Makefile 制造选项-r-r的可能性是什么_Makefile

Makefile 制造选项-r-r的可能性是什么

makefile

Makefile 制造选项-r-r的可能性是什么,makefile,Makefile,从make--help其状态： -r, --no-builtin-rules Disable the built-in implicit rules. -R, --no-builtin-variables Disable the built-in variable settings. 我什么时候需要使用这些选项？有时我确实看到人们同时使用-rR禁用内置规则和变量主要是为了调试，尽管在某些情况下禁用规则可能会提高性能大多数在野外“认真”的makefile都倾向于声明自己的规则和配方

从

make--help

其状态：

-r, --no-builtin-rules      Disable the built-in implicit rules.
-R, --no-builtin-variables  Disable the built-in variable settings.

我什么时候需要使用这些选项？有时我确实看到人们同时使用-rR

禁用内置规则和变量主要是为了调试，尽管在某些情况下禁用规则可能会提高性能

大多数在野外“认真”的makefile都倾向于声明自己的规则和配方，因此内置规则通常是多余的。禁用它们可能会加快makefile的执行速度，具体取决于它的写入方式

假设您有以下makefile以及一个名为

foo.cpp

foo: foo.o

Make对此的调试转储是

Reading makefiles...
Reading makefile 'Makefile'...
Updating makefiles....
 Considering target file 'Makefile'.
  Looking for an implicit rule for 'Makefile'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.o'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.c'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.cc'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.C'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.cpp'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.p'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.f'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.F'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.m'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.r'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.s'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.S'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.mod'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.sh'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile,v'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'RCS/Makefile,v'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'RCS/Makefile'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 's.Makefile'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'SCCS/s.Makefile'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.o'.
  Looking for a rule with intermediate file 'Makefile.o'.
   Avoiding implicit rule recursion.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.c'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.cc'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.C'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.cpp'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.p'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.f'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.F'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.m'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.r'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.s'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.S'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.mod'.
   Trying pattern rule with stem 'Makefile.o'.
   Trying implicit prerequisite 'Makefile.o,v'.
   Trying pattern rule with stem 'Makefile.o'.
   Trying implicit prerequisite 'RCS/Makefile.o,v'.
   Trying pattern rule with stem 'Makefile.o'.
   Trying implicit prerequisite 'RCS/Makefile.o'.
   Trying pattern rule with stem 'Makefile.o'.
   Trying implicit prerequisite 's.Makefile.o'.
   Trying pattern rule with stem 'Makefile.o'.
   Trying implicit prerequisite 'SCCS/s.Makefile.o'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.c'.
   Looking for a rule with intermediate file 'Makefile.c'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.y'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.l'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.w'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.w'.
    Trying pattern rule with stem 'Makefile.c'.
    Trying implicit prerequisite 'Makefile.c,v'.
    Trying pattern rule with stem 'Makefile.c'.
    Trying implicit prerequisite 'RCS/Makefile.c,v'.
