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

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

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.
The first configure takes this long because we generate command-list.h
and config-list.h.
This process is really slow under Windows.

Thank You,
Sibi Siddharthan