fix for #49 and #50

required/amsmath/amsmath.dtx

@@ -2,7 +2,7 @@
 % \iffalse meta-comment
 %
 % Copyright 1995, 2000, 2013 American Mathematical Society.
-% Copyright 2016-2017 LaTeX3 Project and American Mathematical Society.
+% Copyright 2016-2018 LaTeX3 Project and American Mathematical Society.
 %
 % This work may be distributed and/or modified under the
 % conditions of the LaTeX Project Public License, either version 1.3c
@@ -74,7 +74,19 @@ Bug reports can be opened (category \texttt{#1}) at\\%
 %    \begin{macrocode}
 \NeedsTeXFormat{LaTeX2e}% LaTeX 2.09 can't be used (nor non-LaTeX)
 [1994/12/01]% LaTeX date must be December 1994 or later
-\ProvidesPackage{amsmath}[2017/09/02 v2.17a AMS math features]
+%    \end{macrocode}
+%
+%    Not yet used but for the future \ldots
+%    \begin{macrocode}
+%\providecommand\DeclareRelease[3]{}
+%\providecommand\DeclareCurrentRelease[2]{}
+%
+%\DeclareRelease{}{2017-09-02}{amsmath-2017-09-02.sty}
+%\DeclareCurrentRelease{}{2018-12-01}
+%    \end{macrocode}
+%
+%    \begin{macrocode}
+\ProvidesPackage{amsmath}[2018/12/01 v2.17b AMS math features]
 %    \end{macrocode}
 %
 % \section{Catcode defenses}
@@ -405,9 +417,18 @@ For additional information on amsmath, use the \lq ?\rq\space option.%
 %    mathstyle, and the result is left in the box named by the first
 %    arg. It is assumed that we are already in math mode, so we can turn
 %    off |\everymath| (in particular, |\check@mathfonts|).
+%
+%    As of 2018/12 release we don't turn off |\evermath| as this
+%    optimization can be harmful.
+% \changes{v2.17b}{2018/12/01}{Don't drop \cs{frozen@everymath}}
 %    \begin{macrocode}
+\ifx\leavevmode@ifvmode\@undefined  % kernel is < 2018/12
 \def\@mathmeasure#1#2#3{\setbox#1\hbox{\frozen@everymath\@emptytoks
+    \m@th$#2#3$}}
+\else
+\def\@mathmeasure#1#2#3{\setbox#1\hbox{%
   \m@th$#2#3$}}
+\fi
 %    \end{macrocode}
 %  \end{macro}
 %
@@ -440,9 +461,16 @@ For additional information on amsmath, use the \lq ?\rq\space option.%
 %    them. The standard \cs{relax} before the \cs{ifmmode} is not
 %    necessary because of the \cs{protect} added by
 %    \cs{DeclareRobustCommand}.
+% \changes{v2.17b}{2018/12/01}{Start LR-mode for \cs{thinspace} and
+%   friends if necessary (github/49)}
 %    \begin{macrocode}
+\ifx\leavevmode@ifvmode\@undefined
 \DeclareRobustCommand{\tmspace}[3]{%
   \ifmmode\mskip#1#2\else\kern#1#3\fi\relax}
+\else
+\DeclareRobustCommand{\tmspace}[3]{%
+  \ifmmode\mskip#1#2\else\leavevmode@ifvmode\kern#1#3\fi\relax}
+\fi
 \renewcommand{\,}{\tmspace+\thinmuskip{.1667em}}
 \let\thinspace\,
 \renewcommand{\!}{\tmspace-\thinmuskip{.1667em}}
@@ -1538,7 +1566,10 @@ Foreign command \@backslashchar#1;\MessageBreak
 % \begin{macro}{\bBigg@}
 %    Now we tackle the macro which has to do the real work. It
 %    actually has two arguments, the factor and the wanted delimiter.
+% \changes{v2.17b}{2018/12/01}{Start LR-mode for \cs{bigl} and
+%   friends if necessary (github/49)}
 %    \begin{macrocode}
+\ifx\leavevmode@ifvmode\@undefined
 \def\bBigg@#1#2{%
 %    \end{macrocode}
 %    We start with an extra set of braces because we want
@@ -1548,6 +1579,12 @@ Foreign command \@backslashchar#1;\MessageBreak
   {\@mathmeasure\z@{\nulldelimiterspace\z@}%
      {\left#2\vcenter to#1\big@size{}\right.}%
    \box\z@}}
+\else
+\def\bBigg@#1#2{\leavevmode@ifvmode
+  {\@mathmeasure\z@{\nulldelimiterspace\z@}%
+     {\left#2\vcenter to#1\big@size{}\right.}%
+   \box\z@}}
+\fi
 %    \end{macrocode}
 % \end{macro}
 %
@@ -2072,14 +2109,26 @@ Foreign command \@backslashchar#1;\MessageBreak
 % \begin{macro}{\smash}
 %    We add to the \cn{smash} command an optional argument
 %    denoting the part of the formula to be smashed.
+% \changes{v2.17b}{2018/12/01}{Start LR-mode for \cs{smash}
+%   if necessary (github/49)}
 %    \begin{macrocode}
+\ifx\leavevmode@ifvmode\@undefined
 \renewcommand{\smash}[1][tb]{%
   \def\mb@t{\ht}\def\mb@b{\dp}\def\mb@tb{\ht\z@\z@\dp}%
-  \edef\finsm@sh{\csname mb@#1\endcsname\z@\z@ \box\z@}%
+  \edef\finsm@sh{\csname mb@#1\endcsname\z@\z@\box\z@}%
   \ifmmode \@xp\mathpalette\@xp\mathsm@sh
   \else \@xp\makesm@sh
   \fi
 }
+\else
+\renewcommand{\smash}[1][tb]{%
+  \def\mb@t{\ht}\def\mb@b{\dp}\def\mb@tb{\ht\z@\z@\dp}%
+  \edef\finsm@sh{\csname mb@#1\endcsname\z@\z@ \leavevmode@ifvmode\box\z@}%
+  \ifmmode \@xp\mathpalette\@xp\mathsm@sh
+  \else \@xp\makesm@sh
+  \fi
+}
+\fi
 %    \end{macrocode}
 % \end{macro}
 %

required/amsmath/changes.txt

@@ -1,3 +1,11 @@
+2018-10-09  Frank Mittelbach  <Frank.Mittelbach@latex-project.org>
+
+	* amsmath.dtx
+	Don't drop \frozen@everymath
+	Start LR-mode for \thinspace and friends if necessary (github/49)
+	Start LR-mode for \bigl and friends if necessary (github/49)
+	Start LR-mode for \smash if necessary (github/49)
+
 2017-09-02  David Carlisle  <latex-bugs@latex-project.org>
 
 	* amsmath.dtx: ensure that overfull alignments give warnings in more cases

required/amsmath/testfiles/github-amsmath-0049.lvt

@@ -0,0 +1,116 @@
+% test for git #49
+
+\documentclass{article}
+
+\usepackage{amsmath}
+
+\input{test2e}
+
+\showoutput
+
+\begin{document}
+
+\START
+
+\section{smash}
+
+A test sentence.  
+
+\smash{A smash} 
+
+Another test sentence. 
+
+\smash{A second smash} at the start and \smash{in the middle} of a paragraph. 
+
+
+\section{phantom}
+
+A test sentence.  
+
+\phantom{A phantom} 
+
+Another test sentence. 
+
+\phantom{A second phantom} at the start and \phantom{in the middle} of a paragraph. 
+
+
+\section{hphantom}
+
+A test sentence.  
+
+\hphantom{A hphantom} 
+
+Another test sentence. 
+
+\hphantom{A second hphantom} at the start and \hphantom{in the middle} of a paragraph. 
+
+
+\section{vphantom}
+
+A test sentence.  
+
+\vphantom{A vphantom} 
+
+Another test sentence. 
+
+\vphantom{A second vphantom} at the start and \vphantom{in the middle} of a paragraph. 
+
+\section{big(}
+
+A test sentence.  
+
+
+\big(
+
+Another test sentence. 
+
+\big(A big ( at the start and \big) in the middle of a paragraph.
+
+And $\big( a\big) \neq (a)$  in math.
+
+And also $x^\big)$
+
+\newpage
+
+\section{thinspace}
+
+A test sentence.  
+
+\,\,\,\,\,
+
+Another test sentence. 
+
+\,\,\,\,\,A few at the start and \,\,\,\,\, in the middle of a paragraph.
+
+
+\section{negthinspace}
+
+A test sentence.  
+
+\negthinspace\negthinspace\negthinspace\negthinspace\negthinspace
+
+Another test sentence. 
+
+\negthinspace\negthinspace\negthinspace\negthinspace\negthinspace A few at the start and \negthinspace\negthinspace\negthinspace\negthinspace\negthinspace in the middle of a paragraph.
+
+\section{enspace and the like}
+
+A test sentence.  
+
+\enspace
+
+Another test sentence. 
+
+\enspace A few at the start and \enspace in the middle of a paragraph.
+
+Now the same with a quad:
+
+\quad
+
+Another test sentence. 
+
+\quad A few at the start and \quad in the middle of a paragraph.
+
+
+\end{document}
+