Makefile doesn't check for updates in header file

user_4213849 0
Viewed 645

I thought my makefile is pretty good but then I tried to update only a header file and recompile my library, but it doesn't change anything.

How can I make it work and recompile also the code in the h file.

My makefile:

SHELL = /bin/sh
SOURCE_FILES_DIRS = -I./../frmwrk/ -I./../Utils/
CXX = g++
CXXFLAGS = $(SOURCE_FILES_DIRS) -std=c++17 -rdynamic -fPIC -g -Wall
LDFLAGS = -shared

LIBS_DIR = ../../libs/
LIB_NAME = libIni.so
TARGET  = $(LIBS_DIR)$(LIB_NAME)
SOURCES = $(shell echo *.cpp)
HEADERS = $(shell echo *.h)
OBJECTS = $(SOURCES:.cpp=.o)
LINK_LIBS = -lFrmwrk -lUtils

PREFIX = $(DESTDIR)/usr/local
BINDIR = $(PREFIX)/bin

all: $(TARGET)

$(TARGET): $(OBJECTS) $(HEADERS)
    $(CXX) $(CXXFLAGS) -L$(LIBS_DIR) $(LDFLAGS) -o $(TARGET) $(OBJECTS) $(HEADERS) $(LINK_LIBS)

clean:
    rm -f *.o $(TARGET)/*.so
    rm -rf $(TARGET)
header-files compilation makefile c++
1 Answers
$(TARGET): $(OBJECTS) $(HEADERS)
   [relink command]

This forces only a relink when the header file is changed. make has no idea, whatsoever, which C++ source file includes which header file. make knows only about dependencies explicitly declared in the header file. The only dependency stated here is that $(TARGET), the executable, has a dependency on the header file.

In order to force, for example, main.o to be recompiled when declarations.h are included, because main.cpp #includes declarations.h, you have to be explicit:

main.o: declarations.h

This directs make to rebuild main.o, from main.cpp, whenever declarations.h changes, which is what you want.

Manually tracking which object modules need to be rebuilt due to changes to which header files does not scale. make, of course, has no knowledge about anything C++ related, so you'll have to manually keep track of all the dependencies, manually, but that again doesn't scale.

The solution here is to migrate to some higher level build tools, like GNU autoconf and automake which will write the Makefile for you, complete with a bunch of rules that use compiler flags to dump the dependencies, and update the rules automatically, for you. You can always use the same compiler flags (there are flags that, and build all the scaffolding yourself, without autoconf and automake. But why bother, when autoconf automake will do it for you?

user_39433120
Related