CMake: use object libraries to avoid redundant builds

Some source files are duplicated via add_executable. Assuming that these
are not affected by target-specific preprocessor macros, they can be
built only once and shared among executables.

In one configuration, this reduces the number of object files by 55
(cli_main.c and version_info.c alone were built 15 times each).

Removes the version dependency from each target since the 'version_info'
target can now declare this dependency. Remove CLEAN_C_FILES from extcap
since it is not used to set -Werror. Due to removing some files from
wireshark_FILES (and others), these are no longer part of checkAPIs
though. Hopefully that is acceptable.

Change-Id: I0a3f1ffb950e70a6176c96d867f694fbc6476f58
Reviewed-on: https://code.wireshark.org/review/31509
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: João Valverde <j@v6e.pt>
Petri-Dish: João Valverde <j@v6e.pt>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

6 files changed, 89 insertions, 83 deletions

diff --git a/.gitignore b/.gitignore
index cc67c2b7d4..8b312845a3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,7 +36,6 @@ epan/dissectors/dissectors.in.txt
 epan/dtd_parse.c
 epan/dtd_preparse.c
 epan/uat_load.c
-epan/version_info.c
 epan/wslua/declare_wslua.h
 epan/wslua/register_wslua.c
 epan/wslua/taps.txt
@@ -51,7 +50,6 @@ tshark-tap-register.c
 wiretap/ascend.c
 wiretap/ascend.h
 wiretap/k12text.c
-wiretap/version_info.c
 wireshark-tap-register.c
 
 # CMake #
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 09297ba560..912a47562d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1614,17 +1614,6 @@ elseif(APPLE)
 	)
 endif()
 
-# sources common for wireshark, tshark, rawshark and sharkd
-set(SHARK_COMMON_SRC
-	cfile.c
-	file_packet_provider.c
-	frame_tvbuff.c
-	sync_pipe_write.c
-	version_info.c
-	extcap.c
-	extcap_parser.c
-)
-
 set(TSHARK_TAP_SRC
 	${CMAKE_SOURCE_DIR}/ui/cli/tap-camelsrt.c
 	${CMAKE_SOURCE_DIR}/ui/cli/tap-diameter-avp.c
@@ -2115,16 +2104,38 @@ list(APPEND copy_data_files_depends
 add_custom_target(copy_data_files ALL DEPENDS ${copy_data_files_depends} )
 set_target_properties(copy_data_files PROPERTIES FOLDER "Copy Tasks")
 
+
+# Shared code, build object files once for all users.
+add_library(version_info OBJECT version_info.c)
+add_dependencies(version_info version)
+# sources common for wireshark, tshark, rawshark and sharkd
+add_library(shark_common OBJECT
+	cfile.c
+	extcap.c
+	extcap_parser.c
+	file_packet_provider.c
+	frame_tvbuff.c
+	sync_pipe_write.c
+)
+add_library(cli_main OBJECT cli_main.c)
+add_library(capture_opts OBJECT capture_opts.c)
+set_target_properties(version_info shark_common cli_main capture_opts
+	PROPERTIES
+	COMPILE_FLAGS "${WERROR_COMMON_FLAGS}"
+)
+
+
 if(BUILD_wireshark AND QT_FOUND)
 	set(WIRESHARK_SRC
 		capture_info.c
-		capture_opts.c
 		file.c
 		fileset.c
-		${SHARK_COMMON_SRC}
 		${PLATFORM_UI_SRC}
 	)
 	set(wireshark_FILES
+		$<TARGET_OBJECTS:capture_opts>
+		$<TARGET_OBJECTS:shark_common>
+		$<TARGET_OBJECTS:version_info>
 		${WIRESHARK_SRC}
 		${PLATFORM_UI_RC_FILES}
 	)
@@ -2224,7 +2235,6 @@ if(BUILD_wireshark AND QT_FOUND)
 	)
 
