Explicit 'all' target overrides implicit 'all' target.

[epoger, 2012-10-12 16:19:14]

I don't think we (Skia) necessarily want to specify our own "all" target that
only builds a subset of the targets.  Maybe, maybe not.

Either way, it's problematic that gyp automatically generates an "all" target
for SOME build flavors but not ALL.  As Ben wrote, there's more detail at
http://code.google.com/p/skia/issues/detail?id=932 ('gyp automatically creates
"all" target on some build flavors (ninja, make) but not others (xcode)')

[bungeman-chromium, 2012-10-12 19:32:41]

Without this, Skia is going to have to create an 'everything' target and pretend
that 'all' is an unwanted appendage. Skia really wants to use consistent target
names across platforms and generators. Currently, if Skia specifies its own
explicit 'all' target it will get one on xcode and msvs, but then ninja will
complain about multiple 'all' targets. If Skia doesn't specify its own 'all'
target, there isn't one for xcode and msvs.

The only way around this is for Skia to use 'everything' instead and just ignore
'all' so that it can use the same target name with all generators on all
platforms to mean 'build everything'. Note that this is true even if Skia wants
'all' to still mean 'build everything'.

If gyp is going to reserve the 'all' target to itself it needs to error/warn if
any target has the name 'all' and all generators need to create an 'all' target.
At least then Skia would not need an 'everything' target.

[Sam Clegg, 2012-10-12 20:25:27]

On 2012/10/12 19:32:41, bungeman2 wrote:
> Without this, Skia is going to have to create an 'everything' target and
pretend
> that 'all' is an unwanted appendage. Skia really wants to use consistent
target
> names across platforms and generators. Currently, if Skia specifies its own
> explicit 'all' target it will get one on xcode and msvs, but then ninja will
> complain about multiple 'all' targets. If Skia doesn't specify its own 'all'
> target, there isn't one for xcode and msvs.
> 
> The only way around this is for Skia to use 'everything' instead and just
ignore
> 'all' so that it can use the same target name with all generators on all
> platforms to mean 'build everything'. Note that this is true even if Skia
wants
> 'all' to still mean 'build everything'.
> 
> If gyp is going to reserve the 'all' target to itself it needs to error/warn
if
> any target has the name 'all' and all generators need to create an 'all'
target.
> At least then Skia would not need an 'everything' target.

Seems like you are saying that there is no easy/obvious way to get
the "all" behavior that exists in ninja/scons/make in msvs and xcode.

If true then it seems worth fixing by generating an all project in 
xcode automatically.  I was under the impression it was easy to do 
"build all projects" in both xcode and msvs...

[bungeman-chromium, 2012-10-19 18:08:06]

> Seems like you are saying that there is no easy/obvious way to get
> the "all" behavior that exists in ninja/scons/make in msvs and xcode.

> If true then it seems worth fixing by generating an all project in 
> xcode automatically.
This would at least be consistent, and Skia would not need an 'everything'
target, as 'all' would be useful. This would also be needed in the other
generators as well.

> I was under the impression it was easy to do 
> "build all projects" in both xcode and msvs...
Sure, it's simple from the UI. But I can also make a command line tool/GUI which
reads a make or ninja file, finds all the targets, and presents a button to
'build all' which then simply runs make <listOfTargets>. Since the 'all' project
in make and ninja is no more than that, why generate it at all? In other words,
if I can trivially create a script which does the same thing as the 'all' target
produced by make and ninja generators, why stomp on the namespace? This is, I
suspect, the original argument for not having an 'all' target in xcode and msvs.

What I think Skia really wants in this specific case is to not have to special
case the 'build everything' step for its command line build. It doesn't want to
know any gritty details about checking for 'all' and running a special line (to
build a solution, special project, or list of targets). The command line build
tool should just need to know the command line for building a target. If there
is always an 'all' target, then it is possible to just build that target,
without needing to know anything other than how to build a single target. This
is what Skia's 'everything' target is being used for.

[bungeman-chromium, 2012-10-20 06:02:45]

Based on discussion at gyp-developer, Patch Set 2 does not add any flags.
Instead, the auto-generated 'all' targets in ninja and make generators are not
generated if there is already an 'all' target present.

[bungeman-chromium, 2012-10-25 15:27:11]

Mark, Patch Set 2 here seems to be what you were describing as to how gyp was
originally supposed to work. Is this accurate?