Consider header files when determining whether to use csquotes.

README

@@ -184,10 +184,10 @@ document contains images), [`color`], [`hyperref`], [`ulem`],
 [`mathspec`], [`polyglossia`] (with `lang`), [`xecjk`], and
 [`bidi`] (with the `dir` variable set). The [`upquote`] and
 [`microtype`] packages are used if available, and [`csquotes`] will
-be used for [smart punctuation] if added to the template. The
-[`natbib`], [`biblatex`], [`bibtex`], and [`biber`] packages can
-optionally be used for [citation rendering]. These are included with
-all recent versions of [TeX Live].
+be used for [smart punctuation] if added to the template or included in
+any header file. The [`natbib`], [`biblatex`], [`bibtex`], and [`biber`]
+packages can optionally be used for [citation rendering]. These are
+included with all recent versions of [TeX Live].
 
 PDF output can be controlled using [variables for LaTeX].
 
@@ -2377,8 +2377,9 @@ correct output, converting straight quotes to curly quotes, `---` to
 em-dashes, `--` to en-dashes, and `...` to ellipses. Nonbreaking spaces
 are inserted after certain abbreviations, such as "Mr."
 
-Note:  if your LaTeX template calls for the [`csquotes`] package, pandoc will
-detect this automatically and use `\enquote{...}` for quoted text.
+Note:  if your LaTeX template or any included header file call for the
+[`csquotes`] package, pandoc will detect this automatically and use
+`\enquote{...}` for quoted text.
 
 Inline formatting
 -----------------

src/Text/Pandoc/Writers/LaTeX.hs

@@ -38,7 +38,7 @@ import Text.Pandoc.Options
 import Text.Pandoc.Templates
 import Text.Printf ( printf )
 import Network.URI ( isURI, unEscapeString )
-import Data.Aeson (object, (.=))
+import Data.Aeson ( object, (.=), FromJSON )
 import Data.List ( (\\), isInfixOf, stripPrefix, intercalate, intersperse )
 import Data.Char ( toLower, isPunctuation, isAscii, isLetter, isDigit, ord )
 import Data.Maybe ( fromMaybe )
@@ -129,7 +129,12 @@ pandocToLaTeX options (Pandoc meta blocks) = do
                  | otherwise               -> return ()
   -- check for \usepackage...{csquotes}; if present, we'll use
   -- \enquote{...} for smart quotes:
-  when ("{csquotes}" `isInfixOf` template) $
+  let headerIncludesField :: FromJSON a => Maybe a
+      headerIncludesField = getField "header-includes" metadata
+  let headerIncludes = fromMaybe [] $ mplus
+                       (fmap return headerIncludesField)
+                       headerIncludesField
+  when (any (isInfixOf "{csquotes}") (template : headerIncludes)) $
     modify $ \s -> s{stCsquotes = True}
   let (blocks'', lastHeader) = if writerCiteMethod options == Citeproc then
                                  (blocks', [])