llvm dev - Sep 2014 - [LLVMdev] proposal to avoid zlib dependency.

On 17 September 2014 15:47, Mueller-Roemer, Johannes Sebastian
<Johannes.Sebastian.Mueller-Roemer at igd.fraunhofer.de>
wrote:
> It's half the way there. Configuring and compiling works, but linking
fails, probably some definition mismatches...
It configured, compiled and linked okay for me. Could you look into it?
>
> But it can definitely be simplified, as due to the "REQUIRED"
flag CMake will already fail if zlib isn't found, so no need for the
>
>   if (ZLIB_FOUND)
>     ...
>   else()
>     message(FATAL_ERROR "zlib was requested but it could not be
found")
>   endif()
>
Thanks. I'm aware that's what REQUIRED would do but I thought I'd
try
to be "defensive" just in case someone later on thinks removing
"REQUIRED" is a good idea...

If you think its unnecessary clutter I'd happily remove it.

I'll have another look tomorrow.

IMO, it is unnecessary clutter. It will fail if ${ZLIB_LIBRARIES} or
${ZLIB_INCLUDE_DIRS} are used anyways as they will be set to NOTFOUND. Or we go
back to a silent-fail solution:

find_package(ZLIB QUIET)
if (LLVM_ENABLE_ZLIB AND ZLIB_FOUND)
  set(HAVE_ZLIB_H 1)
  set(HAVE_LIBZ 1)
  list(APPEND CMAKE_REQUIRED_LIBRARIES ${ZLIB_LIBRARIES})
  list(APPEND CMAKE_REQUIRED_INCLUDES ${ZLIB_INCLUDE_DIRS})
else()
  set(HAVE_ZLIB_H 0)
  set(HAVE_LIBZ 0)
endif()

--
Johannes S. Mueller-Roemer, MSc
Wiss. Mitarbeiter - Interactive Engineering Technologies (IET)

Fraunhofer-Institut für Graphische Datenverarbeitung IGD
Fraunhoferstr. 5  |  64283 Darmstadt  |  Germany
Tel +49 6151 155-606  |  Fax +49 6151 155-139
johannes.mueller-roemer at igd.fraunhofer.de  |  www.igd.fraunhofer.de


-----Original Message-----
From: Dan Liew [mailto:dan at su-root.co.uk] 
Sent: Wednesday, September 17, 2014 17:26
To: Mueller-Roemer, Johannes Sebastian
Cc: llvmdev at cs.uiuc.edu
Subject: Re: [LLVMdev] proposal to avoid zlib dependency.

On 17 September 2014 15:47, Mueller-Roemer, Johannes Sebastian
<Johannes.Sebastian.Mueller-Roemer at igd.fraunhofer.de>
wrote:
> It's half the way there. Configuring and compiling works, but linking
fails, probably some definition mismatches...
It configured, compiled and linked okay for me. Could you look into it?
>
> But it can definitely be simplified, as due to the "REQUIRED"
flag
> CMake will already fail if zlib isn't found, so no need for the
>
>   if (ZLIB_FOUND)
>     ...
>   else()
>     message(FATAL_ERROR "zlib was requested but it could not be
found")
>   endif()
>
Thanks. I'm aware that's what REQUIRED would do but I thought I'd
try to be "defensive" just in case someone later on thinks removing
"REQUIRED" is a good idea...

If you think its unnecessary clutter I'd happily remove it.

On 17 September 2014 16:34, Mueller-Roemer, Johannes Sebastian
<Johannes.Sebastian.Mueller-Roemer at igd.fraunhofer.de>
wrote:
> I'll have another look tomorrow.
Thanks.
> IMO, it is unnecessary clutter. It will fail if ${ZLIB_LIBRARIES} or
${ZLIB_INCLUDE_DIRS} are used anyways as they will be set to NOTFOUND. Or we go
back to a silent-fail solution:
Fair enough. I've never been a big fan of silent failure. So perhaps
just this...

```
if (LLVM_ENABLE_ZLIB )
  find_package(ZLIB REQUIRED)
    set(HAVE_ZLIB_H 1)
    set(HAVE_LIBZ 1)
    list(APPEND CMAKE_REQUIRED_LIBRARIES ${ZLIB_LIBRARIES})
    list(APPEND CMAKE_REQUIRED_INCLUDES ${ZLIB_INCLUDE_DIRS})
else()
  set(HAVE_ZLIB_H 0)
  set(HAVE_LIBZ 0)
endif()
```

-- 
Dan Liew
PhD Student - Imperial College London