Re: [PATCH 2/3] cmake: create compile_commands.json by default

[Sibi Siddharthan <sibisiddharthan.github@gmail.com>]

On Sun, Jun 6, 2021 at 4:06 AM Matt Rogers <mattr94@gmail.com> wrote:
>
> On Fri, Jun 4, 2021 at 5:09 PM Sibi Siddharthan
> <sibisiddharthan.github@gmail.com> wrote:
> >
> > On Fri, Jun 4, 2021 at 11:13 PM Matthew Rogers via GitGitGadget
> > <gitgitgadget@gmail.com> wrote:
> > >
> > > A straightforward way to accomplish this is to make it as simple as
> > > possible is to enable the generation of the compile_commands.json file,
> > > which is supported by many tools such as: clang-tidy, clang-format,
> > > sourcetrail, etc.
> > >
> > > This does come with a small run-time overhead during the configuration
> > > step (~6 seconds on my machine):
> > >
> > >     Time to configure with CMAKE_EXPORT_COMPILE_COMMANDS=TRUE
> > >
> > >     real    1m9.840s
> > >     user    0m0.031s
> > >     sys     0m0.031s
> > >
> > >     Time to configure with CMAKE_EXPORT_COMPILE_COMMANDS=FALSE
> > >
> > >     real    1m3.195s
> > >     user    0m0.015s
> > >     sys     0m0.015s
> > >
> > > This seems like a small enough price to pay to make the project more
> > > accessible to newer users.  Additionally there are other large projects
> > > like llvm [2] which has had this enabled by default for >6 years at the
> > > time of this writing, and no real negative consequences that I can find
> > > with my search-skills.
> > >
> >
> > The overhead is actually much smaller than that. In my system it is
> > less than 150ms.
>
> Is that 150 ms for the whole process or just the difference between the two
> options?  I'm running this on windows via the git bash provided by the
> git sdk.

The difference between the two. Without exporting compile_commands.json
it takes around 650ms, with it around 750ms.
NOTE: This is for subsequent CMake runs. (Excludes the initial run)

Thank You,
Sibi Siddharthan