ENH: Create notion of a 'weak' policy stack entry

A 'weak' poilcy stack entry responds normally to queries.  However,
setting a policy in a weak entry will recursively set the policy in the
next entry too.  This also gives the internal interface to create a weak
entry the option to provide an initial PolicyMap for it.

1 files changed, 9 insertions, 5 deletions

diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index b7b9dc7..a5fcec1 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -349,7 +349,9 @@ public:
   class PolicyPushPop
   {
   public:
-    PolicyPushPop(cmMakefile* m);
+    PolicyPushPop(cmMakefile* m,
+                  bool weak = false,
+                  cmPolicies::PolicyMap const& pm = cmPolicies::PolicyMap());
     ~PolicyPushPop();
     void Quiet() { this->ReportError = false; }
   private:
@@ -943,7 +945,8 @@ private:
   std::map<cmStdString, cmTarget*> ImportedTargets;
 
   // Internal policy stack management.
-  void PushPolicy();
+  void PushPolicy(bool weak = false,
+                  cmPolicies::PolicyMap const& pm = cmPolicies::PolicyMap());
   void PopPolicy();
   void PushPolicyBarrier();
   void PopPolicyBarrier(bool reportError = true);
@@ -955,9 +958,10 @@ private:
   struct PolicyStackEntry: public cmPolicies::PolicyMap
   {
     typedef cmPolicies::PolicyMap derived;
-    PolicyStackEntry(): derived() {}
-    PolicyStackEntry(derived const& d): derived(d) {}
-    PolicyStackEntry(PolicyStackEntry const& r): derived(r) {}
+    PolicyStackEntry(bool w = false): derived(), Weak(w) {}
+    PolicyStackEntry(derived const& d, bool w = false): derived(d), Weak(w) {}
+    PolicyStackEntry(PolicyStackEntry const& r): derived(r), Weak(r.Weak) {}
+    bool Weak;
   };
   typedef std::vector<PolicyStackEntry> PolicyStackType;
   PolicyStackType PolicyStack;