Avoid a deprecation warning on Ruby 3.4 with the uri gem

I openend a PR to tapioca, which needs the same change: Shopify/tapioca#2026

lib/core_ext/uri.rb

@@ -3,19 +3,24 @@
 
 module URI
   class Generic
+    # Avoid a deprecation warning with Ruby 3.4 where the default parser was changed to RFC3986.
+    # This condition must remain even after support for 3.4 has been dropped for users that have
+    # `uri` in their lockfile, decoupling it from the ruby version.
+    PARSER = T.let(const_defined?(:RFC2396_PARSER) ? RFC2396_PARSER : DEFAULT_PARSER, RFC2396_Parser)
+
     class << self
       extend T::Sig
 
       sig { params(path: String, fragment: T.nilable(String), scheme: String).returns(URI::Generic) }
       def from_path(path:, fragment: nil, scheme: "file")
         # On Windows, if the path begins with the disk name, we need to add a leading slash to make it a valid URI
         escaped_path = if /^[A-Z]:/i.match?(path)
-          DEFAULT_PARSER.escape("/#{path}")
+          PARSER.escape("/#{path}")
         elsif path.start_with?("//?/")
           # Some paths on Windows start with "//?/". This is a special prefix that allows for long file paths
-          DEFAULT_PARSER.escape(path.delete_prefix("//?"))
+          PARSER.escape(path.delete_prefix("//?"))
         else
-          DEFAULT_PARSER.escape(path)
+          PARSER.escape(path)
         end
 
         build(scheme: scheme, path: escaped_path, fragment: fragment)
@@ -29,7 +34,7 @@ def to_standardized_path
       parsed_path = path
       return unless parsed_path
 
-      unescaped_path = DEFAULT_PARSER.unescape(parsed_path)
+      unescaped_path = PARSER.unescape(parsed_path)
 
       # On Windows, when we're getting the file system path back from the URI, we need to remove the leading forward
       # slash

lib/ruby_lsp/requests/support/source_uri.rb

@@ -19,6 +19,13 @@ class Source < URI::File
       T::Array[Symbol],
     )
 
+    # `uri` for Ruby 3.4 switched the default parser from RFC2396 to RFC3986. The new parser emits a deprecation
+    # warning on a few methods and delegates them to RFC2396, namely `extract`/`make_regexp`/`escape`/`unescape`.
+    # On earlier versions of the uri gem, the RFC2396_PARSER constant doesn't exist, so it needs some special
+    # handling to select a parser that doesn't emit deprecations. While it was backported to Ruby 3.1, users may
+    # have the uri gem in their own bundle and thus not use a compatible version.
+    PARSER = T.let(const_defined?(:RFC2396_PARSER) ? RFC2396_PARSER : DEFAULT_PARSER, RFC2396_Parser)
+
     T.unsafe(self).alias_method(:gem_name, :host)
     T.unsafe(self).alias_method(:line_number, :fragment)
 
@@ -41,7 +48,7 @@ def build(gem_name:, gem_version:, path:, line_number:)
           {
             scheme: "source",
             host: gem_name,
-            path: DEFAULT_PARSER.escape("/#{gem_version}/#{path}"),
+            path: PARSER.escape("/#{gem_version}/#{path}"),
             fragment: line_number,
           }
         )