[GHC] #11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc
#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime | Version: 7.10.3 System | Keywords: c++ | Operating System: Unknown/Multiple exceptions | Architecture: | Type of failure: Runtime crash Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider the C++ program {{{ // Main_cc.cc #include <iostream> #include <exception> extern "C" { int func() { try { throw std::runtime_error("THIS FAILS!"); } catch(const std::runtime_error &c) { std::cerr << c.what(); } return 0; } } }}} and the Haskell program {{{#!hs -- Main.hs module Main where import Foreign.C.Types foreign import ccall func :: IO CInt main :: IO () main = print =<< func }}} When compiled with {{{ ghc --make Main.hs Main_cc.cc -lstdc++ }}} and being run on mac os x 10.11.3 the result is {{{ libc++abi.dylib: terminating with uncaught exception of type std::runtime_error: THIS FAILS! Abort trap: 6 }}} and not (as it should be): {{{ THIS FAILS!0 }}} When compiled in a similar way under windows some c++ exceptions of a larger project are not caught as well. However, these were hard to track down and I was unable to construct a simple example like the one above. As a workaround one can * write a main() function in c++ and call from there into Haskell, * compile the Haskell-Module with the options "-c -no-hs-main", and * link the application using g++ (not ghc!). When being compiled / linked this way, all c++ exceptions are being caught in mac os x as well as under windows. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11829 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.10.3 Resolution: | Keywords: c++ | exceptions Operating System: MacOS X | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by thomie): * os: Unknown/Multiple => MacOS X Comment: Nice testcase. Works fine on Linux though. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11829#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.10.3 Resolution: | Keywords: c++ | exceptions Operating System: MacOS X | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by mtolly): This is still the case on macOS 10.12.5 and GHC 8.0.2. By examining the `ld` call from `g++` and experimenting, I discovered the fix is a flag that Clang's linker needs. Place this in the cabal file executable section: {{{ ld-options: -lto_library }}} Or use the following flag for GHC: {{{ ghc (source files) -lstdc++ -optl-lto_library }}} In the cabal file this amusingly parses the flag wrong and produces the incorrect advice: {{{ Warning: Instead of 'ld-options: -lto_library' use 'extra-libraries: to_library' }}} and it also prints the message from #5019 for some reason: {{{ ld: warning: could not create compact unwind for _ffi_call_unix64: does not use RBP or RSP based frame }}} [http://llvm.org/docs/LinkTimeOptimization.html Here is some info on what the flag does], but I don't quite understand how it is connected to exceptions. And [https://reviews.llvm.org/D25932 this page] suggests that a newer Clang will supply the flag automatically. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11829#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.10.3 Resolution: | Keywords: c++ | exceptions Operating System: MacOS X | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by syntheorem): I just ran into this, but the `-lto_library` flag didn't fix the problem (Clang is passing it automatically now anyway). What ultimately worked for me was adding `-Wl,-keep_dwarf_unwind` to my `ld-options`. I tried your method of writing `main` in C++ and manually linking via Clang to see what it does. Interestingly, just linking against the Haskell libraries and RTS with no other flags broke exceptions for me. But I also got the same warning: {{{ ld: warning: could not create compact unwind for _ffi_call_unix64: does not use RBP or RSP based frame }}} I searched for that and discovered that you could use `-Wl,-no_compact_unwind` to disable the warning; and GHC already passes that flag to Clang during linking. But that option also somehow breaks the exception handling tables; the system will fall back on the DWARF exception tables if you include them by passing `-Wl,-keep_dwarf_unwind`. Also worth noting that I'm on macOS 10.12.6, which is about a year out of date, so the issue might be fixed on the most recent version. Using GHC 8.4.3 and Clang 6.0.1. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11829#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.10.3 Resolution: | Keywords: c++ | exceptions Operating System: MacOS X | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by basvandijk): [[https://mail.haskell.org/pipermail/ghc-devs/2019-January/016748.html|As explained on GHC-devs]] I ran into this in our `haskell-opencv` library. I can confirm that adding the following to the cabal file of my minimal isolated test-case fixes the problem: {{{ if os(darwin) ld-options: -Wl,-keep_dwarf_unwind }}} Shouldn't GHC pass these options by default when linking on OS X? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11829#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#11829: C++ does not catch exceptions when used with Haskell-main and linked by ghc -------------------------------------+------------------------------------- Reporter: pl | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.10.3 Resolution: | Keywords: c++ | exceptions Operating System: MacOS X | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by basvandijk): * cc: basvandijk (added) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11829#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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