为什么在食谱中使用 $(MAKE) 制作 '--dry-运行' 会导致错误？
Why make '--dry-run' with $(MAKE) in a recipe result in an error?
当我运行make --dry-run在
all:
false # $(MAKE)
使用 GNU Make 4.2.1，我收到以下错误。为什么？
false # make all
make: *** [Makefile:2: all] Error 1
https://www.gnu.org/software/make/manual/make.html#Instead-of-Execution:
The -n, -t, and -q options do not affect recipe lines that begin with + characters or contain the strings $(MAKE) or ${MAKE}.
(--dry-run 是 -n 的别名。)
https://www.gnu.org/software/make/manual/make.html#MAKE-Variable:
subsystem:
cd subdir && $(MAKE)
[...]
As a special feature, using the variable MAKE in the recipe of a rule alters the effects of the -t (--touch), -n (--just-print), or -q (--question) option. Using the MAKE variable has the same effect as using a + character at the beginning of the recipe line.
[...]
Consider the command make -t in the above example. (The -t option marks targets as up to date without actually running any recipes; see Instead of Execution.) Following the usual definition of -t, a make -t command in the example would create a file named subsystem and do nothing else. What you really want it to do is run cd subdir && make -t; but that would require executing the recipe, and -t says not to execute recipes.
The special feature makes this do what you want: whenever a recipe line of a rule contains the variable MAKE, the flags -t, -n and -q do not apply to that line. Recipe lines containing MAKE are executed normally despite the presence of a flag that causes most recipes not to be run.
您的食谱包含 $(MAKE)，因此尽管 --dry-run 仍会执行。 false returns 退出状态 1，被 make 视为错误。
当我运行make --dry-run在
all:
false # $(MAKE)
使用 GNU Make 4.2.1，我收到以下错误。为什么？
false # make all
make: *** [Makefile:2: all] Error 1
https://www.gnu.org/software/make/manual/make.html#Instead-of-Execution:
The
-n,-t, and-qoptions do not affect recipe lines that begin with+characters or contain the strings$(MAKE)or${MAKE}.
(--dry-run 是 -n 的别名。)
https://www.gnu.org/software/make/manual/make.html#MAKE-Variable:
subsystem: cd subdir && $(MAKE)[...]
As a special feature, using the variable
MAKEin the recipe of a rule alters the effects of the-t(--touch),-n(--just-print), or-q(--question) option. Using theMAKEvariable has the same effect as using a+character at the beginning of the recipe line.[...]
Consider the command
make -tin the above example. (The-toption marks targets as up to date without actually running any recipes; see Instead of Execution.) Following the usual definition of-t, amake -tcommand in the example would create a file named subsystem and do nothing else. What you really want it to do is runcd subdir && make -t; but that would require executing the recipe, and-tsays not to execute recipes.The special feature makes this do what you want: whenever a recipe line of a rule contains the variable
MAKE, the flags-t,-nand-qdo not apply to that line. Recipe lines containingMAKEare executed normally despite the presence of a flag that causes most recipes not to be run.
您的食谱包含 $(MAKE)，因此尽管 --dry-run 仍会执行。 false returns 退出状态 1，被 make 视为错误。