Allow rules without output artifacts

It is occasionally useful to have a rule whose purpose lies solely in
its "side effects", that is, it does not produce any actual files.
This patch removes the necessity to declare a dummy artifact in that
case.

[ChangeLog] Added support for rules without output artifacts

Change-Id: I38e76a5ddc78ffa768e8ae1f270ae2f7461c5ee7
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

1 files changed, 6 insertions, 7 deletions

diff --git a/src/lib/corelib/language/projectresolver.cpp b/src/lib/corelib/language/projectresolver.cpp
index 5364184fc..b7535c2eb 100644
--- a/src/lib/corelib/language/projectresolver.cpp
+++ b/src/lib/corelib/language/projectresolver.cpp
@@ -1174,19 +1174,18 @@ void ProjectResolver::resolveRule(Item *item, ProjectContext *projectContext)
     rule->prepareScript.initialize(scriptFunctionValue(item, StringConstants::prepareProperty()));
     rule->outputArtifactsScript.initialize(scriptFunctionValue(
                                                item, StringConstants::outputArtifactsProperty()));
+    rule->outputFileTags = m_evaluator->fileTagsValue(
+                item, StringConstants::outputFileTagsProperty());
     if (rule->outputArtifactsScript.isValid()) {
         if (hasArtifactChildren)
             throw ErrorInfo(Tr::tr("The Rule.outputArtifacts script is not allowed in rules "
                                    "that contain Artifact items."),
                         item->location());
-        rule->outputFileTags = m_evaluator->fileTagsValue(
-                    item, StringConstants::outputFileTagsProperty());
-        if (rule->outputFileTags.empty())
-            throw ErrorInfo(Tr::tr("Rule.outputFileTags must be specified if "
-                                   "Rule.outputArtifacts is specified."),
-                            item->location());
     }
-
+    if (!hasArtifactChildren && rule->outputFileTags.empty()) {
+        throw ErrorInfo(Tr::tr("A rule needs to have Artifact items or a non-empty "
+                               "outputFileTags property."), item->location());
+    }
     rule->multiplex = m_evaluator->boolValue(item, StringConstants::multiplexProperty());
     rule->alwaysRun = m_evaluator->boolValue(item, StringConstants::alwaysRunProperty());
     rule->inputs = m_evaluator->fileTagsValue(item, StringConstants::inputsProperty());