Signal the problem on the whole expression span

This is more consistent with what other lints are doing: the use of
`default` to create a unit struct is the whole expression.

Author: samueltardieu

Diff for: clippy_lints/src/default_constructed_unit_structs.rs

@@ -1,5 +1,6 @@
-use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::is_ty_alias;
+use clippy_utils::sugg::DiagExt as _;
 use hir::ExprKind;
 use hir::def::Res;
 use rustc_errors::Applicability;
@@ -73,14 +74,19 @@ impl LateLintPass<'_> for DefaultConstructedUnitStructs {
             // do not suggest replacing an expression by a type name with placeholders
             && !base.is_suggestable_infer_ty()
         {
-            span_lint_and_sugg(
+            span_lint_and_then(
                 cx,
                 DEFAULT_CONSTRUCTED_UNIT_STRUCTS,
-                expr.span.with_lo(qpath.qself_span().hi()),
+                expr.span,
                 "use of `default` to create a unit struct",
-                "remove this call to `default`",
-                String::new(),
-                Applicability::MachineApplicable,
+                |diag| {
+                    diag.suggest_remove_item(
+                        cx,
+                        expr.span.with_lo(qpath.qself_span().hi()),
+                        "remove this call to `default`",
+                        Applicability::MachineApplicable,
+                    );
+                },
             );
         }
     }

Diff for: tests/ui/default_constructed_unit_structs.fixed

@@ -8,8 +8,7 @@ struct UnitStruct;
 impl UnitStruct {
     fn new() -> Self {
         //should lint
-        Self
-        //~^ default_constructed_unit_structs
+        Self//~^ default_constructed_unit_structs
     }
 }
 

Diff for: tests/ui/default_constructed_unit_structs.stderr

@@ -1,41 +1,53 @@
 error: use of `default` to create a unit struct
-  --> tests/ui/default_constructed_unit_structs.rs:11:13
+  --> tests/ui/default_constructed_unit_structs.rs:11:9
    |
-LL |         Self::default()
-   |             ^^^^^^^^^^^ help: remove this call to `default`
+LL |           Self::default()
+   |  _________^^^^-^^^^^^^^^^
+LL | |
+   | |________- help: remove this call to `default`
    |
    = note: `-D clippy::default-constructed-unit-structs` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::default_constructed_unit_structs)]`
 
 error: use of `default` to create a unit struct
-  --> tests/ui/default_constructed_unit_structs.rs:54:31
+  --> tests/ui/default_constructed_unit_structs.rs:54:20
    |
 LL |             inner: PhantomData::default(),
-   |                               ^^^^^^^^^^^ help: remove this call to `default`
+   |                    ^^^^^^^^^^^-----------
+   |                               |
+   |                               help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> tests/ui/default_constructed_unit_structs.rs:128:33
+  --> tests/ui/default_constructed_unit_structs.rs:128:13
    |
 LL |     let _ = PhantomData::<usize>::default();
-   |                                 ^^^^^^^^^^^ help: remove this call to `default`
+   |             ^^^^^^^^^^^^^^^^^^^^-----------
+   |                                 |
+   |                                 help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> tests/ui/default_constructed_unit_structs.rs:130:42
+  --> tests/ui/default_constructed_unit_structs.rs:130:31
    |
 LL |     let _: PhantomData<i32> = PhantomData::default();
-   |                                          ^^^^^^^^^^^ help: remove this call to `default`
+   |                               ^^^^^^^^^^^-----------
+   |                                          |
+   |                                          help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> tests/ui/default_constructed_unit_structs.rs:132:55
+  --> tests/ui/default_constructed_unit_structs.rs:132:31
    |
 LL |     let _: PhantomData<i32> = std::marker::PhantomData::default();
-   |                                                       ^^^^^^^^^^^ help: remove this call to `default`
+   |                               ^^^^^^^^^^^^^^^^^^^^^^^^-----------
+   |                                                       |
+   |                                                       help: remove this call to `default`
 
 error: use of `default` to create a unit struct
-  --> tests/ui/default_constructed_unit_structs.rs:134:23
+  --> tests/ui/default_constructed_unit_structs.rs:134:13
    |
 LL |     let _ = UnitStruct::default();
-   |                       ^^^^^^^^^^^ help: remove this call to `default`
+   |             ^^^^^^^^^^-----------
+   |                       |
+   |                       help: remove this call to `default`
 
 error: aborting due to 6 previous errors