cmake_parse_arguments: Restore ;-list argument flattening

The re-implementation in commit v3.5.0-rc1~116^2~1 (CMakeParseArguments:
replace by native cmake_parse_arguments command, 2015-12-05) introduced
a regression when parsing the ARGN arguments with cmake_parse_arguments.
The original implementation used

    foreach(currentArg ${ARGN})

to iterate over input arguments.  This flattened ;-lists within the
arguments whether they were quoted or not.  Fix our new implementation
to preserve this behavior and add a test case to cover it.

Signed-off-by: Dimitar Yordanov <[email protected]>
Signed-off-by: Matthias Maennich <[email protected]>

Source/cmParseArgumentsCommand.cxx

@@ -97,10 +97,18 @@ bool cmParseArgumentsCommand
   } insideValues = NONE;
   std::string currentArgName;
 
-  // now iterate over the remaining arguments
-  // and fill in the values where applicable
+  // Flatten ;-lists in the arguments into a single list as was done
+  // by the original function(CMAKE_PARSE_ARGUMENTS).
+  list.clear();
   for(; argIter != argEnd; ++argIter)
     {
+    cmSystemTools::ExpandListArgument(*argIter, list);
+    }
+
+  // iterate over the arguments list and fill in the values where applicable
+  for (argIter = list.begin(), argEnd = list.end();
+       argIter != argEnd; ++argIter)
+    {
     const options_map::iterator optIter = options.find(*argIter);
     if (optIter != options.end())
       {

Tests/RunCMake/cmake_parse_arguments/CornerCases.cmake

@@ -13,3 +13,22 @@ cmake_parse_arguments(MY_INSTALL "${options}" "${oneValueArgs}"
 
 TEST(MY_INSTALL_DESTINATION UNDEFINED)
 TEST(MY_INSTALL_OPTIONAL TRUE)
+
+macro(foo)
+  set(_options )
+  set(_oneValueArgs FOO)
+  set(_multiValueArgs )
+  cmake_parse_arguments(_FOO2 "${_options}"
+                              "${_oneValueArgs}"
+                              "${_multiValueArgs}"
+                              "${ARGN}")
+  cmake_parse_arguments(_FOO1 "${_options}"
+                              "${_oneValueArgs}"
+                              "${_multiValueArgs}"
+                              ${ARGN})
+endmacro()
+
+foo(FOO foo)
+
+TEST(_FOO1_FOO foo)
+TEST(_FOO2_FOO foo)