Conditionally overriding variables set by Autoconf

[Marius Bakke]

Hi!

Noob question.  I have a Makefile.am that looks like this:

--8<---------------cut here---------------start------------->8---
pkglibdir = $(versiondir)$(libdir)/ganeti
myexeclibdir = $(pkglibdir)
bindir = $(versiondir)/$(BINDIR)
sbindir = $(versiondir)$(SBINDIR)
mandir = $(versionedsharedir)/root$(MANDIR)
pythondir = $(versionedsharedir)
pkgpythondir = $(versionedsharedir)/ganeti
pkgpython_rpc_stubdir = $(versionedsharedir)/ganeti/rpc/stub
gntpythondir = $(versionedsharedir)
pkgpython_bindir = $(versionedsharedir)
gnt_python_sbindir = $(versionedsharedir)
tools_pythondir = $(versionedsharedir)
--8<---------------cut here---------------end--------------->8---

(from https://github.com/ganeti/ganeti/blob/master/Makefile.am)

It works fine.  Great, even.

Locally, I have patched it with a new configure flag that introduces a
USE_VERSION_LINKS variable, and tried changing the code above to read:

--8<---------------cut here---------------start------------->8---
if USE_VERSION_LINKS
pkglibdir = $(versiondir)$(libdir)/ganeti
myexeclibdir = $(pkglibdir)
bindir = $(versiondir)/$(BINDIR)
sbindir = $(versiondir)$(SBINDIR)
mandir = $(versionedsharedir)/root$(MANDIR)
pythondir = $(versionedsharedir)
pkgpythondir = $(versionedsharedir)/ganeti
pkgpython_rpc_stubdir = $(versionedsharedir)/ganeti/rpc/stub
gntpythondir = $(versionedsharedir)
pkgpython_bindir = $(versionedsharedir)
gnt_python_sbindir = $(versionedsharedir)
tools_pythondir = $(versionedsharedir)
else
myexeclibdir = $(pkglibdir)
pkgpython_rpc_stubdir = $(pkgpythondir)/rpc/stub
gntpythondir = $(sbindir)
pkgpython_bindir = $(pkglibdir)
gnt_python_sbindir = $(sbindir)
tools_pythondir = $(pkglibdir)
versionedsharedir = $(pkglibdir)
versiondir =
endif
--8<---------------cut here---------------end--------------->8---

It works, but now 'autoreconf' is throwing warnings:

--8<---------------cut here---------------start------------->8---
autoreconf: running: automake --add-missing --copy --force-missing
Makefile.am:86: warning: pkglibdir was already defined in condition TRUE, which 
includes condition USE_VERSION_LINKS ...
/gnu/store/1l38jl5mhkb1ypw922njxmnsb6w8zwaw-automake-1.16.2/share/automake-1.16/am/header-vars.am:
 ... 'pkglibdir' previously defined here
Makefile.am:88: warning: bindir was already defined in condition TRUE, which 
includes condition USE_VERSION_LINKS ...
configure.ac:12: ... 'bindir' previously defined here
Makefile.am:89: warning: sbindir was already defined in condition TRUE, which 
includes condition USE_VERSION_LINKS ...
configure.ac:12: ... 'sbindir' previously defined here
Makefile.am:90: warning: mandir was already defined in condition TRUE, which 
includes condition USE_VERSION_LINKS ...
configure.ac:12: ... 'mandir' previously defined here
Makefile.am:91: warning: pythondir was already defined in condition TRUE, which 
includes condition USE_VERSION_LINKS ...
configure.ac:905: ... 'pythondir' previously defined here
Makefile.am:92: warning: pkgpythondir was already defined in condition TRUE, 
which includes condition USE_VERSION_LINKS ...
configure.ac:905: ... 'pkgpythondir' previously defined here
autoreconf: Leaving directory `.'
--8<---------------cut here---------------end--------------->8---

What would be the "correct" way to deal with this?