Bug#950217: cjs: please Build-Depend on libgirepository1.0-dev (>= 1.62.0-4~) and libffi-dev (>= 3.3)

[Simon McVittie <smcv@debian.org>]

Source: cjs
Severity: normal
Tags: bullseye sid

During the libffi transition, we've encountered an autopkgtest regression
in pygobject that might also indicate crashes on arm64 in other bindings
that use GObject-Introspection and libffi. The libffi maintainer
recommended that we add some versioned Depends/Breaks to force the right
things to happen. To be safe, cjs should probably do the same.

The libffi6 -> libffi7 transition involves an ABI break on arm64, and
GObject-Introspection exposes libffi data structures in its own API,
which are used by bindings like pygobject and cjs. We've found that in
practice, pygobject crashes on arm64 if either:

(A) gobject-introspection is old (built against libffi6) and pygobject is
    new (built against libffi7), or

(B) gobject-introspection is new (built against libffi7) and pygobject is
    old (built against libffi6)

cjs seems to call into GObject-Introspection's libffi-related APIs, so it
probably has a similar issue, replacing pygobject with cjs.

To prevent broken partial upgrades, please make cjs Build-Depend on
libgirepository1.0-dev (>= 1.62.0-4~) and libffi-dev (>= 3.3); this will
result in a runtime dependency on libgirepository-1.0-0 (>= 1.62.0-4~)
and libffi7, preventing (A). Then we can add a Breaks: libcjs0 (<< x~) in
libgirepository-1.0-0, where x is the version in which you made that
change, to prevent (B).

cjs seems to call ffi_call() from its own source code, so an explicit
Build-Depends on libffi-dev is probably a good idea to have anyway.

Thanks,
    smcv