Auto merge of rust-lang#6611 - pastchick3:master, r=flip1995

Fix the reversed suggestion message of `stable_sort_primitive`.

Now Clippy emits `stable_sort_primitive` warning as follows:

```
warning: used sort instead of sort_unstable to sort primitive type `usize`
  --> src\asm.rs:41:13
   |
41 |             self.successors.sort();
   |             ^^^^^^^^^^^^^^^^^^^^^^ help: try: `self.successors.sort_unstable()`
   |
   = note: `#[warn(clippy::stable_sort_primitive)]` on by default
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#stable_sort_primitive
```

I think the position of `sort` and `sort_unstable` in the first line should be reversed.

changelog: Fix the reversed suggestion message of `stable_sort_primitive`.

Author: bors

clippy_lints/src/stable_sort_primitive.rs

@@ -1,4 +1,4 @@
-use crate::utils::{is_slice_of_primitives, span_lint_and_sugg, sugg::Sugg};
+use crate::utils::{is_slice_of_primitives, span_lint_and_then, sugg::Sugg};
 
 use if_chain::if_chain;
 
@@ -107,25 +107,32 @@ fn detect_stable_sort_primitive(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option
 impl LateLintPass<'_> for StableSortPrimitive {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
         if let Some(detection) = detect_stable_sort_primitive(cx, expr) {
-            span_lint_and_sugg(
+            span_lint_and_then(
                 cx,
                 STABLE_SORT_PRIMITIVE,
                 expr.span,
                 format!(
-                    "used {} instead of {} to sort primitive type `{}`",
+                    "used `{}` on primitive type `{}`",
                     detection.method.stable_name(),
-                    detection.method.unstable_name(),
                     detection.slice_type,
                 )
                 .as_str(),
-                "try",
-                format!(
-                    "{}.{}({})",
-                    detection.slice_name,
-                    detection.method.unstable_name(),
-                    detection.method_args
-                ),
-                Applicability::MachineApplicable,
+                |diag| {
+                    diag.span_suggestion(
+                        expr.span,
+                        "try",
+                        format!(
+                            "{}.{}({})",
+                            detection.slice_name,
+                            detection.method.unstable_name(),
+                            detection.method_args,
+                        ),
+                        Applicability::MachineApplicable,
+                    );
+                    diag.note(
+                        "an unstable sort would perform faster without any observable difference for this data type",
+                    );
+                },
             );
         }
     }

tests/ui/stable_sort_primitive.stderr

@@ -1,46 +1,59 @@
-error: used sort instead of sort_unstable to sort primitive type `i32`
+error: used `sort` on primitive type `i32`
   --> $DIR/stable_sort_primitive.rs:7:5
    |
 LL |     vec.sort();
    |     ^^^^^^^^^^ help: try: `vec.sort_unstable()`
    |
    = note: `-D clippy::stable-sort-primitive` implied by `-D warnings`
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
-error: used sort instead of sort_unstable to sort primitive type `bool`
+error: used `sort` on primitive type `bool`
   --> $DIR/stable_sort_primitive.rs:9:5
    |
 LL |     vec.sort();
    |     ^^^^^^^^^^ help: try: `vec.sort_unstable()`
+   |
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
-error: used sort instead of sort_unstable to sort primitive type `char`
+error: used `sort` on primitive type `char`
   --> $DIR/stable_sort_primitive.rs:11:5
    |
 LL |     vec.sort();
    |     ^^^^^^^^^^ help: try: `vec.sort_unstable()`
+   |
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
-error: used sort instead of sort_unstable to sort primitive type `str`
+error: used `sort` on primitive type `str`
   --> $DIR/stable_sort_primitive.rs:13:5
    |
 LL |     vec.sort();
    |     ^^^^^^^^^^ help: try: `vec.sort_unstable()`
+   |
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
-error: used sort instead of sort_unstable to sort primitive type `tuple`
+error: used `sort` on primitive type `tuple`
   --> $DIR/stable_sort_primitive.rs:15:5
    |
 LL |     vec.sort();
    |     ^^^^^^^^^^ help: try: `vec.sort_unstable()`
+   |
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
-error: used sort instead of sort_unstable to sort primitive type `array`
+error: used `sort` on primitive type `array`
   --> $DIR/stable_sort_primitive.rs:17:5
    |
 LL |     vec.sort();
    |     ^^^^^^^^^^ help: try: `vec.sort_unstable()`
+   |
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
-error: used sort instead of sort_unstable to sort primitive type `i32`
+error: used `sort` on primitive type `i32`
   --> $DIR/stable_sort_primitive.rs:19:5
    |
 LL |     arr.sort();
    |     ^^^^^^^^^^ help: try: `arr.sort_unstable()`
+   |
+   = note: an unstable sort would perform faster without any observable difference for this data type
 
 error: aborting due to 7 previous errors