[semicolon_if_nothing_returned]: add an autofix

Author: sylvestre

clippy_lints/src/semicolon_if_nothing_returned.rs

@@ -1,5 +1,5 @@
 use crate::rustc_lint::LintContext;
-use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::source::snippet_with_context;
 use if_chain::if_chain;
 use rustc_errors::Applicability;
@@ -52,14 +52,19 @@ impl<'tcx> LateLintPass<'tcx> for SemicolonIfNothingReturned {
                 if let ExprKind::DropTemps(..) = &expr.kind {
                     return;
                 }
-                span_lint_and_sugg(
+                span_lint_and_then(
                     cx,
                     SEMICOLON_IF_NOTHING_RETURNED,
                     expr.span.source_callsite(),
                     "consider adding a `;` to the last statement for consistent formatting",
-                    "add a `;` here",
-                    format!("{snippet};"),
-                    app,
+                    |diag| {
+                        diag.span_suggestion(
+                            expr.span,
+                            "add a `;` here",
+                            format!("{snippet};"),
+                            Applicability::MachineApplicable,
+                        );
+                    }
                 );
             }
         }