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-rw-r--r--stdlib/source/lux/compiler/default/phase/analysis/case/coverage.lux57
1 files changed, 30 insertions, 27 deletions
diff --git a/stdlib/source/lux/compiler/default/phase/analysis/case/coverage.lux b/stdlib/source/lux/compiler/default/phase/analysis/case/coverage.lux
index 1f90bdcff..cf9abecd4 100644
--- a/stdlib/source/lux/compiler/default/phase/analysis/case/coverage.lux
+++ b/stdlib/source/lux/compiler/default/phase/analysis/case/coverage.lux
@@ -158,8 +158,9 @@
## always be a pattern prior to them that would match the input.
## Because of that, the presence of redundant patterns is assumed to
## be a bug, likely due to programmer carelessness.
-(exception: #export (redundant-pattern)
- "")
+(exception: #export (redundant-pattern {so-far Coverage} {addition Coverage})
+ (ex.report ["Coverage so-far" (%coverage so-far)]
+ ["Coverage addition" (%coverage addition)]))
(def: (flatten-alt coverage)
(-> Coverage (List Coverage))
@@ -214,7 +215,7 @@
(case [addition so-far]
## The addition cannot possibly improve the coverage.
[_ #Exhaustive]
- (ex.throw redundant-pattern [])
+ (ex.throw redundant-pattern [so-far addition])
## The addition completes the coverage.
[#Exhaustive _]
@@ -237,7 +238,7 @@
(ex.throw variants-do-not-match [addition-cases so-far-cases])
(:: (dictionary.Equivalence<Dictionary> Equivalence<Coverage>) = casesSF casesA)
- (ex.throw redundant-pattern [])
+ (ex.throw redundant-pattern [so-far addition])
## else
(do error.Monad<Error>
@@ -252,7 +253,9 @@
#.None
(wrap (dictionary.put tagA coverageA casesSF'))))
casesSF (dictionary.entries casesA))]
- (wrap (if (and (n/= (inc (n/max addition-cases so-far-cases))
+ (wrap (if (and (or (known-cases? addition-cases)
+ (known-cases? so-far-cases))
+ (n/= (inc (n/max addition-cases so-far-cases))
(dictionary.size casesM))
(list.every? exhaustive? (dictionary.values casesM)))
#Exhaustive
@@ -268,7 +271,7 @@
(case [(coverage/= leftSF leftA) (coverage/= rightSF rightA)]
## There is nothing the addition adds to the coverage.
[#1 #1]
- (ex.throw redundant-pattern [])
+ (ex.throw redundant-pattern [so-far addition])
## The 2 sequences cannot possibly be merged.
[#0 #0]
@@ -294,7 +297,7 @@
## The left part will always match, so the addition is redundant.
(^multi [(#Seq left right) single]
(coverage/= left single))
- (ex.throw redundant-pattern [])
+ (ex.throw redundant-pattern [so-far addition])
## The right part is not necessary, since it can always match the left.
(^multi [single (#Seq left right)]
@@ -315,38 +318,38 @@
[#let [fuse-once (: (-> Coverage (List Coverage)
(Error [(Maybe Coverage)
(List Coverage)]))
- (function (_ coverage possibilities)
- (loop [alts possibilities]
- (case alts
+ (function (_ coverageA possibilitiesSF)
+ (loop [altsSF possibilitiesSF]
+ (case altsSF
#.Nil
- (wrap [#.None (list coverage)])
+ (wrap [#.None (list coverageA)])
- (#.Cons alt alts')
- (case (merge coverage alt)
- (#error.Success altM)
- (case altM
+ (#.Cons altSF altsSF')
+ (case (merge coverageA altSF)
+ (#error.Success altMSF)
+ (case altMSF
(#Alt _)
(do @
- [[success alts+] (recur alts')]
- (wrap [success (#.Cons alt alts+)]))
+ [[success altsSF+] (recur altsSF')]
+ (wrap [success (#.Cons altSF altsSF+)]))
_
- (wrap [(#.Some altM) alts']))
+ (wrap [(#.Some altMSF) altsSF']))
(#error.Error error)
(error.fail error))
))))]
- [success possibilities] (fuse-once addition (flatten-alt so-far))]
- (loop [success success
- possibilities possibilities]
- (case success
- (#.Some coverage')
+ [successA possibilitiesSF] (fuse-once addition (flatten-alt so-far))]
+ (loop [successA successA
+ possibilitiesSF possibilitiesSF]
+ (case successA
+ (#.Some coverageA')
(do @
- [[success' possibilities'] (fuse-once coverage' possibilities)]
- (recur success' possibilities'))
+ [[successA' possibilitiesSF'] (fuse-once coverageA' possibilitiesSF)]
+ (recur successA' possibilitiesSF'))
#.None
- (case (list.reverse possibilities)
+ (case (list.reverse possibilitiesSF)
(#.Cons last prevs)
(wrap (list/fold (function (_ left right) (#Alt left right))
last
@@ -358,6 +361,6 @@
_
(if (coverage/= so-far addition)
## The addition cannot possibly improve the coverage.
- (ex.throw redundant-pattern [])
+ (ex.throw redundant-pattern [so-far addition])
## There are now 2 alternative paths.
(error/wrap (#Alt so-far addition)))))