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

[GHC]

#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>
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