C ++ Makefile错误-没有使目标'％.cpp'的规则 [英] C++ Makefile error - No rule to make target '%.cpp'

问题描述

早上好，我正在运行一个教程来编写自己的makefile，我在这里找到了该教程:

Good day, I am running through a tutorial to write my own makefiles, I found the tutorial here:

http://www.cs.colby.edu/maxwell/courses /tutorials/maketutor/

我知道本教程适用于C makefile，但是我相信C和C ++之间的相似之处意味着makefile的功能几乎没有区别(例如，我使用的是g ++而不是gcc).我希望我对这一点的假设不是一个因素，因为前4个教程中的每一个似乎都工作得很好.

I know this tutorial is for C makefiles, however I believe that the similiarities between C and C++ would mean there is little difference in how the makefiles function (for instance, I am using g++ rather than gcc). I hope my assumption on this point isn't a factor, since each of the previous 4 tutorials appear to have worked just fine.

在本教程中遍历Makefile 5时，从.cpp文件构造目标文件时出现错误:

When running through Makefile 5 in the tutorial, I am getting an error regarding the construction of the object files from the .cpp files:

make: *** No rule to make target '%.cpp', needed by 'obj'. Stop.

我似乎无法弄清为什么会这样，非常令人困惑和沮丧，因为我觉得这不应该发生.我将完整的Makefile包含在下面，非常感谢您的协助:

I cannot seem to figure out why this is happening, very confusing and frustrating as I feel like this shouldn't be happening. I include my full Makefile below, any assistance would be greatly appreciated:

 # Example Makefile                                                                                                                                                                                             
 # ----------------
 # Please remember to turn off the vim option: 'expandtab' so that tabs are 
 # actually displayed as tabs (do so like this - :set noexpandtab )
 #

 # This file specifies dependencies, which means that the two c++ files must
 # be compiled before the executable is built

 # ------------------
 # Makefile Constants
 # ------------------

 # Directory constants
 IDIR =../include  # Specifies location of include directory
 ODIR =obj        # Specifies location of object directory
 LDIR =../lib      # Specifies location of library directory

 LIBS=-lm  # ?

 # Options constants
 CC=g++            # Specifies the specific C compiler to use, g++ specifies C++ compiler
 CFLAGS=-I$(IDIR)  # List of flags to pass to compilation command

 # Dependency Constants
 DEP_FILES=helloMake.h                      # Specifies dependency files
 DEPS=$(patsubst %,$(IDIR)/%,$(DEP_FILES))  # Specifies path to dependencies and dependency files

 # Object constants
 OBJ_FILES=helloMake.o helloFunc.o         # Specify object files
 OBJ=$(patsubst %,$(ODIR)/%,$(OBJ_FILES))  # Specifies path to objects and object files


 # -----------
 # Compilation
 # -----------

 # Specify rules to make object files
 $(ODIR)/%.o: %.cpp $(DEPS)       # Specifies that .o files depend on the .cpp version of the file and the .h files included in the DEPS macro
     $(CC) -c -o $@ $< $(CFLAGS)  # The -c flag says to generate the object file, the -o $@ says to put the output of the compilation in the
                                  # file named on the left side of the : the $< is the first item in the dependencies list

 # Specify rules to make target executable
 helloMake: $(OBJ)                     # Target : Dependencies
     $(CC) -o $@ $^ $(CFLAGS) $(LIBS)  # This is the actual compilation command

 .PHONY: clean  # Prevent the make command from attempting to do something with a file named 'clean'

 # Specify rules to clean the object files
 clean:
     rm -f $(ODIR)/*.o *~ core $(INCDIR)/*~  # Removes all compiled object files

推荐答案

不幸的是，此简单"教程会推广不良做法.

This "simple" tutorial unfortunately promotes bad practices.

基本上，您首先需要一个正确的C Makefile:

Basically, you first need a correct C Makefile:

# Specify the final target name
EXE := helloMake

# Specify the source files
# Effectively list all source files in the current directory
SRC := $(wildcard *.c)

# From the source file list, get the corresponding object file list
# This is a clearer syntax for $(patsubst %.c,%.o,$(SRC))
OBJ := $(SRC:.c=.o)

# From the object file list, get the dependency file list to handle automatic
# recompilation when a header file is modified
DEP := $(OBJ:.o=.d)

# Specify preprocessor flags (this is a built-in variable)
CPPFLAGS := -I../include
# Required flags to enable the automatic dependency generation by the compiler
CPPFLAGS += -MMD -MP