 	add_executable(wireshark WIN32 MACOSX_BUNDLE ${wireshark_FILES} ${EXTRA_BUNDLE_FILES})
-	add_dependencies(wireshark version)
 	set(PROGLIST ${PROGLIST} wireshark)
 	set_target_properties(wireshark PROPERTIES
 		LINK_FLAGS "${WS_LINK_FLAGS}"
@@ -2332,17 +2342,17 @@ if(BUILD_tshark)
 		${M_LIBRARIES}
 	)
 	set(tshark_FILES
-		cli_main.c
-		capture_opts.c
+		$<TARGET_OBJECTS:capture_opts>
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:shark_common>
+		$<TARGET_OBJECTS:version_info>
 		tshark-tap-register.c
 		tshark.c
 		${TSHARK_TAP_SRC}
-		${SHARK_COMMON_SRC}
 	)
 
 	set_executable_resources(tshark "TShark" UNIQUE_RC)
 	add_executable(tshark ${tshark_FILES})
-	add_dependencies(tshark version)
 	set_extra_executable_properties(tshark "Executables")
 	target_link_libraries(tshark ${tshark_LIBS})
 	install(TARGETS tshark RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2358,14 +2368,14 @@ if(BUILD_tfshark)
 		${APPLE_SYSTEM_CONFIGURATION_LIBRARY}
 	)
 	set(tfshark_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:shark_common>
+		$<TARGET_OBJECTS:version_info>
 		tfshark.c
 		${TSHARK_TAP_SRC}
-		${SHARK_COMMON_SRC}
 	)
 	set_executable_resources(tfshark "TFShark")
 	add_executable(tfshark ${tfshark_FILES})
-	add_dependencies(tfshark version)
 	set_extra_executable_properties(tfshark "Executables")
 	target_link_libraries(tfshark ${tfshark_LIBS})
 	install(TARGETS tfshark RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2382,13 +2392,13 @@ if(BUILD_rawshark AND PCAP_FOUND)
 		${APPLE_SYSTEM_CONFIGURATION_LIBRARY}
 	)
 	set(rawshark_FILES
-		cli_main.c
-		${SHARK_COMMON_SRC}
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:shark_common>
+		$<TARGET_OBJECTS:version_info>
 		rawshark.c
 	)
 	set_executable_resources(rawshark "Rawshark")
 	add_executable(rawshark ${rawshark_FILES})
-	add_dependencies(rawshark version)
 	set_extra_executable_properties(rawshark "Executables")
 	target_link_libraries(rawshark ${rawshark_LIBS})
 	install(TARGETS rawshark RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2407,16 +2417,16 @@ if(BUILD_sharkd)
 	set(sharkd_FILES
 		#
 		# XXX - currently doesn't work on Windows if it uses
-		# cli_main.c and has real_main().
+		# $<TARGET_OBJECTS:cli_main> and has real_main().
 		#
+		$<TARGET_OBJECTS:shark_common>
+		$<TARGET_OBJECTS:version_info>
 		sharkd.c
 		sharkd_daemon.c
 		sharkd_session.c
-		${SHARK_COMMON_SRC}
 	)
 	set_executable_resources(sharkd "SharkD")
 	add_executable(sharkd ${sharkd_FILES})
-	add_dependencies(sharkd version)
 	set_extra_executable_properties(sharkd "Executables")
 	target_link_libraries(sharkd ${sharkd_LIBS})
 	if(WIN32)
@@ -2437,7 +2447,6 @@ if(BUILD_dftest)
 		dftest.c
 	)
 	add_executable(dftest ${dftest_FILES})
-	add_dependencies(dftest version)
 	set_extra_executable_properties(dftest "Tests")
 	target_link_libraries(dftest ${dftest_LIBS})
 endif()
@@ -2454,12 +2463,11 @@ if(BUILD_randpkt)
 		${ZLIB_LIBRARIES}
 	)
 	set(randpkt_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		randpkt.c
-		version_info.c
 	)
 	add_executable(randpkt ${randpkt_FILES})
-	add_dependencies(randpkt version)
 	set_extra_executable_properties(randpkt "Executables")
 	target_link_libraries(randpkt ${randpkt_LIBS})
 	install(TARGETS randpkt RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2477,9 +2485,9 @@ if(BUILD_text2pcap)
 		${ZLIB_LIBRARIES}
 	)
 	set(text2pcap_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		text2pcap.c
-		version_info.c
 	)
 	add_lex_files(text2pcap_LEX_FILES text2pcap_FILES
 		text2pcap-scanner.l
