Compile modules that are needed by template haskell, even with -fno-code.
This patch relates to Trac Trac #8025
The goal here is to enable typechecking of packages that contain some
template haskell. Prior to this patch, compilation of a package with
-fno-code would fail if any functions in the package were called from
within a splice.
downsweep is changed to do an additional pass over the modules,
targetting any ModSummaries transitively depended on by a module that
has LangExt.TemplateHaskell enabled. Those targeted modules have
hscTarget changed from HscNothing to the default target of the platform.
There is a small change to the prevailing_target logic to enable this.
A simple test is added.
I have benchmarked with and without a patched haddock
lation). Running cabal haddock on the wreq package results in a 25%
speedup on my machine:
time output from patched cabal haddock:
time output from unpatched cabal haddock:
Reviewers: austin, bgamari, ezyang
Reviewed By: bgamari
Subscribers: bgamari, DanielG, rwbarton, thomie
GHC Trac Issues: Trac #8025
Differential Revision: https://phabricator.haskell.org/D3441