From f406e904567459113c27e4248d49032178f0d5f9 Mon Sep 17 00:00:00 2001
From: nick evans <nick@rubinick.dev>
Date: Tue, 10 Feb 2026 18:24:24 -0500
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20Fix=20parser=20backtrace=20detai?=
 =?UTF-8?q?ls=20for=20ruby=20<=3D=203.3?=
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Since the backtrace_locations don't _explicitly_ include the class name,
this still feelds inherently brittle.  But it's very useful!  It's a
worthwhile tradeoff, IMO.
---
 lib/net/imap/errors.rb       | 11 ++++++++---
 test/net/imap/test_errors.rb |  9 +++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/lib/net/imap/errors.rb b/lib/net/imap/errors.rb
index cfa21fbe..a64cab41 100644
--- a/lib/net/imap/errors.rb
+++ b/lib/net/imap/errors.rb
@@ -101,8 +101,9 @@ def initialize(message = "unspecified parse error",
       # included.  Defaults to the value of Net::IMAP.debug.
       #
       # When +parser_backtrace+ is true, a simplified backtrace is included,
-      # containing only frames which belong to methods in parser_class.  Most
-      # parser method names are based on rules in the IMAP grammar.
+      # containing only frames for methods in parser_class (since ruby 3.4) or
+      # which have "net/imap/response_parser" in the path (before ruby 3.4).
+      # Most parser method names are based on rules in the IMAP grammar.
       def detailed_message(parser_state: Net::IMAP.debug,
                            parser_backtrace: false,
                            **)
@@ -124,7 +125,11 @@ def detailed_message(parser_state: Net::IMAP.debug,
           backtrace_locations&.each_with_index do |loc, idx|
             next  if    loc.base_label.include? "parse_error"
             break if    loc.base_label == "parse"
-            next unless loc.label.include?(parser_class.name)
+            if loc.label.include?("#") # => Class#method, since ruby 3.4
+              next unless loc.label&.include?(parser_class.name)
+            else
+              next unless loc.path&.include?("net/imap/response_parser")
+            end
             msg << "\n  caller[%2d]: %-30s (%s:%d)" % [
               idx,
               loc.base_label,
diff --git a/test/net/imap/test_errors.rb b/test/net/imap/test_errors.rb
index 61370af5..3c0b70e7 100644
--- a/test/net/imap/test_errors.rb
+++ b/test/net/imap/test_errors.rb
@@ -88,6 +88,15 @@ def self.SGR(*attr) = CSI attr.join(?;), ?m
       "#{BOLD}#{msg} (#{BOLD_UNDERLINE}#{name}#{RESET}#{BOLD})#{RESET}",
       err.detailed_message(highlight: true)
     )
+
+    # with parser_backtrace
+    Net::IMAP.debug = false
+    parser = Net::IMAP::ResponseParser.new
+    error  = parser.parse("* 123 FETCH (UNKNOWN ...)\r\n") rescue $!
+    no_hl    = error.detailed_message(parser_backtrace: true)
+    no_color = error.detailed_message(parser_backtrace: true, highlight: true)
+    assert_include no_hl,    "caller[ 1]: %-30s ("          % "msg_att"
+    assert_include no_color, "caller[ 1]: %-30s ("          % "msg_att"
   end
 
   test "ResponseTooLargeError" do