    Trying pattern rule with stem 'Makefile.c'.
    Trying implicit prerequisite 'RCS/Makefile.c'.
    Trying pattern rule with stem 'Makefile.c'.
    Trying implicit prerequisite 's.Makefile.c'.
    Trying pattern rule with stem 'Makefile.c'.
    Trying implicit prerequisite 'SCCS/s.Makefile.c'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.y'.
    Looking for a rule with intermediate file 'Makefile.y'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.y'.
     Trying implicit prerequisite 'Makefile.y,v'.
     Trying pattern rule with stem 'Makefile.y'.
     Trying implicit prerequisite 'RCS/Makefile.y,v'.
     Trying pattern rule with stem 'Makefile.y'.
     Trying implicit prerequisite 'RCS/Makefile.y'.
     Trying pattern rule with stem 'Makefile.y'.
     Trying implicit prerequisite 's.Makefile.y'.
     Trying pattern rule with stem 'Makefile.y'.
     Trying implicit prerequisite 'SCCS/s.Makefile.y'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.l'.
    Looking for a rule with intermediate file 'Makefile.l'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.l'.
     Trying implicit prerequisite 'Makefile.l,v'.
     Trying pattern rule with stem 'Makefile.l'.
     Trying implicit prerequisite 'RCS/Makefile.l,v'.
     Trying pattern rule with stem 'Makefile.l'.
     Trying implicit prerequisite 'RCS/Makefile.l'.
     Trying pattern rule with stem 'Makefile.l'.
     Trying implicit prerequisite 's.Makefile.l'.
     Trying pattern rule with stem 'Makefile.l'.
     Trying implicit prerequisite 'SCCS/s.Makefile.l'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.w'.
    Looking for a rule with intermediate file 'Makefile.w'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.w'.
     Trying implicit prerequisite 'Makefile.w,v'.
     Trying pattern rule with stem 'Makefile.w'.
     Trying implicit prerequisite 'RCS/Makefile.w,v'.
     Trying pattern rule with stem 'Makefile.w'.
     Trying implicit prerequisite 'RCS/Makefile.w'.
     Trying pattern rule with stem 'Makefile.w'.
     Trying implicit prerequisite 's.Makefile.w'.
     Trying pattern rule with stem 'Makefile.w'.
     Trying implicit prerequisite 'SCCS/s.Makefile.w'.
    Trying pattern rule with stem 'Makefile'.
    Rejecting impossible implicit prerequisite 'Makefile.w'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.cc'.
   Looking for a rule with intermediate file 'Makefile.cc'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile.cc'.
    Trying implicit prerequisite 'Makefile.cc,v'.
    Trying pattern rule with stem 'Makefile.cc'.
    Trying implicit prerequisite 'RCS/Makefile.cc,v'.
    Trying pattern rule with stem 'Makefile.cc'.
    Trying implicit prerequisite 'RCS/Makefile.cc'.
    Trying pattern rule with stem 'Makefile.cc'.
    Trying implicit prerequisite 's.Makefile.cc'.
    Trying pattern rule with stem 'Makefile.cc'.
    Trying implicit prerequisite 'SCCS/s.Makefile.cc'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.C'.
   Looking for a rule with intermediate file 'Makefile.C'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile.C'.
    Trying implicit prerequisite 'Makefile.C,v'.
    Trying pattern rule with stem 'Makefile.C'.
    Trying implicit prerequisite 'RCS/Makefile.C,v'.
    Trying pattern rule with stem 'Makefile.C'.
    Trying implicit prerequisite 'RCS/Makefile.C'.
    Trying pattern rule with stem 'Makefile.C'.
    Trying implicit prerequisite 's.Makefile.C'.
    Trying pattern rule with stem 'Makefile.C'.
    Trying implicit prerequisite 'SCCS/s.Makefile.C'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.cpp'.
   Looking for a rule with intermediate file 'Makefile.cpp'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile.cpp'.
    Trying implicit prerequisite 'Makefile.cpp,v'.
    Trying pattern rule with stem 'Makefile.cpp'.
