CODEWITHSUNDEEP
makefilegnu-make
Moop
Moop

Reputation: 3601

Pattern Rule is not working as expected

I have part of a GNU-make makefile (gcc v4.1.2) that is not working as I would expected. I have a four libraries in sub diretiories that I want to recursively build if make is ran in the base /build directory

/prj
|--/build
|  |--makefile
|  |--/Tables.lib
|  |  |--makefile
|  |--/General.lib
|  |  |--makefile (etc..)
|--/lib
|--/src

Brief code for /prj/build/makefile:

LIB_DIR = /prj/lib

LIBRARY := libcomposition_adjustment.a libtables.a libgeneral.a libbiblio.a
DIRS := Tables.lib Composition_adjustment.lib General.lib Biblio.lib

all: $(LIBRARY)
#all: $(LIB_DIR)/libcomposition_adjustment.a # this line works

%.a : $(LIB_DIR)/%.a

$(LIB_DIR)/libtables.a:
    cd Tables.lib; $(MAKE)

$(LIB_DIR)/libcomposition_adjustment.a:
    cd Composition_adjustment.lib; $(MAKE)

$(LIB_DIR)/libgeneral.a:
    cd General.lib; $(MAKE)

$(LIB_DIR)/libbiblio.a: libgeneral.a
    cd Biblio.lib; $(MAKE)

It says that "No rule to make target 'libcomposition_adjustment.a', needed by 'all'. stop". But I thought the line %.a : $(LIB_DIR)/%.a would handle that. I am making this pattern rule incorrectly?

If i try the second all: line that is commented out, it works as expected.

Upvotes: 0

Views: 306

Answers (1)

Beta
Beta

Reputation: 99084

The problem is here:

%.a : $(LIB_DIR)/%.a

This is a pattern rule with no commands, which Make does not interpret as an independent rule at all. There's more than one way to fix this; the simplest is probably to give it a do-nothing command:

%.a : $(LIB_DIR)/%.a
    @:

but a better way is to do without the questionable rule altogether:

LIB_DIR = /prj/lib

LIBRARY := libcomposition_adjustment.a libtables.a libgeneral.a libbiblio.a
LIBRARY := $(addprefix $(LIB_DIR)/,$(LIBRARY))

all: $(LIBRARY)

$(LIB_DIR)/libtables.a:
    cd Tables.lib; $(MAKE)

$(LIB_DIR)/libcomposition_adjustment.a:
    cd Composition_adjustment.lib; $(MAKE)

$(LIB_DIR)/libgeneral.a:
    cd General.lib; $(MAKE)

$(LIB_DIR)/libbiblio.a: $(LIB_DIR)/libgeneral.a
    cd Biblio.lib; $(MAKE)

Upvotes: 3

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