Re: [webkit-dev] OK to flatten WTF's header directory?

[Fujii Hironori via webkit-dev]

On Fri, Feb 4, 2022 at 8:31 AM Darin Adler via webkit-dev <
webkit-dev@lists.webkit.org> wrote:

>
> Those original forwarding headers were not copies of the headers, they
> were simply files “in the right place” with include statements in them. I’m
> not sure at what point along the way we started making copies of headers,
> and we may be solving other problems with that.
>

The Apple Internal Build System separately compiles out AppleWin port's
each module, so the forwarding headers don't work, they need to copy
headers.
 https://bugs.webkit.org/show_bug.cgi?id=180064

https://bugs.webkit.org/show_bug.cgi?id=180063
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Re: [webkit-dev] OK to flatten WTF's header directory?

[Elliott Williams via webkit-dev]

Thanks for the detailed response! I should be clear that I don’t have a strong 
opinion for or against flattened headers, I’m just interested in ironing out a 
perceived inconsistency.

> On Feb 3, 2022, at 15:31, Darin Adler  wrote:
> 
> Long ago, I originally created the forwarding headers to bridge the gap 
> between framework-style includes that those of us at Apple wanted to do, 
> where headers are flattened and you write #include 
> , and Unix-style installed libraries, where 
> things are not flattened. I wanted us to be able to write include statements 
> in WebKit in the traditional non-Apple-framework style so they would work on 
> those other platforms, and the forwarding headers were originally just for 
> the Apple platforms, making those includes work with the framework structure 
> provided automatically by the Apple framework build system.

IIUC, what we have today is the opposite situation. JavaScriptCore, WebCore, et 
al. have flattened headers, and it’s the _other platforms_ whose build systems 
do extra work to accommodate flattened includes. WTF and PAL are the exceptions.

> This proposal, to flatten the WTF headers, seems to be a step in of the 
> opposite direction, making the non-Apple platforms do something akin to 
> framework-style including. Not sure I understand the pros and cons are of 
> that.

The factors motivating me are…

- Consistency with other targets: It’s not clear to me why JSC and WebCore have 
flattened their headers but WTF hasn’t.
- Pleasing Xcode’s build system, which _really_ wants a target’s headers to 
always be copied to the same directory. Right now, WTF hacks around this by 
using an rsync script to copy its headers because Xcode’s native copy files 
phase doesn’t provide enough flexibility.

Build system limitations shouldn’t influence ergonomic decisions, so perhaps 
you should disregard the latter.

> I am currently suffering when working on WebKit development because of the 
> copies of headers made by the build system. I can’t count the number of times 
> I’ve edited a WTF header and then later realized I had edited the copy, not 
> the original. I would very much like a solution that resolved that problem. I 
> use Xcode features, and it seems the copies are what Xcode thinks are the 
> “real” headers.

If what you’ve experienced is unique to WTF, I’d be suspicious of the 
non-standard approach we’ve taken to copying WTF’s headers I mentioned above.

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Re: [webkit-dev] OK to flatten WTF's header directory?

[Darin Adler via webkit-dev]

> On Feb 3, 2022, at 5:16 PM, Elliott Williams  wrote:
> 
> If what you’ve experienced is unique to WTF, I’d be suspicious of the 
> non-standard approach we’ve taken to copying WTF’s headers I mentioned above.

Great news. I hope this plan works out.

— Darin
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Re: [webkit-dev] OK to flatten WTF's header directory?

[Darin Adler via webkit-dev]

Long ago, I originally created the forwarding headers to bridge the gap between 
framework-style includes that those of us at Apple wanted to do, where headers 
are flattened and you write #include , and 
Unix-style installed libraries, where things are not flattened. I wanted us to 
be able to write include statements in WebKit in the traditional 
non-Apple-framework style so they would work on those other platforms, and the 
forwarding headers were originally just for the Apple platforms, making those 
includes work with the framework structure provided automatically by the Apple 
framework build system.

Those original forwarding headers were not copies of the headers, they were 
simply files “in the right place” with include statements in them. I’m not sure 
at what point along the way we started making copies of headers, and we may be 
solving other problems with that.

This proposal, to flatten the WTF headers, seems to be a step in of the 
opposite direction, making the non-Apple platforms do something akin to 
framework-style including. Not sure I understand the pros and cons are of that.

I am currently suffering when working on WebKit development because of the 
copies of headers made by the build system. I can’t count the number of times 
I’ve edited a WTF header and then later realized I had edited the copy, not the 
original. I would very much like a solution that resolved that problem. I use 
Xcode features, and it seems the copies are what Xcode thinks are the “real” 
headers.

— Dar
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Re: [webkit-dev] OK to flatten WTF's header directory?

[Elliott Williams via webkit-dev]

> On Feb 1, 2022, at 22:12, Tim Horton  wrote:
> 
> Question: If they're flattened in the SDK, and not flattened in the source 
> tree, which include path do we use when including a WTF header in e.g. 
> WebCore?
> 
> Right now you say `#include `. In your world, would you 
> say `#include `?

