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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2019-06-03 14:46:39 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2019-06-07 10:24:00 -0400 |
| commit | da26ffe795f1861783c1b031ed93f9fa59550f85 (patch) | |
| tree | a19114acaf010962e81bdcd2e49f53a781ce33aa /docs/core-spec | |
| parent | 387050d0e26a9e6466b31c9d8e4e4f6273c64c9e (diff) | |
| download | haskell-da26ffe795f1861783c1b031ed93f9fa59550f85.tar.gz | |
Preserve ShadowInfo when rewriting evidence
When the canonicaliser rewrites evidence of a Wanted, it
should preserve the ShadowInfo (ctev_nosh) field. That is,
a WDerive should rewrite to WDerive, and WOnly to WOnly.
Previously we were unconditionally making a WDeriv, thereby
rewriting WOnly to WDeriv. This bit Nick Frisby (issue #16735)
in the context of his plugin, but we don't have a compact test
case.
The fix is simple, but does involve a bit more plumbing,
to pass the old ShadowInfo around, to use when building
the new Wanted.
Diffstat (limited to 'docs/core-spec')
0 files changed, 0 insertions, 0 deletions