I have the impression that in the configuration step, when Cabal sees the line
Extra-Libraries: IL
it writes a small C program that tries to include that library, and reports the library is missing if there's an error in compiling and linking the C program. Maybe Cabal needs to interpret
#648: Cabal incorrectly reports missing C library IL ----------------------------+----------------------------------------------- Reporter: GregoryWeber | Owner: Type: defect | Status: new Priority: normal | Milestone: Component: Cabal library | Version: 1.6.0.1 Severity: normal | Keywords: Difficulty: unknown | Ghcversion: Platform: Linux | ----------------------------+----------------------------------------------- Comment(by duncan): Replying to [ticket:648 GregoryWeber]: the C compiler's and linker's error messages more carefully. This is correct. We cannot in general interpret the C compilers error messages. They are too varied. We should consult what autoconf does here. It takes the same strategy and does not try to interpret error messages. Perhaps we can just improve the message, to make clear it's only the mostly likely reason, not an absolute conclusion. We should also save the log for users to inspect if they choose. This should make it easier to see what is really going on. See also #532 for other instances of this problem. As you say, although the error message is wrong here, the problem is real. The package does depend on pthread or rt but does not say so. -- Ticket URL: http://hackage.haskell.org/trac/hackage/ticket/648#comment:1 Hackage http://haskell.org/cabal/ Hackage: Cabal and related projects