Fix CMake ordering to find correct compiler:

* `CMAKE_C_COMPILER` and `CMAKE_CXX_COMPILER` must be defined
  before `project`. However, it will clear `CMAKE_BUILD_TYPE`.
  Use `CACHE` variables and reorder some code to work around
  these constraints.
* Also correct a couple of copy paste errors.

Author: ximinez

Builds/CMake/CMakeFuncs.cmake

@@ -33,16 +33,16 @@ macro(parse_target)
       if (${cur_component} STREQUAL gcc)
         if (DEFINED ENV{GNU_CC})
           set(CMAKE_C_COMPILER $ENV{GNU_CC})
-        elseif ($ENV{CXX} MATCHES .*gcc.*)
-          set(CMAKE_CXX_COMPILER $ENV{CC})
+        elseif ($ENV{CC} MATCHES .*gcc.*)
+          set(CMAKE_C_COMPILER $ENV{CC})
         else()
           find_program(CMAKE_C_COMPILER gcc)
         endif()
 
         if (DEFINED ENV{GNU_CXX})
-          set(CMAKE_C_COMPILER $ENV{GNU_CXX})
+          set(CMAKE_CXX_COMPILER $ENV{GNU_CXX})
         elseif ($ENV{CXX} MATCHES .*g\\+\\+.*)
-          set(CMAKE_C_COMPILER $ENV{CC})
+          set(CMAKE_CXX_COMPILER $ENV{CXX})
         else()
           find_program(CMAKE_CXX_COMPILER g++)
         endif()
@@ -51,16 +51,16 @@ macro(parse_target)
       if (${cur_component} STREQUAL clang)
         if (DEFINED ENV{CLANG_CC})
           set(CMAKE_C_COMPILER $ENV{CLANG_CC})
-        elseif ($ENV{CXX} MATCHES .*clang.*)
-          set(CMAKE_CXX_COMPILER $ENV{CC})
+        elseif ($ENV{CC} MATCHES .*clang.*)
+          set(CMAKE_C_COMPILER $ENV{CC})
         else()
           find_program(CMAKE_C_COMPILER clang)
         endif()
 
         if (DEFINED ENV{CLANG_CXX})
-          set(CMAKE_C_COMPILER $ENV{CLANG_CXX})
+          set(CMAKE_CXX_COMPILER $ENV{CLANG_CXX})
         elseif ($ENV{CXX} MATCHES .*clang.*)
-          set(CMAKE_C_COMPILER $ENV{CC})
+          set(CMAKE_CXX_COMPILER $ENV{CXX})
         else()
           find_program(CMAKE_CXX_COMPILER clang++)
         endif()
@@ -105,16 +105,40 @@ macro(parse_target)
       endif()
 
     endwhile()
+    # Promote these values to the CACHE, then unset the locals
+    # to prevent shadowing.
+    set(CMAKE_C_COMPILER ${CMAKE_C_COMPILER} CACHE FILEPATH
+      "Path to a program" FORCE)
+    unset(CMAKE_C_COMPILER)
+    set(CMAKE_CXX_COMPILER ${CMAKE_CXX_COMPILER} CACHE FILEPATH
+      "Path to a program" FORCE)
+    unset(CMAKE_CXX_COMPILER)
 
     if (release)
       set(CMAKE_BUILD_TYPE Release)
     else()
       set(CMAKE_BUILD_TYPE Debug)
     endif()
 
+    # ensure that the unity flags are set and exclusive
+    if (NOT DEFINED unity OR unity)
+      # Default to unity builds
+      set(unity true)
+      set(nonunity false)
+    else()
+      set(unity false)
+      set(nonunity true)
+    endif()
+
     if (NOT unity)
       set(CMAKE_BUILD_TYPE ${CMAKE_BUILD_TYPE}Classic)
     endif()
+    # Promote this value to the CACHE, then unset the local
+    # to prevent shadowing.
+    set(CMAKE_BUILD_TYPE ${CMAKE_BUILD_TYPE} CACHE INTERNAL
+      "Choose the type of build, options are in CMAKE_CONFIGURATION_TYPES"
+      FORCE)
+    unset(CMAKE_BUILD_TYPE)
   endif()
 
 endmacro()
@@ -149,8 +173,11 @@ macro(setup_build_cache)
       ReleaseClassic)
   endif()
 
+  # Promote this value to the CACHE, then unset the local
+  # to prevent shadowing.
   set(CMAKE_CONFIGURATION_TYPES
     ${CMAKE_CONFIGURATION_TYPES} CACHE STRING "" FORCE)
+  unset(CMAKE_CONFIGURATION_TYPES)
 endmacro()
 
 ############################################################

CMakeLists.txt

@@ -52,11 +52,22 @@
 
 ############################################################
 
+#########################################################
+# CMAKE_C_COMPILER and CMAKE_CXX_COMPILER must be defined
+# before the project statement; However, the project
+# statement will clear CMAKE_BUILD_TYPE. CACHE variables,
+# along with the order of this code, are used to work
+# around these constraints.
+#
+# Don't put any code above or in this block, unless it
+# has similar constraints.
 cmake_minimum_required(VERSION 3.1.0)
-
-# The project command can override some computed values.
-# Don't put any code above this line.
+set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/Builds/CMake")
+include(CMakeFuncs)
+set(openssl_min 1.0.2)
+parse_target()
 project(rippled)
+#########################################################
 
 if("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
   set(dir "build")
@@ -86,18 +97,6 @@ if("${CMAKE_GENERATOR}" MATCHES "Visual Studio" AND
     -G\"${CMAKE_GENERATOR} Win64\"")
 endif()
 
-set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/Builds/CMake")
-include(CMakeFuncs)
-
-set(openssl_min 1.0.2)
-
-parse_target()
-
-if (NOT DEFINED unity)
-  set(unity true)
-  set(nonunity false)
-endif()
-
 setup_build_cache()
 
 if(nonunity)