After setting a breakpoint in Qt, gdb says: “Error accessing memory address”

Question

I wrote a very simple Qt program here:

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);

    QTableView table(&frame         


        

Answer 1

OK for me I got this when building with mingw-w64 (native or cross compiler). I'm not sure what the exact problem was, but if I build it using gcc mingw-w64 i686-5.1.0-posix-sjlj-rt_v4-rev0 then it creates (finally) debuggable builds. Otherwise

(gdb) break main
...
(gdb) r
...
Cannot insert breakpoint 1.
Cannot access memory at address 0x42445c

message 19 times out of 20, though sometimes it did actually work (very rarely).

gdb 7.8.1 and 7.9.1 seemed to be able to debug the created exe. So it's probably not the version of gdb that makes a difference.

My current theory/suspect is either it was the version of gcc or possibly the sljl vs. dwarf2 "aspect" to the compiler [?] (i686-492-posix-dwarf-rt_v3-rev1 didn't work, and cross compiling with some form of gcc 4.9.2 didn't either). Didn't try other versions of gcc.

update: newer gcc (5.1.0) but cross compiling I still got this failure. The cause in this case turned out to be a dependency library that my build (FFmpeg) was using by linking against (libgme in this case) which is exporting a few errant "shared" symbols (when I am building a static executable). Because of this, "shared" builds brake (https://trac.ffmpeg.org/ticket/282) and somehow it screws up gdb as well. For instance possibly linking against SDL can do this to you as well. My thought is possibly an ld bug [?]