#12983: Loading temp shared object failed: TemplateHaskell and recompilation -------------------------------------+------------------------------------- Reporter: StefanWehr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: template | Operating System: Unknown/Multiple haskell, recompilation | Architecture: | Type of failure: Compile-time Unknown/Multiple | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In our project, we get from time to time an error like this: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40483_0/libghc_1.dylib, 5): Symbol not found: _ShortText_ShortText_con_info Referenced from: /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40483_0/libghc_1.dylib Expected in: flat namespace in /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40483_0/libghc_1.dylib }}} I was able to create a somewhat minimal setup for reproducing the problem. I've reproduced the problem on Mac and Linux with GHC 8.0.1, didn't try on Windows. The root of the problem seems to be an interaction with template haskell and the recompilation manager. I'll now explain the setup. I've attached an archive which contains all code and a simple build script. Just unpack the archive and execute ./build.sh to reproduce the problem. The setup consists of four files. (Don't be confused by the module names. They are derived from our project). The problem arises after a change to one of these files and a recompilation. Here are the initial versions of the four files. {{{#!hs -- src/ShortText.hs module ShortText where data ShortText = ShortText String toString :: ShortText -> String toString (ShortText s) = s }}} {{{#!hs -- src/Hospital.hs module Hospital where foo :: Int -> String foo i = show i }}} {{{#!hs -- src/Types.hs {-# LANGUAGE TemplateHaskell #-} module Types where import qualified Hospital import Language.Haskell.TH genCode :: Q [Dec] genCode = let s = Hospital.foo 5 in [d|string = s|] }}} {{{#!hs -- src/MetaHandler.hs {-# LANGUAGE TemplateHaskell #-} module Main where import qualified Types -- splices in "string :: String" $(Types.genCode) main :: IO () main = putStrLn string }}} Compiling the project for the first time works without problems: {{{ $ /Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/bin/ghc -O0 -isrc -ibuild -dynamic -outputdir build -package template-haskell --make src/MetaHandler.hs [1 of 3] Compiling Hospital ( src/Hospital.hs, build/Hospital.o ) [2 of 3] Compiling Types ( src/Types.hs, build/Types.o ) [3 of 3] Compiling Main ( src/MetaHandler.hs, build/Main.o ) Linking src/MetaHandler ... }}} I then changed the content of src/Hospital.hs to use the ShortText module. Here is the new content: {{{#!hs -- src/Hospital.hs module Hospital where import ShortText foo :: Int -> String foo i = toString (ShortText (show i)) }}} Then recompilation fails: {{{ [1 of 4] Compiling ShortText ( src/ShortText.hs, build/ShortText.o ) [2 of 4] Compiling Hospital ( src/Hospital.hs, build/Hospital.o ) [4 of 4] Compiling Main ( src/MetaHandler.hs, build/Main.o ) [TH] ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40827_0/libghc_7.dylib, 5): Symbol not found: _ShortText_ShortText_con_info Referenced from: /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40827_0/libghc_7.dylib Expected in: flat namespace in /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40827_0/libghc_7.dylib Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Looking at the output when compiling with -v3 gives a clue why: {{{ ... *** Linker: /usr/bin/gcc -m64 -fno-stack-protector -DTABLES_NEXT_TO_CODE -m64 -dynamiclib -o /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0/libghc_7.dylib build/Hospital.o build/Types.o -undefined dynamic_lookup -single_module -install_name '@rpath/libghc_7.dylib' -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1 /template-haskell-2.11.0.0 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1 /template-haskell-2.11.0.0 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/pretty-1.1.3.3 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/pretty-1.1.3.3 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/deepseq-1.4.2.0 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/deepseq-1.4.2.0 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/array-0.5.1.1 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/array-0.5.1.1 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/ghc- boot-th-8.0.1 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/ghc- boot-th-8.0.1 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/base-4.9.0.0 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/base-4.9.0.0 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/integer- gmp-1.0.0.1 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1 /integer-gmp-1.0.0.1 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/ghc- prim-0.5.0.0 -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/ghc- prim-0.5.0.0 -L/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/rts -Wl,-rpath -Wl,/Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/lib/ghc-8.0.1/rts -lHStemplate-haskell-2.11.0.0-ghc8.0.1 -lHSpretty-1.1.3.3-ghc8.0.1 -lHSdeepseq-1.4.2.0-ghc8.0.1 -lHSarray-0.5.1.1-ghc8.0.1 -lHSghc-boot- th-8.0.1-ghc8.0.1 -lHSbase-4.9.0.0-ghc8.0.1 -lHSinteger- gmp-1.0.0.1-ghc8.0.1 -lHSghc-prim-0.5.0.0-ghc8.0.1 -liconv *** Deleting temp files: Deleting: /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0/ghc_8.rsp /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0/libghc_7.dylib *** Deleting temp dirs: Deleting: /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0 ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-apple-darwin): Loading temp shared object failed: dlopen(/var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0/libghc_7.dylib, 5): Symbol not found: _ShortText_ShortText_con_info Referenced from: /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0/libghc_7.dylib Expected in: flat namespace in /var/folders/8r/25v12lxd02zdm7lpky3xcnh80000gn/T/ghc40913_0/libghc_7.dylib }}} We can see here that the .o file for ShortText is not passed to gcc when building libghc_7.dylib. I suspect that libghc_7.dylib is used to run template haskell code, but this is only a guess. Looking at the .hi file for MetaHandler, we can see why gcc does not get the .o file for ShortText: ShortText is not included in the module dependencies: {{{ $ /Users/swehr/.stack/programs/x86_64-osx/ghc-8.0.1/bin/ghc --show-iface build/Main.hi Magic: Wanted 33214052, got 33214052 Version: Wanted [8, 0, 0, 1], got [8, 0, 0, 1] Way: Wanted [], got [d, y, n] interface Main 8001 interface hash: def8085a5dcb4980922089d5d21cf0f9 ABI hash: 1a46783c6a6c6b308503cf705db45d4d export-list hash: d2d75d71ebb6963f6e9c9a5b4050ef71 orphan hash: 693e9af84d3dfcc71e640e005bdc5e2e flag hash: 3468616c2ba87fe39e866ff30d651f01 sig of: Nothing used TH splices: True where exports: main string module dependencies: Hospital Types package dependencies: array-0.5.1.1 base-4.9.0.0 deepseq-1.4.2.0 ghc-boot-th-8.0.1 ghc-prim-0.5.0.0 integer- gmp-1.0.0.1 pretty-1.1.3.3 template-haskell-2.11.0.0 orphans: GHC.Base GHC.Float }}} I think the main problem is that src/Types.hs is not recompiled in the second run. I also experimented with compiling each file separately, using the -c flag. When I then compile src/Types.hs, ghc outputs "compilation NOT required" in the second run. If a compile src/Types.hs with -fforce- recomp in the 2nd run, everything works fine. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12983 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler