python-cffi: fix out-of-tree build

The main idea is to replace the hack of copying version.txt into the
bindings source with a generated _notmuch_config.py file.

This will mean that the bindings only build after configuring and
building notmuch itself. Given those constraints, "pip install ."
should work.

Makefile.local

@@ -54,7 +54,6 @@ update-versions:
 	sed -i -e "s/^__VERSION__[[:blank:]]*=.*$$/__VERSION__ = \'${VERSION}\'/" \
 	    -e "s/^SOVERSION[[:blank:]]*=.*$$/SOVERSION = \'${LIBNOTMUCH_VERSION_MAJOR}\'/" \
 	    ${PV_FILE}
-	cp version.txt bindings/python-cffi
 
 # We invoke make recursively only to force ordering of our phony
 # targets in the case of parallel invocation of make (-j).

bindings/python-cffi/notmuch2/_build.py

@@ -1,5 +1,5 @@
 import cffi
-
+from _notmuch_config import *
 
 ffibuilder = cffi.FFI()
 ffibuilder.set_source(
@@ -16,8 +16,8 @@ ffibuilder.set_source(
         #ERROR libnotmuch  version < 5.1 not supported
     #endif
     """,
-    include_dirs=['../../lib'],
-    library_dirs=['../../lib'],
+    include_dirs=[NOTMUCH_INCLUDE_DIR],
+    library_dirs=[NOTMUCH_LIB_DIR],
     libraries=['notmuch'],
 )
 ffibuilder.cdef(

bindings/python-cffi/setup.py

@@ -1,6 +1,7 @@
 import setuptools
+from _notmuch_config import *
 
-with open('version.txt') as fp:
+with open(NOTMUCH_VERSION_FILE) as fp:
     VERSION = fp.read().strip()
 
 setuptools.setup(

bindings/python-cffi/version.txt

@@ -1 +0,0 @@
-0.34.1

configure

@@ -1579,6 +1579,14 @@ EOF
     printf "rsti_dir = '%s'\n" "$(cd emacs && pwd -P)"
 } > sphinx.config
 
+cat > bindings/python-cffi/_notmuch_config.py <<EOF
+# _notmuch_config.py was automatically generated by the configure
+# script in the root of the notmuch source tree.
+NOTMUCH_VERSION_FILE='${NOTMUCH_SRCDIR}/version.txt'
+NOTMUCH_INCLUDE_DIR='${NOTMUCH_SRCDIR}/lib'
+NOTMUCH_LIB_DIR='${NOTMUCH_SRCDIR}/lib'
+EOF
+
 # Finally, after everything configured, inform the user how to continue.
 cat <<EOF