Yes, exactly.

> If yes, how does that work for the other build systems that are building with 
> the full source tree? (maybe we have all directories in WTF listed as header 
> search paths, or something? or maybe they look in `usr/lib/include/wtf` in 
> the build directory?)


My understanding is that "maybe we have all directories in WTF listed as header 
search paths” is how we’ve set up WebCore, JSC, and other frameworks which 
already flatten their headers in their build directory. For example, JSC adds 
all its header directories here 
>.
 IIUC, these paths become part of the JSC’s target that is used downstream.___
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Re: [webkit-dev] OK to flatten WTF's header directory?

[Tim Horton via webkit-dev]

> On Feb 1, 2022, at 12:30 PM, Elliott Williams via webkit-dev 
>  wrote:
> 
> Hi webkit-dev,
> 
> I’m working on fixing some ambiguities in our Xcode projects to permit 
> adoption of Xcode’s new build system and better parallelize our builds. I 
> noticed that WTF’s headers (/usr/lib/include/wtf) are atypical in that they 
> aren’t copied into a single directory – they’re deeply nested and mirror the 
> same directory hierarchy as exists in WTF’s sources.
> 
> Is this intentional, and if not, would there be opposition to me flattening 
> them into a single directory? Flattening them makes it easier to explain to 
> Xcode what headers go where, which is useful for tracking dependencies 
> between targets and ensuring proper build order. Headers would still be in 
> their same source locations (alongside implementation files) but would be 
> copied to the top-level /usr/lib/include/wtf directory at build time.

Question: If they're flattened in the SDK, and not flattened in the source 
tree, which include path do we use when including a WTF header in e.g. WebCore?

Right now you say `#include `. In your world, would you 
say `#include `?

If no, how does that work in the case where you only have WTF from the SDK?

If yes, how does that work for the other build systems that are building with 
the full source tree? (maybe we have all directories in WTF listed as header 
search paths, or something? or maybe they look in `usr/lib/include/wtf` in the 
build directory?)

> The only other place in our projects [1] I’m aware of with deeply-nested 
> headers is PAL, and there’s a bug to change that: 
> https://bugs.webkit.org/show_bug.cgi?id=175705 
> 
> 
> -Elliott
> 
> [1]: libwebrtc also produces deeply-nested headers, but since it’s a 
> third-party project, I don’t think our header conventions should apply.
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Re: [webkit-dev] OK to flatten WTF's header directory?

[Ryosuke Niwa via webkit-dev]

On Tue, Feb 1, 2022 at 12:30 PM Elliott Williams via webkit-dev <
webkit-dev@lists.webkit.org> wrote:

> I’m working on fixing some ambiguities in our Xcode projects to permit
> adoption of Xcode’s new build system and better parallelize our builds. I
> noticed that WTF’s headers (/usr/lib/include/wtf) are atypical in that they
> aren’t copied into a single directory – they’re deeply nested and mirror
> the same directory hierarchy as exists in WTF’s sources.
>

What do you mean by this? Could you give us examples?

Is this intentional, and if not, would there be opposition to me flattening
> them into a single directory? Flattening them makes it easier to explain to
> Xcode what headers go where, which is useful for tracking dependencies
> between targets and ensuring proper build order. Headers would still be in
> their same source locations (alongside implementation files) but would be
> copied to the top-level /usr/lib/include/wtf directory at build time.
>
> The only other place in our projects [1] I’m aware of with deeply-nested
> headers is PAL, and there’s a bug to change that:
> https://bugs.webkit.org/show_bug.cgi?id=175705
>
> -Elliott
>
> [1]: libwebrtc also produces deeply-nested headers, but since it’s a
> third-party project, I don’t think our header conventions should apply.
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[webkit-dev] OK to flatten WTF's header directory?

[Elliott Williams via webkit-dev]

Hi webkit-dev,

I’m working on fixing some ambiguities in our Xcode projects to permit adoption 
of Xcode’s new build system and better parallelize our builds. I noticed that 
WTF’s headers (/usr/lib/include/wtf) are atypical in that they aren’t copied 
into a single directory – they’re deeply nested and mirror the same directory 
hierarchy as exists in WTF’s sources.

Is this intentional, and if not, would there be opposition to me flattening 
them into a single directory? Flattening them makes it easier to explain to 
Xcode what headers go where, which is useful for tracking dependencies between 
targets and ensuring proper build order. Headers would still be in their same 
source locations (alongside implementation files) but would be copied to the 
top-level /usr/lib/include/wtf directory at build time.

The only other place in our projects [1] I’m aware of with deeply-nested 
headers is PAL, and there’s a bug to change that: 
https://bugs.webkit.org/show_bug.cgi?id=175705 


-Elliott

[1]: libwebrtc also produces deeply-nested headers, but since it’s a 
third-party project, I don’t think our header conventions should apply.___
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