3
votes

I'm debugging a project that uses precompiled headers under GDB. While inspecting crash stack trace, I found that GDB prints correct functions names but incorrect file and line number information.

Look at the following examples:

file.h

#ifndef FILE_H_
#define FILE_H
    #include "../precompiled_header.h"

    void func_A();
    void func_B();
#endif //FILE_H

Notice that there are only five lines in the header.

file.cpp

#include "file.h"

void func_A()
{
    int *a = 0;
    *a =0;
}
void func_B()
{
    func_A();
}

int main()
{
    func_B();

    return 0;
}

gdb program -> run -> bt: will print something like

....
func_A(): file.h at 32 <- incorrect file and line information
func_B(): file.h at 40 <- incorrect file and line information
main():   file.cpp at 14

As soon as I remove precompiled_header.h.gch, gdb prints

func_A(): file.cpp at 5  <- OK!
func_B(): file.cpp at 10 <- OK!
main():   file.cpp at 14

I'm sure that precompiled head and all the files are compiled with the same set of command line flags and that this precompiled header is really found and used(checked with -H option). No optimizations are turned on.

The program is compiled with

-D_GNU_SOURCE -D_REENTRANT -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -Wno-unused -fexceptions -std=gnu++0x-fPIC -Winvalid-pch -Wdisabled-optimization -Wuninitialized -Wsequence-point -Winit-self

gcc -v gives the following output

Using built-in specs.

Target: x86_64-linux-gnu

Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.4.3-4ubuntu5.1' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i486 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux- gnu --target=x86_64-linux-gnu

Thread model: posix

gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5.1)

What could be wrong here?

1

1 Answers

3
votes

This is a compiler bug: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44550

It's been fixed in g++ 4.5, so you should upgrade your compiler.

Nevertheless, it'd be better to include your pre-compiled header as the first line of the cpp file instead of the h file, as the pre-compiled header inclusion needs to be at the top of the compilation unit. In your case, you would include it every time your include your header file. This change would stop that bug from affecting you.