* lib/irb.rb: Prevent irb from crashing when exception with

  nil backtrace is raised.
  [fix GH-434][ruby-core:58078][Bug #9063]
* test/irb/test_raise_no_backtrace_exception.rb: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47164 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 11 deletions

diff --git a/lib/irb.rb b/lib/irb.rb
index 9bd37c8b0b..1bbb6eceb8 100644
--- a/lib/irb.rb
+++ b/lib/irb.rb
@@ -497,7 +497,7 @@ module IRB
           end
           if exc
             print exc.class, ": ", exc, "\n"
-            if exc.backtrace[0] =~ /irb(2)?(\/.*|-.*|\.rb)?:/ && exc.class.to_s !~ /^IRB/ &&
+            if exc.backtrace && exc.backtrace[0] =~ /irb(2)?(\/.*|-.*|\.rb)?:/ && exc.class.to_s !~ /^IRB/ &&
                 !(SyntaxError === exc)
               irb_bug = true
             else
@@ -507,16 +507,18 @@ module IRB
             messages = []
             lasts = []
             levels = 0
-            for m in exc.backtrace
-              m = @context.workspace.filter_backtrace(m) unless irb_bug
-              if m
-                if messages.size < @context.back_trace_limit
-                  messages.push "\tfrom "+m
-                else
-                  lasts.push "\tfrom "+m
-                  if lasts.size > @context.back_trace_limit
-                    lasts.shift
-                    levels += 1
+            if exc.backtrace
+              for m in exc.backtrace
+                m = @context.workspace.filter_backtrace(m) unless irb_bug
+                if m
+                  if messages.size < @context.back_trace_limit
+                    messages.push "\tfrom "+m
+                  else
+                    lasts.push "\tfrom "+m
+                    if lasts.size > @context.back_trace_limit
+                      lasts.shift
+                      levels += 1
+                    end
                   end
                 end
               end