#3896: Make the GHC build system accommodate extra packages
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Reporter: simonpj | Owner:
Type: task | Status: new
Priority: normal | Milestone: 6.14 branch
Component: Build System | Version:
Keywords: | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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Simon and I discussed the extra-packages story in GHC's build system.
Here's a summary:
* Simon added these 'extra-packages' stuff to help automate the
process of downloading and building packages
- that are not boot packages
- but which we want to test regularly
* DPH is another such package. It's not really a boot package, in the
sense that (a) it's not necessary to build GHC and (b) it can only
be built with a stage-2 compiler. The main reason it's treated as a
boot package today is so that new patches are validated against it;
it is a particularly good stress test. But it seems a bit overkill
for it to masquerade as a boot package for that reason alone.
* The current extra-packages story is a bit of a mess:
- The extra packages are listed in $(TOP)/packages
- But they are, quite separately listed in a make variable
EXTRA_PACKAGES, and then stuffed into PACKAGES by 'addPackage' in
$(TOP)/ghc.mk.
- A series of addPackage calls in ghc.mk duplicates the list of
boot packages in $(TOP)/packages.
- Moreover, the list in EXTRA_PACKAGES must be in dependency order.
We propose the following plan
* Make the list in $(TOP)/packages the authoritative list.
* Make 'sh boot' construct the list $(PACKAGES) from $(TOP)/packages
and stuff it somewhere appropriate. ['sh boot' has to iterate over
the packages anyhow, to boot them, but doesn't currently consult
$(TOP)/packages to do so; it looks a the file system, which is less
good.]
* Make DPH into an extra package
* And/or add a tag 'validated' to mean "this is an extra package,
not a boot package, but it should be validated before pushing patches".
That doesn't necessarily apply to all extra packages (eg stm).
* The list in $(TOP)/packages is really a list of '''repositories''' not
a list
of '''packages'''. For example, utils/hcs2hs isn't a package. We
probably
want a tag ("util"?) to distinguish non-packages from packages.
* DPH is unusual because it is a '''single repository''' that contains
'''several packages'''.
We can tell this because it has a file ghc-packages in its root
directory,
that lists the packages it contains. 'sh boot' must understand this
when
constructing $(PACKAGES); indeed it already does understand this.
* Packages must be built in dependency order, and the build system has
no way of figuring out the right order. But it would be easy to
stipulate that $(TOP)/packages (and the ghc-packages file, if any,
in the repo) should list the packages in dependency order.
We don't need to execute this plan right away, but would be a very
nice clean-up if anyone felt up to doing something about it.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3896>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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