#15970: Recompilation bug with default class methods -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: bug | Status: patch Priority: highest | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5394 Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonmar): * status: new => patch * differential: => Phab:D5394 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15970#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#15970: Recompilation bug with default class methods -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: bug | Status: patch Priority: highest | Milestone: 8.8.1 Component: Compiler | Version: 8.6.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5394 Wiki Page: | -------------------------------------+------------------------------------- Description changed by bgamari: Old description:

Repro as follows.

A.hs: {{{#!hs {-# OPTIONS_GHC -fno-full-laziness #-} module A (toTypedData, toTypedDataNoDef) where

toTypedData :: String -> IO Int toTypedData s = wrapPrint "yoyo" $ toTypedDataNoDef s

wrapPrint :: String -> IO Int -> IO Int wrapPrint s act = do putStrLn s act

toTypedDataNoDef :: String -> IO Int toTypedDataNoDef s = return $ length s }}}

B.hs: {{{#!hs module B ( TypeClass(..) ) where

import A

class Show a => TypeClass a where getSize :: a -> IO Int getSize a = toTypedData (show a)

printA :: a -> IO () }}}

C.hs: {{{ module Main where

import B

data MyDataType = MyDataType String Int deriving Show

instance TypeClass MyDataType where printA = putStrLn . show

main :: IO () main = do let myValue = MyDataType "haha" 99 sz <- getSize myValue putStrLn $ show sz printA myValue }}}

1. Comment out the `-fno-full-laziness` option in A.hs 2. `rm *.o *.hi; ghc -O2 C.hs` 3. Re-enable the `-fno-full-laziness` option in A.hs 4. `ghc -O2 C.hs`

Produces a linker error:

{{{ C.o:Main_main1_info: error: undefined reference to 'A_toTypedData2_closure' C.o(.data.rel.ro+0x48): error: undefined reference to 'A_toTypedData2_closure' collect2: error: ld returned 1 exit status }}}

Reproduced in 8.0, 8.4 and master. Probably happens in all released versions of GHC.

New description: Repro as follows. A.hs: {{{#!hs {-# OPTIONS_GHC -fno-full-laziness #-} module A (toTypedData, toTypedDataNoDef) where toTypedData :: String -> IO Int toTypedData s = wrapPrint "yoyo" $ toTypedDataNoDef s wrapPrint :: String -> IO Int -> IO Int wrapPrint s act = do putStrLn s act toTypedDataNoDef :: String -> IO Int toTypedDataNoDef s = return $ length s }}} B.hs: {{{#!hs module B ( TypeClass(..) ) where import A class Show a => TypeClass a where getSize :: a -> IO Int getSize a = toTypedData (show a) printA :: a -> IO () }}} C.hs: {{{#!hs module Main where import B data MyDataType = MyDataType String Int deriving Show instance TypeClass MyDataType where printA = putStrLn . show main :: IO () main = do let myValue = MyDataType "haha" 99 sz <- getSize myValue putStrLn $ show sz printA myValue }}} 1. Comment out the `-fno-full-laziness` option in A.hs 2. `rm *.o *.hi; ghc -O2 C.hs` 3. Re-enable the `-fno-full-laziness` option in A.hs 4. `ghc -O2 C.hs` Produces a linker error: {{{ C.o:Main_main1_info: error: undefined reference to 'A_toTypedData2_closure' C.o(.data.rel.ro+0x48): error: undefined reference to 'A_toTypedData2_closure' collect2: error: ld returned 1 exit status }}} Reproduced in 8.0, 8.4 and master. Probably happens in all released versions of GHC. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15970#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#15970: Recompilation bug with default class methods -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: bug | Status: patch Priority: highest | Milestone: 8.8.1 Component: Compiler | Version: 8.6.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5394 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"288f681e06accbae690c46eb8a6e997fa9e5f56a/ghc" 288f681/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="288f681e06accbae690c46eb8a6e997fa9e5f56a" Fix recompilation bug with default class methods (#15970) If a module uses a class, then it can instantiate the class and thereby use its default methods, so we must include the default methods when calculating the fingerprint for the class. Test Plan: New unit test: driver/T15970 Before: ``` =====> T15970(normal) 1 of 1 [0, 0, 0] cd "T15970.run" && $MAKE -s --no-print-directory T15970 Wrong exit code for T15970()(expected 0 , actual 2 ) Stdout ( T15970 ): Makefile:13: recipe for target 'T15970' failed Stderr ( T15970 ): C.o:function Main_zdfTypeClassMyDataType1_info: error: undefined reference to 'A_toTypedData2_closure' C.o:function Main_main1_info: error: undefined reference to 'A_toTypedData2_closure' C.o(.data+0x298): error: undefined reference to 'A_toTypedData2_closure' C.o(.data+0x480): error: undefined reference to 'A_toTypedData2_closure' collect2: error: ld returned 1 exit status `gcc' failed in phase `Linker'. (Exit code: 1) ``` After: test passes. Reviewers: bgamari, simonpj, erikd, watashi, afarmer Subscribers: rwbarton, carter GHC Trac Issues: #15970 Differential Revision: https://phabricator.haskell.org/D5394 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15970#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#15970: Recompilation bug with default class methods -------------------------------------+------------------------------------- Reporter: simonmar | Owner: simonmar Type: bug | Status: closed Priority: highest | Milestone: 8.6.4 Component: Compiler | Version: 8.6.2 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5394 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: merge => closed * resolution: => fixed Comment: This was merged with 08cfa6153171d7289e799b97940f51d322d8dd32. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15970#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler