FindMatlab: code comment and ordering of the finders

Modules/FindMatlab.cmake

@@ -1537,7 +1537,9 @@ if(MATLAB_FIND_DEBUG)
   message(STATUS "[MATLAB] Current version is ${Matlab_VERSION_STRING} located ${Matlab_ROOT_DIR}")
 endif()
 
-if(NOT ${Matlab_VERSION_STRING} VERSION_LESS "9.4") # MATLAB 9.4 (R2018a) and newer have a new C++ API
+# MATLAB 9.4 (R2018a) and newer have a new C++ API
+# This API pulls additional required libraries.
+if(NOT ${Matlab_VERSION_STRING} VERSION_LESS "9.4")
   set(Matlab_HAS_CPP_API 1)
 endif()
 
@@ -1623,6 +1625,10 @@ endfunction()
 
 set(_matlab_required_variables)
 
+# Order is as follow:
+# - unconditionally required libraries/headers first
+# - then library components
+# - then program components
 
 # the MEX library/header are required
 find_path(
@@ -1648,34 +1654,6 @@ list(APPEND _matlab_required_variables Matlab_MEX_EXTENSION)
 # the matlab root is required
 list(APPEND _matlab_required_variables Matlab_ROOT_DIR)
 
-# component Mex Compiler
-if("MEX_COMPILER" IN_LIST Matlab_FIND_COMPONENTS)
-  find_program(
-    Matlab_MEX_COMPILER
-    "mex"
-    PATHS ${Matlab_BINARIES_DIR}
-    DOC "Matlab MEX compiler"
-    NO_DEFAULT_PATH
-  )
-  if(Matlab_MEX_COMPILER)
-    set(Matlab_MEX_COMPILER_FOUND TRUE)
-  endif()
-endif()
-
-# component Matlab program
-if("MAIN_PROGRAM" IN_LIST Matlab_FIND_COMPONENTS)
-  find_program(
-    Matlab_MAIN_PROGRAM
-    matlab
-    PATHS ${Matlab_ROOT_DIR} ${Matlab_ROOT_DIR}/bin
-    DOC "Matlab main program"
-    NO_DEFAULT_PATH
-  )
-  if(Matlab_MAIN_PROGRAM)
-    set(Matlab_MAIN_PROGRAM_FOUND TRUE)
-  endif()
-endif()
-
 # The MX library is required
 _Matlab_find_library(
   ${_matlab_lib_prefix_for_search}
@@ -1689,9 +1667,40 @@ if(Matlab_MX_LIBRARY)
   set(Matlab_MX_LIBRARY_FOUND TRUE)
 endif()
 
+if(Matlab_HAS_CPP_API)
+
+  # The MatlabEngine library is required for R2018a+
+  _Matlab_find_library(
+    ${_matlab_lib_prefix_for_search}
+    Matlab_ENGINE_LIBRARY
+    MatlabEngine
+    PATHS ${_matlab_lib_dir_for_search}
+    DOC "MatlabEngine Library"
+    NO_DEFAULT_PATH
+  )
+  list(APPEND _matlab_required_variables Matlab_ENGINE_LIBRARY)
+  if(Matlab_ENGINE_LIBRARY)
+    set(Matlab_ENGINE_LIBRARY_FOUND TRUE)
+  endif()
+
+  # The MatlabDataArray library is required for R2018a+
+  _Matlab_find_library(
+    ${_matlab_lib_prefix_for_search}
+    Matlab_DATAARRAY_LIBRARY
+    MatlabDataArray
+    PATHS ${_matlab_lib_dir_for_search}
+    DOC "MatlabDataArray Library"
+    NO_DEFAULT_PATH
+  )
+  list(APPEND _matlab_required_variables Matlab_DATAARRAY_LIBRARY)
+  if(Matlab_DATAARRAY_LIBRARY)
+    set(Matlab_DATAARRAY_LIBRARY_FOUND TRUE)
+  endif()
+
+endif()
+
 # Component ENG library
-list(FIND Matlab_FIND_COMPONENTS ENG_LIBRARY _matlab_find_eng)
-if(_matlab_find_eng GREATER -1)
+if("ENG_LIBRARY" IN_LIST Matlab_FIND_COMPONENTS)
   _Matlab_find_library(
     ${_matlab_lib_prefix_for_search}
     Matlab_ENG_LIBRARY
@@ -1703,11 +1712,9 @@ if(_matlab_find_eng GREATER -1)
     set(Matlab_ENG_LIBRARY_FOUND TRUE)
   endif()
 endif()
-unset(_matlab_find_eng)
 
