[cmake-developers] Generator expressions for <archive|library|runtime> output directory

[Brad King]

On 07/15/2015 05:27 PM, Robert Goulet wrote:
> I didn't know about the two signature of
> cmCompiledGeneratorExpression::Evaluate, what's the difference?
> 
> As for the TARGET_PROPERTY generator expression, are you suggesting
> this could potentially be an issue? I haven't tried it.

If cmCompiledGeneratorExpression::Evaluate is given the current
target ("this") as the headTarget then one can use the
TARGET_PROPERTY generator expression to refer to other properties
on the target whose name is being determined.  This would be nice
to have but could also be enabled by future changes so I won't
insist on it now.

Your original patch did not evaluate the generator expressions
in quite the right place.  On Wednesday I had updated the patch
and applied for testing in 'next':

 Add genex for {ARCHIVE,LIBRARY,RUNTIME}_OUTPUT_DIRECTORY[_<CONFIG>]
 http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=f6f05443

Although testing was clean, I reverted the change from 'next'
this morning after Steve's review led me to realize that the
change causes a crash in a self-reference case like:

 set_property(TARGET myexe PROPERTY RUNTIME_OUTPUT_DIRECTORY $<TARGET_FILE_DIR:myexe>)

This is also a problem for the recent OUTPUT_NAME changes:

 set_property(TARGET myexe PROPERTY OUTPUT_NAME $<TARGET_FILE_NAME:myexe>)

In each case the implementation fails to diagnose the ill-defined
self-reference case.  Fixing these cases may require some kind
of check in cmTarget methods to see if they end up being called
recursively.

Thanks,
-Brad