[gnome-shell] lint: Allow marking variables/arguments as unused

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 0257de1b7eb160e54e928f499e95dfbec6b634cf
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Jan 28 01:37:12 2019 +0100

    lint: Allow marking variables/arguments as unused
    
    Unused variables or arguments can indicate bugs, but they can also
    help document the code, in particular in case of signal handlers
    and destructuring.
    
    Account for this by keeping the error, but set up patterns that allow
    us to opt out of if for individual variables/arguments. For arguments
    we pick a '_' prefix, while for variables we go with a suffix instead,
    to not accidentally exempt private module-scope variables.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/627

 lint/eslintrc-shell.json | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/lint/eslintrc-shell.json b/lint/eslintrc-shell.json
index d8a940bbb..1cae2f4e7 100644
--- a/lint/eslintrc-shell.json
+++ b/lint/eslintrc-shell.json
@@ -16,6 +16,13 @@
                 "afterColon": true
             }
         ],
+        "no-unused-vars": [
+            "error",
+            {
+                "argsIgnorePattern": "^_",
+                "varsIgnorePattern": "_$"
+            }
+        ],
         "object-curly-spacing": [
             "error",
             "always"