LaTeX reader: keep ASCII quotes when ligatures are disabled.

Commit 47610fe3d (#10781) disabled the `--`, `---`, and `"` ligatures
inside `\texttt`, but single `` ` `` and `'` characters were still
converted to curly quotes, so `\texttt{it's}` produced code containing
a Unicode right single quotation mark.  Gate those conversions on the
ligatures flag too, so quote characters inside `\texttt` stay as
typed.  Update test/command/3958.md accordingly.

Co-Authored-By: Claude <noreply@anthropic.com>

src/Text/Pandoc/Readers/LaTeX.hs

@@ -823,13 +823,16 @@ inline = do
                 -> eatOneToken *>
                     option (str "-") (symbol '-' *>
                       option (str "–") (str "—" <$ symbol '-'))
-        "'"     -> eatOneToken *>
-                    option (str "’") (str  "”" <$ (guard ligatures *> symbol '\''))
+        "'" | ligatures
+                -> eatOneToken *>
+                    option (str "’") (str "”" <$ symbol '\'')
+            | otherwise
+                -> symbolAsString
         "~"     -> str "\160" <$ eatOneToken
         "`" | ligatures
                 -> doubleQuote <|> singleQuote <|> (str "‘" <$ symbol '`')
             | otherwise
-                -> str "‘" <$ symbol '`'
+                -> symbolAsString
         "\"" | ligatures
                 -> doubleQuote <|> singleQuote <|> symbolAsString
         "“"     -> doubleQuote <|> symbolAsString

test/Tests/Readers/LaTeX.hs

@@ -262,6 +262,15 @@ tests = [ testGroup "basic"
             "\\newif\\foobar\\foobar hi\\fi" =?>
             para (str "hi")
           ]
+        , testGroup "ligatures"
+          [ "quote ligatures in normal text" =:
+            "it's ``x'' `y'" =?>
+            para ("it\8217s " <> doubleQuoted "x" <> " " <> singleQuoted "y")
+          , "apostrophe in texttt stays ASCII" =:
+            "\\texttt{it's}" =?> para (code "it's")
+          , "backtick in texttt stays ASCII" =:
+            "\\texttt{`x'}" =?> para (code "`x'")
+          ]
         , testGroup "urls"
           [ "url with escaped %" =:
             "\\url{http://example.com/a\\%b}" =?>

test/command/3958.md

@@ -9,12 +9,12 @@
 % pandoc -f latex -t native
 \texttt{``hi''}
 ^D
-[ Para [ Code ( "" , [] , [] ) "\8216\8216hi\8217\8217" ] ]
+[ Para [ Code ( "" , [] , [] ) "``hi''" ] ]
 ```
 
 ```
 % pandoc -f latex -t native
 \texttt{`hi'}
 ^D
-[ Para [ Code ( "" , [] , [] ) "\8216hi\8217" ] ]
+[ Para [ Code ( "" , [] , [] ) "`hi'" ] ]
 ```