LaTeX writer: Protect VERB in caption (#11139)

Also apply hlint suggestions for fewer imports and
moving brackets to avoid $.

src/Text/Pandoc/Writers/LaTeX.hs

@@ -32,7 +32,7 @@ import Control.Monad
       unless )
 import Crypto.Hash (hashWith, MD5(MD5))
 import Data.Containers.ListUtils (nubOrd)
-import Data.Char (isDigit, isAscii)
+import Data.Char (isDigit, isAscii, isLetter)
 import Data.List (intersperse, (\\))
 import Data.Maybe (catMaybes, fromMaybe, isJust, mapMaybe, isNothing)
 import Data.Monoid (Any (..))
@@ -68,7 +68,6 @@ import Text.Pandoc.Writers.Shared
 import qualified Data.Attoparsec.Text as A
 import qualified Text.Pandoc.UTF8 as UTF8
 import qualified Text.Pandoc.Writers.AnnotatedTable as Ann
-import Data.Char (isLetter)
 import Control.Applicative ((<|>))
 
 -- Work around problems with notes inside emphasis (see #8982)
@@ -677,7 +676,7 @@ blockToLaTeX (Figure (ident, _, kvs) captnode body) = do
       , stSubfigure = stSubfigure st || isSubfigure
       }
 
-  let containsTable = getAny . (query $ \case
+  let containsTable = getAny . query (\case
         Table {}  -> Any True
         _         -> Any False)
   st <- get
@@ -948,6 +947,7 @@ inlineToLaTeX (Code (_,classes,kvs) str) = do
   inHeading <- gets stInHeading
   inItem <- gets stInItem
   inSoul <- gets stInSoulCommand
+  inCaption <- gets stInCaption
   let listingsCode = do
         let listingsopts = (case getListingsLanguage classes of
                                 Just l  -> (("language", mbBraced l):)
@@ -1000,7 +1000,14 @@ inlineToLaTeX (Code (_,classes,kvs) str) = do
   -- (see #1294). with regular texttt we don't get an error, but we get
   -- incorrect results if there is a space (see #5529).
   let inMbox x = "\\mbox" <> braces x
-  (if inSoul then inMbox else id) <$>
+
+  -- for captions we need to protect VERB with \protect (see #6821)
+  let protect x = "\\protect" <> x
+
+  let optionalProtect = case () of _ | inSoul -> inMbox
+                                     | inCaption -> protect
+                                     | otherwise -> id
+  optionalProtect <$>
    case writerHighlightMethod opts of
      _ | inHeading || inItem  -> rawCode  -- see #5574
      IdiomaticHighlighting    -> listingsCode

src/Text/Pandoc/Writers/LaTeX/Caption.hs

@@ -23,7 +23,7 @@ import Text.Pandoc.Shared
 import Text.Pandoc.Walk
 import Text.Pandoc.Writers.LaTeX.Notes (notesToLaTeX)
 import Text.Pandoc.Writers.LaTeX.Types
-  ( LW, WriterState (stExternalNotes, stNotes) )
+  ( LW, WriterState (stExternalNotes, stNotes, stInCaption) )
 
 
 -- | Produces the components of a LaTeX 'caption' command. Returns a triple
@@ -35,6 +35,7 @@ getCaption :: PandocMonad m
            -> Caption
            -> LW m (Doc Text, Doc Text, Doc Text)
 getCaption inlineListToLaTeX externalNotes (Caption maybeShort long) = do
+  modify $ \st -> st{ stInCaption = True }
   let long' = blocksToInlines long
   oldExternalNotes <- gets stExternalNotes
   modify $ \st -> st{ stExternalNotes = externalNotes, stNotes = [] }
@@ -53,4 +54,5 @@ getCaption inlineListToLaTeX externalNotes (Caption maybeShort long) = do
                              then toShortCapt long'
                              else return empty
                   Just short -> toShortCapt short
+  modify $ \st -> st{ stInCaption = False }
   return (capt, captForLof, footnotes)

src/Text/Pandoc/Writers/LaTeX/Types.hs

@@ -54,6 +54,7 @@ data WriterState =
   , stLang          :: Maybe Lang    -- ^ lang specified in metadata
   , stInSoulCommand :: Bool          -- ^ in a soul command like ul
   , stCancel        :: Bool          -- ^ true if document uses \cancel
+  , stInCaption     :: Bool          -- ^ true if in a caption
   }
 
 startingState :: WriterOptions -> WriterState
@@ -95,4 +96,5 @@ startingState options =
   , stLang = Nothing
   , stInSoulCommand = False
   , stCancel = False
+  , stInCaption = False
   }

test/command/6821.md

@@ -0,0 +1,80 @@
+```
+% pandoc -f native -t latex
+[ Para [ Code ( "" , [ "python" ] , [] ) "x = 5" ]
+, Figure
+    ( "" , [] , [] )
+    (Caption
+       Nothing
+       [ Plain
+           [ Str "This"
+           , Space
+           , Str "is"
+           , Space
+           , Str "a"
+           , Space
+           , Str "test"
+           , Space
+           , Code ( "" , [ "python" ] , [] ) "x = 5"
+           ]
+       ])
+    [ Plain
+        [ Image
+            ( "" , [] , [] )
+            [ Str "This"
+            , Space
+            , Str "is"
+            , Space
+            , Str "a"
+            , Space
+            , Str "test"
+            , Space
+            , Code ( "" , [ "python" ] , [] ) "x = 5"
+            ]
+            ( "test.png" , "" )
+        ]
+    ]
+, Table
+    ( "" , [] , [] )
+    (Caption
+       Nothing
+       [ Plain [ Code ( "" , [ "cpp" ] , [] ) "caption" ] ])
+    [ ( AlignDefault , ColWidthDefault ) ]
+    (TableHead ( "" , [] , [] ) [])
+    [ TableBody ( "" , [] , [] ) (RowHeadColumns 0) [] [] ]
+    (TableFoot
+       ( "" , [] , [] )
+       [ Row
+           ( "" , [] , [] )
+           [ Cell
+               ( "" , [] , [] )
+               AlignDefault
+               (RowSpan 1)
+               (ColSpan 1)
+               [ Plain [ Str "A" ] ]
+           ]
+       ])
+, Para [ Code ( "" , [ "cpp" ] , [] ) "caption" ]
+]
+^D
+\VERB|\NormalTok{x }\OperatorTok{=} \DecValTok{5}|
+
+\begin{figure}
+\centering
+\pandocbounded{\includegraphics[keepaspectratio,alt={This is a test x = 5}]{test.png}}
+\caption{This is a test
+\protect\VERB|\NormalTok{x }\OperatorTok{=} \DecValTok{5}|}
+\end{figure}
+
+\begin{longtable}[]{@{}l@{}}
+\caption{\protect\VERB|\NormalTok{caption}|}\tabularnewline
+\toprule\noalign{}
+\endfirsthead
+\endhead
+\midrule\noalign{}
+A \\
+\bottomrule\noalign{}
+\endlastfoot
+\end{longtable}
+
+\VERB|\NormalTok{caption}|
+```