c++ - Writing an MCVE (minimal source code that reproduces an error) automatically? -


when want ask question on e.g. stackoverflow have post source code.

the problem is, using quite big custom framework, classes structure etc. , problem-related parts may localized in many places (sometimes it's hard detect parts of code important question). cannot post full source code (it big read efficiently).

for reason make effort write minimal code (usually in 1 main.cpp instead of tons of classes) reproduces problem.

i wonder - is possible automate process? typical things here replace methods/functions' calls bodies, merge files 1 .cpp, remove "not called" methods & classes, unused variables etc.

the real difficulty here telling difference between "it doesn't want", "the bug went away because removed essential code" , case of "it crashes because removed important". , really, hitting delete key after marking code "don't need it" easy part.

finding out essential show problem hard part, , it's difficult automate - because necessary understand difference between code should , does. randomly removing code not work, because "new" code may broken because removed essential step, not because remove unused crud - humans [that understand problem] can that.

consider this:

object* something;  void initialize() {     = new object(1, 2, 3); }  int main() {    initialize();    // more code, of sets = null.    something->dostuff();  // crash if object null. }

if remove initialize, code fail every time, not every third time. it's because object has not been initialized, rather bug in code [which may should add if (something) before something->dostuff(), or because shouldn't set null in "some more code", "don't that"].

when work on tricky problem, @ work have test systems automatically produce code testing different functionality under different conditions, first step make [or take existing] code "small standalone test", small , simple, , "what necessary", rather trying reduce many thousands of lines of complex code lots of stuff.

for projects, there tools around helps identifying "which bit of code problem", example [bugpoint][1] finds "pass" in llvm guily of causing crash.

if have version control system supports can "bisect" code come version introduced particular fault [at least sometimes]. however, had case @ work of code "apparently broke things", turns out other code "broken time since long time back" because other code not clearing pointer field api manual says should set null, , code inspecting pointer find out if pointing @ right type thing - goes horribly wrong when value "whatever happens in part of stack", not null , not valid pointer. added code made bug apparent rather hiding itself.

[1] http://llvm.org/docs/commandguide/bugpoint.html


Comments

Post a Comment

Popular posts from this blog

powershell Start-Process exit code -1073741502 when used with Credential from a windows service environment -

i'm running strange behavior powershell start-process call. here call: $process = start-process ` "c:\somepath\mybinary.exe" ` -passthru ` -credential $defaultcredential ` -wait ` -workingdirectory "c:\somepath" ` -loaduserprofile if ($process.exitcode -ne 0) { #do } this call return exit code - 1073741502 . after quick search, exit code seems related generic error when program not load required dll (aka. status_dll_init_failed ). when run without -credential $credential program runs correctly. in order isolate problem, manually launched some.exe in prompt target credential , runs smoothly. so problem seems come way start-process cmdlet launch process. i found potential solutions problem tried apply no luck : link , link . would have idea of what's going on here ? edit 1: run proc mon monitoring program activities when launched directly or via powershell script. problem seems occur when loading kernelbase
Read more

twig - Using Twigbridge in a Laravel 5.1 Package -

i'm trying create laravel 5.1 package uses twigbridge instead of .php views. can normal .php views display fine, when try make use of .twig templates i'm met error. possible use twigbridge templates when creating views laravel package or pretty stuck blade , php ? edit 1: loading twig template without extending works. it's when start using {% extends 'file' %} error comes out. i error error loading /virtual/laravel/packages/username/mypackage/src/views/sample.twig: template "templates.master" not defined () in "/virtual/laravel/packages/username/mypackage/src/views/sample.twig" @ line 1. my folders username |_ mypackage |_ src |_ controllers - samplecontroller.php |_ views |_ templates - master.twig - sample.twig twig template sample.twig {% extends 'templates.master' %} {% block content %} {{ parent()
Read more

c# - LINQ join Entities from HashSet's, Join vs Dictionary vs HashSet performance -

i have hashset's each stores t, have written test application compares different relation algorithms can think of, i'm not pleased results getting. does there exist more efficient ways of achieving object relations, once testing? using system; using system.collections.generic; using system.linq; using system.text; using system.threading.tasks; using system.diagnostics; namespace linqtests { class program { static void main(string[] args) { hashset<user> usertable = new hashset<user>(); hashset<userproperty> userpropertytable = new hashset<userproperty>(); #region lets create dummy data. console.writeline("please wait while creating dummy data, can take while..."); console.writeline(""); int rows = 1000000; for(int x = 0; x < rows; x++) { random rnd = new random(); // ad
Read more