Fix false positives in artifacts map change tracking

We used to invalidate a script if it accessed the artifacts map and that
map's keys are now different from what they were. However, that logic
was too coarse: All rules that run after the command will add new
artifacts, so such changes will be the norm, at least when the project
is built for the first time. As a result, some artifacts might get
rebuilt unnecessarily on the next qbs invocation.
The reason why we did it that way was that we needed to consider the
case where a script iterated over the elements of an artifacts map, e.g.
using a for..in loop. In such a case, we cannot know which part of the
map the code is interested in and the script needs to be re-run if the
keys change. This is now solved with the help of a QScriptClass, which
informs us if a script enumerates the keys. In all other cases, the
script only accesses well-known tags, so we only have to compare the
respective artifact lists and do not care about other keys getting added
or removed.

Change-Id: I182a50c34ece28f7ff3f7eba7a8f246e9b79b30e
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 27 insertions, 0 deletions

diff --git a/tests/auto/blackbox/testdata/artifacts-map-change-tracking/artifacts-map-change-tracking.qbs b/tests/auto/blackbox/testdata/artifacts-map-change-tracking/artifacts-map-change-tracking.qbs
index 92579ad7c..0d3c361f6 100644
--- a/tests/auto/blackbox/testdata/artifacts-map-change-tracking/artifacts-map-change-tracking.qbs
+++ b/tests/auto/blackbox/testdata/artifacts-map-change-tracking/artifacts-map-change-tracking.qbs
@@ -56,4 +56,31 @@ Project {
             }
         }
     }
+
+    Product {
+        name: "p"
+        type: "p_type"
+        Rule {
+            multiplex: true
+            Artifact { filePath: "dummy1"; fileTags: "d_type" }
+            prepare: {
+                var cmd = new JavaScriptCommand();
+                cmd.description = "generating " + output.fileName;
+                cmd.sourceCode = function() {
+                    var blubb = product.artifacts.qbs;
+                };
+                return cmd;
+            }
+        }
+        Rule {
+            inputs: "d_type"
+            Artifact { filePath: "dummy2"; fileTags: "p_type" }
+            prepare: {
+                var cmd = new JavaScriptCommand();
+                cmd.description = "generating " + output.fileName;
+                cmd.sourceCode = function() { };
+                return cmd;
+            }
+        }
+    }
 }