New USE_FOLDERS property OFF by default. (#3796)

Visual Studio Express editions do not support solution folders,
so default behavior should be as if USE_FOLDERS global property
is OFF.

Also, allow folder names to be the same as target names: internally,
use a prefix to distinguish folder GUIDs from target GUIDs. Add
a target and folder with the same name in the ExternalProject
test to exercise this code.

For CMake itself, provide a new option CMAKE_USE_FOLDERS that
defaults to ON so that Visual Studio users get a nicely organized
CMake project. Express edition users will have to turn off the
CMAKE_USE_FOLDERS option in order to build CMake in the VS Express
IDE.

CMakeLists.txt

@@ -173,7 +173,22 @@ MACRO(CMAKE_SETUP_TESTING)
 ENDMACRO(CMAKE_SETUP_TESTING)
 
 
+# Provide a way for Visual Studio Express users to turn OFF the new FOLDER
+# organization feature. Default to ON for non-Express users. Express users must
+# explicitly turn off this option to build CMake in the Express IDE...
+#
+OPTION(CMAKE_USE_FOLDERS "Enable folder grouping of projects in IDEs." ON)
+MARK_AS_ADVANCED(CMAKE_USE_FOLDERS)
+
+
+#-----------------------------------------------------------------------
+# a macro that only sets the FOLDER target property if it's
+# "appropriate"
+#-----------------------------------------------------------------------
 MACRO(CMAKE_SET_TARGET_FOLDER tgt folder)
+  IF(CMAKE_USE_FOLDERS)
+    SET_PROPERTY(GLOBAL PROPERTY USE_FOLDERS ON)
+
     # Really, I just want this to be an "if(TARGET ${tgt})" ...
     # but I'm not sure that our min req'd., CMake 2.4.5 can handle
     # that... so I'm just activating this for now, with a version
@@ -183,6 +198,9 @@ MACRO(CMAKE_SET_TARGET_FOLDER tgt folder)
         SET_PROPERTY(TARGET "${tgt}" PROPERTY FOLDER "${folder}")
       ENDIF()
     ENDIF()
+  ELSE()
+    SET_PROPERTY(GLOBAL PROPERTY USE_FOLDERS OFF)
+  ENDIF()
 ENDMACRO(CMAKE_SET_TARGET_FOLDER)
 
 

Source/cmGlobalGenerator.cxx

@@ -1863,9 +1863,10 @@ bool cmGlobalGenerator::UseFolderProperty()
     return cmSystemTools::IsOn(prop);
     }
 
-  // By default, this feature is ON:
+  // By default, this feature is OFF, since it is not supported in the
+  // Visual Studio Express editions:
   //
-  return true;
+  return false;
 }
 
 //----------------------------------------------------------------------------

Source/cmGlobalVisualStudio7Generator.cxx

@@ -323,7 +323,7 @@ void cmGlobalVisualStudio7Generator::WriteTargetsToSolution(
 
               if (cumulativePath.empty())
                 {
-                cumulativePath = *iter;
+                cumulativePath = "CMAKE_FOLDER_GUID_" + *iter;
                 }
               else
                 {
@@ -431,14 +431,22 @@ void cmGlobalVisualStudio7Generator
 //----------------------------------------------------------------------------
 void cmGlobalVisualStudio7Generator::WriteFolders(std::ostream& fout)
 {
+  const char *prefix = "CMAKE_FOLDER_GUID_";
+  const std::string::size_type skip_prefix = strlen(prefix);
   std::string guidProjectTypeFolder = "2150E333-8FDC-42A3-9474-1A3956D46DE8";
   for(std::map<std::string,std::set<std::string> >::iterator iter =
     VisualStudioFolders.begin(); iter != VisualStudioFolders.end(); ++iter)
     {
     std::string fullName = iter->first;
     std::string guid = this->GetGUID(fullName.c_str());
-    std::string nameOnly = cmSystemTools::GetFilenameName(fullName);
+
     cmSystemTools::ReplaceString(fullName, "/", "\\");
+    if (cmSystemTools::StringStartsWith(fullName.c_str(), prefix))
+      {
+      fullName = fullName.substr(skip_prefix);
+      }
+
+    std::string nameOnly = cmSystemTools::GetFilenameName(fullName);
 
     fout << "Project(\"{" <<
       guidProjectTypeFolder << "}\") = \"" <<

Source/cmake.cxx

@@ -3486,7 +3486,7 @@ void cmake::DefineProperties(cmake *cm)
   cm->DefineProperty
     ("USE_FOLDERS", cmProperty::GLOBAL,
      "Use the FOLDER target property to organize targets into folders.",
-     "If not set, CMake treats this property as ON by default. "
+     "If not set, CMake treats this property as OFF by default. "
      "CMake generators that are capable of organizing into a "
      "hierarchy of folders use the values of the FOLDER target "
      "property to name those folders. See also the documentation "

Tests/ExternalProject/CMakeLists.txt

@@ -7,6 +7,13 @@ find_package(CVS)
 find_package(Subversion)
 find_package(Git)
 
+option(ExternalProjectTest_USE_FOLDERS "Enable folder grouping in IDEs." ON)
+if(ExternalProjectTest_USE_FOLDERS)
+  set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+else()
+  set_property(GLOBAL PROPERTY USE_FOLDERS OFF)
+endif()
+
 set_property(GLOBAL PROPERTY PREDEFINED_TARGETS_FOLDER
   "CMakePredefinedTargets-in-ExternalProjectTest")
 
@@ -60,6 +67,15 @@ ExternalProject_Add(${proj}
   INSTALL_COMMAND ""
 )
 
+set(proj TargetNameSameAsFolder)
+ExternalProject_Add(${proj}
+  BUILD_COMMAND ""
+  CONFIGURE_COMMAND ""
+  DOWNLOAD_COMMAND ""
+  INSTALL_COMMAND ""
+)
+set_property(TARGET ${proj} PROPERTY FOLDER "${proj}")
+
 set(proj MinimalNoOpProject)
 ExternalProject_Add(${proj}
   BUILD_COMMAND ""