Show warnings if invalid dimension units found

CHANGES

@@ -49,6 +49,8 @@ Features added
   lines wrapped to fit table cell (ref: #2704)
 * #2597: Show warning messages as darkred
 * latex, allow image dimensions using px unit (default is 96px=1in)
+* Show warnings if invalid dimension units found
+
 
 Bugs fixed
 ----------

sphinx/writers/latex.py

@@ -275,6 +275,24 @@ def escape_abbr(text):
     return re.sub('\.(?=\s|$)', '.\\@', text)
 
 
+def rstdim_to_latexdim(width_str):
+    """Convert `width_str` with rst length to LaTeX length."""
+    match = re.match('(\d*\.?\d*)\s*(\S*)', width_str)
+    if not match:
+        raise ValueError
+    res = width_str
+    amount, unit = match.groups()[:2]
+    if not unit:
+        return None
+    elif unit == 'pt':
+        res = '%sbp' % amount  # convert to 'bp'
+    elif unit == "px":
+        res = "%.3f\\sphinxpxdimen" % (float(amount))
+    elif unit == "%":
+        res = "%.3f\\linewidth" % (float(amount) / 100.0)
+    return res
+
+
 class LaTeXTranslator(nodes.NodeVisitor):
     sectionnames = ["part", "chapter", "section", "subsection",
                     "subsubsection", "paragraph", "subparagraph"]
@@ -1360,25 +1378,10 @@ class LaTeXTranslator(nodes.NodeVisitor):
         pass
 
     def latex_image_length(self, width_str):
-        """Convert `width_str` with rst length to LaTeX length.
-
-        This function is copied from docutils' latex writer
-        """
-        match = re.match('(\d*\.?\d*)\s*(\S*)', width_str)
-        if not match:
-            # fallback
-            return width_str
-        res = width_str
-        amount, unit = match.groups()[:2]
-        if not unit:
-            return None
-        elif unit == 'pt':
-            res = '%sbp' % amount  # convert to 'bp'
-        elif unit == "px":
-            res = "%.3f\\sphinxpxdimen" % (float(amount))
-        elif unit == "%":
-            res = "%.3f\\linewidth" % (float(amount) / 100.0)
-        return res
+        try:
+            return rstdim_to_latexdim(width_str)
+        except ValueError:
+            self.builder.warn('dimension unit %s is invalid. Ignored.' % width_str)
 
     def is_inline(self, node):
         """Check whether a node represents an inline element."""

tests/test_writer_latex.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+"""
+    test_writer_latex
+    ~~~~~~~~~~~~~~~~
+
+    Test the LaTeX writer
+
+    :copyright: Copyright 2007-2016 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+from __future__ import print_function
+from sphinx.writers.latex import rstdim_to_latexdim
+
+
+def test_rstdim_to_latexdim():
+    # Length units docutils supported
+    # http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#length-units
+    assert rstdim_to_latexdim('160em') == '160em'
+    assert rstdim_to_latexdim('160px') == '160.000\\sphinxpxdimen'
+    assert rstdim_to_latexdim('160in') == '160in'
+    assert rstdim_to_latexdim('160cm') == '160cm'
+    assert rstdim_to_latexdim('160mm') == '160mm'
+    assert rstdim_to_latexdim('160pt') == '160bp'
+    assert rstdim_to_latexdim('160pc') == '160pc'
+    assert rstdim_to_latexdim('30%') == '0.300\\linewidth'
+    assert rstdim_to_latexdim('160') is None
+
+    assert rstdim_to_latexdim('160.0em') == '160.0em'