生成文件错误未找到规则，但存在规则

Question

This 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引用目录OBJDIRCOMMON中包含的对象文件*.o作为输入$(OBJECTSCOMMON)。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 $@

我认为这会产生错误。我期待定义OBJECTSCOMMON := $(patsubst $(COMMONDIR)/%.c,$(OBJDIRCOMMON)/%.o, $(SOURCESCOMMON))制定规则并有效生成$()

但是，类似的规则用于在同一Makefile中生成$(OBJECTS)，并且它适用于：

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

那么，为什么规则之间的行为不同呢？

Answer 1

$(SOURCESCOMMON)/%.c扩展到$(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）。 此文件不存在，因此将忽略模式规则。

另一个规则使用 $(SOURCEDIR) ，所以它没有这个问题。