From 8bfdb090e179558110d2be30f27c261419d8e6a8 Mon Sep 17 00:00:00 2001
From: n-ogawa <fy59.kou-729@live.jp>
Date: Wed, 7 May 2025 23:59:14 +0900
Subject: [PATCH 1/3] Fix nil error on debugger prompt

---
 lib/irb.rb                            |  2 ++
 test/irb/test_debugger_integration.rb | 50 +++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/lib/irb.rb b/lib/irb.rb
index fd0bfe35c..8c933d4ae 100644
--- a/lib/irb.rb
+++ b/lib/irb.rb
@@ -613,9 +613,11 @@ def format_prompt(format, ltype, indent, line_no) # :nodoc:
           @context.irb_name
         when "m"
           main_str = @context.safe_method_call_on_main(:to_s) rescue "!#{$!.class}"
+          main_str = main_str || "!#{@context.safe_method_call_on_main(:class)}"
           truncate_prompt_main(main_str)
         when "M"
           main_str = @context.safe_method_call_on_main(:inspect) rescue "!#{$!.class}"
+          main_str = main_str || "!#{@context.safe_method_call_on_main(:class)}"
           truncate_prompt_main(main_str)
         when "l"
           ltype
diff --git a/test/irb/test_debugger_integration.rb b/test/irb/test_debugger_integration.rb
index 45ffb2a52..c19faa423 100644
--- a/test/irb/test_debugger_integration.rb
+++ b/test/irb/test_debugger_integration.rb
@@ -51,6 +51,56 @@ def test_debug
       assert_match(/=>   2\| puts "hello"/, output)
     end
 
+    def test_debug_class_to_s_return_string
+      write_ruby <<~'ruby'
+        class ToSReturnsString
+          def to_s
+            'ok'
+          end
+
+          def do_something
+            binding.irb
+          end
+        end
+
+        ToSReturnsString.new.do_something
+      ruby
+
+      output = run_ruby_file do
+        type "debug"
+        type "next"
+        type "continue"
+      end
+
+      assert_match(/irb\(ok\):001> debug/, output)
+      assert_match(/irb:rdbg\(ok\):002> next/, output)
+    end
+
+    def test_debug_class_to_s_return_nil
+      write_ruby <<~'ruby'
+        class ToSReturnsNil
+          def to_s
+            nil
+          end
+
+          def do_something
+            binding.irb
+          end
+        end
+
+        ToSReturnsNil.new.do_something
+      ruby
+
+      output = run_ruby_file do
+        type "debug"
+        type "next"
+        type "continue"
+      end
+
+      assert_match(/irb\(!ToSReturnsNil\):001> debug/, output)
+      assert_match(/irb:rdbg\(!ToSReturnsNil\):002> next/, output)
+    end
+
     def test_debug_command_only_runs_once
       write_ruby <<~'ruby'
         binding.irb

From 47ec270a267494b959b6cc55458ac6b756f165d6 Mon Sep 17 00:00:00 2001
From: n-ogawa <fy59.kou-729@live.jp>
Date: Thu, 8 May 2025 08:26:02 +0900
Subject: [PATCH 2/3] Delete unnecessary test case

---
 test/irb/test_debugger_integration.rb | 25 -------------------------
 1 file changed, 25 deletions(-)

diff --git a/test/irb/test_debugger_integration.rb b/test/irb/test_debugger_integration.rb
index c19faa423..856e06864 100644
--- a/test/irb/test_debugger_integration.rb
+++ b/test/irb/test_debugger_integration.rb
@@ -51,31 +51,6 @@ def test_debug
       assert_match(/=>   2\| puts "hello"/, output)
     end
 
-    def test_debug_class_to_s_return_string
-      write_ruby <<~'ruby'
-        class ToSReturnsString
-          def to_s
-            'ok'
-          end
-
-          def do_something
-            binding.irb
-          end
-        end
-
-        ToSReturnsString.new.do_something
-      ruby
-
-      output = run_ruby_file do
-        type "debug"
-        type "next"
-        type "continue"
-      end
-
-      assert_match(/irb\(ok\):001> debug/, output)
-      assert_match(/irb:rdbg\(ok\):002> next/, output)
-    end
-
     def test_debug_class_to_s_return_nil
       write_ruby <<~'ruby'
         class ToSReturnsNil

From 03599ecc6ab60d75e9944bc37b4fe774ad9f5758 Mon Sep 17 00:00:00 2001
From: n-ogawa <fy59.kou-729@live.jp>
Date: Thu, 8 May 2025 08:30:23 +0900
Subject: [PATCH 3/3] Use empty string on prompt when to_s returns nil.

---
 lib/irb.rb                            | 6 ++----
 test/irb/test_debugger_integration.rb | 4 ++--
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/lib/irb.rb b/lib/irb.rb
index 8c933d4ae..6d9c96c8f 100644
--- a/lib/irb.rb
+++ b/lib/irb.rb
@@ -612,12 +612,10 @@ def format_prompt(format, ltype, indent, line_no) # :nodoc:
         when "N"
           @context.irb_name
         when "m"
-          main_str = @context.safe_method_call_on_main(:to_s) rescue "!#{$!.class}"
-          main_str = main_str || "!#{@context.safe_method_call_on_main(:class)}"
+          main_str = "#{@context.safe_method_call_on_main(:to_s)}" rescue "!#{$!.class}"
           truncate_prompt_main(main_str)
         when "M"
-          main_str = @context.safe_method_call_on_main(:inspect) rescue "!#{$!.class}"
-          main_str = main_str || "!#{@context.safe_method_call_on_main(:class)}"
+          main_str = "#{@context.safe_method_call_on_main(:inspect)}" rescue "!#{$!.class}"
           truncate_prompt_main(main_str)
         when "l"
           ltype
diff --git a/test/irb/test_debugger_integration.rb b/test/irb/test_debugger_integration.rb
index 856e06864..e125dbf85 100644
--- a/test/irb/test_debugger_integration.rb
+++ b/test/irb/test_debugger_integration.rb
@@ -72,8 +72,8 @@ def do_something
         type "continue"
       end
 
-      assert_match(/irb\(!ToSReturnsNil\):001> debug/, output)
-      assert_match(/irb:rdbg\(!ToSReturnsNil\):002> next/, output)
+      assert_match(/irb\(\):001> debug/, output)
+      assert_match(/irb:rdbg\(\):002> next/, output)
     end
 
     def test_debug_command_only_runs_once