A few more cleanups

CMake/BuildFlatBuffers.cmake

@@ -175,15 +175,14 @@ function(build_flatbuffers flatbuffers_schemas
   endif()
 endfunction()
 
-# Creates a target that can be linked against that generates flatbuffer headers.
+# Creates a target that can be linked against that provides compiled versions of flatbuffer schemas.
 #
-# This function takes a target name and a list of schemas. You can also specify
-# other flagc flags using the FLAGS option to change the behavior of the flatc
-# tool.
+# This function takes a target name and a list of schemas. Custom commands will be created
+# to generate the schemas, such that linking to the target passed as the TARGET argument
+# will make the schema headers available.
 #
-# When the target_link_libraries is done within a different directory than
-# flatbuffers_generate_headers is called, then the target should also be dependent
-# the custom generation target called GENERATE_<TARGET>.
+# You can also specify other flagc flags using the FLAGS option to change the behavior of the flatc
+# tool.
 #
 # Arguments:
 #   TARGET: The name of the target to generate.
@@ -211,8 +210,6 @@ endfunction()
 #         PRIVATE my_generated_headers_target
 #     )
 #
-# Optional (only needed within different directory):
-#     add_dependencies(app GENERATE_my_generated_headers_target)
 function(flatbuffers_generate_headers)
   # Parse function arguments.
   set(options)
@@ -315,7 +312,13 @@ function(flatbuffers_generate_headers)
   # Set up interface library.
   # This library is for users to link to, and depends on the custom target (so all the custom commands get run).
   # It also adds the appropriate include paths.
-  add_library(${FLATBUFFERS_GENERATE_HEADERS_TARGET} INTERFACE)
+  # If there are no source files we use an interface library, otherwise compile the source files into a static lib.
+  if("${all_generated_source_files}" STREQUAL "")
+    add_library(${FLATBUFFERS_GENERATE_HEADERS_TARGET} INTERFACE)
+  else()
+    add_library(${FLATBUFFERS_GENERATE_HEADERS_TARGET} STATIC ${all_generated_source_files})
+  endif()
+
   add_dependencies(
     ${FLATBUFFERS_GENERATE_HEADERS_TARGET}
     ${generate_target})

CMake/FindFlatBuffers.cmake

@@ -23,6 +23,9 @@
 #
 # If flatc is found, the following imported target is created:
 # * flatbuffers::flatc - Imported target for the compiler
+#
+# If flatc is found, the following function is provided to compile the schemas into C headers:
+# * flatbuffers_generate_headers() [see BuildFlatBuffers.cmake for signature]
 
 set(FLATBUFFERS_CMAKE_DIR ${CMAKE_CURRENT_LIST_DIR})
 
@@ -58,7 +61,7 @@ if(FlatBuffers_FOUND)
 
   # LEGACY function for generating C headers from a flatbuffer.
   # Deprecated, use flatbuffers_generate_headers() from BuildFlatBuffers.cmake instead,
-  # which allows passing options and generating C++ targets
+  # which allows passing options and generating library targets
   function(FLATBUFFERS_GENERATE_C_HEADERS Name)
     set(FLATC_OUTPUTS)
     foreach(FILE ${ARGN})
@@ -76,6 +79,6 @@ if(FlatBuffers_FOUND)
     endforeach()
     set(${Name}_OUTPUTS ${FLATC_OUTPUTS} PARENT_SCOPE)
   endfunction()
-endif()
 
-include("${FLATBUFFERS_CMAKE_DIR}/BuildFlatBuffers.cmake")
+  include("${FLATBUFFERS_CMAKE_DIR}/BuildFlatBuffers.cmake")
+endif()

CMakeLists.txt

@@ -86,7 +86,7 @@ endif()
 if(NOT FLATBUFFERS_BUILD_FLATC)
   # If we aren't supposed to build flatc, see if we can find it.
   find_package(FlatBuffers ${FLATBUFFERS_VERSION_NOCOMMIT})
-  set(FLATBUFFERS_FLATC_TARGET ${FLATBUFFERS_FLATC_EXECUTABLE})
+  set(FLATBUFFERS_FLATC_COMMAND ${FLATBUFFERS_FLATC_EXECUTABLE})
 
   if(NOT FlatBuffers_FOUND AND FLATBUFFERS_BUILD_TESTS)
     message(WARNING
@@ -469,7 +469,7 @@ if(FLATBUFFERS_BUILD_FLATC)
   endif()
   if(NOT FLATBUFFERS_FLATC_EXECUTABLE)
     set(FLATBUFFERS_FLATC_EXECUTABLE $<TARGET_FILE:flatc>)
-    set(FLATBUFFERS_FLATC_TARGET flatc)
+    set(FLATBUFFERS_FLATC_COMMAND flatc)
   endif()
   if(FLATBUFFERS_STATIC_FLATC AND NOT MSVC)
     target_link_libraries(flatc PRIVATE -static)
@@ -506,7 +506,7 @@ function(compile_schema SRC_FBS OPT OUT_GEN_FILE)
       ${OPT}
       -o "${SRC_FBS_DIR}"
       "${CMAKE_CURRENT_SOURCE_DIR}/${SRC_FBS}"
-    DEPENDS ${FLATBUFFERS_FLATC_TARGET} ${SRC_FBS}
+    DEPENDS ${FLATBUFFERS_FLATC_COMMAND} ${SRC_FBS}
     COMMENT "flatc generation: `${SRC_FBS}` -> `${GEN_HEADER}`"
     )
   set(${OUT_GEN_FILE} ${GEN_HEADER} PARENT_SCOPE)