From 2a663ee71c6dc91baab41c438135f4207cb6eaf1 Mon Sep 17 00:00:00 2001
From: Georg Brandl <georg@python.org>
Date: Sat, 11 Jan 2014 09:50:27 +0100
Subject: [PATCH] Closes #901: Emit a warning when using docutils' new "math"
 markup without a Sphinx math extension active.

---
 CHANGES                   |  3 +++
 sphinx/builders/text.py   |  1 +
 sphinx/writers/html.py    |  7 +++++++
 sphinx/writers/latex.py   |  9 +++++++++
 sphinx/writers/manpage.py |  8 ++++++++
 sphinx/writers/texinfo.py |  8 ++++++++
 sphinx/writers/text.py    | 10 ++++++++++
 7 files changed, 46 insertions(+)

diff --git a/CHANGES b/CHANGES
index a28c6ea33..c14656394 100644
--- a/CHANGES
+++ b/CHANGES
@@ -43,6 +43,9 @@ Bugs fixed
   pngmath-generated images.  This rebuilds them correctly when
   ``pngmath_latex_preamble`` changes.
 
+* #901: Emit a warning when using docutils' new "math" markup without a Sphinx
+  math extension active.
+
 Documentation
 -------------
 
diff --git a/sphinx/builders/text.py b/sphinx/builders/text.py
index 4b73167b1..f09ad6541 100644
--- a/sphinx/builders/text.py
+++ b/sphinx/builders/text.py
@@ -54,6 +54,7 @@ class TextBuilder(Builder):
         self.writer = TextWriter(self)
 
     def write_doc(self, docname, doctree):
+        self.current_docname = docname
         destination = StringOutput(encoding='utf-8')
         self.writer.write(doctree, destination)
         outfilename = path.join(self.outdir, os_path(docname) + self.out_suffix)
diff --git a/sphinx/writers/html.py b/sphinx/writers/html.py
index 1abe7b3a6..c54f3369a 100644
--- a/sphinx/writers/html.py
+++ b/sphinx/writers/html.py
@@ -551,6 +551,13 @@ class HTMLTranslator(BaseTranslator):
             node['classes'].append('field-odd')
         self.body.append(self.starttag(node, 'tr', '', CLASS='field'))
 
+    def visit_math(self, node, math_env=''):
+        self.builder.warn('using "math" markup without a Sphinx math extension '
+                          'active, please use one of the math extensions '
+                          'described at http://sphinx-doc.org/ext/math.html',
+                          (self.builder.current_docname, node.line))
+        raise nodes.SkipNode
+
     def unknown_visit(self, node):
         raise NotImplementedError('Unknown node: ' + node.__class__.__name__)
 
diff --git a/sphinx/writers/latex.py b/sphinx/writers/latex.py
index 80080752e..58c7f5f82 100644
--- a/sphinx/writers/latex.py
+++ b/sphinx/writers/latex.py
@@ -1532,5 +1532,14 @@ class LaTeXTranslator(nodes.NodeVisitor):
     def depart_system_message(self, node):
         self.body.append('\n')
 
+    def visit_math(self, node):
+        self.builder.warn('using "math" markup without a Sphinx math extension '
+                          'active, please use one of the math extensions '
+                          'described at http://sphinx-doc.org/ext/math.html',
+                          (self.curfilestack[-1], node.line))
+        raise nodes.SkipNode
+
+    visit_math_block = visit_math
+
     def unknown_visit(self, node):
         raise NotImplementedError('Unknown node: ' + node.__class__.__name__)
diff --git a/sphinx/writers/manpage.py b/sphinx/writers/manpage.py
index f652e9188..bc4da17ab 100644
--- a/sphinx/writers/manpage.py
+++ b/sphinx/writers/manpage.py
@@ -342,5 +342,13 @@ class ManualPageTranslator(BaseTranslator):
     def depart_inline(self, node):
         pass
 
+    def visit_math(self, node):
+        self.builder.warn('using "math" markup without a Sphinx math extension '
+                          'active, please use one of the math extensions '
+                          'described at http://sphinx-doc.org/ext/math.html')
+        raise nodes.SkipNode
+
+    visit_math_block = visit_math
+
     def unknown_visit(self, node):
         raise NotImplementedError('Unknown node: ' + node.__class__.__name__)
diff --git a/sphinx/writers/texinfo.py b/sphinx/writers/texinfo.py
index 66a0e0392..7b70485aa 100644
--- a/sphinx/writers/texinfo.py
+++ b/sphinx/writers/texinfo.py
@@ -1393,3 +1393,11 @@ class TexinfoTranslator(nodes.NodeVisitor):
         pass
     def depart_pending_xref(self, node):
         pass
+
+    def visit_math(self, node):
+        self.builder.warn('using "math" markup without a Sphinx math extension '
+                          'active, please use one of the math extensions '
+                          'described at http://sphinx-doc.org/ext/math.html')
+        raise nodes.SkipNode
+
+    visit_math_block = visit_math
diff --git a/sphinx/writers/text.py b/sphinx/writers/text.py
index 3bf7588ab..57a40b296 100644
--- a/sphinx/writers/text.py
+++ b/sphinx/writers/text.py
@@ -152,6 +152,7 @@ class TextTranslator(nodes.NodeVisitor):
 
     def __init__(self, document, builder):
         nodes.NodeVisitor.__init__(self, document)
+        self.builder = builder
 
         newlines = builder.config.text_newlines
         if newlines == 'windows':
@@ -838,5 +839,14 @@ class TextTranslator(nodes.NodeVisitor):
             self.body.append(node.astext())
         raise nodes.SkipNode
 
+    def visit_math(self, node):
+        self.builder.warn('using "math" markup without a Sphinx math extension '
+                          'active, please use one of the math extensions '
+                          'described at http://sphinx-doc.org/ext/math.html',
+                          (self.builder.current_docname, node.line))
+        raise nodes.SkipNode
+
+    visit_math_block = visit_math
+
     def unknown_visit(self, node):
         raise NotImplementedError('Unknown node: ' + node.__class__.__name__)