Merge #147: cmake: EXTERNAL_MPGEN cleanups

21b92b6 cmake: EXTERNAL_MPGEN cleanups (Ryan Ofsky)

Pull request description:

  Suggested by hebasto in #142 (review)

Top commit has no ACKs.

Tree-SHA512: 2e991a0387477d04219308b33d2dbcd5139561a8023c0de5d901dea3272a934b0247a721aab552da185432652e11f058da586b22eef8d9012b5ffcbef121ee5d

Author: ryanofsky

CMakeLists.txt

@@ -24,7 +24,7 @@ if(Libmultiprocess_ENABLE_CLANG_TIDY)
   set(CMAKE_CXX_CLANG_TIDY "${CLANG_TIDY_EXECUTABLE}")
 endif()
 
-set(EXTERNAL_MPGEN "" CACHE STRING "Use the supplied mpgen binary rather than the one built internally")
+set(Libmultiprocess_EXTERNAL_MPGEN "" CACHE FILEPATH "If specified, should be full path to an external mpgen binary to use rather than the one built internally.")
 
 include("cmake/compat_config.cmake")
 include("cmake/pthread_checks.cmake")

cmake/TargetCapnpSources.cmake

@@ -61,15 +61,15 @@ function(target_capnp_sources target include_prefix)
   )
 
   set(MPGEN_BINARY "")
-  if(EXTERNAL_MPGEN)
-    set(MPGEN_BINARY "${EXTERNAL_MPGEN}")
+  if(Libmultiprocess_EXTERNAL_MPGEN)
+    set(MPGEN_BINARY "${Libmultiprocess_EXTERNAL_MPGEN}")
     if(NOT EXISTS "${MPGEN_BINARY}")
-      message(FATAL_ERROR "EXTERNAL_MPGEN: \"${MPGEN_BINARY}\" does not exist.")
+      message(FATAL_ERROR "Libmultiprocess_EXTERNAL_MPGEN: \"${MPGEN_BINARY}\" does not exist.")
     endif()
   elseif(TARGET Libmultiprocess::multiprocess)
-    set(MPGEN_BINARY $<TARGET_FILE:Libmultiprocess::mpgen>)
+    set(MPGEN_BINARY Libmultiprocess::mpgen)
   else()
-    message(FATAL_ERROR "No usable mpgen. Set EXTERNAL_MPGEN or enable the internal target.")
+    message(FATAL_ERROR "No usable mpgen. Set Libmultiprocess_EXTERNAL_MPGEN or enable the internal target.")
   endif()
 
   set(generated_headers "")