I've started a wiki page to document some of this discussion
https://gitlab.haskell.org/ghc/ghc/wikis/Developing-Hadrian. We'll also
need to deal with ouputs as well as inputs (dependencies) soon. Hence
I've expanded a bit on my understanding of rule *outputs* and added the
terms "vital input" and "vital output" (does it make sense? is there a
better name here?). I've slightly changed the definition of "shallow
dependencies" so that by definition it is a (minimal) subset of direct
dependencies such that "/no change in the shallow dependencies -> no
change in the vial output/" The important part to take away is that
rules must:
* `need` all shallow dependencies.
* |`produces|` all vital outputs (excluding the rule target).
David E
On 3/27/19 11:23 PM, Andrey Mokhov wrote:
Simon:
> Perhaps the remaining un-tracked dependencies will be fewer and
easier to nail?
There are a few other cases where we `need` only a subset of direct
dependencies that "cover" all others. For example, `setup-config`
files produced when configuring a package are used to signal the
completion of package configuration, which might produce a few other
hard-to-predict files, such as “build/include/HsBaseConfig.h”.
I just realised that if one wants to have “hermetic builds”, where
build commands are executed in a sandbox, then it is absolutely
necessary to declare all direct dependencies without exception,
because they will need to be made available in the sandbox for the
build command to succeed.
David:
> Perhaps the best step forward is to simply silence the linting
> using `trackAllow ["//*.hi"]` for haskell object rules. Then
> I can continue tracking down other missing dependencies in
> Hadrian with fsatrace linting.
Yes, this looks like the best approach for now.
Cheers,
Andrey
--
David Eichmann, Haskell Consultant
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