On Sun, 2025-08-10 at 22:02 +0200, Jonathan Wakely wrote:
>
>
> On Sun, 10 Aug 2025, 20:28 Basile Starynkevitch, <basile@xxxxxxxxxxxxxxxxx> wrote:
> > On Sun, 2025-08-10 at 23:38 +0530, Rajeev Bansal via Gcc-help wrote:
> > > Hello,
> > >
> > > I am working on a large C/C++ project compiled with GCC and am looking for
> > > ways to identify unnecessary header files. I'm wondering if there's a tool
> > > similar to `include-what-you-use` (IWYU) that can help with this
> > > information in gcc.
> > >
> > > Any advice or recommendations would be greatly appreciated.
> >
> > In addition of the previous reply, don't forget link time optimization and precompiled headers in GCC. Sometimes both are improving things.
> >
> > Observe that even the optimization level is known (and used) in some Linux system header files.
> > (so your goal depend upon the compilation options)
>
>
> how is this answer related to the question?!
Simply because a header file "gee.h" might contain
#if __OPTIMIZE__
#include "boo.h" /* which declare foo */
static inline int bar(int y) { return foo(y)+2; }
#else
int bar (int);
#endif
Hence the set of included header files depend upon the optimization levels
(IIRC the Qt library might use similar tricks; in addition Qt is generating C++ code at build time)
Regards.
--
Basile STARYNKEVITCH <basile@xxxxxxxxxxxxxxxxx>
8 rue de la Faïencerie http://starynkevitch.net/Basile/
92340 Bourg-la-Reine https://github.com/bstarynk
France https://github.com/RefPerSys/RefPerSys
