Include trailing {}s in raw latex commands.

Change is in rawLaTeXInline in LaTeX reader, but
it affects the markdown reader and other readers
that allow raw LaTeX.

Previously, trailing `{}` would be included for
unknown commands, but not for known commands.
However, they are sometimes used to avoid a trailing
space after the command.  The chances that a `{}`
after a LaTeX command is not part of the command
are very small.

Closes #5439.

src/Text/Pandoc/Readers/LaTeX.hs

@@ -155,10 +155,15 @@ rawLaTeXInline :: (PandocMonad m, HasMacros s, HasReaderOptions s)
                => ParserT String s m String
 rawLaTeXInline = do
   lookAhead (try (char '\\' >> letter))
-  snd <$> (  rawLaTeXParser True
+  raw <- snd <$>
+          (   rawLaTeXParser True
               (mempty <$ (controlSeq "input" >> skipMany opt >> braced))
               inlines
-        <|> rawLaTeXParser True (inlineEnvironment <|> inlineCommand') inlines)
+          <|> rawLaTeXParser True (inlineEnvironment <|> inlineCommand')
+              inlines
+          )
+  finalbraces <- mconcat <$> many (try (string "{}")) -- see #5439
+  return $ raw <> finalbraces
 
 inlineCommand :: PandocMonad m => ParserT String ParserState m Inlines
 inlineCommand = do

test/command/5439.md

@@ -0,0 +1,6 @@
+```
+% pandoc -t latex
+namespace\fshyp{}container
+^D
+namespace\fshyp{}container
+```