Error messages: Tweak how parse errors from parsec parser are displayed

* Error messages are indented by 2 spaces
* 0:0 positions are never shown
* More attempts are made to remove extra newlines.

Author: mpickering

cabal-install/src/Distribution/Client/Errors/Parser.hs

@@ -154,7 +154,7 @@ renderInstalledPackageInfoSourceMsgs PInstalledPackageInfo (errors, warnings) =
 
 renderParseErrorNoFile :: String -> [PError] -> [PWarning] -> String
 renderParseErrorNoFile herald errors warnings =
-  renderParseErrorGeneral herald "" Nothing (const []) errors warnings
+  renderParseErrorGeneral herald Nothing Nothing (const []) errors warnings
 
 -- | Render a parse error which resulted from a file on disk
 renderParseErrorFile
@@ -169,7 +169,7 @@ renderParseErrorFile
   -> ([PError], [PWarning])
   -> String
 renderParseErrorFile herald filepath provenance contents (errors, warnings) =
-  renderParseErrorGeneral (herald <> " file " <> filepath) (filepath' <> ":") provenance formatInput errors warnings
+  renderParseErrorGeneral (herald <> " file " <> filepath) (Just (filepath' <> ":")) provenance formatInput errors warnings
   where
     filepath' = normalise filepath
 
@@ -217,20 +217,25 @@ renderParseErrorFile herald filepath provenance contents (errors, warnings) =
 -- | A generic rendering function which can render from many sources.
 renderParseErrorGeneral
   :: String
-  -> String
+  -- ^ What we were parsing when the error occurred.
+  -> Maybe String
+  -- ^ A simpler/shorter header to display when displaying each error (normally a filepath)
   -> Maybe String
+  -- ^ Provenance, used to print additional context about what file failed (used to print the import path of a project
+  -- file which failed to parse)
   -> (Position -> [String])
   -- ^ Extra information to render based on the position
   -> [PError]
   -> [PWarning]
   -> String
 renderParseErrorGeneral header err_header provenance extra_info errors warnings =
   unlines $
-    [ warningsOrErrors <> " encountered when parsing" <> header' <> ":"
+    [ warningsOrErrors <> " parsing" <> header' <> ":"
     ]
       ++ [p | Just p <- [provenance]]
-      ++ renderedErrors
-      ++ renderedWarnings
+      ++ [""] -- Place a newline between the header and the errors/warnings
+      -- Place a newline between each error and warning
+      ++ intersperse "" (renderedWarnings ++ renderedErrors)
   where
     warningsOrErrors = case errors of
       [] -> case warnings of
@@ -241,24 +246,36 @@ renderParseErrorGeneral header err_header provenance extra_info errors warnings
 
     header' = if null header then "" else (" " <> header)
 
-    renderedErrors = concatMap renderError (sortBy (comparing perrorPosition) errors)
-    renderedWarnings = concatMap renderWarning (sortBy (comparing pwarningPosition) warnings)
+    renderedErrors = map renderError (sortBy (comparing perrorPosition) errors)
+    renderedWarnings = map renderWarning (sortBy (comparing pwarningPosition) warnings)
 
-    renderError :: PError -> [String]
-    renderError (PError pos msg)
+    renderErrorOrWarning :: String -> Position -> String -> String
+    renderErrorOrWarning err_type pos msg
       -- if position is 0:0, then it doesn't make sense to show input
       -- looks like, Parsec errors have line-feed in them
-      | pos == zeroPos = msgs
-      | otherwise = msgs ++ extra_info pos
-      where
-        msgs = ["", err_header ++ showPos pos ++ ": error:", trimLF msg, ""]
-
-    renderWarning :: PWarning -> [String]
-    renderWarning (PWarning _ pos msg)
-      | pos == zeroPos = msgs
-      | otherwise = msgs ++ extra_info pos
+      | pos == zeroPos = unlines (herald : map indent user_msg)
+      | otherwise = unlines (herald : map indent (user_msg ++ extra_info pos))
       where
-        msgs = ["", err_header ++ showPos pos ++ ": warning:", trimLF msg, ""]
+        herald = renderErrorHerald pos ++ err_type ++ ":"
+        user_msg = lines (trimLF msg)
+
+    indent :: String -> String
+    indent s = replicate 2 ' ' ++ s
+
+    -- Don't render the 0:0 position
+    renderErrorHerald :: Position -> String
+    renderErrorHerald pos =
+      case (err_header, pos == zeroPos) of
+        (Nothing, True) -> ""
+        (Nothing, False) -> showPos pos ++ ": "
+        (Just herald, True) -> herald ++ " "
+        (Just herald, False) -> herald ++ showPos pos ++ ": "
+
+    renderError :: PError -> String
+    renderError (PError pos msg) = renderErrorOrWarning "error" pos msg
+
+    renderWarning :: PWarning -> String
+    renderWarning (PWarning _ pos msg) = renderErrorOrWarning "warning" pos msg
 
