lib/bundled_gems.rb: more reliable caller detection

The `2` skipped frames went out of sync and now it should be `3`.

Rather than just update the offset, we can implement a way that
is adaptative as long as all require decorators are also called require.

Also we should compute the corresponding `uplevel` otherwise the
warning will still point decorators.

Co-authored-by: "Hiroshi SHIBATA" <hsbt@ruby-lang.org>

Author: byroot

lib/bundled_gems.rb

@@ -66,7 +66,7 @@ def self.replace_require(specs)
       kernel_class.send(:alias_method, :no_warning_require, :require)
       kernel_class.send(:define_method, :require) do |name|
         if message = ::Gem::BUNDLED_GEMS.warning?(name, specs: spec_names) # rubocop:disable Style/HashSyntax
-          Kernel.warn message, :uplevel => 1
+          Kernel.warn message, uplevel: ::Gem::BUNDLED_GEMS.uplevel
         end
         kernel_class.send(:no_warning_require, name)
       end
@@ -78,6 +78,29 @@ def self.replace_require(specs)
     end
   end
 
+  def self.uplevel
+    frames_to_skip = 3
+    uplevel = 0
+    require_found = false
+    Thread.each_caller_location do |cl|
+      if frames_to_skip >= 1
+        frames_to_skip -= 1
+        next
+      end
+      uplevel += 1
+      if require_found
+        if cl.base_label != "require"
+          return uplevel
+        end
+      else
+        if cl.base_label == "require"
+          require_found = true
+        end
+      end
+    end
+    1
+  end
+
   def self.find_gem(path)
     if !path
       return
@@ -143,29 +166,35 @@ def self.warning?(name, specs: nil)
   end
 
   def self.build_message(gem)
-    msg = " #{RUBY_VERSION < SINCE[gem] ? "will no longer be" : "is not"} part of the default gems since Ruby #{SINCE[gem]}."
+    msg = " #{RUBY_VERSION < SINCE[gem] ? "will no longer be" : "is not"} part of the default gems starting from Ruby #{SINCE[gem]}."
 
     if defined?(Bundler)
-      msg += " Add #{gem} to your Gemfile or gemspec."
+      msg += "\nYou can add #{gem} to your Gemfile or gemspec to silence this warning."
 
-      # We detect the gem name from caller_locations. We need to skip 2 frames like:
-      # lib/ruby/3.3.0+0/bundled_gems.rb:90:in `warning?'",
-      # lib/ruby/3.3.0+0/bundler/rubygems_integration.rb:247:in `block (2 levels) in replace_require'",
+      # We detect the gem name from caller_locations. First we walk until we find `require`
+      # then take the first frame that's not from `require`.
       #
       # Additionally, we need to skip Bootsnap and Zeitwerk if present, these
       # gems decorate Kernel#require, so they are not really the ones issuing
       # the require call users should be warned about. Those are upwards.
-      frames_to_skip = 2
+      frames_to_skip = 3
       location = nil
+      require_found = false
       Thread.each_caller_location do |cl|
         if frames_to_skip >= 1
           frames_to_skip -= 1
           next
         end
 
-        if cl.base_label != "require"
-          location = cl.path
-          break
+        if require_found
+          if cl.base_label != "require"
+            location = cl.path
+            break
+          end
+        else
+          if cl.base_label == "require"
+            require_found = true
+          end
         end
       end
 
@@ -178,7 +207,7 @@ def self.build_message(gem)
           end
         end
         if caller_gem
-          msg += " Also contact author of #{caller_gem} to add #{gem} into its gemspec."
+          msg += "\nAlso please contact the author of #{caller_gem} to request adding #{gem} into its gemspec."
         end
       end
     else
@@ -199,7 +228,7 @@ def message
 
     name = path.tr("/", "-")
     if !defined?(Bundler) && Gem::BUNDLED_GEMS::SINCE[name] && !Gem::BUNDLED_GEMS::WARNED[name]
-      warn name + Gem::BUNDLED_GEMS.build_message(name)
+      warn name + Gem::BUNDLED_GEMS.build_message(name), uplevel: Gem::BUNDLED_GEMS.uplevel
     end
     super
   end