# Specify compiler flags (this is a built-in variable)
# Here some basic warning flags
CFLAGS := -Wall -W -pedantic

# Specify linker flags (this is a built-in variable)
LDFLAGS := -L../lib

# Specify linker libraries (this is a built-in variable)
# m is the maths library
LDLIBS := -lm

# Tell make that these target are not real files
.PHONY: all clean

# Now the standard primary rule
all: $(EXE)

# How do we make $(EXE) ? Remember the recipe describe the linking phase
$(EXE): $(OBJ)
    $(CC) $(LDFLAGS) $^ $(LDLIBS) -o $@

# Let's clean up the mess
clean:
    $(RM) $(EXE) $(OBJ) $(DEP)

# Don't forget to include the dependency files to let make know when to recompile
-include $(DEP)

然后，您需要了解C Makefile和C ++ Makefile之间的区别:

Then you need to know the difference between a C Makefile and a C++ Makefile:

• 使用$(CXX)代替$(CC)
• 使用$(CXXFLAGS)代替$(CFLAGS)
• 使用.cpp代替.c.

• Use $(CXX) instead of $(CC),
• Use $(CXXFLAGS) instead of $(CFLAGS),
• Use .cpp instead of .c.

您完成了.

# Specify the final target name
EXE := helloMake

# Specify the source files
# Effectively list all source files in the current directory
SRC := $(wildcard *.cpp)

# From the source file list, get the corresponding object file list
# This is a clearer syntax for $(patsubst %.cpp,%.o,$(SRC))
OBJ := $(SRC:.cpp=.o)

# From the object file list, get the dependency file list to handle automatic
# recompilation when a header file is modified
DEP := $(OBJ:.o=.d)

# Specify preprocessor flags (this is a built-in variable)
CPPFLAGS := -I../include
# Required flags to enable the automatic dependency generation by the compiler
CPPFLAGS += -MMD -MP

# Specify compiler flags (this is a built-in variable)
# Here some basic warning flags
CXXFLAGS := -Wall -W -pedantic

# Specify linker flags (this is a built-in variable)
LDFLAGS := -L../lib

# Specify linker libraries (this is a built-in variable)
# m is the maths library
LDLIBS := -lm

# Tell make that these target are not real files
.PHONY: all clean

# Now the standard primary rule
all: $(EXE)

# How do we make $(EXE) ? Remember the recipe describe the linking phase
$(EXE): $(OBJ)
    $(CXX) $(LDFLAGS) $^ $(LDLIBS) -o $@

# Let's clean up the mess
clean:
    $(RM) $(EXE) $(OBJ) $(DEP)

# Don't forget to include the dependency files to let make know when to recompile
-include $(DEP)

---

要能够重新定位构建文件(.o和.d文件)，您需要进行一些调整:

---

To be able to relocate the build files (.o and .d files), you need a few adjustments:

# Specify the final target name
EXE := helloMake

# Specify the source files
# Effectively list all source files in the current directory
SRC := $(wildcard *.cpp)

# Specify where to put the build temporary files
BLD := obj

# From the source file list, get the corresponding object file list
# This is a clearer syntax for $(patsubst %.cpp,$(BLD)/%.o,$(SRC))
OBJ := $(SRC:%.cpp=$(BLD)/%.o)

# From the object file list, get the dependency file list to handle automatic
# recompilation when a header file is modified
DEP := $(OBJ:.o=.d)

# Specify preprocessor flags (this is a built-in variable)
CPPFLAGS := -I../include
# Required flags to enable the automatic dependency generation by the compiler
CPPFLAGS += -MMD -MP

# Specify compiler flags (this is a built-in variable)
# Here some basic warning flags
CXXFLAGS := -Wall -W -pedantic

# Specify linker flags (this is a built-in variable)
LDFLAGS := -L../lib

# Specify linker libraries (this is a built-in variable)
# m is the maths library
LDLIBS := -lm

# Tell make that these target are not real files
.PHONY: all clean

# Now the standard primary rule
all: $(EXE)

# How do we make $(EXE) ? Remember the recipe describe the linking phase
$(EXE): $(OBJ)
    $(CXX) $(LDFLAGS) $^ $(LDLIBS) -o $@

# The build directory is custom so we need to tell make how to do it
# The build directory must exist before trying to compile
$(BLD)/%.o: %.cpp | $(BLD)
    $(CXX) $(CPPFLAGS) $(CXXFLAGS) -o $@ -c $<

# Simple rule to create the build directory if needed
$(BLD):
    mkdir $@

# Let's clean up the mess, we can just remove the build directory alonside the executable
clean:
    $(RM) -r $(BLD) $(EXE)

# Don't forget to include the dependency files to let make know when to recompile
-include $(DEP)

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