This was originally reported as -QBS-270-, but because that was about version 0.3 and we are now at 1.9 and since then at least the documentation has changed, I made a new report.

outer.concat() fails inside a Properties block when 'outer' depends on a property set in the outside scope.

ERROR: /home/tvanengelen/Sources/QbsCppDefinesExample/QbsCppDefinesExample.qbs:14:5 ReferenceError: Can't find variable: foo

Example:

import qbs 1.0

CppApplication {
  name: "outerconcat"

  Depends { name: "cpp" }
  
  files: [
    'main.cpp'
  ]

  property string foo: "foo"
  
  cpp.includePaths: [ foo ]
  
  Properties {
    condition: true
    cpp.includePaths: outer.concat([ "bar" ])
  }
}

When

  cpp.includePaths: [ foo ] 

is changed to

  cpp.includePaths: [ "foo" ] 

there is no error and everything works as expected.