{"action":"created","issue":{"url":"https://api.github.com/repos/gap-system/gap/issues/55","labels_url":"https://api.github.com/repos/gap-system/gap/issues/55/labels{/name}","comments_url":"https://api.github.com/repos/gap-system/gap/issues/55/comments","events_url":"https://api.github.com/repos/gap-system/gap/issues/55/events","html_url":"https://github.com/gap-system/gap/issues/55","id":62359797,"number":55,"title":"Segfault when/after calling Enumerate on a partial perm orbit","user":{"login":"wilfwilson","id":8956868,"avatar_url":"https://avatars.githubusercontent.com/u/8956868?v=3","gravatar_id":"","url":"https://api.github.com/users/wilfwilson","html_url":"https://github.com/wilfwilson","followers_url":"https://api.github.com/users/wilfwilson/followers","following_url":"https://api.github.com/users/wilfwilson/following{/other_user}","gists_url":"https://api.github.com/users/wilfwilson/gists{/gist_id}","starred_url":"https://api.github.com/users/wilfwilson/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/wilfwilson/subscriptions","organizations_url":"https://api.github.com/users/wilfwilson/orgs","repos_url":"https://api.github.com/users/wilfwilson/repos","events_url":"https://api.github.com/users/wilfwilson/events{/privacy}","received_events_url":"https://api.github.com/users/wilfwilson/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/gap-system/gap/labels/gapdays2015","name":"gapdays2015","color":"fbca04"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":3,"created_at":"2015-03-17T10:51:09Z","updated_at":"2015-03-17T15:13:14Z","closed_at":null,"body":"In the most recent development version of non-HPC GAP (commit ```51025ca```) using Orb 4.7.3 (whether or not it is compiled) [https://github.com/gap-system/orb/] testing of the Semigroups package has revealed a segfault:\r\n\r\nIf load GAP with:\r\n```bin/gap.sh -r -A```\r\nAnd then call:\r\n```gap\r\ngap> LoadPackage(\"orb\", false);\r\ngap> comp := BlistList([ 1 .. 3 ], [  ]);;\r\ngap> opts := \r\n> rec(lookingfor := function(o, x)\r\n>   if not IsEmpty(x) then\r\n>     return IsPosInt(comp[ x[ 1 ] ]);\r\n>   fi;\r\n>   return false;\r\n> end);;\r\ngap> gens := [ PartialPerm( [ 1, 3 ], [ 3, 2 ] ) ];;\r\ngap> o := Orb(gens, [ 1 ], OnSets, opts);;\r\ngap> Enumerate(o);;\r\ngap> Elements(o);\r\n[ [  ], [ 1 ], [ 2 ], [ 3 ] ]\r\ngap> Elements(o);;\r\nSegmentation fault: 11\r\n```\r\nCalling ```Elements(o)``` the second time triggers a segfault.\r\n\r\nLLDB says the segfault seems to happen in the GAP library in ```src/plist.c``` on line 706:\r\n\r\n```gap\r\n/* This had better return the cyclotomics family, could be speeded up */\r\nfamily = FAMILY_TYPE( TYPE_OBJ( ELM_PLIST( list, 1 ) ) );\r\n```\r\nThe list ```list``` is empty but this is not expected. Markus thinks this might be a problem with partial perms in GAP.\r\n\r\nI originally found by using the most recent HPC-GAP. Using HPC-GAP, the segfault happens in the ```Enumerate(o)``` function. Perhaps these are different bugs, but it seems reasonable to think it is the same problem."},"comment":{"url":"https://api.github.com/repos/gap-system/gap/issues/comments/82400714","html_url":"https://github.com/gap-system/gap/issues/55#issuecomment-82400714","issue_url":"https://api.github.com/repos/gap-system/gap/issues/55","id":82400714,"user":{"login":"james-d-mitchell","id":6686071,"avatar_url":"https://avatars.githubusercontent.com/u/6686071?v=3","gravatar_id":"","url":"https://api.github.com/users/james-d-mitchell","html_url":"https://github.com/james-d-mitchell","followers_url":"https://api.github.com/users/james-d-mitchell/followers","following_url":"https://api.github.com/users/james-d-mitchell/following{/other_user}","gists_url":"https://api.github.com/users/james-d-mitchell/gists{/gist_id}","starred_url":"https://api.github.com/users/james-d-mitchell/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/james-d-mitchell/subscriptions","organizations_url":"https://api.github.com/users/james-d-mitchell/orgs","repos_url":"https://api.github.com/users/james-d-mitchell/repos","events_url":"https://api.github.com/users/james-d-mitchell/events{/privacy}","received_events_url":"https://api.github.com/users/james-d-mitchell/received_events","type":"User","site_admin":false},"created_at":"2015-03-17T15:13:14Z","updated_at":"2015-03-17T15:13:14Z","body":"How so? "}}