Issue #19529 has been updated by Eregon (Benoit Daloze). byroot (Jean Boussier) wrote in #note-9:
Hum, this raise the question of wether `GC.compact` should actually be undef when it's not supported.
That's already the case, right? (undef if unsupported)
I think in general you don't care much if it's supported or not, you can call it and worst case it's a noop. Very few code out there expect it not to be there.
The docs say: ``` To test whether GC compaction is supported, use the idiom: GC.respond_to?(:compact) ``` So it doesn't seem good to break that. Also old Rubies and TruffleRuby don't define it for instance, and it doesn't seem entirely right to make it a noop as it would ignore the user intent. ---------------------------------------- Bug #19529: [BUG] ObjectSpace::WeakMap can segfault after compaction https://bugs.ruby-lang.org/issues/19529#change-102704 * Author: byroot (Jean Boussier) * Status: Closed * Priority: Normal * ruby -v: 3.2.1, 2.7.5p203 * Backport: 2.7: WONTFIX, 3.0: REQUIRED, 3.1: DONE, 3.2: REQUIRED ---------------------------------------- Reproduction script: ```ruby wm = ObjectSpace::WeakMap.new obj = Object.new 100.times do |i| GC.compact wm[i] = obj # [BUG] Segmentation fault at 0x0000000000000001 end ``` Crash report: ``` /tmp/weakmap.rb:5: [BUG] Segmentation fault at 0x0000000000000003 ruby 3.2.1 (2023-02-08 revision 31819e82c8) [arm64-darwin22] -- Crash Report log information -------------------------------------------- See Crash Report log file in one of the following locations: * ~/Library/Logs/DiagnosticReports * /Library/Logs/DiagnosticReports for more details. Don't forget to include the above Crash Report log file in bug reports. -- Control frame information ----------------------------------------------- c:0005 p:---- s:0023 e:000022 CFUNC :[]= c:0004 p:0016 s:0017 e:000015 BLOCK /tmp/weakmap.rb:5 [FINISH] c:0003 p:---- s:0012 e:000011 CFUNC :times c:0002 p:0017 s:0008 E:0025b0 EVAL /tmp/weakmap.rb:3 [FINISH] c:0001 p:0000 s:0003 E:0010b0 DUMMY [FINISH] -- Ruby level backtrace information ---------------------------------------- /tmp/weakmap.rb:3:in `<main>' /tmp/weakmap.rb:3:in `times' /tmp/weakmap.rb:5:in `block in <main>' /tmp/weakmap.rb:5:in `[]=' -- Machine register context ------------------------------------------------ x0: 0x000000016da8a6b0 x1: 0x000000016da8a6a8 x2: 0x000000000000003d x3: 0x0000000000000001 x4: 0x0000000000000000 x5: 0x0000000000000b00 x6: 0x0000600002db4b00 x7: 0x0000000000000000 x18: 0x0000000000000000 x19: 0x000000016da8a6a8 x20: 0x000000000000003d x21: 0x0000000000000003 x22: 0x0000000000000001 x23: 0x00000001023df7b8 x24: 0x0000000000000001 x25: 0x0000000000000000 x26: 0x00006000027bdf80 x27: 0xffffffffffffffff x28: 0xffffffffffffffff lr: 0x0000000102ca28f0 fp: 0x000000016da8a680 sp: 0x000000016da8a640 -- C level backtrace information ------------------------------------------- /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_vm_bugreport+0x9a0) [0x102d3ba98] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_bug_for_fatal_signal+0x160) [0x102b5fe14] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(sig_do_nothing+0x0) [0x102c9a354] /usr/lib/system/libsystem_platform.dylib(_sigtramp+0x38) [0x19b63c2a4] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_st_update+0x328) [0x102ca28f0] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_st_update+0x328) [0x102ca28f0] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(wmap_aset+0x90) [0x102b88e9c] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_call_cfunc_with_frame+0xe8) [0x102d2fc7c] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_sendish+0x4cc) [0x102d31fdc] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_exec_core+0x239c) [0x102d136c8] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_vm_exec+0xad4) [0x102d26bf0] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(invoke_block_from_c_bh+0x398) [0x102d36438] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_yield_1+0x7c) [0x102d1f208] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(int_dotimes+0x148) [0x102bff3ec] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_call_cfunc_with_frame+0xe8) [0x102d2fc7c] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_sendish+0x4cc) [0x102d31fdc] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(vm_exec_core+0x2350) [0x102d1367c] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_vm_exec+0xad4) [0x102d26bf0] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(rb_ec_exec_node+0x12c) [0x102b6b4ac] /opt/rubies/3.2.1/lib/libruby.3.2.dylib(ruby_run_node+0x60) [0x102b6b318] /opt/rubies/3.2.1/bin/ruby(main+0x68) [0x102377f34] ``` Seems to happens since 2.7. -- https://bugs.ruby-lang.org/