = -100_i32 as f64;
+    100. as f32;
+    100. as f64;
     // Should not trigger
     #[rustfmt::skip]
     let v = vec!(1);

tests/ui/unnecessary_cast_fixable.stderr

@@ -36,59 +36,71 @@ error: casting integer literal to `f64` is unnecessary
 LL |     let _ = -100_i32 as f64;
    |             ^^^^^^^^^^^^^^^ help: try: `-100_f64`
 
+error: casting float literal to `f32` is unnecessary
+  --> $DIR/unnecessary_cast_fixable.rs:14:5
+   |
+LL |     100. as f32;
+   |     ^^^^^^^^^^^ help: try: `100_f32`
+
+error: casting float literal to `f64` is unnecessary
+  --> $DIR/unnecessary_cast_fixable.rs:15:5
+   |
+LL |     100. as f64;
+   |     ^^^^^^^^^^^ help: try: `100_f64`
+
 error: casting integer literal to `u32` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:25:5
+  --> $DIR/unnecessary_cast_fixable.rs:27:5
    |
 LL |     1 as u32;
    |     ^^^^^^^^ help: try: `1_u32`
 
 error: casting integer literal to `i32` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:26:5
+  --> $DIR/unnecessary_cast_fixable.rs:28:5
    |
 LL |     0x10 as i32;
    |     ^^^^^^^^^^^ help: try: `0x10_i32`
 
 error: casting integer literal to `usize` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:27:5
+  --> $DIR/unnecessary_cast_fixable.rs:29:5
    |
 LL |     0b10 as usize;
    |     ^^^^^^^^^^^^^ help: try: `0b10_usize`
 
 error: casting integer literal to `u16` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:28:5
+  --> $DIR/unnecessary_cast_fixable.rs:30:5
    |
 LL |     0o73 as u16;
    |     ^^^^^^^^^^^ help: try: `0o73_u16`
 
 error: casting integer literal to `u32` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:29:5
+  --> $DIR/unnecessary_cast_fixable.rs:31:5
    |
 LL |     1_000_000_000 as u32;
    |     ^^^^^^^^^^^^^^^^^^^^ help: try: `1_000_000_000_u32`
 
 error: casting float literal to `f64` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:31:5
+  --> $DIR/unnecessary_cast_fixable.rs:33:5
    |
 LL |     1.0 as f64;
    |     ^^^^^^^^^^ help: try: `1.0_f64`
 
 error: casting float literal to `f32` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:32:5
+  --> $DIR/unnecessary_cast_fixable.rs:34:5
    |
 LL |     0.5 as f32;
    |     ^^^^^^^^^^ help: try: `0.5_f32`
 
 error: casting integer literal to `i32` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:36:13
+  --> $DIR/unnecessary_cast_fixable.rs:38:13
    |
 LL |     let _ = -1 as i32;
    |             ^^^^^^^^^ help: try: `-1_i32`
 
 error: casting float literal to `f32` is unnecessary
-  --> $DIR/unnecessary_cast_fixable.rs:37:13
+  --> $DIR/unnecessary_cast_fixable.rs:39:13
    |
 LL |     let _ = -1.0 as f32;
    |             ^^^^^^^^^^^ help: try: `-1.0_f32`
 
-error: aborting due to 15 previous errors
+error: aborting due to 17 previous errors