refactor: latex: Deprecate settings.* attributes based on latex_documents

CHANGES

@@ -18,6 +18,11 @@ Deprecated
 * ``sphinx.pycode.ModuleAnalyzer.encoding``
 * ``sphinx.util.detect_encoding()``
 * ``sphinx.util.get_module_source()``
+* ``sphinx.writers.latex.LaTeXTranslator.settings.author``
+* ``sphinx.writers.latex.LaTeXTranslator.settings.contentsname``
+* ``sphinx.writers.latex.LaTeXTranslator.settings.docclass``
+* ``sphinx.writers.latex.LaTeXTranslator.settings.docname``
+* ``sphinx.writers.latex.LaTeXTranslator.settings.title``
 
 Features added
 --------------

doc/extdev/deprecated.rst

@@ -66,6 +66,31 @@ The following is a list of deprecated interfaces.
      - 4.0
      - ``tokenize.detect_encoding()``
 
+   * - ``sphinx.writers.latex.LaTeXTranslator.settings.author``
+     - 2.4
+     - 4.0
+     - N/A
+
+   * - ``sphinx.writers.latex.LaTeXTranslator.settings.contentsname``
+     - 2.4
+     - 4.0
+     - ``document['contentsname']``
+
+   * - ``sphinx.writers.latex.LaTeXTranslator.settings.docclass``
+     - 2.4
+     - 4.0
+     - ``document['docclass']``
+
+   * - ``sphinx.writers.latex.LaTeXTranslator.settings.docname``
+     - 2.4
+     - 4.0
+     - N/A
+
+   * - ``sphinx.writers.latex.LaTeXTranslator.settings.title``
+     - 2.4
+     - 4.0
+     - N/A
+
    * - ``sphinx.builders.gettext.POHEADER``
      - 2.3
      - 4.0

sphinx/builders/latex/__init__.py

@@ -221,6 +221,7 @@ class LaTeXBuilder(Builder):
             defaults=self.env.settings,
             components=(docwriter,),
             read_config_files=True).get_default_values()  # type: Any
+        patch_settings(docsettings)
 
         self.init_document_data()
         self.write_stylesheet()
@@ -243,16 +244,18 @@ class LaTeXBuilder(Builder):
                 doctree = self.assemble_doctree(
                     docname, toctree_only,
                     appendices=(self.config.latex_appendices if docclass != 'howto' else []))
+                doctree['docclass'] = docclass
+                doctree['contentsname'] = self.get_contentsname(docname)
                 doctree['tocdepth'] = tocdepth
                 self.post_process_images(doctree)
                 self.update_doc_context(title, author)
 
             with progress_message(__("writing")):
-                docsettings.author = author
-                docsettings.title = title
-                docsettings.contentsname = self.get_contentsname(docname)
-                docsettings.docname = docname
-                docsettings.docclass = docclass
+                docsettings._author = author
+                docsettings._title = title
+                docsettings._contentsname = doctree['contentsname']
+                docsettings._docname = docname
+                docsettings._docclass = docclass
 
                 doctree.settings = docsettings
                 docwriter.write(doctree, destination)
@@ -400,6 +403,44 @@ class LaTeXBuilder(Builder):
         copy_asset_file(filename, self.outdir, context=context, renderer=LaTeXRenderer())
 
 
+def patch_settings(settings: Any):
+    """Make settings object to show deprecation messages."""
+
+    class Values(type(settings)):  # type: ignore
+        @property
+        def author(self):
+            warnings.warn('settings.author is deprecated',
+                          RemovedInSphinx40Warning, stacklevel=2)
+            return self._author
+
+        @property
+        def title(self):
+            warnings.warn('settings.title is deprecated',
+                          RemovedInSphinx40Warning, stacklevel=2)
+            return self._title
+
+        @property
+        def contentsname(self):
+            warnings.warn('settings.contentsname is deprecated',
+                          RemovedInSphinx40Warning, stacklevel=2)
+            return self._contentsname
+
+        @property
+        def docname(self):
+            warnings.warn('settings.docname is deprecated',
+                          RemovedInSphinx40Warning, stacklevel=2)
+            return self._docname
+
+        @property
+        def docclass(self):
+            warnings.warn('settings.docclass is deprecated',
+                          RemovedInSphinx40Warning, stacklevel=2)
+            return self._docclass
+
+    # dynamic subclassing
+    settings.__class__ = Values
+
+
 def validate_config_values(app: Sphinx, config: Config) -> None:
     for key in list(config.latex_elements):
         if key not in DEFAULT_SETTINGS:

sphinx/writers/latex.py

@@ -322,12 +322,12 @@ class LaTeXTranslator(SphinxTranslator):
         self.elements = self.builder.context.copy()
 
         # but some have other interface in config file
-        self.elements['wrapperclass'] = self.format_docclass(self.settings.docclass)
+        self.elements['wrapperclass'] = self.format_docclass(document.get('docclass'))
 
         # we assume LaTeX class provides \chapter command except in case
         # of non-Japanese 'howto' case
         self.sectionnames = LATEXSECTIONNAMES[:]
-        if self.settings.docclass == 'howto':
+        if document.get('docclass') == 'howto':
             docclass = self.config.latex_docclass.get('howto', 'article')
             if docclass[0] == 'j':  # Japanese class...
                 pass
@@ -429,7 +429,7 @@ class LaTeXTranslator(SphinxTranslator):
             #   tocdepth =  1: show parts, chapters and sections
             #   tocdepth =  2: show parts, chapters, sections and subsections
             #   ...
-            tocdepth = self.document['tocdepth'] + self.top_sectionlevel - 2
+            tocdepth = self.document.get('tocdepth', 999) + self.top_sectionlevel - 2
             if len(self.sectionnames) < len(LATEXSECTIONNAMES) and \
                self.top_sectionlevel > 0:
                 tocdepth += 1  # because top_sectionlevel is shifted by -1
@@ -447,7 +447,7 @@ class LaTeXTranslator(SphinxTranslator):
             self.elements['secnumdepth'] = '\\setcounter{secnumdepth}{%d}' %\
                                            minsecnumdepth
 
-        contentsname = self.settings.contentsname
+        contentsname = document.get('contentsname')
         if contentsname:
             self.elements['contentsname'] = self.babel_renewcommand('\\contentsname',
                                                                     contentsname)