LaTeX reader: better handling of colwidths.

Previously the parser just failed if the column width
specified in `p{}` wasn't a multiple of `\linewidth`.
This led to cases where content was skipped.
Now we treat these as ColWidthDefault and silently
parse the table.

A future improvement could be to guess relative column
widths from the dimensions specified, based on a default
line width.

Closes #9579.

src/Text/Pandoc/Readers/LaTeX/Table.hs

@@ -87,11 +87,12 @@ parseAligns = try $ do
   let alignPrefix = symbol '>' >> braced
   let alignSuffix = symbol '<' >> braced
   let colWidth = try $ do
-        symbol '{'
-        ds <- trim . untokenize <$> manyTill anyTok (controlSeq "linewidth")
-        spaces
-        symbol '}'
-        return $ safeRead ds
+        ts <- braced
+        let isLinewidth (Tok _ (CtrlSeq "linewidth") _) = True
+            isLinewidth _ = False
+        case break isLinewidth ts of
+          (ds, _:_) -> return $ safeRead $ trim $ untokenize ds
+          _ -> return Nothing
   let alignSpec = do
         pref <- option [] alignPrefix
         spaces

test/command/9579.md

@@ -0,0 +1,46 @@
+```
+% pandoc -t native
+\begin{tabular}{p{2in}}
+\end{tabular}
+
+# Test
+
+\begin{tabular}{p{2\linewidth}}
+\end{tabular}
+^D
+[ RawBlock
+    (Format "tex") "\\begin{tabular}{p{2in}}\n\\end{tabular}"
+, Header 1 ( "test" , [] , [] ) [ Str "Test" ]
+, RawBlock
+    (Format "tex")
+    "\\begin{tabular}{p{2\\linewidth}}\n\\end{tabular}"
+]
+```
+
+```
+% pandoc -f latex -t native
+\begin{tabular}{p{2in}}
+\end{tabular}
+
+Test
+
+\begin{tabular}{p{2\linewidth}}
+\end{tabular}
+^D
+[ Table
+    ( "" , [] , [] )
+    (Caption Nothing [])
+    [ ( AlignLeft , ColWidthDefault ) ]
+    (TableHead ( "" , [] , [] ) [])
+    [ TableBody ( "" , [] , [] ) (RowHeadColumns 0) [] [] ]
+    (TableFoot ( "" , [] , [] ) [])
+, Para [ Str "Test" ]
+, Table
+    ( "" , [] , [] )
+    (Caption Nothing [])
+    [ ( AlignLeft , ColWidth 2.0 ) ]
+    (TableHead ( "" , [] , [] ) [])
+    [ TableBody ( "" , [] , [] ) (RowHeadColumns 0) [] [] ]
+    (TableFoot ( "" , [] , [] ) [])
+]
+```