cmake_policy: Add undocumented PARENT_SCOPE option to GET

Policies affecting the behavior of CMake-provided macros and functions
need to be able to get the policy setting as of the call site rather
than the definition site.  Add an undocumented option to do this.

6 files changed, 28 insertions, 9 deletions

diff --git a/Source/cmCMakePolicyCommand.cxx b/Source/cmCMakePolicyCommand.cxx
index 7ca1cbc..adf9ef8 100644
--- a/Source/cmCMakePolicyCommand.cxx
+++ b/Source/cmCMakePolicyCommand.cxx
@@ -95,7 +95,11 @@ bool cmCMakePolicyCommand::HandleSetMode(std::vector<std::string> const& args)
 
 bool cmCMakePolicyCommand::HandleGetMode(std::vector<std::string> const& args)
 {
-  if (args.size() != 3) {
+  bool parent_scope = false;
+  if (args.size() == 4 && args[3] == "PARENT_SCOPE") {
+    // Undocumented PARENT_SCOPE option for use within CMake.
+    parent_scope = true;
+  } else if (args.size() != 3) {
     this->SetError("GET must be given exactly 2 additional arguments.");
     return false;
   }
@@ -115,7 +119,8 @@ bool cmCMakePolicyCommand::HandleGetMode(std::vector<std::string> const& args)
   }
 
   // Lookup the policy setting.
-  cmPolicies::PolicyStatus status = this->Makefile->GetPolicyStatus(pid);
+  cmPolicies::PolicyStatus status =
+    this->Makefile->GetPolicyStatus(pid, parent_scope);
   switch (status) {
     case cmPolicies::OLD:
       // Report that the policy is set to OLD.
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 9aeeb5c..490d516 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -4089,10 +4089,10 @@ const char* cmMakefile::GetDefineFlagsCMP0059() const
   return this->DefineFlagsOrig.c_str();
 }
 
-cmPolicies::PolicyStatus cmMakefile::GetPolicyStatus(
-  cmPolicies::PolicyID id) const
+cmPolicies::PolicyStatus cmMakefile::GetPolicyStatus(cmPolicies::PolicyID id,
+                                                     bool parent_scope) const
 {
-  return this->StateSnapshot.GetPolicy(id);
+  return this->StateSnapshot.GetPolicy(id, parent_scope);
 }
 
 bool cmMakefile::PolicyOptionalWarningEnabled(std::string const& var)
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index d2626cd..8589deb 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -284,7 +284,8 @@ public:
      */
   bool SetPolicy(cmPolicies::PolicyID id, cmPolicies::PolicyStatus status);
   bool SetPolicy(const char* id, cmPolicies::PolicyStatus status);
-  cmPolicies::PolicyStatus GetPolicyStatus(cmPolicies::PolicyID id) const;
+  cmPolicies::PolicyStatus GetPolicyStatus(cmPolicies::PolicyID id,
+                                           bool parent_scope = false) const;
   bool SetPolicyVersion(std::string const& version_min,
                         std::string const& version_max);
   void RecordPolicies(cmPolicies::PolicyMap& pm);
diff --git a/Source/cmStateSnapshot.cxx b/Source/cmStateSnapshot.cxx
index 0d97c33..0229a77 100644
--- a/Source/cmStateSnapshot.cxx
+++ b/Source/cmStateSnapshot.cxx
@@ -160,8 +160,8 @@ void cmStateSnapshot::SetPolicy(cmPolicies::PolicyID id,
   }
 }
 
-cmPolicies::PolicyStatus cmStateSnapshot::GetPolicy(
-  cmPolicies::PolicyID id) const
+cmPolicies::PolicyStatus cmStateSnapshot::GetPolicy(cmPolicies::PolicyID id,
+                                                    bool parent_scope) const
 {
   cmPolicies::PolicyStatus status = cmPolicies::GetPolicyStatus(id);
 
@@ -180,6 +180,10 @@ cmPolicies::PolicyStatus cmStateSnapshot::GetPolicy(
     cmLinkedTree<cmStateDetail::PolicyStackEntry>::iterator root =
       dir->DirectoryEnd->PolicyRoot;
     for (; leaf != root; ++leaf) {
+      if (parent_scope) {
+        parent_scope = false;
+        continue;
+      }
       if (leaf->IsDefined(id)) {
         status = leaf->Get(id);
         return status;
diff --git a/Source/cmStateSnapshot.h b/Source/cmStateSnapshot.h
index 94d6274..af5653b 100644
--- a/Source/cmStateSnapshot.h
+++ b/Source/cmStateSnapshot.h
@@ -43,7 +43,8 @@ public:
   cmStateEnums::SnapshotType GetType() const;
 
   void SetPolicy(cmPolicies::PolicyID id, cmPolicies::PolicyStatus status);
-  cmPolicies::PolicyStatus GetPolicy(cmPolicies::PolicyID id) const;
+  cmPolicies::PolicyStatus GetPolicy(cmPolicies::PolicyID id,
+                                     bool parent_scope = false) const;
   bool HasDefinedPolicyCMP0011();
   void PushPolicy(cmPolicies::PolicyMap const& entry, bool weak);
   bool PopPolicy();
diff --git a/Tests/PolicyScope/CMakeLists.txt b/Tests/PolicyScope/CMakeLists.txt
index 413195a..353842b 100644
--- a/Tests/PolicyScope/CMakeLists.txt
+++ b/Tests/PolicyScope/CMakeLists.txt
@@ -52,6 +52,10 @@ if(1)
     # CMP0002 should be changed when this function is invoked
     cmake_policy(GET CMP0002 cmp)
     check(CMP0002 "OLD" "${cmp}")
+
+    # The undocumented PARENT_SCOPE option sees the caller's setting.
+    cmake_policy(GET CMP0002 cmp PARENT_SCOPE)
+    check(CMP0002 "NEW" "${cmp}")
   endfunction()
 
   # Unset CMP0002
@@ -61,6 +65,10 @@ if(1)
     cmake_policy(GET CMP0002 cmp)
     check(CMP0002 "" "${cmp}")
 
+    # The undocumented PARENT_SCOPE option sees the caller's setting.
+    cmake_policy(GET CMP0002 cmp PARENT_SCOPE)
+    check(CMP0002 "NEW" "${cmp}")
+
     # Setting the policy should work here and also in the caller.
     cmake_policy(SET CMP0002 OLD)
     cmake_policy(GET CMP0002 cmp)