makefile库依赖项-解析循环依赖项

Question

我试图在makefile中构建一个特性，它允许我指定一个库列表，这个列表是依赖于的特定库

这将允许库的受抚养人在重新构建库的依赖项时自动重建，并将依赖项添加到链接行中。

我在SO here上问了一个相关的问题，并给出了一个答案，我想出了下面的测试

uniq = $(if $1,$(firstword $1) $(call uniq,$(filter-out $(firstword $1),$1)))
expand-deps = $1 $(foreach _,$1, $(call expand-deps,$($__deps)))
make-dep-list = $(call uniq,$(call expand-deps,$1))

define make-lib
    $(warning $1_deps: $2)
    # capture the list of libraries this library depends on
    $1_deps = $2
endef

define make-bin
    # show the fully expanded list of libraries this binary depends on
    $(warning $1 dep-list: [$(call make-dep-list,$2)])
endef

#$(eval $(call make-lib, thread, log utils)) circular-dependency log->thread; thread->log
$(eval $(call make-lib, thread, utils))
$(eval $(call make-lib, log, thread))
$(eval $(call make-lib, order, log))
$(eval $(call make-lib, price, log))
$(eval $(call make-bin, test, order price))

运行上述makefile将得到以下结果：

$ make
makefile:15:  thread_deps:  utils
makefile:16:  log_deps:  thread
makefile:17:  order_deps:  log
makefile:18:  price_deps:  log
makefile:19:  test dep-list: [order price log thread utils ]
make: *** No targets.  Stop.

库有可能具有循环依赖关系。

例如:日志库是多线程的，因此需要线程库。线程库可以发出日志语句，因此需要日志库。

如果取消对具有循环依赖项的行的注释

$(eval $(call make-lib, thread, log utils))
$(eval $(call make-lib, log, thread))

makefile将被困在一个无限循环中。

如何允许用户指定循环依赖项，并打破无限循环？

Answer 1

因此，您的问题是，您正在递归地展开lib_deps (例如)。在这样做的同时，您又开始扩展lib_deps。无限循环(呃，堆栈崩溃)。为了阻止自己，你需要保留一张清单，列出你已经扩展过的东西。退出功能风格，将答案保留在全球expansion (呜！)中，如下所示：

expand-deps = \
  $(foreach _,$1, \
    $(if $(filter $_,${expansion}),, \
      $(eval expansion += $_)$(call expand-deps,${$__deps})))

make-dep-list = $(eval expansion :=)$(call expand-deps,$1)${expansion}

define make-lib
  $(warning $1_deps: $2)
  # capture the list of libraries this library depends on
  $1_deps := $2
endef

define make-bin
  # show the fully expanded list of libraries this binary depends on
  $(warning $1 dep-list: [$(call make-dep-list,$2)])
endef

$(eval $(call make-lib,thread,log utils))#circular-dependency log->thread; thread->log
#$(eval $(call make-lib,thread,utils))
$(eval $(call make-lib,log,thread))
$(eval $(call make-lib,order,log))
$(eval $(call make-lib,price,log))
$(eval $(call make-bin,test,order price))

(作为练习，您可能希望用函数式重写它，即去掉全局$expansion，代之以传递给它的参数。)