Almost working, but a few unwanted newlines slipped in. Notably, the line break after DESTDIR makes it so that DESTDIR is not applied to a command in the next line.

% rpm -E '%zig_install'

    DESTDIR="/home/alebastr/rpmbuild/BUILDROOT/%{NAME}-%{VERSION}-%{RELEASE}.x86_64"
    /usr/bin/zig \
        build \
        --verbose  \
        --cache-dir zig-cache \
        install \
        --prefix "/usr" \
        --prefix-lib-dir "/usr/lib64" \
        --prefix-exe-dir "/usr/bin" \
        --prefix-include-dir "/usr/include"

Overall, it's not a good practice to start macro with a newline; for example, xvfb-run %zig_test will not do what any experienced packager expects it to do.

Yeah that is known the problem was that the %zig_build macro starts with a newline putting DESTDIR on a new line problem is gonna get fixed on the next release