Makefile中的簡單字符串替換

我想用libswscale.so（分別稱爲$(SLIBNAME_WITH_MAJOR)和$(SLIBNAME)的變量）替換字符串libswscale.so.2。這是我在Makefile嘗試：Makefile中的簡單字符串替換

$(SUBDIR)$(SLIBNAME_WITH_MAJOR): $(OBJS) $(SUBDIR)lib$(NAME).ver 
    [...] 
    @echo SHFLAGS=$(SHFLAGS) 
    @echo SLIBNAME_WITH_MAJOR=$(SLIBNAME_WITH_MAJOR) 
    @echo SLIBNAME=$(SLIBNAME) 
    @echo A $(patsubst $(SLIBNAME_WITH_MAJOR),$(SLIBNAME),$(SHFLAGS)) 
    @echo B $(SHFLAGS:$(SLIBNAME_WITH_MAJOR)=$(SLIBNAME)) 
    @echo C $($(SHFLAGS):$(SLIBNAME_WITH_MAJOR)=$(SLIBNAME)) 
    @echo D $(SHFLAGS:$(SLIBNAME_WITH_MAJOR)=$(SLIBNAME)) 
    @echo E $(subst $(SLIBNAME_WITH_MAJOR),$(SLIBNAME),$(SHFLAGS)) 
    @echo F $(subst l,L,$(SHFLAGS))

輸出是

SHFLAGS=-shared -Wl,-soname,libswscale.so.2 -Wl,-Bsymbolic -Wl,--version-script,libswscale/libswscale.ver 
SLIBNAME_WITH_MAJOR=libswscale.so.2 
SLIBNAME=libswscale.so 
A -shared -Wl,-soname,libswscale.so.2 -Wl,-Bsymbolic -Wl,--version-script,libswscale/libswscale.ver 
B -shared -Wl,-soname,libswscale.so.2 -Wl,-Bsymbolic -Wl,--version-script,libswscale/libswscale.ver 
C 
D -shared -Wl,-soname,libswscale.so.2 -Wl,-Bsymbolic -Wl,--version-script,libswscale/libswscale.ver 
E -shared -Wl,-soname,libswscale.so.2 -Wl,-Bsymbolic -Wl,--version-script,libswscale/libswscale.ver 
F -shared -WL,-soname,libswscale.so.2 -WL,-BsymboLic -WL,--version-script,LibswscaLe/LibswscaLe.ver

最後一個（F）特別可笑。這裏有什麼問題？是否因爲$(SHFLAGS)也由變量組成？

來源

2013-01-25 AndiDog

發現：$(SHFLAGS)被定義爲

SHFLAGS=-shared -Wl,-soname,$$(@F) blablafoo

，並使用它的任何替換，直到$$(@F)是行不通的實際評估（在我的情況下libswscale.so.2）。

我解決它通過替換可變基準：

@echo $(subst $$(@F),$(SLIBNAME),$(SHFLAGS))

上分配小暗示：使用時VAR = $(OTHERVAR)進行評價時，VAR := $(OTHERVAR)立即評估。

來源

2013-01-25 13:30:16 AndiDog

Makefile中的簡單字符串替換

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