imp: show a clearer error message on unicode en/decoding failures [#73]
A very long-awaited improvement: for unicode exceptions, and I/O exceptions which look like they were caused by a unicode error (usually text decoding failure), our error message now includes an explanation and advice on what to do. Currently this uses the GHC.IO.Encoding API, which is not ideal: "The API of this module is unstable and not meant to be consumed by the general public. If you absolutely must depend on it, make sure to use a tight upper bound, e.g., base < 4.X rather than base < 5, because the interface can change rapidly without much warning." Also it relies on scanning for patterns in GHC's various unicode-related error messages, which may not be complete and could change in future. To do: try the encoding package's IO helpers, perhaps they give more specific exceptions.
This commit is contained in:
Simon Michael
parent
06cd0f9472
commit
45d5fd7963
@ -131,6 +131,7 @@ import Data.List hiding (uncons)
|
||||
import Data.Maybe (isJust, catMaybes)
|
||||
import Data.Ord (comparing, Down (Down))
|
||||
import qualified Data.Text as T
|
||||
import Data.Text.Encoding.Error (UnicodeException)
|
||||
import qualified Data.Text.IO as T
|
||||
import qualified Data.Text.Lazy as TL
|
||||
import qualified Data.Text.Lazy.Builder as TB
|
||||
@ -139,6 +140,7 @@ import Data.Time.LocalTime (LocalTime, ZonedTime, getCurrentTimeZone,
|
||||
import Data.Word (Word16)
|
||||
import Debug.Trace
|
||||
import Foreign.C.Error (Errno(..), ePIPE)
|
||||
import GHC.IO.Encoding (getLocaleEncoding, textEncodingName)
|
||||
import GHC.IO.Exception (IOException(..), IOErrorType (ResourceVanished))
|
||||
import Language.Haskell.TH.Syntax (Q, Exp)
|
||||
import Safe (headMay, maximumDef)
|
||||
@ -159,7 +161,6 @@ import Text.Pretty.Simple (CheckColorTty(..), OutputOptions(..), defau
|
||||
import Hledger.Utils.Text (WideBuilder(WideBuilder))
|
||||
|
||||
|
||||
|
||||
-- Pretty showing/printing
|
||||
-- using pretty-simple
|
||||
|
||||
@ -236,48 +237,120 @@ ansiFormatWarning = (<> sgrresetall) . ((sgrbrightyellow <> sgrbold) <>)
|
||||
modifyFirstLine :: (String -> String) -> String -> String
|
||||
modifyFirstLine f s = intercalate "\n" $ map f l <> ls where (l,ls) = splitAt 1 $ lines s -- total
|
||||
|
||||
-- | This wraps a program's main routine, to handle program-terminating exceptions
|
||||
-- in a consistent compiler-independent way.
|
||||
-- In particular it catches @error'@/@error@/@errorWithoutStackTrace@ calls and IO errors,
|
||||
-- strips any outer whitespace from their output, and passes this to exitWithErrorMsg.
|
||||
-- This prevents GHC 9.10's trailing newlines and GHC 9.12's "uncaught exception" output,
|
||||
-- while exitWithErrorMsg ensures a consistent prefix, and styles the first line if allowed.
|
||||
--
|
||||
-- Some program-terminating exceptions this does not handle:
|
||||
-- ExitCode (triggered by a call to exitSuccess, exitFailure, or exitWith)
|
||||
-- and UserInterrupt (triggered by control-C).
|
||||
--
|
||||
[Handler (\(e::ErrorCall) -> exitWithError $ rstrip $ show e)
|
||||
,Handler (\(e::IOError) -> exitWithError $ rstrip $ show e)
|
||||
-- ,Handler (\(x::ExitCode) -> exitWith x) -- falls through
|
||||
-- ,Handler (\UserInterrupt -> exitFailure) -- falls through
|
||||
]
|
||||
where
|
||||
rstrip = reverse . dropWhile isSpace . reverse
|
||||
|
||||
-- | Print an error message with printError,
|
||||
-- then exit the program with a non-zero exit code.
|
||||
|
||||
-- | Print an error message to stderr,
|
||||
-- with a standard program name prefix,
|
||||
-- and styling the first line with ansiFormatError if that's allowed.
|
||||
{- | Print an error message to stderr, with a consistent "programname: " prefix,
|
||||
and applying ANSI styling (bold bright red) to the first line if that is supported and allowed.
|
||||
-}
|
||||
printError :: String -> IO ()
|
||||
printError msg = do
|
||||
progname <- getProgName
|
||||
usecolor <- useColorOnStderr
|
||||
let
|
||||
style = if usecolor then modifyFirstLine ansiFormatError else id
|
||||
prefix = progname <> ": "
|
||||
-- error' prepends an "Error: " prefix. But that seems to have been removed when I catch the ErrorCall exception - unless I'm running in GHCI.
|
||||
-- Is it possible something in GHC or base is removing it ?
|
||||
-- Use a stupid heuristic for now: add it again unless already there.
|
||||
<> (if "Error:" `isPrefixOf` msg then "" else "Error: ")
|
||||
prefix =
|
||||
progname
|
||||
<> ": "
|
||||
-- error' prepends an "Error: " prefix. But that seems to have been removed when I catch the ErrorCall exception - unless I'm running in GHCI.
