Just to make this 100% explicit:
* Cabal uses ghc --make to build a bunch of .o files (including Match.o)
* Cabal then links the .o files that are listed in dm.cabal
(as exposed or other) to make a .a file. This list accidentally
excludes Match.o
* Cabal copies the .a file and the .hi files listed in dm.cabal
(as exposed or other) to the install place, and registers them.
Again, this list excludes Match.o
As a result, a client of the package compiles all right (so long as it does not
import Match) but fails at the link stage, lacking symbols in Match.
This seems like a bug in Cabal, because it allows you to build and install an
unusable package. Possible solutions I can think of:
- Cabal does its own dependency analysis and calls GHC one module at a time
- GHC gets a flag which prevents it finding any module other than those listed
on the command line (although it may still do dependency analysis to figure out
which order to compile them in)
- The .cabal file is no longer reqd to list non-exposed modules. Instead Cabal
works out what the non-exposed modules are (perhaps by calling GHC -M or
something similar).
Simon
| -----Original Message-----
| From: Duncan Coutts [mailto:[EMAIL PROTECTED]
| Sent: 24 June 2007 04:33
| To: Serge D. Mechveliani
| Cc: glasgow-haskell-bugs@haskell.org; Simon Peyton-Jones
| Subject: Re: skipping module in .cabal
|
| On Sat, 2007-06-23 at 12:08 +0400, Serge D. Mechveliani wrote:
| > Dear GHC developers,
| >
| > Recently I submitted a bug report #1452 for ghc-6.6.1
| > of undefined references at the stage of linking executable,
| > and also of ignoring un-existing module import.
| >
| > Now I discovered the following strange effect
| > (see the report source modules) which, probably, explains much.
| >
| > 1. (minor note) The file Match.hs-boot is not needed.
| > All the effects preserve after its removal.
| >
| > 2. The name `Match' must be in the list `other-modules:'
| > in the file
| > dm.cabal, which describes the package.
| >
| > But it is not in dm.cabal !
| > Because I have forgotten to put it there.
|
| Currently Cabal uses ghc --make to build packages. It starts from all
| the modules listed in the exposed-modules but ghc --make will find any
| other modules that are imported, even if they are not listed in
| the .cabal file in the exposed-modules or other-modules fields.
|
| That's the current system. The right system I think is for Cabal to do
| the dependency analysis itself (it needs to do that for proper support
| of pre-processors anyway). That would allow Cabal to notice when
| modules
| are imported but not listed in either the exposed-modules or
| other-modules fields. It could issue a warning or an error.
|
| Duncan
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