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| author | Vladislav Zavialov <vlad.z.4096@gmail.com> | 2019-02-05 20:01:36 -0500 |
|---|---|---|
| committer | Ben Gamari <ben@well-typed.com> | 2019-06-03 17:28:12 -0400 |
| commit | 605869c7b776ce6071a31ff447998b081e0354ed (patch) | |
| tree | 276edeca1aa742ae9a92898af7573b36d68b46ee | |
| parent | 334dd6da47326f47ba3425376728feda6245c7c1 (diff) | |
| download | haskell-605869c7b776ce6071a31ff447998b081e0354ed.tar.gz | |
Fix optSemi type in Parser.y
The definition of 'optSemi' claimed it had type
([Located a],Bool)
Note that its production actually returns ([Located Token],Bool):
: ';' { ([$1],True) } -- $1 :: Located Token
Due to an infelicity in the implementation of 'happy -c', it effectively
resulted in 'unsafeCoerce :: Token -> a'.
See https://github.com/simonmar/happy/pull/134
If any consumer of 'optSemi' tried to instantiate 'a' to something not
representationally equal to 'Token', they would experience a segfault.
In addition to that, this definition made it impossible to compile Parser.y
without the -c flag (as it's reliant on this bug to cast 'Token' to 'forall
a. a').
| -rw-r--r-- | compiler/parser/Parser.y | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y index 6c863d5bd6..5b0a3c055a 100644 --- a/compiler/parser/Parser.y +++ b/compiler/parser/Parser.y @@ -1,4 +1,3 @@ - -- -*-haskell-*- -- --------------------------------------------------------------------------- -- (c) The University of Glasgow 1997-2003 @@ -2586,7 +2585,7 @@ exp10 :: { LHsExpr GhcPs } | scc_annot exp {% ams (sLL $1 $> $ HsSCC noExt (snd $ fst $ unLoc $1) (snd $ unLoc $1) $2) (fst $ fst $ unLoc $1) } -optSemi :: { ([Located a],Bool) } +optSemi :: { ([Located Token],Bool) } : ';' { ([$1],True) } | {- empty -} { ([],False) } |