Genex: Track whether an expression depends on the 'head' target

Source/cmGeneratorExpression.cxx

@@ -97,6 +97,7 @@ const char *cmCompiledGeneratorExpression::Evaluate(
   context.Quiet = quiet;
   context.HadError = false;
   context.HadContextSensitiveCondition = false;
+  context.HadHeadSensitiveCondition = false;
   context.HeadTarget = headTarget;
   context.EvaluateForBuildsystem = this->EvaluateForBuildsystem;
   context.CurrentTarget = currentTarget ? currentTarget : headTarget;
@@ -124,6 +125,7 @@ const char *cmCompiledGeneratorExpression::Evaluate(
   if (!context.HadError)
     {
     this->HadContextSensitiveCondition = context.HadContextSensitiveCondition;
+    this->HadHeadSensitiveCondition = context.HadHeadSensitiveCondition;
     }
 
   this->DependTargets = context.DependTargets;
@@ -137,6 +139,7 @@ cmCompiledGeneratorExpression::cmCompiledGeneratorExpression(
               const std::string& input)
   : Backtrace(backtrace), Input(input),
     HadContextSensitiveCondition(false),
+    HadHeadSensitiveCondition(false),
     EvaluateForBuildsystem(false)
 {
   cmGeneratorExpressionLexer l;

Source/cmGeneratorExpression.h

@@ -111,6 +111,10 @@ public:
   {
     return this->HadContextSensitiveCondition;
   }
+  bool GetHadHeadSensitiveCondition() const
+  {
+    return this->HadHeadSensitiveCondition;
+  }
 
   void SetEvaluateForBuildsystem(bool eval)
   {
@@ -141,6 +145,7 @@ private:
                                                           MaxLanguageStandard;
   mutable std::string Output;
   mutable bool HadContextSensitiveCondition;
+  mutable bool HadHeadSensitiveCondition;
   bool EvaluateForBuildsystem;
 };
 

Source/cmGeneratorExpressionEvaluator.cxx

@@ -840,6 +840,10 @@ getLinkedTargetsContent(
       {
       context->HadContextSensitiveCondition = true;
       }
+    if (cge->GetHadHeadSensitiveCondition())
+      {
+      context->HadHeadSensitiveCondition = true;
+      }
     }
   linkedTargetsContent =
     cmGeneratorExpression::StripEmptyListElements(linkedTargetsContent);
@@ -871,6 +875,10 @@ static const struct TargetPropertyNode : public cmGeneratorExpressionNode
     cmTarget const* target = context->HeadTarget;
     std::string propertyName = *parameters.begin();
 
+    if (parameters.size() == 1)
+      {
+      context->HadHeadSensitiveCondition = true;
+      }
     if (!target && parameters.size() == 1)
       {
       reportError(context, content->GetOriginalExpression(),
@@ -1190,6 +1198,10 @@ static const struct TargetPropertyNode : public cmGeneratorExpressionNode
         {
         context->HadContextSensitiveCondition = true;
         }
+      if (cge->GetHadHeadSensitiveCondition())
+        {
+        context->HadHeadSensitiveCondition = true;
+        }
       if (!linkedTargetsContent.empty())
         {
         result += (result.empty() ? "" : ";") + linkedTargetsContent;
@@ -1313,6 +1325,7 @@ static const struct CompileFeaturesNode : public cmGeneratorExpressionNode
           "not be used with add_custom_command or add_custom_target.");
       return std::string();
       }
+    context->HadHeadSensitiveCondition = true;
 
     typedef std::map<std::string, std::vector<std::string> > LangMap;
     static LangMap availableFeatures;
@@ -1446,6 +1459,7 @@ static const struct TargetPolicyNode : public cmGeneratorExpressionNode
       }
 
     context->HadContextSensitiveCondition = true;
+    context->HadHeadSensitiveCondition = true;
 
     for (size_t i = 1; i < cmArraySize(targetPolicyWhitelist); ++i)
       {

Source/cmGeneratorExpressionEvaluator.h

@@ -41,6 +41,7 @@ struct cmGeneratorExpressionContext
   bool Quiet;
   bool HadError;
   bool HadContextSensitiveCondition;
+  bool HadHeadSensitiveCondition;
   bool EvaluateForBuildsystem;
 };