#5967: incompatible implicit declaration of function 'memcpy'
------------------------------+---------------------------------------------
Reporter: nomeata | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.4.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Other | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by nomeata):
Ok, here is almost a minimal example:
{{{
{-# LANGUAGE MagicHash, ForeignFunctionInterface #-}
module Test where
import GHC.Prim
import Foreign.Ptr
import Foreign.C
foreign import ccall unsafe "memcpy"
memcpy :: Ptr a -> Ptr a -> CSize -> IO (Ptr ())
test = copyByteArray#
}}}
Compiling this yields
{{{
'/usr/bin/gcc' '-fno-stack-protector' '-Wl,--hash-size=31' '-Wl,--reduce-
memory-overheads' '-x' 'c' '/tmp/ghc13588_0/ghc13588_0.hc' \
'-o' '/tmp/ghc13588_0/ghc13588_0.s' '-fwrapv' '-fno-strict-aliasing' '-S'
'-Wimplicit' '-O' '-D__GLASGOW_HASKELL__=704'\
'-DNO_REGS' '-DUSE_MINIINTERPRETER' '-I' '.' '-I'
'/usr/lib/ghc/base-4.5.0.0/include' '-I' '/usr/lib/ghc/include'\
/tmp/ghc13588_0/ghc13588_0.hc: In function ‘Test_test_entry’:
/tmp/ghc13588_0/ghc13588_0.hc:29:1:
warning: implicit declaration of function ‘memcpy’ [-Wimplicit-
function-declaration]
/tmp/ghc13588_0/ghc13588_0.hc:29:1:
warning: incompatible implicit declaration of built-in function
‘memcpy’ [enabled by default]
/tmp/ghc13588_0/ghc13588_0.hc: In function ‘Test_zdwccall_entry’:
/tmp/ghc13588_0/ghc13588_0.hc:56:2:
warning: conflicting types for built-in function ‘memcpy’ [enabled by
default]
}}}
But if I then modify the .hc file and move the {{{memcpy((void *)_c19o,
(void *)_c19n, _c19m);}}} call to the bottom of the file, after the
{{{EF_(memcpy)}}}, then I get:
{{{
/tmp/ghc13380_0/ghc13380_0.hc: In function ‘Test_zdwccall_entry’:
/tmp/ghc13380_0/ghc13380_0.hc:43:2: warning: conflicting types for built-
in function ‘memcpy’ [enabled by default]
/tmp/ghc13380_0/ghc13380_0.hc: In function ‘Test_test_entry’:
/tmp/ghc13380_0/ghc13380_0.hc:181:1: warning: implicit declaration of
function ‘memcpy’ [-Wimplicit-function-declaration]
/tmp/ghc13380_0/ghc13380_0.hc:74:2: note: previous declaration of ‘memcpy’
was here
/tmp/ghc13380_0/ghc13380_0.hc:181:1: error: incompatible implicit
declaration of function ‘memcpy’
/tmp/ghc13380_0/ghc13380_0.hc:74:2: note: previous implicit declaration of
‘memcpy’ was here
}}}
so the order of declarations gets important.
So a solution seems to be to generate the {{{EF_(...)}}} style call also
for memcpy (is there a runtime performance penalty)? The code to look at
seems to be source:compiler/cmm/PprC.hs, especially {{{pprStmt}}}, where a
memcpy can occur as a {{{CmmPrim MO_Memcpy}}} or as a {{{CmmCall}}} (which
does the EF_ stuff).
Commentary/Compiler/Backends/PprC#Prototypes seems to be related.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5967#comment:2>
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