@@ -2487,7 +2495,6 @@ if(BUILD_text2pcap)
 	set_executable_resources(text2pcap "Text2pcap"
 		COPYRIGHT_INFO "2001 Ashok Narayanan <ashokn@cisco.com>")
 	add_executable(text2pcap ${text2pcap_FILES})
-	add_dependencies(text2pcap version)
 	set_extra_executable_properties(text2pcap "Executables")
 	target_link_libraries(text2pcap ${text2pcap_LIBS})
 	install(TARGETS text2pcap RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2501,13 +2508,12 @@ if(BUILD_mergecap)
 		${CMAKE_DL_LIBS}
 	)
 	set(mergecap_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		mergecap.c
-		version_info.c
 	)
 	set_executable_resources(mergecap "Mergecap")
 	add_executable(mergecap ${mergecap_FILES})
-	add_dependencies(mergecap version)
 	set_extra_executable_properties(mergecap "Executables")
 	target_link_libraries(mergecap ${mergecap_LIBS})
 	install(TARGETS mergecap RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2521,13 +2527,12 @@ if(BUILD_reordercap)
 		${CMAKE_DL_LIBS}
 	)
 	set(reordercap_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		reordercap.c
-		version_info.c
 	)
 	set_executable_resources(reordercap "Reordercap")
 	add_executable(reordercap ${reordercap_FILES})
-	add_dependencies(reordercap version)
 	set_extra_executable_properties(reordercap "Executables")
 	target_link_libraries(reordercap ${reordercap_LIBS})
 	install(TARGETS reordercap RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2543,13 +2548,12 @@ if(BUILD_capinfos)
 		${CMAKE_DL_LIBS}
 	)
 	set(capinfos_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		capinfos.c
-		version_info.c
 	)
 	set_executable_resources(capinfos "Capinfos")
 	add_executable(capinfos ${capinfos_FILES})
-	add_dependencies(capinfos version)
 	set_extra_executable_properties(capinfos "Executables")
 	target_link_libraries(capinfos ${capinfos_LIBS})
 	install(TARGETS capinfos RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2564,13 +2568,12 @@ if(BUILD_captype)
 		${CMAKE_DL_LIBS}
 	)
 	set(captype_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		captype.c
-		version_info.c
 	)
 	set_executable_resources(captype "Captype")
 	add_executable(captype ${captype_FILES})
-	add_dependencies(captype version)
 	set_extra_executable_properties(captype "Executables")
 	target_link_libraries(captype ${captype_LIBS})
 	install(TARGETS captype RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2585,13 +2588,12 @@ if(BUILD_editcap)
 		${CMAKE_DL_LIBS}
 	)
 	set(editcap_FILES
-		cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		editcap.c
-		version_info.c
 	)
 	set_executable_resources(editcap "Editcap")
 	add_executable(editcap ${editcap_FILES})
-	add_dependencies(editcap version)
 	set_extra_executable_properties(editcap "Executables")
 	target_link_libraries(editcap ${editcap_LIBS})
 	install(TARGETS editcap RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
@@ -2613,16 +2615,15 @@ if(BUILD_dumpcap AND PCAP_FOUND)
 		${NL_LIBRARIES}
 	)
 	set(dumpcap_FILES
-		cli_main.c
-		capture_opts.c
+		$<TARGET_OBJECTS:capture_opts>
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:version_info>
 		dumpcap.c
 		ringbuffer.c
 		sync_pipe_write.c
-		version_info.c
 	)
 	set_executable_resources(dumpcap "Dumpcap" UNIQUE_RC)
 	add_executable(dumpcap ${dumpcap_FILES})
-	add_dependencies(dumpcap version)
 	set_extra_executable_properties(dumpcap "Executables")
 	target_link_libraries(dumpcap ${dumpcap_LIBS})
 	install(TARGETS dumpcap
@@ -2948,6 +2949,7 @@ if (WIN32)
 	list(FILTER CLEAN_C_FILES EXCLUDE REGEX ".*\\.rc")
 endif (WIN32)
 
