Simplify LaTeX mark-up for table column widths (ref sphinx-doc#3379)

The ``\X`` token is used as column-specifier: this does not define or
redefine ``\X`` as a LaTeX macro. Using a letter could have led to
conflict with user extra packages or macro definitions. This column
specifier takes two arguments which must be positive integers, as
produced by LaTeX writer for ``:widths:`` option or for equal widths
columns. As it always uses ``\linewidth`` the latter was not abstracted
into a third argument.

sphinx/texinputs/sphinx.sty

@@ -6,7 +6,7 @@
 %
 
 \NeedsTeXFormat{LaTeX2e}[1995/12/01]
-\ProvidesPackage{sphinx}[2017/01/16 v1.6 LaTeX package (Sphinx markup)]
+\ProvidesPackage{sphinx}[2017/02/01 v1.6 LaTeX package (Sphinx markup)]
 
 % we delay handling of options to after having loaded packages, because
 % of the need to use \definecolor.
@@ -24,6 +24,9 @@
 ******** ERROR !! PLEASE UPDATE titlesec.sty !!********^^J%
 ******** THIS VERSION SWALLOWS SECTION NUMBERS.********}}}}{}
 \RequirePackage{tabulary}
+% use of \X to minimize possibility of conflict with one-character column types
+\newcolumntype{\X}[2]{p{\dimexpr
+      (\linewidth-\arrayrulewidth)*#1/#2-\tw@\tabcolsep-\arrayrulewidth\relax}}
 \RequirePackage{makeidx}
 % For framing code-blocks and warning type notices, and shadowing topics
 \RequirePackage{framed}

sphinx/writers/latex.py

@@ -1206,14 +1206,12 @@ def depart_table(self, node):
             self.body.append(self.table.colspec)
         elif self.table.colwidths:
             total = sum(self.table.colwidths)
-            colspec = ['p{\\dimexpr(\\linewidth-\\arrayrulewidth)*%d/%d'
-                       '-2\\tabcolsep-\\arrayrulewidth\\relax}' % (width, total)
+            colspec = ['\\X{%d}{%d}' % (width, total)
                        for width in self.table.colwidths]
             self.body.append('{|%s|}\n' % '|'.join(colspec))
         else:
             if self.table.has_problematic:
-                colspec = ('*{%d}{p{\\dimexpr(\\linewidth-\\arrayrulewidth)/%d'
-                           '-2\\tabcolsep-\\arrayrulewidth\\relax}|}' %
+                colspec = ('*{%d}{\\X{1}{%d}|}' %
                            (self.table.colcount, self.table.colcount))
                 self.body.append('{|' + colspec + '}\n')
             elif self.table.longtable: