[MPlayer-dev-eng] Linking mplayer fails

[Reimar Döffinger]

On 1 Apr 2013, at 14:51, Nicolas George <nicolas.george at normalesup.org> wrote:
> Le duodi 12 germinal, an CCXXI, Reimar Döffinger a écrit :
>> I am not sure about any other systems, but since we do not enable PIE by
>> default for them it should't matter much.
> 
> Hum:
> 
> r35083 | reimar | Build as relocatable PIE binary by default on x86.
> r35094 | reimar | Disable building as PIE binary by default.
> r35953 | reimar | Enable auto-detection of PIE linking again.
> 
> Currently, it seems that PIE is enabled by default. I have no idea what are
> the benefits and drawbacks in mplayer's case, but I suppose at some point
> someone will need to make a decision, document it and stick to it.

It greatly hinders exploits, which I think is quite a benefit, particularly when it costs almost nothing.

> Also, if PIC is required with PIE, then moving the PIC test before PIE seems
> wrong, so I suggest to start by reverting r36098.

Wish it was so simple. PIE requires PIC on x86-64, but PIC has almost no cost, so it's ok.
PIE does not require PIC on x86-32, and PIC has a very high cost there, so it should not be enabled unnecessarily there.
But I think the compiler is supposed to figure that out, so I agree that that commit probably should be reverted, it seems like it is actually a bug in clang, and if necessary we should work around it without breaking PIE everywhere else.