    Trying implicit prerequisite 'RCS/Makefile.cpp,v'.
    Trying pattern rule with stem 'Makefile.cpp'.
    Trying implicit prerequisite 'RCS/Makefile.cpp'.
    Trying pattern rule with stem 'Makefile.cpp'.
    Trying implicit prerequisite 's.Makefile.cpp'.
    Trying pattern rule with stem 'Makefile.cpp'.
    Trying implicit prerequisite 'SCCS/s.Makefile.cpp'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.p'.
   Looking for a rule with intermediate file 'Makefile.p'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.web'.
    Trying pattern rule with stem 'Makefile.p'.
    Trying implicit prerequisite 'Makefile.p,v'.
    Trying pattern rule with stem 'Makefile.p'.
    Trying implicit prerequisite 'RCS/Makefile.p,v'.
    Trying pattern rule with stem 'Makefile.p'.
    Trying implicit prerequisite 'RCS/Makefile.p'.
    Trying pattern rule with stem 'Makefile.p'.
    Trying implicit prerequisite 's.Makefile.p'.
    Trying pattern rule with stem 'Makefile.p'.
    Trying implicit prerequisite 'SCCS/s.Makefile.p'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.web'.
    Looking for a rule with intermediate file 'Makefile.web'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.web'.
     Trying implicit prerequisite 'Makefile.web,v'.
     Trying pattern rule with stem 'Makefile.web'.
     Trying implicit prerequisite 'RCS/Makefile.web,v'.
     Trying pattern rule with stem 'Makefile.web'.
     Trying implicit prerequisite 'RCS/Makefile.web'.
     Trying pattern rule with stem 'Makefile.web'.
     Trying implicit prerequisite 's.Makefile.web'.
     Trying pattern rule with stem 'Makefile.web'.
     Trying implicit prerequisite 'SCCS/s.Makefile.web'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.f'.
   Looking for a rule with intermediate file 'Makefile.f'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.F'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.r'.
    Trying pattern rule with stem 'Makefile.f'.
    Trying implicit prerequisite 'Makefile.f,v'.
    Trying pattern rule with stem 'Makefile.f'.
    Trying implicit prerequisite 'RCS/Makefile.f,v'.
    Trying pattern rule with stem 'Makefile.f'.
    Trying implicit prerequisite 'RCS/Makefile.f'.
    Trying pattern rule with stem 'Makefile.f'.
    Trying implicit prerequisite 's.Makefile.f'.
    Trying pattern rule with stem 'Makefile.f'.
    Trying implicit prerequisite 'SCCS/s.Makefile.f'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.F'.
    Looking for a rule with intermediate file 'Makefile.F'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.F'.
     Trying implicit prerequisite 'Makefile.F,v'.
     Trying pattern rule with stem 'Makefile.F'.
     Trying implicit prerequisite 'RCS/Makefile.F,v'.
     Trying pattern rule with stem 'Makefile.F'.
     Trying implicit prerequisite 'RCS/Makefile.F'.
     Trying pattern rule with stem 'Makefile.F'.
     Trying implicit prerequisite 's.Makefile.F'.
     Trying pattern rule with stem 'Makefile.F'.
     Trying implicit prerequisite 'SCCS/s.Makefile.F'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.r'.
    Looking for a rule with intermediate file 'Makefile.r'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile'.
     Rejecting impossible implicit prerequisite 'Makefile.l'.
     Trying pattern rule with stem 'Makefile.r'.
     Trying implicit prerequisite 'Makefile.r,v'.
     Trying pattern rule with stem 'Makefile.r'.
     Trying implicit prerequisite 'RCS/Makefile.r,v'.
     Trying pattern rule with stem 'Makefile.r'.
     Trying implicit prerequisite 'RCS/Makefile.r'.
     Trying pattern rule with stem 'Makefile.r'.
     Trying implicit prerequisite 's.Makefile.r'.
     Trying pattern rule with stem 'Makefile.r'.
     Trying implicit prerequisite 'SCCS/s.Makefile.r'.
   Trying pattern rule with stem 'Makefile'.
   Rejecting impossible implicit prerequisite 'Makefile.F'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.m'.
   Looking for a rule with intermediate file 'Makefile.m'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.ym'.
    Trying pattern rule with stem 'Makefile.m'.
    Trying implicit prerequisite 'Makefile.m,v'.
    Trying pattern rule with stem 'Makefile.m'.
    Trying implicit prerequisite 'RCS/Makefile.m,v'.
    Trying pattern rule with stem 'Makefile.m'.
    Trying implicit prerequisite 'RCS/Makefile.m'.
    Trying pattern rule with stem 'Makefile.m'.
    Trying implicit prerequisite 's.Makefile.m'.
    Trying pattern rule with stem 'Makefile.m'.
    Trying implicit prerequisite 'SCCS/s.Makefile.m'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.ym'.
    Looking for a rule with intermediate file 'Makefile.ym'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.ym'.
     Trying implicit prerequisite 'Makefile.ym,v'.
     Trying pattern rule with stem 'Makefile.ym'.
     Trying implicit prerequisite 'RCS/Makefile.ym,v'.
     Trying pattern rule with stem 'Makefile.ym'.
     Trying implicit prerequisite 'RCS/Makefile.ym'.
     Trying pattern rule with stem 'Makefile.ym'.
     Trying implicit prerequisite 's.Makefile.ym'.
     Trying pattern rule with stem 'Makefile.ym'.
     Trying implicit prerequisite 'SCCS/s.Makefile.ym'.
   Trying pattern rule with stem 'Makefile'.
   Rejecting impossible implicit prerequisite 'Makefile.r'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.s'.
   Looking for a rule with intermediate file 'Makefile.s'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.S'.
    Trying pattern rule with stem 'Makefile.s'.
    Trying implicit prerequisite 'Makefile.s,v'.
    Trying pattern rule with stem 'Makefile.s'.
    Trying implicit prerequisite 'RCS/Makefile.s,v'.
    Trying pattern rule with stem 'Makefile.s'.
    Trying implicit prerequisite 'RCS/Makefile.s'.
    Trying pattern rule with stem 'Makefile.s'.
    Trying implicit prerequisite 's.Makefile.s'.
    Trying pattern rule with stem 'Makefile.s'.
    Trying implicit prerequisite 'SCCS/s.Makefile.s'.
    Trying pattern rule with stem 'Makefile'.
    Trying implicit prerequisite 'Makefile.S'.
    Looking for a rule with intermediate file 'Makefile.S'.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Avoiding implicit rule recursion.
     Trying pattern rule with stem 'Makefile.S'.
     Trying implicit prerequisite 'Makefile.S,v'.
     Trying pattern rule with stem 'Makefile.S'.
     Trying implicit prerequisite 'RCS/Makefile.S,v'.
     Trying pattern rule with stem 'Makefile.S'.
     Trying implicit prerequisite 'RCS/Makefile.S'.
     Trying pattern rule with stem 'Makefile.S'.
     Trying implicit prerequisite 's.Makefile.S'.
     Trying pattern rule with stem 'Makefile.S'.
     Trying implicit prerequisite 'SCCS/s.Makefile.S'.
   Trying pattern rule with stem 'Makefile'.
   Rejecting impossible implicit prerequisite 'Makefile.S'.
   Trying pattern rule with stem 'Makefile'.
   Trying implicit prerequisite 'Makefile.mod'.
   Looking for a rule with intermediate file 'Makefile.mod'.
    Avoiding implicit rule recursion.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem 'Makefile.mod'.
    Trying implicit prerequisite 'Makefile.mod,v'.
    Trying pattern rule with stem 'Makefile.mod'.
    Trying implicit prerequisite 'RCS/Makefile.mod,v'.
    Trying pattern rule with stem 'Makefile.mod'.
    Trying implicit prerequisite 'RCS/Makefile.mod'.
    Trying pattern rule with stem 'Makefile.mod'.
    Trying implicit prerequisite 's.Makefile.mod'.
    Trying pattern rule with stem 'Makefile.mod'.
