use CFLAGS, CPPFLAGS and LDFLAGS properly

Makefile.in

@@ -1,6 +1,9 @@
+# @configure_input@
 CC           = @CC@
-CFLAGS      ?= @CFLAGS@
-CFLAGS      += @CPPFLAGS@
+CFLAGS       = @CFLAGS@
+CPPFLAGS     = @CPPFLAGS@
+CPPFLAGS    += @CPPFLAGS_ADD@
+LDFLAGS      = @LDFLAGS@
 SHARED       = @SHARED@
 LIBS         = @LIBS@
 
@@ -51,7 +54,7 @@ endif
 
 .PHONY: all strip install clean
 
-all: CFLAGS += -DNDEBUG
+all: CPPFLAGS += -DNDEBUG
 all: bin/lem lem.pc $(clibs)
 
 debug: bin/lem lem.pc $(clibs)
@@ -60,7 +63,7 @@ bin/libev.o: CFLAGS += -w
 include/lem.h: lua/luaconf.h
 bin/lua.o: lua/luaconf.h
 bin/lem.o: include/lem.h bin/pool.c
-bin/lem.o: CFLAGS += -D'LEM_LDIR="$(lmoddir)/"'
+bin/lem.o: CPPFLAGS += -D'LEM_LDIR="$(lmoddir)/"'
 lem/io/core.so: include/lem-parsers.h \
 	lem/io/file.c \
 	lem/io/stream.c \
@@ -72,15 +75,15 @@ lem/http/core.so: include/lem-parsers.h
 
 %.o: %.c
 	$E '  CC    $@'
-	$Q$(CC) $(CFLAGS) -c $< -o $@
+	$Q$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $@
 
 bin/lem: $(objects)
 	$E '  LD    $@'
 	$Q$(CC) $^ -o $@ -rdynamic $(LDFLAGS) $(LIBS)
 
 %.so: %.c include/lem.h
 	$E '  CCLD  $@'
-	$Q$(CC) $(CFLAGS) -fPIC -nostartfiles $(SHARED) $< -o $@ $(LDFLAGS)
+	$Q$(CC) $(CFLAGS) $(CPPFLAGS) -fPIC -nostartfiles $(SHARED) $< -o $@ $(LDFLAGS)
 
 lua/luaconf.h: lua/luaconf.h.in
 	$E '  SED > $@'

configure

@@ -659,6 +659,7 @@ pkgconfigdir
 cmoddir
 lmoddir
 SHARED
+CPPFLAGS_ADD
 objects
 headers
 target_alias
@@ -2155,9 +2156,14 @@ headers='lem.h lem-parsers.h'
 
 objects='bin/lem.o'
 
+CPPFLAGS_ADD='-Iinclude'
+
 SHARED='-shared'
 
-CPPFLAGS='-Iinclude'
+
+if test "x$CFLAGS" = 'x'; then :
+  CFLAGS='-O2 -g -Wall -Wextra'
+fi
 
 
 # Check whether --with-lua was given.
@@ -3751,7 +3757,7 @@ fi
 # Configure libev
 objects="bin/libev.o $objects"
 headers="ev-config.h ev.h $headers"
-CPPFLAGS="$CPPFLAGS -Ilibev"
+CPPFLAGS_ADD="$CPPFLAGS_ADD -Ilibev"
 
 # Configure Lua
 ac_ext=c
@@ -5235,7 +5241,7 @@ fi
 
   objects="bin/lua.o $objects"
   headers="luaconf.h lua.h lauxlib.h $headers"
-  CPPFLAGS="$CPPFLAGS -Ilua"
+  CPPFLAGS_ADD="$CPPFLAGS_ADD -Ilua"
   Lua_CFLAGS=''
   Lua_LIBS=''
   ac_cv_func_luaL_traceback=yes
@@ -5247,7 +5253,7 @@ fi
 fi
 fi
 
