#3799: undefined symbols and undefined references possibly related to template
haskell
---------------------------------+------------------------------------------
Reporter: JeremyShaw | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.1
Resolution: | Keywords: undefined symbols
references template haskell
Difficulty: | Os: Unknown/Multiple
Testcase: | Architecture: Unknown/Multiple
Failure: Compile-time crash |
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Comment (by simonpj):
Another common factor is that all the missing things look like
{{{
sybzmwithzmclasszm0zi6zi1_DataziGenericsziSYBziWithClassziInstances_constrZMad6fZN_closure
}}}
Or possibly `dataType` instead of `constr`. Undoing the z-encoding we
get:
{{{
syb-with-
class-0.6.1_Data.Generics.SYB.WithClass.Instances_constr[ad6f]_closure
}}}
And indeed, I download `syb-with-class` and compile `Instances` with
`-ddump-splices` I see
{{{
Data/Generics/SYB/WithClass/Instances.hs:1:0:
Data/Generics/SYB/WithClass/Instances.hs:1:0: Splicing declarations
deriveData ['ByteString]
======>
Data/Generics/SYB/WithClass/Instances.hs:726:3-27
constr[a2YC] :: Constr
constr[a2YC] = mkConstr dataType[a2YB] "PS" "" Prefix
dataType[a2YB] :: DataType
dataType[a2YB] = mkDataType "ByteString" [constr[a2YC]]
}}}
Those are pretty weird names for top-level bindings! But still, it should
work fine, because they are only used via the instance declaration.
But it does make me wonder: could you have compiled syb-with-class twice?
Each time you compile it you could potentially get different names.
If it happens repeatably, do
{{{
ghc --show-iface Instances.hi
}}}
where the `Instances.hi` file is the one from the syb-with-class package.
Check the names of the top level bindings (as above). Are they the same
as you see with `nm Instances.o`?
Now when compiling `Server.hs` (which gets the offending symbols), use
`-ddump-if-trace` to see what interface files it is loading, and check
that it loads the correct `Instances.hi`.
Does the same thing happen in file-at-a-time batch mode, or just with
`--make`?
Somehow or other, I bet that you are getting two different `Instances.hi`
files, or an `Instances.hi` that does not line up with the `Instances.o`.
Simon
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3799#comment:3>
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