Long arrow composed of line segment and shorter arrow

Question

Consider the following code from egreg:

\documentclass{article}

\newcommand{\strutarrow}[2]{%
  \vrule width 0pt height 2\fontdimen22
  \ifx#1\displaystyle\textfont\else
    \ifx#1\textstyle\textfont\else
      \ifx#1\scriptstyle\scriptfont\else
  \scriptscriptfont\fi\fi\fi 2
  {#2}%
}
\newcommand{\srightarrow}{%
  \mathrel{\mathpalette\strutarrow\longrightarrow}%
}

\begin{document}

\fbox{$\srightarrow$}

\end{document}

As can be seen, the long arrow is composed of line segment and shorter arrow.

How do I "fix" this so that there isn't a dent in the arrow?

Answer 1

The \longrightarrow is defined as

\def\longrightarrow{\relbar\joinrel\rightarrow}

You can correct the flaw mentioned above for example by this:

\def\longrightarrow{\relbar\joinrel\mkern-1mu\rightarrow}

Note that the problem has nothing in common with the code mentioned in your question. The code only adds the invisible strut (depending on the math style).

Answer 2

You can add a small negative space using the \! macro. Inserting it before #2 seems to fix the issue:

\documentclass{article}

\newcommand{\strutarrow}[2]{%
  \vrule width 0pt height 2\fontdimen22
  \ifx#1\displaystyle\textfont\else
    \ifx#1\textstyle\textfont\else
      \ifx#1\scriptstyle\scriptfont\else
  \scriptscriptfont\fi\fi\fi 2
  \!{#2}%
}
\newcommand{\srightarrow}{%
  \mathrel{\mathpalette\strutarrow\longrightarrow}%
}

\begin{document}
\fbox{$\srightarrow$}
\end{document}