-CPPFLAGS="$CPPFLAGS $Lua_CFLAGS"
+CPPFLAGS_ADD="$CPPFLAGS_ADD $Lua_CFLAGS"
 LIBS="$Lua_LIBS $LIBS"
 if test "x$lmoddir" = 'x'; then :
   lmoddir="`$PKG_CONFIG --variable=INSTALL_LMOD $with_lua`"
@@ -5265,7 +5271,7 @@ fi
 
 ac_fn_c_check_func "$LINENO" "luaL_traceback" "ac_cv_func_luaL_traceback"
 if test "x$ac_cv_func_luaL_traceback" = xyes; then :
-  CPPFLAGS="$CPPFLAGS -DHAVE_TRACEBACK"
+  CPPFLAGS_ADD="$CPPFLAGS_ADD -DHAVE_TRACEBACK"
 fi
 
 

configure.ac

@@ -7,8 +7,10 @@ AC_CONFIG_HEADERS([libev/ev-config.h:ev-config.h.in])
 
 AC_SUBST([headers], ['lem.h lem-parsers.h'])
 AC_SUBST([objects], ['bin/lem.o'])
+AC_SUBST([CPPFLAGS_ADD], ['-Iinclude'])
 AC_SUBST([SHARED], ['-shared'])
-CPPFLAGS='-Iinclude'
+
+AS_IF([test "x$CFLAGS" = 'x'], CFLAGS='-O2 -g -Wall -Wextra')
 
 AC_ARG_WITH([lua],
   [AS_HELP_STRING([--with-lua],
@@ -51,7 +53,7 @@ AC_SEARCH_LIBS([pthread_create], [pthread])
 # Configure libev
 objects="bin/libev.o $objects"
 headers="ev-config.h ev.h $headers"
-CPPFLAGS="$CPPFLAGS -Ilibev"
+CPPFLAGS_ADD="$CPPFLAGS_ADD -Ilibev"
 
 # Configure Lua
 AS_CASE(["x$with_lua"],
@@ -76,14 +78,14 @@ AS_IF([test "x$with_lua" = 'xbuiltin'],
   [AC_SEARCH_LIBS([dlopen], [dl])]
   [objects="bin/lua.o $objects"]
   [headers="luaconf.h lua.h lauxlib.h $headers"]
-  [CPPFLAGS="$CPPFLAGS -Ilua"]
+  [CPPFLAGS_ADD="$CPPFLAGS_ADD -Ilua"]
   [Lua_CFLAGS='']
   [Lua_LIBS='']
   [ac_cv_func_luaL_traceback=yes]
   [AS_IF([test "x$lmoddir" = 'x'], [lmoddir="\${datarootdir}/lua/$builtin_lua_version"])]
   [AS_IF([test "x$cmoddir" = 'x'], [cmoddir="\${libdir}/lua/$builtin_lua_version"])])
 
-CPPFLAGS="$CPPFLAGS $Lua_CFLAGS"
+CPPFLAGS_ADD="$CPPFLAGS_ADD $Lua_CFLAGS"
 LIBS="$Lua_LIBS $LIBS"
 AS_IF([test "x$lmoddir" = 'x'], [lmoddir="`$PKG_CONFIG --variable=INSTALL_LMOD $with_lua`"])
 AS_IF([test "x$cmoddir" = 'x'], [cmoddir="`$PKG_CONFIG --variable=INSTALL_CMOD $with_lua`"])
@@ -93,7 +95,7 @@ AS_IF([test "x$lmoddir" = 'x'],
 AS_IF([test "x$cmoddir" = 'x'],
   [AC_MSG_ERROR([unable to deduce Lua C module directory, please use --with-cmoddir=path])])
 
-AC_CHECK_FUNC([luaL_traceback], [CPPFLAGS="$CPPFLAGS -DHAVE_TRACEBACK"])
+AC_CHECK_FUNC([luaL_traceback], [CPPFLAGS_ADD="$CPPFLAGS_ADD -DHAVE_TRACEBACK"])
 
 # Checks for header files.
 AC_CHECK_HEADERS([stddef.h stdlib.h string.h unistd.h sys/time.h time.h pthread.h])