From 31bd83e9fc6c88b7caccd742886b077f387081e9 Mon Sep 17 00:00:00 2001
From: Ben Boeckel <ben.boeckel@kitware.com>
Date: Mon, 22 Jul 2013 17:19:55 -0400
Subject: [PATCH] set_property: Do not remove a property when APPENDing nothing

---
 Source/cmSetPropertyCommand.cxx       | 6 ++++--
 Tests/CMakeLists.txt                  | 1 +
 Tests/EmptyProperty/CMakeLists.txt    | 9 +++++++++
 Tests/EmptyProperty/EmptyProperty.cxx | 1 +
 4 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 Tests/EmptyProperty/CMakeLists.txt
 create mode 100644 Tests/EmptyProperty/EmptyProperty.cxx

diff --git a/Source/cmSetPropertyCommand.cxx b/Source/cmSetPropertyCommand.cxx
index cc10840fd..b5e522515 100644
--- a/Source/cmSetPropertyCommand.cxx
+++ b/Source/cmSetPropertyCommand.cxx
@@ -84,12 +84,14 @@ bool cmSetPropertyCommand
       {
       doing = DoingNone;
       this->AppendMode = true;
+      this->Remove = false;
       this->AppendAsString = false;
       }
     else if(*arg == "APPEND_STRING")
       {
       doing = DoingNone;
       this->AppendMode = true;
+      this->Remove = false;
       this->AppendAsString = true;
       }
     else if(doing == DoingNames)
@@ -160,7 +162,7 @@ bool cmSetPropertyCommand::HandleGlobalMode()
     }
   if(this->AppendMode)
     {
-    cm->AppendProperty(name, value, this->AppendAsString);
+    cm->AppendProperty(name, value ? value : "", this->AppendAsString);
     }
   else
     {
@@ -226,7 +228,7 @@ bool cmSetPropertyCommand::HandleDirectoryMode()
     }
   if(this->AppendMode)
     {
-    mf->AppendProperty(name, value, this->AppendAsString);
+    mf->AppendProperty(name, value ? value : "", this->AppendAsString);
     }
   else
     {
diff --git a/Tests/CMakeLists.txt b/Tests/CMakeLists.txt
index fcefaf906..440cdf08e 100644
--- a/Tests/CMakeLists.txt
+++ b/Tests/CMakeLists.txt
@@ -225,6 +225,7 @@ if(BUILD_TESTING)
   ADD_TEST_MACRO(ObjectLibrary UseCshared)
   ADD_TEST_MACRO(NewlineArgs NewlineArgs)
   ADD_TEST_MACRO(SetLang SetLang)
+  ADD_TEST_MACRO(EmptyProperty EmptyProperty)
   ADD_TEST_MACRO(ExternalOBJ ExternalOBJ)
   ADD_TEST_MACRO(LoadCommand LoadedCommand)
   ADD_TEST_MACRO(LinkDirectory bin/LinkDirectory)
diff --git a/Tests/EmptyProperty/CMakeLists.txt b/Tests/EmptyProperty/CMakeLists.txt
new file mode 100644
index 000000000..39e75f36a
--- /dev/null
+++ b/Tests/EmptyProperty/CMakeLists.txt
@@ -0,0 +1,9 @@
+project (EmptyProperty)
+
+set_property(DIRECTORY APPEND
+    PROPERTY
+        COMPILE_DEFINITIONS)
+
+include(CTest)
+
+add_executable(EmptyProperty EmptyProperty.cxx)
diff --git a/Tests/EmptyProperty/EmptyProperty.cxx b/Tests/EmptyProperty/EmptyProperty.cxx
new file mode 100644
index 000000000..78f2de106
--- /dev/null
+++ b/Tests/EmptyProperty/EmptyProperty.cxx
@@ -0,0 +1 @@
+int main(void) { return 0; }