     -- sometimes there are (especially trailing) newlines.
     trimLF :: String -> String

cabal-install/src/Distribution/Client/ProjectFlags.hs

@@ -59,8 +59,7 @@ defaultProjectFlags =
     { flagProjectDir = mempty
     , flagProjectFile = mempty
     , flagIgnoreProject = toFlag False
-    , -- Should we use 'Last' here?
-      flagProjectFileParser = mempty
+    , flagProjectFileParser = mempty
     }
 
 projectFlagsOptions :: ShowOrParseArgs -> [OptionField ProjectFlags]

cabal-testsuite/PackageTests/Check/ConfiguredPackage/Sanity/NoName/cabal.out

@@ -1,8 +1,8 @@
 # cabal check
 Error: [Cabal-7035]
-Error encountered when parsing cabal file pkg.cabal:
+Error parsing cabal file pkg.cabal:
 
-pkg.cabal:0:0: error:
-"name" field missing
+pkg.cabal: error:
+  "name" field missing
 
 

cabal-testsuite/PackageTests/Check/ConfiguredPackage/Sanity/NoVersion/cabal.out

@@ -1,8 +1,8 @@
 # cabal check
 Error: [Cabal-7035]
-Error encountered when parsing cabal file pkg.cabal:
+Error parsing cabal file pkg.cabal:
 
-pkg.cabal:0:0: error:
-"version" field missing
+pkg.cabal: error:
+  "version" field missing
 
 

cabal-testsuite/PackageTests/ConditionalAndImport/cabal.out

@@ -13,98 +13,98 @@ Warning: The directory <ROOT>/cabal.dist/home/.cabal/store/ghc-<GHCVER>/incoming
 # checking cyclical loopback of a project importing itself
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file cyclical-0-self.project:
+Error parsing project file cyclical-0-self.project:
 
 cyclical-0-self.project:3:1: error:
-cyclical import of cyclical-0-self.project;
-  cyclical-0-self.project
-    imported by: cyclical-0-self.project
+  cyclical import of cyclical-0-self.project;
+    cyclical-0-self.project
+      imported by: cyclical-0-self.project
+      1 | packages: .
+      2 | 
+      3 | import: cyclical-0-self.project
+        | ^
 
-    1 | packages: .
-    2 | 
-    3 | import: cyclical-0-self.project
-      | ^
 
 # checking cyclical with hops; out and back
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file cyclical-1-out-back.config:
+Error parsing project file cyclical-1-out-back.config:
   imported by: cyclical-1-out-back.project
 
 cyclical-1-out-back.config:1:1: error:
-cyclical import of cyclical-1-out-back.project;
-  cyclical-1-out-back.project
-    imported by: cyclical-1-out-back.config
-    imported by: cyclical-1-out-back.project
+  cyclical import of cyclical-1-out-back.project;
+    cyclical-1-out-back.project
+      imported by: cyclical-1-out-back.config
+      imported by: cyclical-1-out-back.project
+      1 | import: cyclical-1-out-back.project
+        | ^
 
