[OpenJDK 2D-Dev] <AWT Dev> RFR: Allow using the system libjpeg

[Erik Joelsson]

On 2014-05-22 02:49, Omair Majid wrote:
> * Andrew Hughes <gnu.andrew at redhat.com> [2014-05-21 20:23]:
>> ----- Original Message -----
>>> * Andrew Hughes <gnu.andrew at redhat.com> [2014-05-21 12:22]:
>>>> I'm not keen on the hardcoding of '-ljpeg'
>>>>
>>>> +  LIBJPEG_LIBS := -ljpeg
>>> There's no pkg-config files for it. Any suggestions on how to get
>>> something generic?
>>>
>> I know there isn't at present. I still think it's better to be consistent
>> and set the values in configure, even if at present they have to be hardcoded
>> defaults.
> Would you mind if I did this as a separate patch? I will need to fix
> other libraries too (libzip, and libgif).
>
>> The make documentation is a little unclear here, and makes it sound like it
>> will always be set if := or = is used.
> Indeed, it is unclear. But I discovered through trial and error that
> given a Makefile like:
>
> FOO=-v
> all:
> 	gcc ${FOO}
>
> these two forms are different:
>
> $ FOO=bar make
>
> $ make FOO=bar
>
> The first one sets the environment variable FOO, and the Makefile
> overrides it (it runs `gcc -v`). The second passes a command line
> argument that overrides the value in the Makefile (it runs `gcc foo`).
This is my experience too. There is the "override" keyword that you can 
use to not allow command line overrides:

override FOO=-v

The above would make both forms behave the same.

/Erik
> Thanks,
> Omair
>