#14523: Confusing link error when specifying the same object repeatedly -------------------------------------+------------------------------------- Reporter: NeilMitchell | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given {{{foo.hs}}} containing {{{main = print 1}}} and {{{foo.c}}} containing {{{void foo(){} }}}, if you run: {{{ $ ghc foo.o foo.hs C:\Neil\temp\dupe-name>ghc foo.hs foo.o [1 of 1] Compiling Main ( foo.hs, foo.o ) Linking foo.exe ... foo.o:fake:(.data+0x0): multiple definition of `__stginit_Main' foo.o:fake:(.data+0x0): first defined here foo.o:fake:(.data+0x10): multiple definition of `Main_main_closure' foo.o:fake:(.data+0x10): first defined here foo.o:fake:(.text+0x18): multiple definition of `Main_main_info' foo.o:fake:(.text+0x18): first defined here foo.o:fake:(.data+0x30): multiple definition of `ZCMain_main_closure' foo.o:fake:(.data+0x30): first defined here foo.o:fake:(.text+0x88): multiple definition of `ZCMain_main_info' foo.o:fake:(.text+0x88): first defined here foo.o:fake:(.data+0x70): multiple definition of `Main_zdtrModule_closure' foo.o:fake:(.data+0x70): first defined here collect2.exe: error: ld returned 1 exit status `gcc.exe' failed in phase `Linker'. (Exit code: 1) }}} It seems GHC compiles both {{{foo.hs}}} and {{{foo.c}}} to {{{foo.o}}}, and then links {{{foo.o}}} twice. Sometimes {{{foo.hs}}} writes last, sometimes {{{foo.c}}} so the error can change. I found the error quite confusing, until I realised what it was doing. One solution might be before linking {{{.o}}} files GHC does {{{canonicalizePath}}} on all the object files, and if any are duplicates, it raises a cleaner error. That check would also catch {{{ghc foo.hs bar.o bar.o}}} as well. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14523 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler