Silence parser/current warnings (#16682)

Gemfile

@@ -107,6 +107,7 @@ gem "twitter", "~> 7.0" # A Ruby interface to the Twitter API
 gem "uglifier", "~> 4.2" # Uglifier minifies JavaScript files
 gem "validate_url", "~> 1.0" # Library for validating urls in Rails
 gem "vault", "~> 0.16" # Used to store secrets
+gem "warning", "~> 1.2" # Adds custom processing for warnings, including the ability to ignore specific warning messages
 gem "wcag_color_contrast", "~> 0.1" # Detect contrast of colors to determine readability and a11y.
 gem "webpacker", "~> 5.4.3" # Use webpack to manage app-like JavaScript modules in Rails
 

Gemfile.lock

@@ -851,6 +851,7 @@ GEM
     vcr (6.0.0)
     warden (1.2.9)
       rack (>= 2.0.9)
+    warning (1.2.1)
     wcag_color_contrast (0.1.0)
     web-console (4.2.0)
       actionview (>= 6.0.0)
@@ -1036,6 +1037,7 @@ DEPENDENCIES
   validate_url (~> 1.0)
   vault (~> 0.16)
   vcr (~> 6.0)
+  warning (~> 1.2)
   wcag_color_contrast (~> 0.1)
   web-console (~> 4.2)
   webdrivers (~> 5.0)

config/boot.rb

@@ -1,4 +1,14 @@
 ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../Gemfile", __dir__)
 
+# NOTE: We need to ignore this warning early during app startup.
+# 1. `parser` is a transitive dependency (`erb_lint` -> `better_html` -> `parser`)
+# 2. The warnings are generated while reading the class body, so we need to ignore
+#    them *before* the gem's code is read.
+# 3. The warning is intentional, it will always occur when the used point release
+#    isn't the most recent. Since our update schedule is somewhat influenced by
+#    Fedora release cycles right now, this can occur frequently.
+require "warning"
+Warning.ignore(%r{parser/current})
+
 require "bundler/setup" # Set up gems listed in the Gemfile.
 require "bootsnap/setup" # Speed up boot time by caching expensive operations.