Add latexpdf support for Greek as main language (via xelatex use)

Closes: #6710

CHANGES

@@ -17,6 +17,7 @@ Bugs fixed
 ----------
 
 * #6641: LaTeX: Undefined control sequence ``\sphinxmaketitle``
+* #6710: LaTeX not well configured for Greek language as main language
 
 Testing
 --------

doc/latex.rst

@@ -289,6 +289,11 @@ into the generated ``.tex`` files.  Its ``'sphinxsetup'`` key is described
 
      .. attention::
 
+        If Greek is main language, do not use this key.  Since Sphinx 2.2.1,
+        ``xelatex`` will be used automatically as :confval:`latex_engine`.
+        Formerly, Sphinx did not support producing PDF via LaTeX with Greek as
+        main language.
+
         Prior to 2.0, Unicode Greek letters were escaped to use LaTeX math
         mark-up.  This is not the case anymore, and the above must be used
         (only in case of ``'pdflatex'`` engine) if the source contains such

doc/usage/configuration.rst

@@ -1841,7 +1841,17 @@ These options influence LaTeX output.
    ``'xelatex'`` or ``'lualatex'`` and making sure to use an OpenType font
    with wide-enough glyph coverage is often easier than trying to make
    ``'pdflatex'`` work with the extra Unicode characters.  Since Sphinx 2.0
-   the default is the GNU FreeFont which covers well Latin, Cyrillic and Greek.
+   the default is the GNU FreeFont which covers well Latin, Cyrillic and
+   Greek.
+
+   .. versionchanged:: 2.1.0
+
+      Use ``xelatex`` (and LaTeX package ``xeCJK``) by default for Chinese
+      documents.
+
+   .. versionchanged:: 2.2.1
+
+      Use ``xelatex`` by default for Greek documents.
 
    Contrarily to :ref:`MathJaX math rendering in HTML output <math-support>`,
    LaTeX requires some extra configuration to support Unicode literals in

sphinx/builders/latex/__init__.py

@@ -418,6 +418,8 @@ def default_latex_engine(config: Config) -> str:
         return 'platex'
     elif (config.language or '').startswith('zh'):
         return 'xelatex'
+    elif (config.language or '') == 'el':
+        return 'xelatex'
     else:
         return 'pdflatex'
 

sphinx/writers/latex.py

@@ -116,6 +116,10 @@ XELATEX_DEFAULT_FONTPKG = r'''
   BoldItalicFont = *BoldOblique,
 ]
 '''
+XELATEX_GREEK_DEFAULT_FONTPKG = (XELATEX_DEFAULT_FONTPKG +
+                                 '\n\\newfontfamily\\greekfont{FreeSerif}' +
+                                 '\n\\newfontfamily\\greekfontsf{FreeSans}' +
+                                 '\n\\newfontfamily\\greekfonttt{FreeMono}')
 LUALATEX_DEFAULT_FONTPKG = XELATEX_DEFAULT_FONTPKG
 
 DEFAULT_SETTINGS = {
@@ -226,6 +230,9 @@ ADDITIONAL_SETTINGS = {
     ('xelatex', 'zh'): {
         'fontenc':      '\\usepackage{xeCJK}',
     },
+    ('xelatex', 'el'): {
+        'fontpkg':      XELATEX_GREEK_DEFAULT_FONTPKG,
+    },
 }  # type: Dict[Any, Dict[str, Any]]
 
 EXTRA_RE = re.compile(r'^(.*\S)\s+\(([^()]*)\)\s*$')

tests/test_build_latex.py

@@ -175,6 +175,17 @@ def test_latex_additional_settings_for_language_code(app, status, warning):
     assert r'\usepackage{xeCJK}' in result
 
 
+@pytest.mark.sphinx('latex', testroot='basic', confoverrides={'language': 'el'})
+def test_latex_additional_settings_for_greek(app, status, warning):
+    app.builder.build_all()
+    result = (app.outdir / 'test.tex').text(encoding='utf8')
+    print(result)
+    print(status.getvalue())
+    print(warning.getvalue())
+    assert '\\usepackage{polyglossia}\n\\setmainlanguage{greek}' in result
+    assert '\\newfontfamily\\greekfonttt{FreeMono}' in result
+
+
 @pytest.mark.sphinx('latex', testroot='latex-title')
 def test_latex_title_after_admonitions(app, status, warning):
     app.builder.build_all()