From 7a0894793ef359679aedad3836d593a83bb4a0a4 Mon Sep 17 00:00:00 2001
From: Oskar Eichler <oskar@songstats.com>
Date: Mon, 31 Aug 2026 00:57:40 +0200
Subject: [PATCH] Propagate errors from custom pretty printers

---
 lib/pp.rb       |  6 +++++-
 test/test_pp.rb | 11 +++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/pp.rb b/lib/pp.rb
index 798a4f4..ad3cf78 100644
--- a/lib/pp.rb
+++ b/lib/pp.rb
@@ -210,7 +210,11 @@ def pp(obj)
       guard_inspect(obj) do
         group do
           obj.pretty_print self
-        rescue NoMethodError
+        rescue NoMethodError => error
+          raise unless
+            error.name == :pretty_print &&
+            error.receiver.equal?(obj) &&
+            !PP.mcall(obj, Kernel, :respond_to?, :pretty_print)
           text Kernel.instance_method(:inspect).bind_call(obj)
         end
       end
diff --git a/test/test_pp.rb b/test/test_pp.rb
index 922ed37..2469f6b 100644
--- a/test/test_pp.rb
+++ b/test/test_pp.rb
@@ -94,6 +94,12 @@ class PrettyPrintInspectWithoutPrettyPrint
   alias inspect pretty_print_inspect
 end
 
+class PrettyPrintRaises
+  def pretty_print(q)
+    self.missing_from_pretty_print
+  end
+end
+
 class PPInspectTest < Test::Unit::TestCase
   def test_hasinspect
     a = HasInspect.new(1)
@@ -157,6 +163,11 @@ def test_basic_object
     a = BasicObject.new
     assert_match(/\A#<BasicObject:0x[\da-f]+>\n\z/, PP.pp(a, ''.dup))
   end
+
+  def test_pretty_print_error
+    error = assert_raise(NoMethodError) { PP.pp(PrettyPrintRaises.new, ''.dup) }
+    assert_equal(:missing_from_pretty_print, error.name)
+  end
 end
 
 class PPCycleTest < Test::Unit::TestCase