-    1 | import: cyclical-1-out-back.project
-      | ^
 
 # checking cyclical with hops; out to a config that imports itself
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file cyclical-1-out-self.config:
+Error parsing project file cyclical-1-out-self.config:
   imported by: cyclical-1-out-self.project
 
 cyclical-1-out-self.config:1:1: error:
-cyclical import of cyclical-1-out-self.config;
-  cyclical-1-out-self.config
-    imported by: cyclical-1-out-self.config
-    imported by: cyclical-1-out-self.project
+  cyclical import of cyclical-1-out-self.config;
+    cyclical-1-out-self.config
+      imported by: cyclical-1-out-self.config
+      imported by: cyclical-1-out-self.project
+      1 | import: cyclical-1-out-self.config
+        | ^
 
-    1 | import: cyclical-1-out-self.config
-      | ^
 
 # checking cyclical with hops; out, out, twice back
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file cyclical-2-out-out-backback-b.config:
+Error parsing project file cyclical-2-out-out-backback-b.config:
   imported by: cyclical-2-out-out-backback-a.config
   imported by: cyclical-2-out-out-backback.project
 
 cyclical-2-out-out-backback-b.config:1:1: error:
-cyclical import of cyclical-2-out-out-backback.project;
-  cyclical-2-out-out-backback.project
-    imported by: cyclical-2-out-out-backback-b.config
-    imported by: cyclical-2-out-out-backback-a.config
-    imported by: cyclical-2-out-out-backback.project
+  cyclical import of cyclical-2-out-out-backback.project;
+    cyclical-2-out-out-backback.project
+      imported by: cyclical-2-out-out-backback-b.config
+      imported by: cyclical-2-out-out-backback-a.config
+      imported by: cyclical-2-out-out-backback.project
+      1 | import: cyclical-2-out-out-backback.project
+        | ^
 
-    1 | import: cyclical-2-out-out-backback.project
-      | ^
 
 # checking cyclical with hops; out, out, once back
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file cyclical-2-out-out-back-b.config:
+Error parsing project file cyclical-2-out-out-back-b.config:
   imported by: cyclical-2-out-out-back-a.config
   imported by: cyclical-2-out-out-back.project
 
 cyclical-2-out-out-back-b.config:1:1: error:
-cyclical import of cyclical-2-out-out-back-a.config;
-  cyclical-2-out-out-back-a.config
-    imported by: cyclical-2-out-out-back-b.config
-    imported by: cyclical-2-out-out-back-a.config
-    imported by: cyclical-2-out-out-back.project
+  cyclical import of cyclical-2-out-out-back-a.config;
+    cyclical-2-out-out-back-a.config
+      imported by: cyclical-2-out-out-back-b.config
+      imported by: cyclical-2-out-out-back-a.config
+      imported by: cyclical-2-out-out-back.project
+      1 | import: cyclical-2-out-out-back-a.config
+        | ^
 
-    1 | import: cyclical-2-out-out-back-a.config
-      | ^
 
 # checking cyclical with hops; out, out to a config that imports itself
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file cyclical-2-out-out-self-b.config:
+Error parsing project file cyclical-2-out-out-self-b.config:
   imported by: cyclical-2-out-out-self-a.config
   imported by: cyclical-2-out-out-self.project
 
 cyclical-2-out-out-self-b.config:1:1: error:
-cyclical import of cyclical-2-out-out-self-b.config;
-  cyclical-2-out-out-self-b.config
-    imported by: cyclical-2-out-out-self-b.config
-    imported by: cyclical-2-out-out-self-a.config
-    imported by: cyclical-2-out-out-self.project
+  cyclical import of cyclical-2-out-out-self-b.config;
+    cyclical-2-out-out-self-b.config
+      imported by: cyclical-2-out-out-self-b.config
+      imported by: cyclical-2-out-out-self-a.config
+      imported by: cyclical-2-out-out-self.project
+      1 | import: cyclical-2-out-out-self-b.config
+        | ^
 
