Re: Forcing a linking error?

Omer, this ticket may be of interest to you: https://ghc.haskell.org/trac/ghc/ticket/7790 Edward Excerpts from Ömer Sinan Ağacan's message of 2015-08-14 03:51:49 -0700:

Here's an example that fails with a link time error when -threaded is not used:

➜ rts_test ghc --make Main.hs [1 of 1] Compiling Main ( Main.hs, Main.o ) Linking Main ... Main.o: In function `rn4_info': (.text+0x26): undefined reference to `wakeUpRts' collect2: error: ld returned 1 exit status

With -threaded it works:

➜ rts_test ghc --make Main.hs -threaded Linking Main ...

Code:

➜ rts_test cat Main.hs {-# LANGUAGE ForeignFunctionInterface #-}

module Main where

foreign import ccall "wakeUpRts" wakeUpRts :: IO ()

main :: IO () main = return ()

What I did is basically I found a function in GHC RTS that is only defined when THREADED_RTS is defined and referred to it in my program.

2015-08-14 3:59 GMT-04:00 Erik de Castro Lopo :

...

Dear ghc-devs,

There is a commonly used library which has at least one function that when compiled into a program, requires the threaded run time system. Without the threaded runtime, the program just hangs.

One kludgy solution to this problem is to have the function check for Control.Concurrent.rtsSupportsBoundThreads being true and throwing an error if its not. However, it would be much nicer if this could be turned into a link time error.

Anyone have any ideas how this might be done?

Cheers, Eri -- ---------------------------------------------------------------------- Erik de Castro Lopo http://www.mega-nerd.com/ _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs