ffmpeg - ffmpeg Makefile中的 "all-yes"是什么意思

Question

在 ffmpeg Makefile 中，
https://github.com/FFmpeg/FFmpeg/blob/master/Makefile#L37
https://github.com/FFmpeg/FFmpeg/blob/master/Makefile#L189
它定义了虚假目标“all”和“all-yes”，但我无法通过搜索整个 ffmpeg 目录找到“all-yes”的先决条件和命令。那么任何人都可以帮助解释“全部是”的确切含义吗？

Answer 1

“include $(SRC_PATH)/fftools/Makefile”中还有另一个“all”目标:https://github.com/FFmpeg/FFmpeg/blob/master/fftools/Makefile#L30

$(foreach P,$(AVPROGS-yes),$(eval $(call DOFFTOOL,$(P))))
all: $(AVPROGS)
fftools/ffprobe.o fftools/cmdutils.o: libavutil/ffversion.h | fftools
OUTDIRS += fftools

4.11 Multiple Rules for One Target

There can only be one recipe to be executed for a file. If more than one rule gives a recipe for the same file, make uses the last one given and prints an error message. (As a special case, if the file’s name begins with a dot, no error message is printed. This odd behavior is only for compatibility with other implementations of make… you should avoid using it). Occasionally it is useful to have the same target invoke multiple recipes which are defined in different parts of your makefile; you can use double-colon rules (see Double-Colon) for this.

有两个目标，make只使用最后一个，所以你可以删除“all-yes”或删除“all:all-yes”然后使用“make all”命令，对编译没有影响。命令行“all:all-yes”只是确保“all”是默认目标。