[cfe-users] Part/complete compilation with clang++

Sian Mountbatten poenikatu at fastmail.co.uk
Sat Jul 20 10:30:01 PDT 2013

On 2013-07-20 18:25, David Blaikie wrote:
> On Sat, Jul 20, 2013 at 10:01 AM, Sian Mountbatten
> <poenikatu at fastmail.co.uk> wrote:
>> On 2013-07-20 17:44, David Blaikie wrote:
>> Nothing obviously wrong with that - yes, jumping in with a debugger
>> might be an option, but the code looks simple enough that I'd wonder
>> if it's an issue with linking or the standard library.
>> On Sat, Jul 20, 2013 at 6:46 AM, Sian Mountbatten
>> <poenikatu at fastmail.co.uk> wrote:
>> Dear List
>> If I compile the file main.cpp to regex using this command:
>>     clang++ -g -std=c++11 -stdlib=libc++ -o regex main.cpp
>> I get no warnings, no errors, in fact no console output from clang++.
>> When the program is run, it produces "\w+\d*" on the console.
>> Now, if I compile with this command:
>>    clang++ -g -std=c++11 -o main.o -c main.cpp
>> and then link with this command:
>>    clang++ -g -stdlib=libc++ -o regex main.o
>> again, I get no output from clang++. Unfortunately, when the output
>> program is run, it fails with "Segmentation violation".
>> Again, I'm assuming you've invoked UB & the two different standard
>> libraries are just failing in different ways. Once we see the code,
>> that might change.
>> What does "UB" mean?
> Undefined Behavior ( a good read on the subject if Chris Lattner's 3
> part series: http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html
> ) - though from your example there's nothing obviously wrong that I
> can see.

The code was lifted from Bjarne's book, so I'd be surprised if there 
*was* anything wrong with it.
Because I succeeded in compiling LLVM/Clang using the GNU C++ library, I 
am now trying to
build LLVM/Clang (svn rev. 186765) using the already compiled Clang++ 
and libc++. We shall
see if that succeeds.

Sian Mountbatten <www.poenikatu.co.uk>
Learning C++!!!
I'm an FSF member (10888)
Help us support software freedom! http://www.fsf.org/jf?referrer=10888

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