Re: Using std types and functions within GCC

[Jonathan Wakely <jwakely.gcc@gmail.com>]

On Thu, 14 Mar 2024 at 14:49, David Malcolm <dmalcolm@redhat.com> wrote:
>
> On Thu, 2024-03-14 at 13:28 +0000, Jonathan Wakely via Gcc wrote:
> > On Thu, 14 Mar 2024 at 12:54, Pierrick Philippe
> > <pierrick.philippe@irisa.fr> wrote:
> > >
> > > Hi all,
>
> Hi Pierrick!  It was good to meet you at FOSDEM.
>
> > >
> > > I was wondering, is there any conventions or guidelines regarding
> > > the
> > > usage of types and/or functions coming from the C++ std library
> > > within
> > > the compiler?
> >
> > The relevant header needs to be included from the gcc/system.h
> > header.
> > Look in there for INCLUDE_STRING, INCLUDE_VECTOR etc. and how those
> > macros are used in other sources.
> >
> > > To explicit a bit more, I am working on modification on the
> > > analyzer and
> > > might need to use a pair.
> >
> > A grep of the source shows that <utility> is already included in
> > gcc/system.h and std::pair is already used in several places.
>
> Thanks Jonathan.
>
> A couple of other things to note:
>
> - bear in mind that we need to be somewhat conservative in our usage of
> C++ internally: our code needs to be C++11, compilable by GCC 4.8.3,
> and parsable by gengtype and by xgettext.  For example, there's at
> least one place where I'd have used std::optional, but that's C++14 and
> so unavailable.

C++17, so even more unavailable!

> - some parts of our code manage memory using our custom garbage
> collector (via GTY and gengtype), and other parts use C++11 move
> semantics.  I suspect that these two approaches to memory management
> aren't especially compatible with each other.  For example, our vec<T>
> class works with the GC but not (I think) with move, whereas
> std::vector works with C++11.  We make the simplifying assumption
> within the analyzer that the garbage collector will never run within
> the analysis pass, and the analyzer makes use of move semantics, ctors,
> dtors, etc.
>
> Feel free to use std::pair in the analyzer.
>
> Hope this is helpful
> Dave
>