From 4f47d655e357a7f09943f199969b437a25665ed2 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Mon, 15 Feb 2021 15:58:45 +0900
Subject: [PATCH] Added Thread::Backtrace.limit [Feature #17479]

---
 common.mk                     | 2 ++
 test/ruby/test_rubyoptions.rb | 2 ++
 vm_backtrace.c                | 8 ++++++++
 3 files changed, 12 insertions(+)

diff --git a/common.mk b/common.mk
index c9507d2ad8..ebbe3a18df 100644
--- a/common.mk
+++ b/common.mk
@@ -15613,10 +15613,12 @@ vm_backtrace.$(OBJEXT): $(hdrdir)/ruby.h
 vm_backtrace.$(OBJEXT): $(hdrdir)/ruby/ruby.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/array.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/compilers.h
+vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/error.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/gc.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/serial.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/static_assert.h
+vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/string.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/vm.h
 vm_backtrace.$(OBJEXT): $(top_srcdir)/internal/warnings.h
 vm_backtrace.$(OBJEXT): {$(VPATH)}assert.h
diff --git a/test/ruby/test_rubyoptions.rb b/test/ruby/test_rubyoptions.rb
index 08f9e98dcf..0d42604b87 100644
--- a/test/ruby/test_rubyoptions.rb
+++ b/test/ruby/test_rubyoptions.rb
@@ -77,6 +77,8 @@ class TestRubyOptions < Test::Unit::TestCase
     assert_in_out_err(%w(--backtrace-limit=3), code, [],
                       [/.*unhandled exception\n/, *[/^\tfrom .*\n/]*3,
                        /^\t \.{3} \d+ levels\.{3}\n/])
+    assert_kind_of(Integer, Thread::Backtrace.limit)
+    assert_in_out_err(%w(--backtrace-limit=1), "p Thread::Backtrace.limit", ['1'], [])
   end
 
   def test_warning
diff --git a/vm_backtrace.c b/vm_backtrace.c
index f2cc21294c..4f1d14af31 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -11,6 +11,7 @@
 
 #include "eval_intern.h"
 #include "internal.h"
+#include "internal/error.h"
 #include "internal/vm.h"
 #include "iseq.h"
 #include "ruby/debug.h"
@@ -839,6 +840,12 @@ backtrace_load_data(VALUE self, VALUE str)
     return self;
 }
 
+static VALUE
+backtrace_limit(VALUE self)
+{
+    return LONG2NUM(rb_backtrace_length_limit);
+}
+
 VALUE
 rb_ec_backtrace_str_ary(const rb_execution_context_t *ec, long lev, long n)
 {
@@ -1201,6 +1208,7 @@ Init_vm_backtrace(void)
     rb_define_alloc_func(rb_cBacktrace, backtrace_alloc);
     rb_undef_method(CLASS_OF(rb_cBacktrace), "new");
     rb_marshal_define_compat(rb_cBacktrace, rb_cArray, backtrace_dump_data, backtrace_load_data);
+    rb_define_singleton_method(rb_cBacktrace, "limit", backtrace_limit, 0);
 
     /*
      *	An object representation of a stack frame, initialized by