 # Component MAT library
-list(FIND Matlab_FIND_COMPONENTS MAT_LIBRARY _matlab_find_mat)
-if(_matlab_find_mat GREATER -1)
+if("MAT_LIBRARY" IN_LIST Matlab_FIND_COMPONENTS)
   _Matlab_find_library(
     ${_matlab_lib_prefix_for_search}
     Matlab_MAT_LIBRARY
@@ -1719,11 +1726,9 @@ if(_matlab_find_mat GREATER -1)
     set(Matlab_MAT_LIBRARY_FOUND TRUE)
   endif()
 endif()
-unset(_matlab_find_mat)
 
 # Component Simulink
-list(FIND Matlab_FIND_COMPONENTS SIMULINK _matlab_find_simulink)
-if(_matlab_find_simulink GREATER -1)
+if("SIMULINK" IN_LIST Matlab_FIND_COMPONENTS)
   find_path(
     Matlab_SIMULINK_INCLUDE_DIR
     simstruc.h
@@ -1735,58 +1740,49 @@ if(_matlab_find_simulink GREATER -1)
     list(APPEND Matlab_INCLUDE_DIRS "${Matlab_SIMULINK_INCLUDE_DIR}")
   endif()
 endif()
-unset(_matlab_find_simulink)
 
-# component MCC Compiler
-list(FIND Matlab_FIND_COMPONENTS MCC_COMPILER _matlab_find_mcc_compiler)
-if(_matlab_find_mcc_compiler GREATER -1)
+# component Matlab program
+if("MAIN_PROGRAM" IN_LIST Matlab_FIND_COMPONENTS)
   find_program(
-    Matlab_MCC_COMPILER
-    "mcc"
-    PATHS ${Matlab_BINARIES_DIR}
-    DOC "Matlab MCC compiler"
+    Matlab_MAIN_PROGRAM
+    matlab
+    PATHS ${Matlab_ROOT_DIR} ${Matlab_ROOT_DIR}/bin
+    DOC "Matlab main program"
     NO_DEFAULT_PATH
   )
-  if(Matlab_MCC_COMPILER)
-    set(Matlab_MCC_COMPILER_FOUND TRUE)
+  if(Matlab_MAIN_PROGRAM)
+    set(Matlab_MAIN_PROGRAM_FOUND TRUE)
   endif()
 endif()
-unset(_matlab_find_mcc_compiler)
-
-if(Matlab_HAS_CPP_API)
 
-  # The MatlabEngine library is required for R2018a+
-  _Matlab_find_library(
-    ${_matlab_lib_prefix_for_search}
-    Matlab_ENGINE_LIBRARY
-    MatlabEngine
-    PATHS ${_matlab_lib_dir_for_search}
-    DOC "MatlabEngine Library"
+# component Mex Compiler
+if("MEX_COMPILER" IN_LIST Matlab_FIND_COMPONENTS)
+  find_program(
+    Matlab_MEX_COMPILER
+    "mex"
+    PATHS ${Matlab_BINARIES_DIR}
+    DOC "Matlab MEX compiler"
     NO_DEFAULT_PATH
   )
-  list(APPEND _matlab_required_variables Matlab_ENGINE_LIBRARY)
-  if(Matlab_ENGINE_LIBRARY)
-    set(Matlab_ENGINE_LIBRARY_FOUND TRUE)
+  if(Matlab_MEX_COMPILER)
+    set(Matlab_MEX_COMPILER_FOUND TRUE)
   endif()
+endif()
 
-  # The MatlabDataArray library is required for R2018a+
-  _Matlab_find_library(
-    ${_matlab_lib_prefix_for_search}
-    Matlab_DATAARRAY_LIBRARY
-    MatlabDataArray
-    PATHS ${_matlab_lib_dir_for_search}
-    DOC "MatlabDataArray Library"
+# component MCC Compiler
+if("MCC_COMPILER" IN_LIST Matlab_FIND_COMPONENTS)
+  find_program(
+    Matlab_MCC_COMPILER
+    "mcc"
+    PATHS ${Matlab_BINARIES_DIR}
+    DOC "Matlab MCC compiler"
     NO_DEFAULT_PATH
   )
-  list(APPEND _matlab_required_variables Matlab_DATAARRAY_LIBRARY)
-  if(Matlab_DATAARRAY_LIBRARY)
-    set(Matlab_DATAARRAY_LIBRARY_FOUND TRUE)
+  if(Matlab_MCC_COMPILER)
+    set(Matlab_MCC_COMPILER_FOUND TRUE)
   endif()
-
 endif()
 
-unset(_matlab_lib_dir_for_search)
-
 set(Matlab_LIBRARIES
   ${Matlab_MEX_LIBRARY} ${Matlab_MX_LIBRARY}
   ${Matlab_ENG_LIBRARY} ${Matlab_MAT_LIBRARY}