Fix uninitialized-variables cmake warnings

tools/FindPythonLibsNew.cmake

@@ -56,6 +56,9 @@ if(PYTHONLIBS_FOUND AND PYTHON_MODULE_EXTENSION)
 endif()
 
 # Use the Python interpreter to find the libs.
+if(NOT PythonLibsNew_FIND_VERSION)
+    set(PythonLibsNew_FIND_VERSION "")
+endif()
 if(PythonLibsNew_FIND_REQUIRED)
     find_package(PythonInterp ${PythonLibsNew_FIND_VERSION} REQUIRED)
 else()
@@ -192,11 +195,18 @@ MARK_AS_ADVANCED(
 # module.
 SET(PYTHON_INCLUDE_DIRS "${PYTHON_INCLUDE_DIR}")
 SET(PYTHON_LIBRARIES "${PYTHON_LIBRARY}")
+if(NOT PYTHON_DEBUG_LIBRARY)
+    SET(PYTHON_DEBUG_LIBRARY "")
+endif()
 SET(PYTHON_DEBUG_LIBRARIES "${PYTHON_DEBUG_LIBRARY}")
 
 find_package_message(PYTHON
     "Found PythonLibs: ${PYTHON_LIBRARY}"
-    "${PYTHON_EXECUTABLE}${PYTHON_VERSION}")
+    "${PYTHON_EXECUTABLE}${PYTHON_VERSION_STRING}")
 
 set(PYTHONLIBS_FOUND TRUE)
 set(PythonLibsNew_FOUND TRUE)
+
+if(NOT PYTHON_MODULE_PREFIX)
+    SET(PYTHON_MODULE_PREFIX "")
+endif()

tools/pybind11Tools.cmake

@@ -33,7 +33,7 @@ if(NOT CMAKE_VERSION VERSION_LESS 3.1)
   endif()
 endif()
 
-# Fall back to heuristics 
+# Fall back to heuristics
 if(NOT PYBIND11_CPP_STANDARD AND NOT CMAKE_CXX_STANDARD)
   if(MSVC)
     set(PYBIND11_CPP_STANDARD /std:c++14)
@@ -142,17 +142,32 @@ function(pybind11_add_module target_name)
 
   if(ARG_EXCLUDE_FROM_ALL)
     set(exclude_from_all EXCLUDE_FROM_ALL)
+  else()
+    set(exclude_from_all "")
   endif()
 
   add_library(${target_name} ${lib_type} ${exclude_from_all} ${ARG_UNPARSED_ARGUMENTS})
 
   if(ARG_SYSTEM)
     set(inc_isystem SYSTEM)
+  else()
+    set(inc_isystem "")
+  endif()
+
+  set(PYBIND11_INCLUDE_DIR_SELECTED "")
+  if(PYBIND11_INCLUDE_DIR)
+    # from project CMakeLists.txt
+    set(PYBIND11_INCLUDE_DIR_SELECTED ${PYBIND11_INCLUDE_DIR})
+  elseif(pybind11_INCLUDE_DIR)
+    # from pybind11Config
+    set(PYBIND11_INCLUDE_DIR_SELECTED ${pybind11_INCLUDE_DIR})
+  else()
+    message(FATAL "No pybind11_INCLUDE_DIR available. Use "
+      "find_package(pybind11) before calling pybind11_add_module.")
   endif()
 
   target_include_directories(${target_name} ${inc_isystem}
-    PRIVATE ${PYBIND11_INCLUDE_DIR}  # from project CMakeLists.txt
-    PRIVATE ${pybind11_INCLUDE_DIR}  # from pybind11Config
+    PRIVATE ${PYBIND11_INCLUDE_DIR_SELECTED}
     PRIVATE ${PYTHON_INCLUDE_DIRS})
 
   # Python debug libraries expose slightly different objects
@@ -201,10 +216,12 @@ function(pybind11_add_module target_name)
   endif()
 
   # Make sure C++11/14 are enabled
-  if(CMAKE_VERSION VERSION_LESS 3.3)
-    target_compile_options(${target_name} PUBLIC ${PYBIND11_CPP_STANDARD})
-  else()
-    target_compile_options(${target_name} PUBLIC $<$<COMPILE_LANGUAGE:CXX>:${PYBIND11_CPP_STANDARD}>)
+  if(PYBIND11_CPP_STANDARD)
+    if(CMAKE_VERSION VERSION_LESS 3.3)
+      target_compile_options(${target_name} PUBLIC ${PYBIND11_CPP_STANDARD})
+    else()
+      target_compile_options(${target_name} PUBLIC $<$<COMPILE_LANGUAGE:CXX>:${PYBIND11_CPP_STANDARD}>)
+    endif()
   endif()
 
   if(ARG_NO_EXTRAS)