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The freeform general-data/folders/build-folder element is apparently ignored by FreeformProjectGenerator - never read, never written. (Unclear whether it is in fact *deleted* by the dialog - did not check because of issue #50933.) I just confirmed that <build-folder> is in fact used at runtime if specified in project.xml, to mark project ownership of an external non-source folder - important if you want to e.g. debug code that you build to an external location, since otherwise the debugger will not be able to locate the corresponding sources. However for nonexpert users, the GUI does not help. Perhaps the build output panel could check to see if any build outputs are specified which are not contained in the project dir (or a registered external source root) and if so, automatically add one or more <build-folder>s to contain them. I guess the algorithm could be: produce a minimal set of build folders which collectively contain all of the outputs. Since all such extra build outputs must be given as absolute paths in the GUI, I don't think you need to worry about Ant property substitutions.
Honestly, I did not know it should be generated and what is it purpose and probably you are the only one who knew that. :-) Otherwise we would discovered this problem earlier. I will impl it as you suggested. FPG should skip <build-folder> elements.
Fixed. Please review/try. I would not want to screw up something just before the High Resistence mode. If wrong reverting change in ProjectModel should be enough. Fixed in: src/org/netbeans/modules/ant/freeform/FreeformProjectGenerator.java; new revision: 1.36; previous revision: 1.35 src/org/netbeans/modules/ant/freeform/ui/ProjectModel.java; new revision: 1.9; previous revision: 1.8 test/unit/src/org/netbeans/modules/ant/freeform/FreeformProjectGeneratorTest.java; new revision: 1.17; previous revision: 1.16
Seems to be working as intended. E.g. I have a sample freeform prj w/ Apache Ant sources (external source root). I claim that it produces as output all of /space/ant162/lib/ant*.jar. Makes a <build-folder> for /space/ant162/lib as intended. Browsing these JARs in Favorites says they are indeed part of the project. Making a j2seproject w/ dep on /space/ant162/lib/ant.jar gives correct code completion w/ Javadoc for org.apache.tools.ant.Project.