+# XXX This also contains object files ($<TARGET_OBJECTS:...>), is that an issue?
 set_source_files_properties(
 	${CLEAN_C_FILES}
 	PROPERTIES
diff --git a/epan/CMakeLists.txt b/epan/CMakeLists.txt
index 8bba076f0d..c53be75210 100644
--- a/epan/CMakeLists.txt
+++ b/epan/CMakeLists.txt
@@ -248,7 +248,6 @@ set(LIBWIRESHARK_NONGENERATED_FILES
 	unit_strings.c
 	xdlc.c
 	${CMAKE_CURRENT_BINARY_DIR}/ps.c
-	${CMAKE_SOURCE_DIR}/version_info.c
 )
 
 set(LIBWIRESHARK_FILES ${LIBWIRESHARK_NONGENERATED_FILES})
@@ -278,13 +277,12 @@ add_library(epan
 	$<TARGET_OBJECTS:dissectors>
 	$<TARGET_OBJECTS:dissectors-corba>
 	$<TARGET_OBJECTS:ftypes>
+	$<TARGET_OBJECTS:version_info>
 	$<TARGET_OBJECTS:wmem>
 	$<$<BOOL:${HAVE_LIBLUA}>:$<TARGET_OBJECTS:wslua>>
 	${CMAKE_BINARY_DIR}/image/libwireshark.rc
 )
 
-add_dependencies(epan version)
-
 if(ENABLE_PLUGINS)
 	target_compile_definitions(epan PUBLIC HAVE_PLUGINS)
 endif()
diff --git a/extcap/CMakeLists.txt b/extcap/CMakeLists.txt
index 0feebe01bf..f85ec5f22e 100644
--- a/extcap/CMakeLists.txt
+++ b/extcap/CMakeLists.txt
@@ -75,6 +75,11 @@ endmacro()
 
 add_custom_target(extcaps)
 
+add_library(extcap-base OBJECT extcap-base.c)
+if(LIBSSH_FOUND)
+	add_library(ssh-base OBJECT ssh-base.c)
+endif()
+
 if(BUILD_androiddump)
 	if(EXTCAP_ANDROIDDUMP_LIBPCAP)
 		if(HAVE_LIBPCAP)
@@ -96,9 +101,9 @@ if(BUILD_androiddump)
 		)
 	endif()
 	set(androiddump_FILES
-		../cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:extcap-base>
 		androiddump.c
-		extcap-base.c
 	)
 
 	set_executable_resources(androiddump "Androiddump")
@@ -117,10 +122,10 @@ if(BUILD_sshdump AND LIBSSH_FOUND)
 		${LIBSSH_LIBRARIES}
 	)
 	set(sshdump_FILES
-		../cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:extcap-base>
+		$<TARGET_OBJECTS:ssh-base>
 		sshdump.c
-		extcap-base.c
-		ssh-base.c
 	)
 
 	set_executable_resources(sshdump "Sshdump")
@@ -143,10 +148,10 @@ if(BUILD_ciscodump AND LIBSSH_FOUND)
 		${LIBSSH_LIBRARIES}
 	)
 	set(ciscodump_FILES
-		../cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:extcap-base>
+		$<TARGET_OBJECTS:ssh-base>
 		ciscodump.c
-		extcap-base.c
-		ssh-base.c
 	)
 
 	set_executable_resources(ciscodump "Ciscodump")
@@ -169,8 +174,8 @@ if(BUILD_dpauxmon AND HAVE_LIBNL3)
 		${NL_LIBRARIES}
 	)
 	set(dpauxmon_FILES
+		$<TARGET_OBJECTS:extcap-base>
 		dpauxmon.c
-		extcap-base.c
 	)
 
