[gentoo-user] verifying GCC version program was compiled with

[gentoo-user] verifying GCC version program was compiled with

[Joseph]

Is there a way to verify GCC version program was compiled with?
I just want to check if all the programs were compiled with latest GCC version as I'm getting an errors at time to time.
-- 
Joseph

Re: [gentoo-user] verifying GCC version program was compiled with

[Daniel Pielmeier]

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Joseph schrieb am 04.04.2009 22:48:
> Is there a way to verify GCC version program was compiled with?
> I just want to check if all the programs were compiled with latest GCC
> version as I'm getting an errors at time to time.

I don't think it is possible to get the compiler or it's version used
for a specific program. If you are upgrading the compiler it is
advisable to recompile the complete system so all programs are compiled
with the same compiler version. Take a look at the gcc upgrading guide
[1] for the necessary steps you need to follow.

[1] http://www.gentoo.org/doc/en/gcc-upgrading.xml

-- 
Daniel Pielmeier


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Re: [gentoo-user] verifying GCC version program was compiled with

[Alan McKinnon]

On Saturday 04 April 2009 23:42:54 Daniel Pielmeier wrote:
> Joseph schrieb am 04.04.2009 22:48:
> > Is there a way to verify GCC version program was compiled with?
> > I just want to check if all the programs were compiled with latest GCC
> > version as I'm getting an errors at time to time.
>
> I don't think it is possible to get the compiler or it's version used
> for a specific program. If you are upgrading the compiler it is
> advisable to recompile the complete system so all programs are compiled
> with the same compiler version. Take a look at the gcc upgrading guide
> [1] for the necessary steps you need to follow.
>
> [1] http://www.gentoo.org/doc/en/gcc-upgrading.xml

This is complete nonsense advice. There is absolutely no need to rebuild the 
entire system every time you upgrade compilers, and whoever told you that is 
flat out wrong. If the gentoo docs told you that, then they are wrong, or 
misplaced, or the person writing them is overcautious to the point of being 
ridiculous. If this advice really was true, then a whole lot of stuff would 
break all over the world:

- every Windows box on the planet would need a complete reinstall whenever a 
Windows Update happened (Yes, Microsoft does upgrade their compiler!)
- third party apps would not run, as you have no way of knowing if Oracle's 
compiler is the same as yours (and you don't even have a guarantee that Oracle 
uses gcc). My Oracle instance at work is working just fine and I know for a 
fact the compilers used for it and SuSE are not even in the same version 
series.
- Compiling any package locally could not work on a binary distro. But they 
do.

There are *some* special cases where the gcc devs break stuff at an ABI level 
between versions (usually related to C++ not to C). These are well known and 
heavily documented - the toolchain devs make sure of this. 3.3 to 3.4 was such 
a case, there was another minor case early in the gcc-4 series. By no means do 
this mean that the fix for those cases must now be applied every time.

-- 
alan dot mckinnon at gmail dot com

Re: [gentoo-user] verifying GCC version program was compiled with

[Daniel Pielmeier]

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Alan McKinnon schrieb am 04.04.2009 23:55:
> On Saturday 04 April 2009 23:42:54 Daniel Pielmeier wrote:
>> Joseph schrieb am 04.04.2009 22:48:
>>> Is there a way to verify GCC version program was compiled with?
>>> I just want to check if all the programs were compiled with latest GCC
>>> version as I'm getting an errors at time to time.
>> I don't think it is possible to get the compiler or it's version used
>> for a specific program. If you are upgrading the compiler it is
>> advisable to recompile the complete system so all programs are compiled
>> with the same compiler version. Take a look at the gcc upgrading guide
>> [1] for the necessary steps you need to follow.
>>
>> [1] http://www.gentoo.org/doc/en/gcc-upgrading.xml
> 
> This is complete nonsense advice. There is absolutely no need to rebuild the 
> entire system every time you upgrade compilers, and whoever told you that is 
> flat out wrong. If the gentoo docs told you that, then they are wrong, or 
> misplaced, or the person writing them is overcautious to the point of being 
> ridiculous. If this advice really was true, then a whole lot of stuff would 
> break all over the world:
> 
> - every Windows box on the planet would need a complete reinstall whenever a 
> Windows Update happened (Yes, Microsoft does upgrade their compiler!)
> - third party apps would not run, as you have no way of knowing if Oracle's 
> compiler is the same as yours (and you don't even have a guarantee that Oracle 
> uses gcc). My Oracle instance at work is working just fine and I know for a 
> fact the compilers used for it and SuSE are not even in the same version 
> series.
> - Compiling any package locally could not work on a binary distro. But they 
> do.
> 
> There are *some* special cases where the gcc devs break stuff at an ABI level 
> between versions (usually related to C++ not to C). These are well known and 
> heavily documented - the toolchain devs make sure of this. 3.3 to 3.4 was such 
> a case, there was another minor case early in the gcc-4 series. By no means do 
> this mean that the fix for those cases must now be applied every time.
> 

