question about meta/class/qmake-base.bbclass

When I read the file meta/class/qmake-base.bbclass, I find that that are 2 lines:

     unset QMAKESPEC || true
     ${OE_QMAKE_QMAKE} -makefile -spec ${QMAKESPEC} -o Makefile

$QMAKE_VARSUBST_PRE $AFTER $PROFILES $QMAKE_VARSUBST_POST || die "Error calling ${OE_QMAKE_QMAKE} on $PROFILES"

I am confused that why unset QMAKESPEC first and then use it a argument for qmake?

Quoted 9 lines · On Monday 22 August 2011 10:42:42 Kang Kai wrote:

When I read the file meta/class/qmake-base.bbclass, I find that that are 2 lines:

      unset QMAKESPEC || true
      ${OE_QMAKE_QMAKE} -makefile -spec ${QMAKESPEC} -o Makefile

$QMAKE_VARSUBST_PRE $AFTER $PROFILES $QMAKE_VARSUBST_POST || die "Error calling ${OE_QMAKE_QMAKE} on $PROFILES"

I am confused that why unset QMAKESPEC first and then use it a argument for qmake?

It's not obvious, but think that the difference here is between $QMAKESPEC and ${QMAKESPEC} - the first one is a reference to an environment variable, the second is a reference to an OE/BitBake variable. So "unset QMAKESPEC" is just clearing out the environment variable; ${QMAKESPEC} would still have a value.

Cheers,
Paul

Quoted 5 lines · Kang Kai

Hi Holger,

I am confused that why unset QMAKESPEC first and then use it a argument for qmake?
Could you help me to get out of that?

Hi,

it has been a long time and I can only speculate right now. It might have been that QMAKESPEC was not shell exported, and we really wanted to make sure that it is using the QMAKESPEC we use in the recipe. Alternatively it might be a style issue, e.g. it is easier to see which spec is used by looking at the qmake invocation (also when changing the .pro in the ${S} the right spec would be used again).

holger