-    1 | import: cyclical-2-out-out-self-b.config
-      | ^
 
 # checking that cyclical check doesn't false-positive on same file names in different folders; hoping within a folder and then into a subfolder
 # cabal v2-build
@@ -121,53 +121,53 @@ Up to date
 # checking that cyclical check catches a same file name that imports itself
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file same-filename/cyclical-same-filename-out-out-self.config:
+Error parsing project file same-filename/cyclical-same-filename-out-out-self.config:
   imported by: cyclical-same-filename-out-out-self.config
   imported by: cyclical-same-filename-out-out-self.project
 
 same-filename/cyclical-same-filename-out-out-self.config:1:1: error:
-cyclical import of same-filename/cyclical-same-filename-out-out-self.config;
-  same-filename/cyclical-same-filename-out-out-self.config
-    imported by: same-filename/cyclical-same-filename-out-out-self.config
-    imported by: cyclical-same-filename-out-out-self.config
-    imported by: cyclical-same-filename-out-out-self.project
+  cyclical import of same-filename/cyclical-same-filename-out-out-self.config;
+    same-filename/cyclical-same-filename-out-out-self.config
+      imported by: same-filename/cyclical-same-filename-out-out-self.config
+      imported by: cyclical-same-filename-out-out-self.config
+      imported by: cyclical-same-filename-out-out-self.project
+      1 | import: cyclical-same-filename-out-out-self.config
+        | ^
 
-    1 | import: cyclical-same-filename-out-out-self.config
-      | ^
 
 # checking that cyclical check catches importing its importer (with the same file name)
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file same-filename/cyclical-same-filename-out-out-backback.config:
+Error parsing project file same-filename/cyclical-same-filename-out-out-backback.config:
   imported by: cyclical-same-filename-out-out-backback.config
   imported by: cyclical-same-filename-out-out-backback.project
 
 same-filename/cyclical-same-filename-out-out-backback.config:1:1: error:
-cyclical import of cyclical-same-filename-out-out-backback.project;
-  cyclical-same-filename-out-out-backback.project
-    imported by: same-filename/cyclical-same-filename-out-out-backback.config
-    imported by: cyclical-same-filename-out-out-backback.config
-    imported by: cyclical-same-filename-out-out-backback.project
+  cyclical import of cyclical-same-filename-out-out-backback.project;
+    cyclical-same-filename-out-out-backback.project
+      imported by: same-filename/cyclical-same-filename-out-out-backback.config
+      imported by: cyclical-same-filename-out-out-backback.config
+      imported by: cyclical-same-filename-out-out-backback.project
+      1 | import: ../cyclical-same-filename-out-out-backback.project
+        | ^
 
-    1 | import: ../cyclical-same-filename-out-out-backback.project
-      | ^
 
 # checking that cyclical check catches importing its importer's importer (hopping over same file names)
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file same-filename/cyclical-same-filename-out-out-back.config:
+Error parsing project file same-filename/cyclical-same-filename-out-out-back.config:
   imported by: cyclical-same-filename-out-out-back.config
   imported by: cyclical-same-filename-out-out-back.project
 
 same-filename/cyclical-same-filename-out-out-back.config:1:1: error:
-cyclical import of cyclical-same-filename-out-out-back.config;
-  cyclical-same-filename-out-out-back.config
-    imported by: same-filename/cyclical-same-filename-out-out-back.config
-    imported by: cyclical-same-filename-out-out-back.config
-    imported by: cyclical-same-filename-out-out-back.project
+  cyclical import of cyclical-same-filename-out-out-back.config;
+    cyclical-same-filename-out-out-back.config
+      imported by: same-filename/cyclical-same-filename-out-out-back.config
+      imported by: cyclical-same-filename-out-out-back.config
+      imported by: cyclical-same-filename-out-out-back.project
+      1 | import: ../cyclical-same-filename-out-out-back.config
+        | ^
 
-    1 | import: ../cyclical-same-filename-out-out-back.config
-      | ^
 
 # checking that imports work skipping into a subfolder and then back out again and again
 # cabal v2-build
@@ -200,10 +200,10 @@ Up to date
 # checking bad conditional
 # cabal v2-build
 Error: [Cabal-7167]
-Error encountered when parsing project file bad-conditional.project:
+Error parsing project file bad-conditional.project:
 
-bad-conditional.project:0:0: error:
-Cannot set compiler in a conditional clause of a cabal project file
+bad-conditional.project: error:
+  Cannot set compiler in a conditional clause of a cabal project file
 
 
 # checking that missing package message lists configuration provenance