Re: [GHC] #9245: In absence of recursive imports, hs-boot files not checked for consistency

28 Jun 2014

      #9245: In absence of recursive imports, hs-boot files not checked for consistency
---------------------------------------+-----------------------------------
        Reporter:  ezyang              |            Owner:  ezyang
            Type:  bug                 |           Status:  new
        Priority:  normal              |        Milestone:
       Component:  Compiler            |          Version:  7.9
      Resolution:                      |         Keywords:
Operating System:  Unknown/Multiple    |     Architecture:
 Type of failure:  Compile-time crash  |  Unknown/Multiple
       Test Case:                      |       Difficulty:  Unknown
        Blocking:                      |       Blocked By:
                                       |  Related Tickets:
---------------------------------------+-----------------------------------
Description changed by ezyang:

Old description:
...
Example:
B.hs-boot
{{{
module B where
b :: Bool
}}}
A.hs
{{{
module A where
import {-# SOURCE #-} B
a = b
}}}
B.hs
{{{
module B where
}}}
Main.hs
{{{
import A
main = print a
}}}
Compilation:
{{{
ghc -c B.hs-boot
ghc -c A.hs
ghc -c B.hs
ghc -c Main.hs
ghc -o main A.o B.o Main.o
}}}
Error:
{{{A.o:(.text+0x79): undefined reference to `B_b_closure'
A.o: In function `A_a_srt':
(.data+0x0): undefined reference to `B_b_closure'
collect2: error: ld returned 1 exit status
}}}
The culprit seems to be this code:
{{{
        -- OK, so we're in one-shot mode.
        -- In that case, we're read all the direct imports by now,
        -- so eps_is_boot will record if any of our imports mention us by
        -- way of hi-boot file
        { eps <- getEps
        ; case lookupUFM (eps_is_boot eps) (moduleName mod) of {
            Nothing -> return emptyModDetails ; -- The typical case
Just (_, False) -> failWithTc moduleLoop ;
                -- Someone below us imported us!
                -- This is a loop with no hi-boot in the way
Just (_mod, True) ->        -- There's a hi-boot interface
below us
}}}
but I am not 100% sure what the correct new logic is yet.
New description:

 Example:

 B.hs-boot
 {{{
 module B where
 b :: Bool
 }}}

 A.hs
 {{{
 module A where
 import {-# SOURCE #-} B
 a = b
 }}}

 B.hs
 {{{
 module B where
 }}}

 Main.hs
 {{{
 import A
 main = print a
 }}}

 Compilation:

 {{{
 ghc -c B.hs-boot
 ghc -c A.hs
 ghc -c B.hs
 ghc -c Main.hs
 ghc -o main A.o B.o Main.o
 }}}

 Error:
 {{{
 A.o:(.text+0x79): undefined reference to `B_b_closure'
 A.o: In function `A_a_srt':
 (.data+0x0): undefined reference to `B_b_closure'
 collect2: error: ld returned 1 exit status
 }}}

 The culprit seems to be this code:

 {{{
         -- OK, so we're in one-shot mode.
         -- In that case, we're read all the direct imports by now,
         -- so eps_is_boot will record if any of our imports mention us by
         -- way of hi-boot file
         { eps <- getEps
         ; case lookupUFM (eps_is_boot eps) (moduleName mod) of {
             Nothing -> return emptyModDetails ; -- The typical case

             Just (_, False) -> failWithTc moduleLoop ;
                 -- Someone below us imported us!
                 -- This is a loop with no hi-boot in the way

             Just (_mod, True) ->        -- There's a hi-boot interface
 below us
 }}}

 but I am not 100% sure what the correct new logic is yet.

--

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9245#comment:1
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler