CODEWITHSUNDEEP
makefilemulticore
Chris Maes
Chris Maes

Reputation: 37742

make multicore (-j) does not handle dependencies correctly?

I have a makefile with this line:

parser_yacc.h parser_yacc.c :   parser_yacc.y
    bison -y -d parser_yacc.y && mv y.tab.h parser_yacc.h && \
            mv y.tab.c parser_yacc.c

now I have several other lines that depend on parser_yacc.h. When I perform make everything runs fine. However when I run make -j4 I always get this warning: 

mv: cannot stat `y.tab.c': No such file or directory

As I understand make tries to build both parser_yacc.c and another file that needs parser_yacc.hat the same time; thus spawning twice the commands

bison -y -d parser_yacc.y && mv y.tab.h parser_yacc.h && \
    mv y.tab.c parser_yacc.c

causing the second to crash... How could I circumvent this problem?

Upvotes: 1

Views: 84

Answers (1)

laune
laune

Reputation: 31290

You might rewrite the rule for either of the targets alone (e.g. the .c), and add another rule for completing the other one.

parser_yacc.c :   parser_yacc.y
    bison -y -d parser_yacc.y && mv y.tab.c parser_yacc.c

parser_yacc.h : parser_yacc.c
    mv y.tab.h parser_yacc.h

Upvotes: 1

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