Question

此Makefile

CC = gcc

INC_PATH = -I../common/

SOURCEDIR := ./
SOURCES := $(wildcard $(SOURCEDIR)/*.c)
OBJDIR :=./obj
OBJECTS := $(patsubst $(SOURCEDIR)/%.c,$(OBJDIR)/%.o, $(SOURCES))
DEPENDS := $(patsubst $(SOURCEDIR)/%.c,$(OBJDIR)/%.d, $(SOURCES))

COMMONDIR     := ../common
SOURCESCOMMON := $(wildcard $(COMMONDIR)/*.c)
OBJDIRCOMMON  := $(COMMONDIR)/obj
OBJECTSCOMMON := $(patsubst $(COMMONDIR)/%.c,$(OBJDIRCOMMON)/%.o, $(SOURCESCOMMON))
DEPENDSCOMMON := $(patsubst $(COMMONDIR)/%.c,$(OBJDIRCOMMON)/%.d, $(SOURCESCOMMON))

# ADD MORE WARNINGS!
WARNING := -Wall -Wextra

# OBJS_LOC is in current working directory,
EXECUTABLE := ../server
# .PHONY means these rules get executed even if
# files of those names exist.
.PHONY: all clean

# The first rule is the default, ie. "make",
# "make all" and "make parking" mean the same
all: $(EXECUTABLE)

clean:
    $(RM) $(OBJECTS) $(DEPENDS) $(EXECUTABLE)

# Linking the executable from the object files
# $^   # "src.c src.h" (all prerequisites)
$(EXECUTABLE): $(OBJECTSCOMMON) $(OBJECTS)
    $(CC) $(WARNING) $^ -o $@

-include $(DEPENDS) $(DEPENDSCOMMON)

$(OBJDIR):
    mkdir -p $(OBJDIR)

$(OBJDIR)/%.o: $(SOURCEDIR)/%.c Makefile | $(OBJDIR)
    $(CC) $(WARNING) -MMD -MP -c $(INC_PATH) $< -o $@

$(OBJDIRCOMMON):
    mkdir -p $(OBJDIRCOMMON)

$(OBJDIRCOMMON)/%.o: $(SOURCESCOMMON)/%.c | $(OBJDIRCOMMON)
    $(CC) $(WARNING) -MMD -MP -c $< -o $@

正在生成错误：

 make[1]: *** No rule to make target '../common/obj/utilities.o', needed by '../server'.  Stop.

生成规则的主规则将输入$(OBJECTSCOMMON)引用目录*.o中包含的对象文件OBJDIRCOMMON。生成此对象的规则没有明确的目标，但它是：

$(OBJDIRCOMMON)/%.o: $(SOURCESCOMMON)/%.c | $(OBJDIRCOMMON)
    $(CC) $(WARNING) -MMD -MP -c $< -o $@

，我认为这正在产生错误。我期待定义OBJECTSCOMMON := $(patsubst $(COMMONDIR)/%.c,$(OBJDIRCOMMON)/%.o, $(SOURCESCOMMON))成为规则并有效地生成$()

但是，在同一$(OBJECTS)中使用相似的规则来生成Makefile，这是可行的：

$(OBJDIR)/%.o: $(SOURCEDIR)/%.c Makefile | $(OBJDIR)
    $(CC) $(WARNING) -MMD -MP -c $(INC_PATH) $< -o $@

那为什么规则之间会有不同的行为？

Answer 1

$(SOURCESCOMMON)/%.c扩展为$(wildcard $(COMMONDIR)/*.c)/%.c，因此模式将包含类似../common/utilities.c/%.c的内容（可能具有不同的文件名）。该文件不存在，因此模式规则将被忽略。

另一个规则使用$(SOURCEDIR)，因此它没有此问题。

Makefile错误，找不到规则，但存在规则

1 个答案: