In this change:

https://fedoraproject.org/wiki/Changes/Make_ambiguous_python_shebangs_error

We have advised the following:

pathfix.py -pni "%{__python3} %{py3_shbang_opts}" <paths>

To fix the shebangs.

-p preserves timestamps -n prevents creating ~backup files -i specifies the interpreter for the shebang

Now we have new features and we ultimately want this for the best experience:

pathfix.py -pni %{python3} -ka %{py3_shbang_opts_nodash}

-k keeps existing flags -a adds our flags (if not already there) %py3_shbang_opts_nodash is derived from %py3_shbang_opts

This is very tedious copypasta.

I propose we macronize this as follows:

We create %py3_shebang_flags. By default, it is the same as %py3_shbang_opts without dash to avoid confusion, but it can be overridden. Note the proper "e" in the name.

We create %py3_shebang_fix:

pathfix.py -pni %{__python3} -k%{?py3_shebang_flags:a %py3_shebang_flags}

Usage:

%prep %autosetup %py3_shebang_fix .

Or:

%install ...install stuff... %py3_shebang_fix %{buildroot}%{python3_sitearch} %{buildroot}%{_bindir}/*

As a side not, is it possible to have conditonal expansion not expand on empty macro?

E.g. this works:

%undefine py3_shebang_flags %{?py3_shebang_flags:a %py3_shebang_flags} -> nothing

But this does not:

%global py3_shebang_flags %{nil} %{?py3_shebang_flags:a %py3_shebang_flags} -> a

If not, we'll advise the users to undefine when they want "empty flags".