From d5c8fd2043f4425c3fe2a87558dfbd80ebff9911 Mon Sep 17 00:00:00 2001
From: nagachika <nagachika@ruby-lang.org>
Date: Sat, 14 Jun 2025 11:39:08 +0900
Subject: [PATCH] merge revision(s) f6cbf499bc98b851034fffb49fcbb59d495f6f7b:
 [Backport #21354]

	Fix Symbol#to_proc (rb_sym_to_proc) to be ractor safe

	In non-main ractors, don't use `sym_proc_cache`. It is not thread-safe
	to add to this array without a lock and also it leaks procs from one
	ractor to another. Instead, we create a new proc each time. If this
	results in poor performance we can come up with a solution later.

	Fixes [Bug #21354]
---
 bootstraptest/test_ractor.rb | 12 ++++++++++++
 common.mk                    |  2 ++
 proc.c                       | 34 +++++++++++++++++++---------------
 version.h                    |  2 +-
 4 files changed, 34 insertions(+), 16 deletions(-)

diff --git a/bootstraptest/test_ractor.rb b/bootstraptest/test_ractor.rb
index ea7c2c197d..c03fbb07d7 100644
--- a/bootstraptest/test_ractor.rb
+++ b/bootstraptest/test_ractor.rb
@@ -1773,3 +1773,15 @@ assert_equal 'ok', %q{
 }
 
 end # if !ENV['GITHUB_WORKFLOW']
+
+# Using Symbol#to_proc inside ractors
+# [Bug #21354]
+assert_equal 'ok', %q{
+  :inspect.to_proc
+  Ractor.new do
+    # It should not use this cached proc, it should create a new one. If it used
+    # the cached proc, we would get a ractor_confirm_belonging error here.
+    :inspect.to_proc
+  end.take
+  'ok'
+}
diff --git a/common.mk b/common.mk
index 714454de60..4cc436dc41 100644
--- a/common.mk
+++ b/common.mk
@@ -12804,6 +12804,8 @@ proc.$(OBJEXT): {$(VPATH)}prism/ast.h
 proc.$(OBJEXT): {$(VPATH)}prism/version.h
 proc.$(OBJEXT): {$(VPATH)}prism_compile.h
 proc.$(OBJEXT): {$(VPATH)}proc.c
+proc.$(OBJEXT): {$(VPATH)}ractor.h
+proc.$(OBJEXT): {$(VPATH)}ractor_core.h
 proc.$(OBJEXT): {$(VPATH)}ruby_assert.h
 proc.$(OBJEXT): {$(VPATH)}ruby_atomic.h
 proc.$(OBJEXT): {$(VPATH)}rubyparser.h
diff --git a/proc.c b/proc.c
index a3fdb1783c..f09f5ec4d8 100644
--- a/proc.c
+++ b/proc.c
@@ -22,6 +22,7 @@
 #include "method.h"
 #include "iseq.h"
 #include "vm_core.h"
+#include "ractor_core.h"
 #include "yjit.h"
 
 const rb_cref_t *rb_vm_cref_in_context(VALUE self, VALUE cbase);
@@ -1508,23 +1509,26 @@ rb_sym_to_proc(VALUE sym)
     long index;
     ID id;
 
-    if (!sym_proc_cache) {
-        sym_proc_cache = rb_ary_hidden_new(SYM_PROC_CACHE_SIZE * 2);
-        rb_gc_register_mark_object(sym_proc_cache);
-        rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE*2 - 1, Qnil);
-    }
-
     id = SYM2ID(sym);
-    index = (id % SYM_PROC_CACHE_SIZE) << 1;
 
-    if (RARRAY_AREF(sym_proc_cache, index) == sym) {
-        return RARRAY_AREF(sym_proc_cache, index + 1);
-    }
-    else {
-        proc = sym_proc_new(rb_cProc, ID2SYM(id));
-        RARRAY_ASET(sym_proc_cache, index, sym);
-        RARRAY_ASET(sym_proc_cache, index + 1, proc);
-        return proc;
+    if (rb_ractor_main_p()) {
+        index = (id % SYM_PROC_CACHE_SIZE) << 1;
+        if (!sym_proc_cache) {
+            sym_proc_cache = rb_ary_hidden_new(SYM_PROC_CACHE_SIZE * 2);
+            rb_gc_register_mark_object(sym_proc_cache);
+            rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE*2 - 1, Qnil);
+        }
+        if (RARRAY_AREF(sym_proc_cache, index) == sym) {
+            return RARRAY_AREF(sym_proc_cache, index + 1);
+        }
+        else {
+            proc = sym_proc_new(rb_cProc, ID2SYM(id));
+            RARRAY_ASET(sym_proc_cache, index, sym);
+            RARRAY_ASET(sym_proc_cache, index + 1, proc);
+            return proc;
+        }
+    } else {
+        return sym_proc_new(rb_cProc, ID2SYM(id));
     }
 }
 
diff --git a/version.h b/version.h
index d5294f759c..27d6146ac7 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 8
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 156
+#define RUBY_PATCHLEVEL 157
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"