fleqn option with standard equation is flushed right in RTL

[Udi-Fogiel]

\documentclass[fleqn]{article}

%\usepackage{amsmath}
\usepackage[english,hebrew,provide*=*,bidi=basic]{babel}

\begin{document}
\begin{equation}
a+b=c
\end{equation}
\end{document}

With amsmath it does not happen, so one of them is wrong.

[Udi-Fogiel]

looks like this is working

\documentclass[fleqn]{article}

\usepackage[english,hebrew,provide*=*,bidi=basic]{babel}
\makeatletter
\bbl@replace\equation{\hb@xt@\linewidth}{\hbox bdir\mathdirection to\linewidth}
\begin{document}
\begin{equation}
a+b=c
\end{equation}

\selectlanguage{english}
\begin{equation}
a+b=c
\end{equation}

\end{document}

[Udi-Fogiel]

Preferably it will be fixed in the kernel and not in babel, as the box direction in this case does not depend on the language or the text direction.

[FrankMittelbach]

When amsmath is loaded (with or without your suggested patch) you get

 a+b=c                             )1(
 a+b=c                             (2)

which doesn't look right to me.

[u-fischer]

@FrankMittelbach I don't get that, the parentheses are fine here.

[FrankMittelbach]

That's odd, because I think my system is up-to-date, but perhaps there is something
wrong which I haven't noticed. Here is my test input and output:

\documentclass[fleqn]{article}

\listfiles

\usepackage{amsmath}
\usepackage[english,hebrew,provide*=*,bidi=basic]{babel}
\makeatletter
\bbl@replace\equation{\hb@xt@\linewidth}{\hbox bdir\mathdirection to\linewidth}
\begin{document}
\hrule
\begin{equation}
a+b=c
\end{equation}
\hrule
\selectlanguage{english}
\begin{equation}
a+b=c
\end{equation}

\end{document}

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Output written on Untitled5.pdf (1 page, 17753 bytes).

[u-fischer]

Ah, sorry, amsmath.

[FrankMittelbach]

yes amsmath :-)

[Udi-Fogiel]

When amsmath is loaded (with or without your suggested patch) you get

 a+b=c                             )1(
 a+b=c                             (2)

which doesn't look right to me.

See #398 :) But IMHO babel should not patch things to fix that, as it works with HarfBuzz. It currently di that for other cases so I reported.