Tweak non_shorthand_field_patterns' suggestion

src/librustc_lint/builtin.rs

@@ -174,18 +174,27 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
                     // (Issue #49588)
                     continue;
                 }
-                if let PatKind::Binding(_, _, ident, None) = fieldpat.pat.kind {
+                if let PatKind::Binding(binding_annot, _, ident, None) = fieldpat.pat.kind {
                     if cx.tcx.find_field_index(ident, &variant) ==
                        Some(cx.tcx.field_index(fieldpat.hir_id, cx.tables)) {
                         let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
                                      fieldpat.span,
                                      &format!("the `{}:` in this pattern is redundant", ident));
-                        let subspan = cx.tcx.sess.source_map().span_through_char(fieldpat.span,
-                                                                                 ':');
-                        err.span_suggestion_short(
-                            subspan,
-                            "remove this",
-                            ident.to_string(),
+                        let binding = match binding_annot {
+                            hir::BindingAnnotation::Unannotated => None,
+                            hir::BindingAnnotation::Mutable => Some("mut"),
+                            hir::BindingAnnotation::Ref => Some("ref"),
+                            hir::BindingAnnotation::RefMut => Some("ref mut"),
+                        };
+                        let ident = if let Some(binding) = binding {
+                            format!("{} {}", binding, ident)
+                        } else {
+                            ident.to_string()
+                        };
+                        err.span_suggestion(
+                            fieldpat.span,
+                            "use shorthand field pattern",
+                            ident,
                             Applicability::MachineApplicable
                         );
                         err.emit();

src/test/ui/lint/lint-shorthand-field.fixed

@@ -0,0 +1,70 @@
+// run-rustfix
+
+#![allow(nonstandard_style, unused_variables, unused_mut)]
+#![deny(non_shorthand_field_patterns)]
+
+struct Foo {
+    x: isize,
+    y: isize,
+}
+
+fn main() {
+    {
+        let Foo {
+            x, //~ ERROR the `x:` in this pattern is redundant
+            ref y, //~ ERROR the `y:` in this pattern is redundant
+        } = Foo { x: 0, y: 0 };
+
+        let Foo {
+            x,
+            ref y,
+        } = Foo { x: 0, y: 0 };
+    }
+
+    {
+        const x: isize = 1;
+
+        match (Foo { x: 1, y: 1 }) {
+            Foo { x: x, ..} => {},
+            _ => {},
+        }
+    }
+
+    {
+        struct Bar {
+            x: x,
+        }
+
+        struct x;
+
+        match (Bar { x: x }) {
+            Bar { x: x } => {},
+        }
+    }
+
+    {
+        struct Bar {
+            x: Foo,
+        }
+
+        enum Foo { x }
+
+        match (Bar { x: Foo::x }) {
+            Bar { x: Foo::x } => {},
+        }
+    }
+
+    {
+        struct Baz {
+            x: isize,
+            y: isize,
+            z: isize,
+        }
+
+        let Baz {
+            mut x, //~ ERROR the `x:` in this pattern is redundant
+            ref y, //~ ERROR the `y:` in this pattern is redundant
+            ref mut z, //~ ERROR the `z:` in this pattern is redundant
+        } = Baz { x: 0, y: 0, z: 0 };
+    }
+}

src/test/ui/lint/lint-shorthand-field.rs

@@ -1,4 +1,6 @@
-#![allow(nonstandard_style, unused_variables)]
+// run-rustfix
+
+#![allow(nonstandard_style, unused_variables, unused_mut)]
 #![deny(non_shorthand_field_patterns)]
 
 struct Foo {
@@ -51,4 +53,18 @@ fn main() {
             Bar { x: Foo::x } => {},
         }
     }
+
+    {
+        struct Baz {
+            x: isize,
+            y: isize,
+            z: isize,
+        }
+
+        let Baz {
+            x: mut x, //~ ERROR the `x:` in this pattern is redundant
+            y: ref y, //~ ERROR the `y:` in this pattern is redundant
+            z: ref mut z, //~ ERROR the `z:` in this pattern is redundant
+        } = Baz { x: 0, y: 0, z: 0 };
+    }
 }

src/test/ui/lint/lint-shorthand-field.stderr

@@ -1,24 +1,38 @@
 error: the `x:` in this pattern is redundant
-  --> $DIR/lint-shorthand-field.rs:12:13
+  --> $DIR/lint-shorthand-field.rs:14:13
    |
 LL |             x: x,
-   |             --^^
-   |             |
-   |             help: remove this
+   |             ^^^^ help: use shorthand field pattern: `x`
    |
 note: lint level defined here
-  --> $DIR/lint-shorthand-field.rs:2:9
+  --> $DIR/lint-shorthand-field.rs:4:9
    |
 LL | #![deny(non_shorthand_field_patterns)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: the `y:` in this pattern is redundant
-  --> $DIR/lint-shorthand-field.rs:13:13
+  --> $DIR/lint-shorthand-field.rs:15:13
    |
 LL |             y: ref y,
-   |             --^^^^^^
-   |             |
-   |             help: remove this
+   |             ^^^^^^^^ help: use shorthand field pattern: `ref y`
 
-error: aborting due to 2 previous errors
+error: the `x:` in this pattern is redundant
+  --> $DIR/lint-shorthand-field.rs:65:13
+   |
+LL |             x: mut x,
+   |             ^^^^^^^^ help: use shorthand field pattern: `mut x`
+
+error: the `y:` in this pattern is redundant
+  --> $DIR/lint-shorthand-field.rs:66:13
+   |
+LL |             y: ref y,
+   |             ^^^^^^^^ help: use shorthand field pattern: `ref y`
+
+error: the `z:` in this pattern is redundant
+  --> $DIR/lint-shorthand-field.rs:67:13
+   |
+LL |             z: ref mut z,
+   |             ^^^^^^^^^^^^ help: use shorthand field pattern: `ref mut z`
+
+error: aborting due to 5 previous errors
 

src/test/ui/lint/suggestions.rs

@@ -60,7 +60,7 @@ fn main() {
         match d {
             Equinox { warp_factor: warp_factor } => {}
             //~^ WARN this pattern is redundant
-            //~| HELP remove this
+            //~| HELP use shorthand field pattern
         }
         println!("{} {}", registry_no, b);
     }

src/test/ui/lint/suggestions.stderr

@@ -77,9 +77,7 @@ warning: the `warp_factor:` in this pattern is redundant
   --> $DIR/suggestions.rs:61:23
    |
 LL |             Equinox { warp_factor: warp_factor } => {}
-   |                       ------------^^^^^^^^^^^^
-   |                       |
-   |                       help: remove this
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^ help: use shorthand field pattern: `warp_factor`
    |
    = note: `#[warn(non_shorthand_field_patterns)]` on by default