Question

我有一个使用自动依赖关系生成的C ++程序的Makefile。％.d配方取自GNU Make手册。

问题是以某种方式将“Makefile”添加为目标，然后隐式规则使其认为它是可执行文件并使用我的src /％。cpp规则来尝试编译src / Makefile.cpp。查看调试信息时，这总是在执行包含后立即发生。

    No need to remake target `build/Sprite.d'.
 Considering target file `Makefile'.
  Looking for an implicit rule for `Makefile'.
  ...
  Trying pattern rule with stem `Makefile'.
  Trying implicit prerequisite `Makefile.o'.
  Looking for a rule with intermediate file `Makefile.o'.

我知道include会导致在必要时重建给定的Makefile。它是否也尝试重建当前的Makefile？如果是这样，我如何阻止它，如果没有，那么为什么“Makefile”被添加为目标？

此外，执行include会导致重新生成.d文件，即使我在命令行中指定目标，例如make clean。有没有办法阻止这种情况发生？



# $(call setsuffix,newsuffix,files)
# Replaces all the suffixes of the given list of files.
setsuffix = $(foreach file,$2,$(subst $(suffix $(file)),$1,$(file)))

# $(call twinfile,newdir,newsuffix,oldfile)
# Turns a path to one file into a path to a corresponding file in a different
# directory with a different suffix.
twinfile = $(addprefix $1,$(call setsuffix,$2,$(notdir $3)))

MAIN = main

SOURCE_DIR = src/
INCLUDE_DIR = include/
BUILD_DIR = build/

SOURCES = $(wildcard $(SOURCE_DIR)*.cpp)
OBJECTS = $(call twinfile,$(BUILD_DIR),.o,$(SOURCES))
DEPENDENCIES = $(call twinfile,$(BUILD_DIR),.d,$(SOURCES))

CXX = g++
LIBS = -lpng
CXXFLAGS = -I $(INCLUDE_DIR)


.PHONY: all
all: $(MAIN)

$(MAIN): $(OBJECTS)
 $(CXX) $(LIBS) $^ -o $(MAIN)

include $(DEPENDENCIES)

%.o: $(BUILD_DIR)stamp
 $(CXX) $(CXXFLAGS) -c $(call twinfile,$(SOURCE_DIR),.cpp,$@) -o $@

$(BUILD_DIR)%.d: $(SOURCE_DIR)%.cpp $(BUILD_DIR)stamp
 @ echo Generate dependencies for $ $@.$$$$; \
 sed 's,\($*\)\.o[ :]*,$(BUILD_DIR)\1.o $@ : ,g'  $@; \
 rm -f $@.$$$$

$(BUILD_DIR)stamp:
 mkdir -p $(BUILD_DIR)
 touch $@

.PHONY: clean
clean:
 rm -rf $(BUILD_DIR)

.PHONY: printvars
printvars:
 @ echo $(SOURCES)
 @ echo $(OBJECTS)
 @ echo $(DEPENDENCIES)

Answer 1

Make将始终尝试在执行Makefile之前重新创建Makefile。为此，make将查找可用于重新创建Makefile的规则。 Make会查找相当多的隐式规则和其他模糊的方法来（重新）创建Makefile。

在您的情况下，以某种方式决定应该使用模式规则%.o: $(BUILD_DIR)/stamp来重新创建失败的Makefile。

要防止make重新生成Makefile，您可以编写一个带有空配方的规则：

Makefile: ;

阅读make手册中的Remaking Makefiles章节以获取更多解释。

关于附带的Makefile：包含的Makefile始终包含在内，无论目标如何。如果包含的makefile缺失（或者早于其先决条件），则首先（重新）创建它们。这意味着make clean将首先生成.d Makefile，但只会再次删除它们。

您可以通过将include指令包装在条件中来阻止包含特定目标：

ifneq ($(MAKECMDGOALS),clean)
include $(DEPENDENCIES)
endif

这是你的整个Makefile，有一些修复。我标记了我改变某些地方的地方。

# Makefile

# $(call setsuffix,newsuffix,files)
# Replaces all the suffixes of the given list of files.
setsuffix = $(foreach file,$2,$(subst $(suffix $(file)),$1,$(file)))

# $(call twinfile,newdir,newsuffix,oldfile)
# Turns a path to one file into a path to a corresponding file in a different
# directory with a different suffix.
twinfile = $(addprefix $1/,$(call setsuffix,$2,$(notdir $3)))

MAIN = main

SOURCE_DIR = src
INCLUDE_DIR = include
BUILD_DIR = build

SOURCES = $(wildcard $(SOURCE_DIR)/*.cpp)
OBJECTS = $(call twinfile,$(BUILD_DIR),.o,$(SOURCES))
DEPENDENCIES = $(call twinfile,$(BUILD_DIR),.d,$(SOURCES))

CXX = g++
LIBS = -lpng
CXXFLAGS = -I $(INCLUDE_DIR)


.PHONY: all
all: $(MAIN)

$(MAIN): $(OBJECTS)
    $(CXX) $(LIBS) $^ -o $(MAIN)

# -------> only include if goal is not clean <---------
ifneq ($(MAKECMDGOALS),clean)
include $(DEPENDENCIES)
endif

# ---------> fixed this target <--------------
$(BUILD_DIR)/%.o: $(SOURCE_DIR)/%.cpp $(BUILD_DIR)/stamp
    $(CXX) $(CXXFLAGS) -c $(call twinfile,$(SOURCE_DIR),.cpp,$@) -o $@

# ---------> and this target <---------------
$(BUILD_DIR)/%.d: $(SOURCE_DIR)/%.cpp $(BUILD_DIR)/stamp
    @ echo Generate dependencies for $@;
    @set -e; rm -f $@; \
    $(CC) -M $(CPPFLAGS) $< > $@.$$$$; \
    sed 's,\($*\)\.o[ :]*,$(BUILD_DIR)\1.o $@ : ,g' < $@.$$$$ > $@; \
    rm -f $@.$$$$

$(BUILD_DIR)/stamp:
    mkdir -p $(BUILD_DIR)
    touch $@

.PHONY: clean
clean:
    rm -rf $(BUILD_DIR)

.PHONY: printvars
printvars:
    @ echo $(SOURCES)
    @ echo $(OBJECTS)
    @ echo $(DEPENDENCIES)

Makefile将自己添加为目标

1 个答案: