Re: [GHC] #11531: ghci with ffi to inline assembly results in "the 'impossible'"

3 Feb 2016

      #11531: ghci with ffi to inline assembly results in "the 'impossible'"
---------------------------------+--------------------------------------
        Reporter:  isovector     |                Owner:
            Type:  bug           |               Status:  closed
        Priority:  normal        |            Milestone:
       Component:  Compiler      |              Version:  7.8.4
      Resolution:  duplicate     |             Keywords:  ffi, asm, ghci
Operating System:  Linux         |         Architecture:  x86_64 (amd64)
 Type of failure:  None/Unknown  |            Test Case:
      Blocked By:                |             Blocking:
 Related Tickets:  #10458        |  Differential Rev(s):
       Wiki Page:                |
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Changes (by rwbarton):

 * status:  new => closed
 * resolution:   => duplicate
 * related:   => #10458

Comment:

 Thanks for the report.

 Actually, the issue here is that you wrote a C++ program. In order to link
 C++-compiled object files with the outside world, you need to link with
 the C++ standard library, `-lstdc++`. So, you could do this:

 {{{
 $ ghci ffi.o Main.hs -lstdc++
 }}}

 This won't actually work in 7.8 or 7.10, because of #10458. But I tested
 that it does work in current HEAD and 8.0. So, closing as a duplicate of
 that ticket.

 In the meantime, you can build your C++ object into a shared library
 yourself, and load that in ghci:
 {{{
 $ g++ -shared -o libmyffi.so ffi.o
 $ ghci Main.hs -L. -lmyffi
 }}}

 Alternatively, just write your inline assembly in C.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11531#comment:1
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