I must confess that I don't know if there is an ABI breakage between
4.1.2 and 4.3.2. So if there is none you may be fine without rebuilding
world.

-- 
Daniel Pielmeier


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Re: [gentoo-user] verifying GCC version program was compiled with

[Joseph]

On 04/04/09 23:55, Alan McKinnon wrote:
[snip]
>> [1] http://www.gentoo.org/doc/en/gcc-upgrading.xml
>
>This is complete nonsense advice. There is absolutely no need to rebuild the 
>entire system every time you upgrade compilers, and whoever told you that is 
>flat out wrong. If the gentoo docs told you that, then they are wrong, or 
>misplaced, or the person writing them is overcautious to the point of being 
>ridiculous. If this advice really was true, then a whole lot of stuff would 
>break all over the world:

[snip]

So in other words it was not necessary to recompile the entire system in this case going from gcc: 
4.3.2 to  4.2.3 ?
Though, according to Gentoo guide, the second number has changed so this is a major upgrade.
Not to mention it is good to take advantage of "native" flag.

-- 
Joseph

Re: [gentoo-user] verifying GCC version program was compiled with

[Alan McKinnon]

On Sunday 05 April 2009 01:31:16 Joseph wrote:
> On 04/04/09 23:55, Alan McKinnon wrote:
> [snip]
>
> >> [1] http://www.gentoo.org/doc/en/gcc-upgrading.xml
> >
> >This is complete nonsense advice. There is absolutely no need to rebuild
> > the entire system every time you upgrade compilers, and whoever told you
> > that is flat out wrong. If the gentoo docs told you that, then they are
> > wrong, or misplaced, or the person writing them is overcautious to the
> > point of being ridiculous. If this advice really was true, then a whole
> > lot of stuff would break all over the world:
>
> [snip]
>
> So in other words it was not necessary to recompile the entire system in
> this case going from gcc: 4.3.2 to  4.2.3 ?
> Though, according to Gentoo guide, the second number has changed so this is
> a major upgrade. Not to mention it is good to take advantage of "native"
> flag.

I mean that you take a step like this when it is required and only when it is 
required. If the documentation says that for *that* version you should rebuild 
everything, then do so. But only do it if it is required. As I already said, 
you only need to do that when new binaries on your system will be incompatible 
with existing binaries resulting in them not loading and linking properly. 
This is extremely rare.

The "native" flag will make almost no difference to your machine either, it 
will not turn your Mini into a Ferrari. All it really is, is a simple way to 
tell your compiler "whatever this cpu is, compile stuff optimized for that 
processor". Now you don't have to go digging to find out what to set march, 
mtune, et al to. So it's a user convenience feature more than anything else.

Your system will work just fine without rebuilding with "native". The previous 
binaries worked, they will still work.

-- 
alan dot mckinnon at gmail dot com

Re: [gentoo-user] verifying GCC version program was compiled with

[Alan McKinnon]

On Sunday 05 April 2009 00:11:52 Daniel Pielmeier wrote:
> > There are some special cases where the gcc devs break stuff at an ABI
> > level between versions (usually related to C++ not to C). These are well
> > known and heavily documented - the toolchain devs make sure of this. 3.3
> > to 3.4 was such a case, there was another minor case early in the gcc-4
> > series. By no means do this mean that the fix for those cases must now be
> > applied every time.
>
> I must confess that I don't know if there is an ABI breakage between
> 4.1.2 and 4.3.2. So if there is none you may be fine without rebuilding
> world.

There isn't one. I know this simply because I have not rebuilt world since 
before 4.1.2 on my desktop, it is currently ~arch and everything works fine.

-- 
alan dot mckinnon at gmail dot com