    Trying implicit prerequisite 'SCCS/s.Makefile.mod'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.c'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.cc'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.C'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.cpp'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.p'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.f'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.F'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.m'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.r'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.s'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.S'.
  Trying pattern rule with stem 'Makefile'.
  Rejecting impossible implicit prerequisite 'Makefile.mod'.
  Trying pattern rule with stem 'Makefile'.
  Trying implicit prerequisite 'Makefile.sh'.
  Looking for a rule with intermediate file 'Makefile.sh'.
   Avoiding implicit rule recursion.
   Trying pattern rule with stem 'Makefile.sh'.
   Trying implicit prerequisite 'Makefile.sh,v'.
   Trying pattern rule with stem 'Makefile.sh'.
   Trying implicit prerequisite 'RCS/Makefile.sh,v'.
   Trying pattern rule with stem 'Makefile.sh'.
   Trying implicit prerequisite 'RCS/Makefile.sh'.
   Trying pattern rule with stem 'Makefile.sh'.
   Trying implicit prerequisite 's.Makefile.sh'.
   Trying pattern rule with stem 'Makefile.sh'.
   Trying implicit prerequisite 'SCCS/s.Makefile.sh'.
  No implicit rule found for 'Makefile'.
  Finished prerequisites of target file 'Makefile'.
 No need to remake target 'Makefile'.
Updating goal targets....
Considering target file 'foo'.
 File 'foo' does not exist.
 Looking for an implicit rule for 'foo'.
 Trying pattern rule with stem 'foo'.
 Trying implicit prerequisite 'foo.o'.
 Found an implicit rule for 'foo'.
  Considering target file 'foo.o'.
   Looking for an implicit rule for 'foo.o'.
   Trying pattern rule with stem 'foo'.
   Trying implicit prerequisite 'foo.c'.
   Trying pattern rule with stem 'foo'.
   Trying implicit prerequisite 'foo.cc'.
   Trying pattern rule with stem 'foo'.
   Trying implicit prerequisite 'foo.C'.
   Trying pattern rule with stem 'foo'.
   Trying implicit prerequisite 'foo.cpp'.
   Found an implicit rule for 'foo.o'.
    Considering target file 'foo.cpp'.
     Looking for an implicit rule for 'foo.cpp'.
     Trying pattern rule with stem 'foo.cpp'.
     Trying implicit prerequisite 'foo.cpp,v'.
     Trying pattern rule with stem 'foo.cpp'.
     Trying implicit prerequisite 'RCS/foo.cpp,v'.
     Trying pattern rule with stem 'foo.cpp'.
     Trying implicit prerequisite 'RCS/foo.cpp'.
     Trying pattern rule with stem 'foo.cpp'.
     Trying implicit prerequisite 's.foo.cpp'.
     Trying pattern rule with stem 'foo.cpp'.
     Trying implicit prerequisite 'SCCS/s.foo.cpp'.
     No implicit rule found for 'foo.cpp'.
     Finished prerequisites of target file 'foo.cpp'.
    No need to remake target 'foo.cpp'.
   Finished prerequisites of target file 'foo.o'.
   Prerequisite 'foo.cpp' is older than target 'foo.o'.
  No need to remake target 'foo.o'.
  Pruning file 'foo.o'.
 Finished prerequisites of target file 'foo'.
Must remake target 'foo'.
cc   foo.o   -o foo
Putting child 0x7fc4d94124c0 (foo) PID 1581 on the chain.
Live child 0x7fc4d94124c0 (foo) PID 1581 
Reaping winning child 0x7fc4d94124c0 PID 1581 
Removing child 0x7fc4d94124c0 PID 1581 from chain.
Successfully remade target file 'foo'.

对于如此琐碎的事情，似乎有很多工作要做，尽管大部分工作都与重新生成makefile有关，而不是目标本身。尽管如此，在一个包含大量源文件和makefiles的大型项目中，这些都可以加起来

现在看看这个文件的调试输出

foo: foo.o
    $(CXX) $(CXXFLAGS) $(CPPFLAGS) $(LDFLAGS) $^ $(LDLIBS) -o $@

%.o: %.cpp
    $(CXX) $(CXXFLAGS) $(CPPFLAGS) -c $(OUTPUT_OPTION) $<

现在，您不仅可以完全控制配方，还可以通过精确指定所需内容来提高效率

<>你说，如果你发现自己完全克隆了内置的规则，你可能会考虑简单地禁用一些你不需要的规则，比如

。

$(MAKEFILE_LIST): ;
%.o: %.c
%.o: %.cc
%.o: %.C
%.cpp: ;
%: ;

至于内置变量，除了调试之外，我不能说我已经找到了

-R

的用途，请记住

-R

已经暗示了

-R

，因为没有变量的内置规则是无用的。

禁用内置规则和变量主要是为了调试目的，尽管在某些情况下禁用规则可能会提高性能