Makefile with different compiler flags for source files - c++

Question

How do I use different compiler flags for different source files in a Makefile? For example, I'd like a Makefile that will produce:
g++ -c -COMPILER_FLAGS_1 -g source1.cpp -o source1.o
g++ -c -COMPILER_FLAGS_2 -g source2.cpp -o source2.o
g++ -c -COMPILER_FLAGS_2 -g source3.cpp -o source3.o
g++ -c -COMPILER_FLAGS_2 -g source4.cpp -o source4.o
g++ -c -COMPILER_FLAGS_3 -g source5.cpp -o source5.o
g++ -c -COMPILER_FLAGS_3 -g source6.cpp -o source6.o
g++ -c -COMPILER_FLAGS_3 -g source7.cpp -o source7.o
g++ -g -o output source1.o source2.o source3.o source4.o source5.o source6.o source7.o
At the moment I've got about 20 source files (and that's expected to grow), so an easy to maintain file would be nice.
Thanks in advance.

Answer 1

You could do something like the following (untested, so the syntax might be slightly off):
OBJS_1 := source1.o
OBJS_2 := source2.o source3.o source4.o
OBJS_3 := source5.o source6.o source7.o
OBJS := $(OBJS_1) $(OBJS_2) $(OBJS_3)
output: $(OBJS)
$(CXX) -g -o $# $^
$(OBJS_1): CXXFLAGS := $(COMPILER_FLAGS_1)
$(OBJS_2): CXXFLAGS := $(COMPILER_FLAGS_2)
$(OBJS_3): CXXFLAGS := $(COMPILER_FLAGS_3)
$(OBJS): %.o: %.cpp
$(CXX) -c $(CXXFLAGS) -g $< -o $#

Answer 2

Here is UNIX/LINUX makefile which I wrote and tested on Solaris LINUX to handle different compilation flags for different sections of a GNUmakefile. Please let me know if it can be improved. Thank you
# GNUmakefile
#
# makefile for mdRightFielder
#
# Builds:
# libmdRightFielder.so or libmdRightFielder.sl
ifndef SUB
include ../header.mk
else
VPATH=../Source:../Source/PCRE:../Source/SQLite:../../cpswindows/Source:../../util/mdLicense
INCL=-I../Include -I../Include/PCRE -I../Include/SQLite -I../../cpswindows/Include -I ../../util -I../../util/mdLicense
APIOBJ=cGlobalDataDestructor.o cPCRE.o CppInterface.o cRightFielder-FillTokenGaps.o
PCREOBJ=pcre_chartables.o pcre_compile.o pcre_exec.o pcre_fullinfo.o pcre_get.o pcre_globals.o pcre_newline.o \
pcre_tables.o pcre_try_flipped.o
SQLITEOBJ=sqlite3.o
CPSWINDOWSOBJ=BinarySearch.o cConfigFile.o cCriticalSection.o cDateTime.o cException.o cFile.o cSQLite.o \
QuickSort.o StringFunctions.o
MDLICENSEOBJ=CBigNum.o mdLicense.o RSA.o
ifeq ($(CPU),sparc)
ifdef workshop
CALIGN=-xmemalign=1s
ifdef release
CXXALIGN=-Qoption cg -xmemalign=1s
else
CXXALIGN=-Qoption ccfe -y-xmemalign=1s
endif
endif
endif
COMPILER_FLAGS_1=-D_NO_GUI
COMPILER_FLAGS_2=-D_NO_GUI -DHAVE_CONFIG_H
CXXFLAGS+=-DPCRE_STATIC -DUSE_STATIC
CFLAGS+=-D_NO_GUI -DHAVE_CONFIG_H -DPCRE_STATIC -DUSE_STATIC
DEPFLAGS+=-DLINK_SIZE=2 -D_NO_GUI -DHAVE_CONFIG_H -DPCRE_STATIC -DUSE_STATIC
.PHONY: all clean
all: libmdRightFielder.so
cp -fp ../Include/mdRightFielder.h ../../util/mdEnums.h libmdRightFielder.so $(SHIP)
if [ `uname` = HP-UX ] ; \
then \
/bin/mv -f $(SHIP)/libmdRightFielder.so $(SHIP)/libmdRightFielder.sl ; \
fi
clean:
rm -f *.o *.so *.sl deps
rm -f core core.[0-9]*
$(APIOBJ): CXXFLAGS+=$(COMPILER_FLAGS_1)
$(PCREOBJ): CXXFLAGS+=$(COMPILER_FLAGS_2)
MARYOBJS = $(APIOBJ) $(PCREOBJ)
libmdRightFielder.so: \
$(MARYOBJS)
-$(CXX) $(CXXFLAGS) $(INCL) $(SHARED) $^ -o $# $(LDLIBS)
mary:
%.o : %.cpp # cancel implicit CPP compilation rule
%.o : %.cpp
$(CXX) $(CXXFLAGS) $(INCL) $(PIC) $< -o $# -c
%.o : %.c # cancel implicit C compilation rule
%.o : %.c
$(CC) $(CFLAGS) $(INCL) $(PIC) $< -o $# -c
endif