Red Hat Bugzilla – Bug 92309
CDT Debug Step issue
Last modified: 2007-04-18 12:54:18 EDT
From Bugzilla Helper: User-Agent: Mozilla/5.0 Galeon/1.2.7 (X11; Linux i686; U;) Gecko/20030131 Description of problem: in the CDT (using C++), while debugging, i for some reason cannot use the stepping through function (to go through the code line by line). it hangs on the first "std::cout <<" line. stepping through works for C code. also, stepping through works with the same code on another machine running Red Hat 9 (i have Red Hat 8.0) but failed on another machine running RH 8 is this an OS problem? Thanks - Bertina Version-Release number of selected component (if applicable): Beehive Eclipse Release How reproducible: Didn't try Steps to Reproduce: 1. 2.see above 3. Actual Results: hangs on the first "std::cout <<" line Expected Results: Output to the console Additional info: Moved from mailing list my pmuldoon on behalf off blee for better tracking see: http://post-office.corp.redhat.com/archives/eclipse-list/2003-May/msg00133.html http://post-office.corp.redhat.com/archives/eclipse-list/2003-June/msg00001.html
In short: debugging applications with no debug info doesn't work very well. When the CDT debugger hits a PC with no debug info, it appears to do nothing. In fact, gdb HAS done something, but it just doesn't look like it. Stepping into a system library is always going to be hit-or-miss in this respect. Most of the time, it will be miss (system libraries stripped or do not contain debug info). Even if you did have debug info, odds that one has the source files for the libraries is slim at best. Under the cover, the CDT is asking gdb for a particular source file (or for the source file for a given PC), and gdb is saying, "I don't know." Well, the CDT then just does nothing. It should open a disassembly window, so that at least the user can see that there is no source. Alas, this option is disabled by default in the CDT. Go to Window->Preferences->C/C++->Debug and select "Automatically switch to disassembly mode" and it will operate as it should. More under the cover: Imagine that you have a program like this: int main (int argc, char *argv[]) { std::cout << "Hello, world" << std::endl; return EXIT_SUCCESS; } You set a break at main. The debugger stops there. If the app has debug info, gdb and the CDT will display the source for main(). If the app has no debug info , the CDT will show nothing (or the disassembly if the preference is set). Now you step into std::cout, a system library... What happens? If your application has no debug info, gdb issues a warning that it doesn't know how to figure out how to step (because there are no line numbers for the current function, main()), and it steps until main() returns! This is normal behavior. If your app has debug info and the library has no debug info, then gdb issues a warning (which the CDT does not display anywhere) that it is going to step OVER the function call, since it has no debug info for it. This is also normal behavior. If your app has debug info and the library has debug info, then gdb and the cdt will happily display the results of the step, but it will only be able to display source code IF the source file is found on your system (in the same place as the when the library was built, which is exceptionally unlikely). [Mumble something about gdb's path command, which adds source file search paths, but that's another topic.] In short: 1) Don't try to step into a system library without having "automatically switch..." set. 2) Don't try to debug an executable with no debug info