[llvm-dev] Errors linking with LLVM 5.0 - dump() missing

Martin J. O'Riordan via llvm-dev
Mon, 25 Sep 2017 20:13:47 -0000

Yes, if it is in the interface it would make more sense to have a null
implementation at the very least.  In my out-of-tree target, I also removed them
from the interface if the build was for Release to ensure that I got
compile-time errors to reveal other places I might have otherwise missed.

All the best,

	MartinO

-----Original Message-----
From: Dibyendu Majumdar [mailto:mobile at majumdar.org.uk]
Sent: 25 September 2017 20:57
To: Martin J. O'Riordan <MartinO at theheart.ie>
Cc: LLVM Developers <llvm-dev at lists.llvm.org>
Subject: Re: [llvm-dev] Errors linking with LLVM 5.0 - dump() missing

Hi Martin,


On 25 September 2017 at 20:35, Martin J. O'Riordan <MartinO at
theheart.ie> wrote:
> Are you building a Debug or Release version of the compiler?

It seems that in Release builds of LLVM 5.0 the dump() implementation is absent,
although the method is available in the interface. This is plain wrong in my
view. If the dump() has to be removed then it should not be present in the
interface.

>
> I had similar problems a few days ago when I was migrating to v5.0, and it
turned out that I had calls to some of the dump routines that were not guarded
by either 'DEBUG(...)' or '#ifndef NDEBUG ... #endif' and I was
seeing the link failures with a Release build.  These had been there since LLVM
v3.1 and had never broken before.  There was some clean-up done in the sources
so that may of the 'dump' routines are enabled only for Debug builds,
and I fixed these (in my code) by adding these guards.
>

Well the problem is that there is no obvious way for a client to detect whether
the dump() implementation is available or not - as it does not depend upon the
Release/Debug build status of the client, but how LLVM 5.0 was originally
compiled. So the guards you have put are not really going to work (that is my
finding anyway).

Regards
Dibyendu

>
> -----Original Message-----
> From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of
> Dibyendu Majumdar via llvm-dev
> Sent: 25 September 2017 19:41
> To: llvm-dev at lists.llvm.org
> Subject: [llvm-dev] Errors linking with LLVM 5.0 - dump() missing
>
> Hi,
>
> I am finding that my project that previously successfully built with
versions 3.5 to 4.0 is now failing to link because of missing implementation for
dump(). Errors I get are:
>
> Undefined symbols for architecture x86_64:
>
>   "llvm::Type::dump() const", referenced from:
>       ravi::LuaLLVMTypes::dump() in ravi_llvmtypes.cpp.o
>       dump_content(lua_State*) in ravi_llvmluaapi.cpp.o
>   "llvm::Value::dump() const", referenced from:
>       dump_content(lua_State*) in ravi_llvmluaapi.cpp.o
>   "llvm::Module::dump() const", referenced from:
>
> This appears to be a change that is not documented in the release notes of
5.0. Please can someone describe what the change is and how I can detect whether
the dump() implementation is available or not?
>
> It also seems strange that dump() implementation was removed - surely it
would have been better ti stub it so that client code does not break?
>
> Regards
> Dibyendu
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