 	set_executable_resources(dpauxmon "dpauxmon")
@@ -192,9 +197,9 @@ if(BUILD_udpdump)
 		writecap
 	)
 	set(udpdump_FILES
-		../cli_main.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:extcap-base>
 		udpdump.c
-		extcap-base.c
 	)
 
 	set_executable_resources(udpdump "udpdump")
@@ -215,8 +220,8 @@ if(BUILD_randpktdump)
 		${CMAKE_DL_LIBS}
 	)
 	set(randpktdump_FILES
-		../cli_main.c
-		extcap-base.c
+		$<TARGET_OBJECTS:cli_main>
+		$<TARGET_OBJECTS:extcap-base>
 		randpktdump.c
 	)
 
@@ -240,7 +245,7 @@ if(BUILD_sdjournal AND SYSTEMD_FOUND)
 		${SYSTEMD_LIBRARIES}
 	)
 	set(sdjournal_FILES
-		extcap-base.c
+		$<TARGET_OBJECTS:extcap-base>
 		sdjournal.c
 	)
 
@@ -254,9 +259,15 @@ elseif (BUILD_sdjournal)
 	#message( WARNING "Cannot find libsystemd, cannot build sdjournal" )
 endif()
 
-set(CLEAN_C_FILES
-	${dumpcap_FILES}
-	${androiddump_FILES}
-	${sshdump_FILES}
-	${ciscodump_FILES}
-)
+#
+# Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+#
+# Local variables:
+# c-basic-offset: 8
+# tab-width: 8
+# indent-tabs-mode: t
+# End:
+#
+# vi: set shiftwidth=8 tabstop=8 noexpandtab:
+# :indentSize=8:tabSize=8:noTabs=false:
+#
diff --git a/fuzz/CMakeLists.txt b/fuzz/CMakeLists.txt
index 127d7f153c..fc9bb1d965 100644
--- a/fuzz/CMakeLists.txt
+++ b/fuzz/CMakeLists.txt
@@ -40,7 +40,7 @@ if(OSS_FUZZ)
 endif()
 set(fuzzshark_FILES
 	fuzzshark.c
-	${CMAKE_SOURCE_DIR}/version_info.c
+	$<TARGET_OBJECTS:version_info>
 )
 set(FUZZ_LINK_FLAGS "${WS_LINK_FLAGS}")
 if(ENABLE_FUZZER)
@@ -63,7 +63,6 @@ string(REPLACE ";" ", " FUZZ_DISABLED_DISSECTORS_MACRO "${FUZZ_DISABLED_DISSECTO
 add_custom_target(all-fuzzers)
 
 function(fuzzshark_set_common_options fuzzer_name)
-	add_dependencies(${fuzzer_name} version)
 	# Sanitizers require a C++ runtime, so use a C++ linker.
 	set_target_properties(${fuzzer_name} PROPERTIES
 		FOLDER "Fuzzers"
diff --git a/wiretap/CMakeLists.txt b/wiretap/CMakeLists.txt
index 7233701f6b..2728f6673b 100644
--- a/wiretap/CMakeLists.txt
+++ b/wiretap/CMakeLists.txt
@@ -83,7 +83,6 @@ set(WIRETAP_NONGENERATED_FILES
 	vwr.c
 	wtap.c
 	wtap_opttypes.c
-	${CMAKE_SOURCE_DIR}/version_info.c
 )
 
 set(WIRETAP_FILES ${WIRETAP_NONGENERATED_FILES})
@@ -108,11 +107,10 @@ set_source_files_properties(
 
 add_library(wiretap
 	${WIRETAP_FILES}
+	$<TARGET_OBJECTS:version_info>
 	${CMAKE_BINARY_DIR}/image/wiretap.rc
 )
 
-add_dependencies(wiretap version)
-
 set_target_properties(wiretap PROPERTIES
 	PREFIX "lib"
 	COMPILE_DEFINITIONS "WS_BUILD_DLL"