|
||||
-- Is it possible something in GHC or base is removing it ?
|
||||
-- Use a stupid heuristic for now: add it again unless already there.
|
||||
<> (if "Error:" `isPrefixOf` msg then "" else "Error: ")
|
||||
hPutStrLn stderr $ style $ prefix <> msg
|
||||
|
||||
{- | Print an error message with printError,
|
||||
then exit the program with a non-zero exit code.
|
||||
-}
|
||||
exitWithErrorMessage :: String -> IO ()
|
||||
exitWithErrorMessage msg = printError msg >> exitFailure
|
||||
|
||||
-- | This wraps a program's main routine so as to display more consistent
|
||||
-- and useful error output for some common program-terminating exceptions,
|
||||
-- independent of compiler version. It catches:
|
||||
--
|
||||
-- - UnicodeException - unicode errors in pure code
|
||||
--
|
||||
-- - IOException AKA IOError - I/O errors, including unicode errors during I/O
|
||||
--
|
||||
-- - ErrorCall - @error@ / @errorWithoutStackTrace@ calls
|
||||
--
|
||||
-- and:
|
||||
--
|
||||
-- - removes the trailing newlines added by some GHC 9.10.*
|
||||
--
|
||||
-- - removes "uncaught exception" output added by some GHC 9.12.*
|
||||
--
|
||||
-- - ensures a consistent "programname: " prefix
|
||||
--
|
||||
-- - applies ANSI styling (bold bright red) to the first line if that is supported and allowed
|
||||
--
|
||||
-- - for unicode exceptions, and I/O exceptions which look like they were
|
||||
-- caused by a unicode error (usually text decoding failure),
|
||||
-- it adds (english) text explaining the problem and what to do.
|
||||
--
|
||||
-- Some exceptions this does not handle:
|
||||
-- ExitCode (exitSuccess / exitFailure / exitWith calls)
|
||||
-- and UserInterrupt (control-C).
|
||||
--
|
||||
exitOnError :: IO () -> IO ()
|
||||
exitOnError = flip catches
|
||||
[Handler (\(e::UnicodeException) -> exitUnicode e)
|
||||
,Handler (\(e::IOException) -> if isUnicodeError e then exitUnicode e else exitOther e)
|
||||
,Handler (\(e::ErrorCall) -> exitOther e)
|
||||
]
|
||||
|
||||
where
|
||||
isUnicodeError :: Exception e => e -> Bool
|
||||
isUnicodeError ex = any (`isInfixOf` msg) unicodeerrorpatterns
|
||||
where
|
||||
msg = map toLower $ show ex
|
||||
unicodeerrorpatterns = [ -- keep updated
|
||||
"illegal byte sequence"
|
||||
, "invalid byte sequence"
|
||||
, "invalid character"
|
||||
, "invalid or incomplete multibyte"
|
||||
, "mkTextEncoding: invalid argument"
|
||||
]
|
||||
|
||||
exitUnicode :: Exception e => e -> IO ()
|
||||
exitUnicode ex = do
|
||||
enc <- getSystemEncoding
|
||||
let
|
||||
noencoding = map toLower enc == "ascii"
|
||||
msg = unlines $ [
|
||||
rstrip $ show ex
|
||||
, "Some text could not be decoded/encoded with the system text encoding: " <> enc
|
||||
] ++
|
||||
if noencoding
|
||||
then [
|
||||
"Please configure a system locale with a text encoding to handle non-ascii text"
|
||||
]
|
||||
else [
|
||||
-- advice suitable for programs which always use the system text encoding:
|
||||
"Please convert all data to the system encoding (eg with iconv),"
|
||||
, "or configure the system encoding to match your data (eg by setting LANG)."
|
||||
]
|
||||
exitWithErrorMessage msg
|
||||
|
||||
exitOther :: Exception e => e -> IO ()
|
||||
exitOther = exitWithErrorMessage . rstrip . show
|
||||
|
||||
rstrip = reverse . dropWhile isSpace . reverse
|
||||
|
||||
-- I18n
|
||||
|
||||
-- encoding has a similar getSystemEncoding :: IO (Maybe DynEncoding)
|
||||
-- but it returns Nothing on Windows or if there's an error.
|
||||
|
||||
-- | Get the name of the text encoding used by the current locale, using GHC's API.
|
||||
getSystemEncoding :: IO String
|
||||
getSystemEncoding = do
|
||||
localeEncoding <- getLocaleEncoding
|
||||
return $ textEncodingName localeEncoding
|
||||
|
||||
-- -- | Get the name of the text encoding currently configured for stdout, using GHC's API.
|
||||
-- getStdoutEncoding :: IO (Maybe String)
|
||||
-- getStdoutEncoding = do
|
||||
-- mEncoding <- hGetEncoding stdout
|
||||
-- return $ fmap textEncodingName mEncoding
|
||||
|
||||
-- Time
|
||||
|
||||
getCurrentLocalTime :: IO LocalTime
|
||||
|
||||
Loading…
Reference in New Issue
Block a user