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| author | George Karachalias <george.karachalias@gmail.com> | 2015-12-30 16:09:29 +0100 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2015-12-30 19:35:20 +0100 |
| commit | bb7f2e33197e667eb694bd1243f125c722a0a868 (patch) | |
| tree | 4e8b0c64052ba3da3117169eef4f3bc485408c8c | |
| parent | 947c8a530e2f977f56601289e1b11cde42f95322 (diff) | |
| download | haskell-bb7f2e33197e667eb694bd1243f125c722a0a868.tar.gz | |
Address #11245: Ensure the non-matched list is always non-empty
When there is an uncovered vector of length 0 (which in turn means that
it represents a guard failure) print "(incomplete guards)" instead of an
empty list of non-covered vectors.
Test Plan: validate
Reviewers: austin, bgamari
Reviewed By: bgamari
Subscribers: thomie
Differential Revision: https://phabricator.haskell.org/D1717
GHC Trac Issues: #11245
| -rw-r--r-- | compiler/deSugar/Check.hs | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/compiler/deSugar/Check.hs b/compiler/deSugar/Check.hs index 78a8eaaa6f..fd0c6e0b59 100644 --- a/compiler/deSugar/Check.hs +++ b/compiler/deSugar/Check.hs @@ -1420,9 +1420,11 @@ dsPmWarn dflags ctx@(DsMatchContext kind loc) mPmResult vcat (map (ppr_eqn f kind) (take maximum_output qs)) $$ dots qs pprEqnsU qs = pp_context ctx (ptext (sLit "are non-exhaustive")) $ \_ -> - let us = map ppr_uncovered qs - in hang (ptext (sLit "Patterns not matched:")) 4 - (vcat (take maximum_output us) $$ dots us) + case qs of -- See #11245 + [([],_)] -> ptext (sLit "Guards do not cover entire pattern space") + _missing -> let us = map ppr_uncovered qs + in hang (ptext (sLit "Patterns not matched:")) 4 + (vcat (take maximum_output us) $$ dots us) dots :: [a] -> SDoc dots qs | qs `lengthExceeds` maximum_output = ptext (sLit "...") |