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| author | Sasa Bogicevic <t4nt0r@protonmail.com> | 2018-10-15 13:47:48 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-10-15 17:41:48 -0400 |
| commit | 0b0cb484eb0b51bf5485dfadff7cd8a079ceb16e (patch) | |
| tree | 8ae642d14e0970391bf713c2a400061f45bd3c04 /compiler | |
| parent | 846fe90464a1916df4ea72659255963a596eec84 (diff) | |
| download | haskell-0b0cb484eb0b51bf5485dfadff7cd8a079ceb16e.tar.gz | |
Surprising error message with bang pattern
Reviewers: bgamari, alanz
Reviewed By: bgamari
Subscribers: sgraf, mpickering, rwbarton, thomie, carter
GHC Trac Issues: #13600
Differential Revision: https://phabricator.haskell.org/D5040
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/main/DynFlags.hs | 5 | ||||
| -rw-r--r-- | compiler/parser/Parser.y | 27 |
2 files changed, 28 insertions, 4 deletions
diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs index 3a14b29806..8cc360fce2 100644 --- a/compiler/main/DynFlags.hs +++ b/compiler/main/DynFlags.hs @@ -816,6 +816,7 @@ data WarningFlag = | Opt_WarnStarIsType -- Since 8.6 | Opt_WarnStarBinder -- Since 8.6 | Opt_WarnImplicitKindVars -- Since 8.6 + | Opt_WarnSpaceAfterBang deriving (Eq, Show, Enum) data Language = Haskell98 | Haskell2010 @@ -3866,6 +3867,7 @@ wWarningFlagsDeps = [ flagSpec "unrecognised-warning-flags" Opt_WarnUnrecognisedWarningFlags, flagSpec "star-binder" Opt_WarnStarBinder, flagSpec "star-is-type" Opt_WarnStarIsType, + flagSpec "missing-space-after-bang" Opt_WarnSpaceAfterBang, flagSpec "partial-fields" Opt_WarnPartialFields ] -- | These @-\<blah\>@ flags can all be reversed with @-no-\<blah\>@ @@ -4564,7 +4566,8 @@ standardWarnings -- see Note [Documenting warning flags] Opt_WarnUnrecognisedWarningFlags, Opt_WarnSimplifiableClassConstraints, Opt_WarnStarBinder, - Opt_WarnInaccessibleCode + Opt_WarnInaccessibleCode, + Opt_WarnSpaceAfterBang ] -- | Things you get with -W diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y index 74db997bbb..d7aef8d77f 100644 --- a/compiler/parser/Parser.y +++ b/compiler/parser/Parser.y @@ -29,7 +29,7 @@ module Parser (parseModule, parseSignature, parseImport, parseStatement, parseBa parseType, parseHeader) where -- base -import Control.Monad ( unless, liftM ) +import Control.Monad ( unless, liftM, when ) import GHC.Exts import Data.Char import Control.Monad ( mplus ) @@ -2483,8 +2483,14 @@ infixexp :: { LHsExpr GhcPs } infixexp_top :: { LHsExpr GhcPs } : exp10_top { $1 } | infixexp_top qop exp10_top - {% ams (sLL $1 $> (OpApp noExt $1 $2 $3)) - [mj AnnVal $2] } + {% do { when (srcSpanEnd (getLoc $2) + == srcSpanStart (getLoc $3) + && checkIfBang $2) $ + warnSpaceAfterBang (comb2 $2 $3); + ams (sLL $1 $> (OpApp noExt $1 $2 $3)) + [mj AnnVal $2] + } + } exp10_top :: { LHsExpr GhcPs } @@ -3705,6 +3711,21 @@ hintExplicitForall' span = do , text "extension to enable explicit-forall syntax: forall <tvs>. <type>" ] +checkIfBang :: LHsExpr GhcPs -> Bool +checkIfBang (L _ (HsVar _ (L _ op))) = op == bang_RDR +checkIfBang _ = False + +-- | Warn about missing space after bang +warnSpaceAfterBang :: SrcSpan -> P () +warnSpaceAfterBang span = do + bang_on <- extension bangPatEnabled + unless bang_on $ + addWarning Opt_WarnSpaceAfterBang span msg + where + msg = text "Did you forget to enable BangPatterns?" $$ + text "If you mean to bind (!) then perhaps you want" $$ + text "to add a space after the bang for clarity." + -- When two single quotes don't followed by tyvar or gtycon, we report the -- error as empty character literal, or TH quote that missing proper type -- variable or constructor. See Trac #13450. |