add requires() function and REQUIRES magic variable

follow suit with qmake ...

Change-Id: I6afc3898a01cc9926b9652b7f0f66becc255f01b
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

src/shared/proparser/qmakebuiltins.cpp

@@ -1023,8 +1023,10 @@ QMakeEvaluator::VisitReturn QMakeEvaluator::evaluateConditionalFunction(
             }
         }
         return ReturnFalse;
-#if 0
+#ifdef PROEVALUATOR_FULL
     case T_REQUIRES:
+        checkRequirements(args);
+        return ReturnFalse; // Another qmake breakage
 #endif
     case T_EVAL: {
             VisitReturn ret = ReturnFalse;

src/shared/proparser/qmakeevaluator.cpp

@@ -117,6 +117,9 @@ void QMakeEvaluator::initStatics()
     statics.strforever = QLatin1String("forever");
     statics.strhost_build = QLatin1String("host_build");
     statics.strTEMPLATE = ProString("TEMPLATE");
+#ifdef PROEVALUATOR_FULL
+    statics.strREQUIRES = ProString("REQUIRES");
+#endif
 
     statics.fakeValue = ProStringList(ProString("_FAKE_")); // It has to have a unique begin() value
 
@@ -837,6 +840,10 @@ void QMakeEvaluator::visitProVariable(
 
     if (varName == statics.strTEMPLATE)
         setTemplate();
+#ifdef PROEVALUATOR_FULL
+    else if (varName == statics.strREQUIRES)
+        checkRequirements(values(varName));
+#endif
 }
 
 void QMakeEvaluator::setTemplate()
@@ -1527,6 +1534,16 @@ bool QMakeEvaluator::evaluateConditional(const QString &cond, const QString &con
     return ret;
 }
 
+#ifdef PROEVALUATOR_FULL
+void QMakeEvaluator::checkRequirements(const ProStringList &deps)
+{
+    ProStringList &failed = valuesRef(ProString("QMAKE_FAILED_REQUIREMENTS"));
+    foreach (const ProString &dep, deps)
+        if (!evaluateConditional(dep.toQString(), fL1S("(requires)")))
+            failed << dep;
+}
+#endif
+
 ProValueMap *QMakeEvaluator::findValues(const ProString &variableName, ProValueMap::Iterator *rit)
 {
     for (int i = m_valuemapStack.size(); --i >= 0; ) {

src/shared/proparser/qmakeevaluator.h

@@ -166,6 +166,9 @@ public:
     VisitReturn evaluateConditionalFunction(const ProString &function, const ushort *&tokPtr);
 
     bool evaluateConditional(const QString &cond, const QString &context);
+#ifdef PROEVALUATOR_FULL
+    void checkRequirements(const ProStringList &deps);
+#endif
 
     QStringList qmakeMkspecPaths() const;
     QStringList qmakeFeaturePaths() const;

src/shared/proparser/qmakeevaluator_p.h

@@ -51,6 +51,9 @@ struct QMakeStatics {
     QString strforever;
     QString strhost_build;
     ProString strTEMPLATE;
+#ifdef PROEVALUATOR_FULL
+    ProString strREQUIRES;
+#endif
     QHash<ProString, int> expands;
     QHash<ProString, int> functions;
     QHash<ProString, ProString> varMap;