History expansion overrides indirect expansion

[Crestwave]

Found this while testing for #697

osh$ foo=bar
osh$ set foo
osh$ echo "${!1}"
! echo "${foo=bar}"
bar

$ foo=bar
$ set foo
$ echo "${!1}"
bar

[andychu]

Ah OK good catch.

I recall that bash's history lexer has a very specific special case for stuff like this, including:

• the ! operator inside [[ ]]
• extended globs like !(foo|bar)
• single quoted strings (but not double quoted strings, which a lot of people are surprised/annoyed by)

I think this is probably possible to fix ...

• Consider expanding history as part of the parser #452 is on my mind but it has some downsides. That would make history a "proper" part of the language and not this weird lexer on top, which is what bash does. I guess the reason I chose to do it bash's way is because history is only on interactively.

[andychu]

Not directly related to this issue but lots of users have reported confusiong over history expansion rules. From Tom Van Vleck:

 Exclamation points,
for example. All I know for sure is that I have to escape
them. Sometimes.  And that they mean several different things.
e.g. when I want to refer to a process ID, how many times do I escape it?

I remember someone else saying they had histexpand off because it expands within double quotes.

[andychu]

Just ran into this one while testing out another bug