[Mesa-stable] [Mesa-dev] [PATCH] configure.ac: detect LLVM patch level when built via cmake

[Jonathan Gray]

On Wed, Sep 17, 2014 at 07:03:56AM -0700, Tom Stellard wrote:
> On Wed, Sep 17, 2014 at 09:29:34PM +1000, Jonathan Gray wrote:
> > On Tue, Sep 16, 2014 at 06:24:40PM -0400, Tom Stellard wrote:
> > > On Tue, Sep 09, 2014 at 07:56:03PM +0100, Emil Velikov wrote:
> > > > On 09/09/14 16:26, Tom Stellard wrote:
> > > > > On Sat, Sep 06, 2014 at 01:43:55AM +1000, Jonathan Gray wrote:
> > > > >> In LLVM 3.4.1 and 3.4.2 the patch level was only set in config.h when
> > > > >> LLVM was built via autoconf and not when it was built with cmake.
> > > > >> Fall back to retrieving the patch level from llvm-config --version to
> > > > >> handle this case.
> > > > >>
> > > > > 
> > > > > We should extract LLVM_VERSION_PATH from $LLVM_VERSION and then we won't
> > > > > have to worry about which config file it is in.
> > > > > 
> > > > I believe you meant VERSION_PATCH above ? Indeed that would nice thing to have
> > > > but I doubt that it will get back-ported to the llvm 3.4 branch.
> > > > 
> > > 
> > > I mean we should do this in Mesa's configure script.  Something like:
> > > 
> > > LLVM_VERSION_PATCH = echo $LLVM_VERSION | sed 's/^[0-9]\+\.[0-9]\+\.//g'
> > 
> > This should be
> > 
> > LLVM_VERSION_PATCH = echo $LLVM_VERSION | sed -E 's/^[0-9]+\.[0-9]+\.//g'
> > 
> > $ echo 3.4.2 | sed 's/^[0-9]\+\.[0-9]\+\.//g'     
> > 3.4.2
> > 
> > $ echo 3.4.2 | sed -E 's/^[0-9]+\.[0-9]+\.//g'  
> > 2
> > 
> > $ echo 3.4.2 | gsed 's/^[0-9]\+\.[0-9]\+\.//g'
> > 2
> > 
> > $ echo 3.4.2 | gsed -E 's/^[0-9]+\.[0-9]+\.//g'
> > 2
> 
> Which of these examples are *BSD compatible?

To be compliant with POSIX you can only use + in extended regular expressions
the use of + in basic regular expressions is apparently a gnu extension?

http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html

Using sed with extended regular expressions via -E is also an extension
but it would seem a more common one.

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html

In the above examples gsed is the gnu one and sed is the
Diomidis Spinellis/BSD/OS X sed.  The way the REs are handled
depends on how REs are implemented in the respective libc versions.

This is really the same issue you reviewed and pushed a
fix for in cdb353539c259d5c5137394f6a7b4dafef9a40da except
there is no 'esed' for EREs with sed.

So the version with -E should be preferred.  But either way there
is a problem with versions of llvm that don't have a patch level.

$ echo 3.4 | sed -E 's/^[0-9]+\.[0-9]+\.//g'   
3.4

so if you want to use sed it should be something like
$ echo 3.4 | sed -E 's/^[0-9]+\.[0-9]+//g'

Then check for an empty string and set it zero.
Or just use 'cut' like the cmake patch did.

LLVM_VERSION_PATCH=`echo $LLVM_VERSION | cut -d. -f3`
if test -z "$LLVM_VERSION_PATCH"; then
	LLVM_VERSION_PATCH=0
fi