CODEWITHSUNDEEP
autotoolsautoconf
RubenLaguna
RubenLaguna

Reputation: 24806

How to generate source code using external tool from configure itself?

I need to generate a .c and .h from a Google Protocol Buffer spec .proto in my build.

Currently I followed the approach of manually recording the dependencies to my generated .h file. That is, I added several:

somefilethatincludesthegenerated.$(OBJEXT): mygenerated.h

and that together with my rules to build mygenerated.h and mygenerated.c works. I know about BUILT_SOURCES but that only works for make all not for make mytarget.

So I wanted to explore the possibility of generating the sources from configure instead, as described in the Automake manual.

The AC_CONFIG_FILES would allow me to generate mygenerated.h from a mygenerated.h.in but really this file is not meant to be generated from a template. The files are to be generated by using an external tool called protoc. In my Makefile.am file the rule to build the generated sources is:

mygenerated.c mygenerated.c: myprotofile.proto
  $(PROTOC) --proto_path=$(srcdir) --c_out=$(builddir) $^

How can achieve something similar from within configure itself?. What I'm after is to build the generated sources always, and before any other target (BUILT_SOURCES will not work for targets other than all, check, and some others)

Upvotes: 0

Views: 498

Answers (1)

RubenLaguna
RubenLaguna

Reputation: 24806

I suceeded using AC_CONFIG_COMMANDS instead of AC_CONFIG_FILES.

So to run protoc (or protoc-c like in this case) from configure add the following to configure.ac:

AC_CONFIG_COMMANDS([src/mygenerated.h],
                   [protoc-c --proto_path=src --c_out=src src/myprotofile.proto])

Then when you run ./configure you will see a 

config.status: executing src/mygenerated.h commands

Note that if you modify the .proto file you need to rerun ./configure. This is a drawback of the "generate sources from configure" approach.

Upvotes: 2

Related Questions