[Pkg-haskell-maintainers] Bug#789104: FTBFS: Constructor ‘L.PatBind’ should have 4 arguments, but has been given 5

[Chris West (Faux)]

Package: hothasktags
Version: 0.3.2
Severity: serious
Tags: sid stretch
Justification: fails to build from source (but built successfully in the past)

Dear Maintainer,

The package fails to build:
Preprocessing executable 'hothasktags' for hothasktags-0.3.2...
[1 of 1] Compiling Main             ( Main.hs, dist/build/hothasktags/hothasktags-tmp/Main.o )

Main.hs:33:14:
    Constructor ‘L.PatBind’ should have 4 arguments, but has been given 5
    In the pattern: L.PatBind _ pat _ _ _
    In an equation for ‘extract’:
        extract (L.PatBind _ pat _ _ _) = extractPat pat
    In an equation for ‘localDecls’:
        localDecls (L.Module _ _ _ _ decls)
[...]

.... and many other similar errors for L.DHead, L.GadtDecl, L.EVar, etc.

The full build log can be seen on the Reproducible Builds builder:
https://reproducible.debian.net/rb-pkg/unstable/amd64/hothasktags.html

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 3.19.0-20-generic (SMP w/8 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)