RE: -fwarn-unused-imports confused by hi-boot files

Yes, you want to say

        import {-# SOURCE #-} A ()

In principle you can just import B.hi-boot, but it says

        module B where
        type AS = [A.A]

so GHC tries to find A.hi.  The error message is bad, and the HEAD
instead says
    Bad interface file: ./A.hi
    ./A.hi: openBinaryFile: does not exist (No such file or directory)
which is better.

The SOURCE import of A is reqd to tell GHC to get the hi-boot file.
Annoying I agree.  I'll add something to the documentation.

Simon

| -----Original Message-----
| From: glasgow-haskell-bugs-bounces@xxxxxxxxxxx
[mailto:glasgow-haskell-bugs-
| bounces@xxxxxxxxxxx] On Behalf Of George Russell
| Sent: 16 September 2004 15:49
| To: glasgow-haskell-bugs@xxxxxxxxxxx
| Subject: -fwarn-unused-imports confused by hi-boot files
| 
| # ghc -fwarn-unused-imports C.hs
| 
| C.hs:1:
|      Warning: Module `A' is imported, but nothing from it is used
|            (except perhaps instances visible in `A')
| 
| 
| 
| However if I comment out the import of A I get
| 
| 
| ./B.hi-boot:3:
|      tcLookup: `A.A' is not in scope
|      In the type synonym declaration for `AS'
| 
| C.hs:1:
|      Failed to load interface for `A':
|       Bad interface file: ./A.hi
|           ./A.hi: openBinaryFile: does not exist (No such file or
directory)
| 
| C.hs:1:
|      Failed to find interface decl for `A.A'
|      from module `A'
| 
| C.hs:1:
|      Failed to find interface decl for `A.A'
|      from module `A'