Merge pull request #587 from harrishancock/fix-capnp_generate_cpp-source-file-check

Fix input schema file existence check in capnp_generate_cpp

c++/cmake/CapnProtoMacros.cmake

@@ -71,11 +71,11 @@ function(CAPNP_GENERATE_CPP SOURCES HEADERS)
   set(${SOURCES})
   set(${HEADERS})
   foreach(schema_file ${ARGN})
-    if(NOT EXISTS "${CAPNPC_SRC_PREFIX}/${schema_file}")
-      message(FATAL_ERROR "Cap'n Proto schema file '${CAPNPC_SRC_PREFIX}/${schema_file}' does not exist!")
-    endif()
     get_filename_component(file_path "${schema_file}" ABSOLUTE)
     get_filename_component(file_dir "${file_path}" PATH)
+    if(NOT EXISTS "${file_path}")
+      message(FATAL_ERROR "Cap'n Proto schema file '${file_path}' does not exist!")
+    endif()
 
     # Figure out where the output files will go
     if (NOT DEFINED CAPNPC_OUTPUT_DIR)