[build] put --as-needed into linker flags instead of cflags

From: Stefan Bühler <stbuehler@web.de>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3026 152afb58-edef-0310-8abb-c4023f1b3aa9

configure.ac

@@ -25,7 +25,7 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES])
 
 
 dnl @synopsis TRY_CFLAGS [compiler flags]
-dnl @summary check whether compiler supports given C flags and adds them to CFLAGS
+dnl @summary check whether compiler supports given flags and adds them to CFLAGS
 AC_DEFUN([TRY_CFLAGS],
 [dnl
   AC_MSG_CHECKING([if $CC supports $1])
@@ -42,6 +42,23 @@ AC_DEFUN([TRY_CFLAGS],
   AC_LANG_POP([C])
 ])
 
+dnl @synopsis TRY_LDFLAGS [linker flags]
+dnl @summary check whether linker supports given flags and adds them to LDFLAGS
+AC_DEFUN([TRY_LDFLAGS],
+[dnl
+  AC_MSG_CHECKING([if $LD supports $1])
+  AC_LANG_PUSH([C])
+  ac_try_ldflags_saved_ldflags="${LDFLAGS}"
+  LDFLAGS="${LDFLAGS} $1"
+  AC_LINK_IFELSE([AC_LANG_PROGRAM([])],
+    [AC_MSG_RESULT([yes])],
+    [
+      AC_MSG_ERROR([no])
+      LDFLAGS="${ac_try_ldflags_saved_cflags}"
+    ]
+  )
+  AC_LANG_POP([C])
+])
 
 dnl Checks for programs.
 AC_PROG_CC
@@ -674,7 +691,8 @@ AC_ARG_ENABLE(extra-warnings,
   esac],[extrawarnings=false])
 
 if test x$extrawarnings = xtrue; then
-  TRY_CFLAGS([-g -O2 -g2 -Wall -Wmissing-declarations -Wdeclaration-after-statement -Wcast-align -Wsign-compare -Wnested-externs -Wpointer-arith -Wl,--as-needed -D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security])
+  TRY_CFLAGS([-g -O2 -g2 -Wall -Wmissing-declarations -Wdeclaration-after-statement -Wcast-align -Wsign-compare -Wnested-externs -Wpointer-arith -D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security])
+  TRY_LDFLAGS([-Wl,--as-needed])
 fi
 
 dnl build version-id

src/CMakeLists.txt

@@ -35,10 +35,9 @@ if(CMAKE_COMPILER_IS_GNUCC)
 	option(BUILD_EXTRA_WARNINGS "extra warnings")
 
 	if(BUILD_EXTRA_WARNINGS)
-		set(WARN_FLAGS "-g -g2 -Wall -Wmissing-declarations -Wdeclaration-after-statement -Wcast-align -Wsign-compare -Wnested-externs -Wpointer-arith -Wl,--as-needed -D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security")
+		set(WARN_CFLAGS "-g -g2 -Wall -Wmissing-declarations -Wdeclaration-after-statement -Wcast-align -Wsign-compare -Wnested-externs -Wpointer-arith -D_FORTIFY_SOURCE=2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security")
+		set(WARN_LDFLAGS "-Wl,--as-needed")
 		# -Werror -Wbad-function-cast -Wmissing-prototypes
-	else()
-		set(WARN_FLAGS "")
 	endif()
 endif()
 
@@ -627,10 +626,12 @@ if(HAVE_MEMCACHE_H)
 endif()
 
 if(CMAKE_COMPILER_IS_GNUCC)
-	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99 -Wall -g -Wshadow -W -pedantic ${WARN_FLAGS}")
+	set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99 -Wall -g -Wshadow -W -pedantic ${WARN_CFLAGS}")
 	set(CMAKE_C_FLAGS_RELEASE        "${CMAKE_C_FLAGS_RELEASE}     -O2")
 	set(CMAKE_C_FLAGS_DEBUG          "${CMAKE_C_FLAGS_DEBUG}       -O0")
 	set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_WITHDEBINFO} -O2")
+	set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${WARN_LDFLAGS}")
+	set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${WARN_LDFLAGS}")
 	add_definitions(-D_GNU_SOURCE)
 endif()