[cmake-developers] RFC: CMake precompiled header support and custom compiler based implementation

[David Cole]

With Visual Studio, you definitely **need** separate pch for each CONFIG.
Every pch is going to include headers which have Debug/Release differences
in them, and it is not safe to mix and match compiler output from separate
configs together.


D


On Friday, December 4, 2015, Daniel Pfeifer <daniel at pfeifer-mail.de> wrote:

> My working branch is here:
> https://github.com/purpleKarrot/CMake/commits/pch
>
> Feel free to comment, evaluate, contribute.
>
> I am nut fully decided regarding these two questions:
> - Do we want to support different pch per CONFIG? I think no, but I
> might be wrong.
> - Do we want to support different pch per LANGUAGE? I first thought
> yes, but I am no longer certain about that.
>
> On Fri, Dec 4, 2015 at 5:12 AM, Taylor Braun-Jones
> <taylor at braun-jones.org <javascript:;>> wrote:
> > Perhaps the Paris Climate talks would be good inspiration for tackling
> > this feature. How many pounds of CO2 are emitted each year due to
> > needless header compilation CPU cycles? :-)
> >
> > On Fri, Oct 30, 2015 at 1:48 AM, James Johnston
> > <johnstonj.public at codenest.com <javascript:;>> wrote:
> >>> -----Original Message-----
> >>
> >>> From: cmake-developers [mailto:cmake-developers-bounces at cmake.org
> <javascript:;>]
> >>
> >>> On Behalf Of Daniel Pfeifer
> >>
> >>> Sent: Wednesday, October 28, 2015 08:57
> >>
> >>> To: Taylor Braun-Jones
> >>
> >>> Cc: CMake Developers
> >>
> >>> Subject: Re: [cmake-developers] RFC: CMake precompiled header support
> >>
> >>> and custom compiler based implementation
> >>
> >>>
> >>
> >>> On Tue, Oct 27, 2015 at 3:53 AM, Taylor Braun-Jones <taylor at braun-
> >>
> >>> jones.org> wrote:
> >>
> >>> > What's the status of this PCH feature? Does it need testers? More
> >>
> >>> > design input? I'd love to see this feature in a future CMake release.
> >>
> >>> > Willing to help.
> >>
> >>>
> >>
> >>> I haven't worked on it for quite some time as I currently don't have a
> >>
> >> project
> >>
> >>> which needs it.
> >>
> >>> But I agree that we should get it into CMake, even if it does not
> >>
> >>> support
> >>
> >> all
> >>
> >>> generators yet.
> >>
> >>> Support for additional generators can be added successively.
> >>
> >>>
> >>
> >>> I will rebase my branch to master on the weekend, ie port it to
> >>
> >>> cmGeneratorTarget.
> >>
> >>> Then you are free to help with review, testing, and additional
> generators.
> >>
> >>>
> >>
> >>> Which generators are the most important for you?
> >>
> >>
> >>
> >> I'd also love to see some progress on PCH support, though I haven't had
> much
> >> time recently... I'd be quite happy to test however with the below
> compilers
> >> and generators - all of which we would use PCH support with:
> >>
> >>
> >>
> >> Generators:
> >>
> >>
> >>
> >> * Ninja
> >>
> >> * Visual Studio 2008 (eventually 2015)
> >>
> >> * Although we're not currently using it, CMake would be pretty broken
> >> without supporting: Unix Makefiles
> >>
> >>
> >>
> >> Compilers:
> >>
> >>
> >>
> >> * Visual C++ 2008 (eventually 2015): both Ninja and VS generators
> >>
> >> * Embarcadero bcc32 compiler: Ninja
> >>
> >> * GCC: Ninja
> >>
> >>
> >>
> >> Best regards,
> >>
> >>
> >>
> >> James Johnston
> >>
> >>
> >> --
> >>
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>
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>
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>
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