code generation - Automake, generated source files and VPATH builds -

i'm doing vpath builds automake. i'm using generated source, swig. i've got rules in makefile.am like:

dist_noinst_data = whatever.swig  whatever.cpp: whatever.swig     swig -c++ -php $^ 

then file gets used later:

myprogram_sources = ... whatever.cpp 

it works fine when $builddir == $srcdir. when doing vpath builds (e.g. mkdir build; cd build; ../configure; make), error messages missing whatever.cpp.

should generated source files go $builddir or $srcdir? (i reckon $builddir.)

how should dependencies , rules specified put generated files in right place?

simple answer

you should assume $srcdir read-only, must not write there. so, generated source-code end in $(builddir).

by default, autotool-generated makefiles source-files in $srcdir, have tell check $builddir well. adding following makefile.am should help:

vpath = $(srcdir) $(builddir) 

after might end no rule make target ... error, should able fix updating source-generating rule in:

$(builddir)/whatever.cpp: whatever.swig         # ... 

a better solution

you might notice in current setup, release tarball (as created make dist) contain whatever.cpp file part of sources, since added file myprogram_sources. if don't want (e.g. because might mean build-process take pregenerated file rather generating again), might want use following. uses wrapper source-file (whatever_includer.cpp) includes generated file, , uses -i$(builddir) find generated file.

makefile.am:

dist_noinst_data = whatever.swig  whatever.cpp: whatever.swig     swig -c++ -php $^  whatever_includer.cpp: whatever.cpp  myprogram_sources = ... whatever_includer.cpp myprogram_cppflags = ... -i$(builddir)  clean-local::     rm -f $(builddir)/whatever.cpp 

whatever_includer.cpp:

#include "whatever.cpp"