bug#3226: here-document syntax inference and completion is broken

[Andrew Hyatt <ahyatt@gmail.com>]

Chong Yidong <cyd@stupidchicken.com> writes:

>> Cook yourself up a bash script and type a line of code like:
>> for i in $(/bin/vim <<
>>
>> A default emacs install will complete with "EOF\n\nEOF" (in a more
>>clever fashion so the rest of the line is undisturbed), and place the
>>cursor on the new blank line.  This is incorrect behaviour, as it
>>breaks entry of BASH here-strings when the user's intent is still
>>ambiguous.  This should only respond to things ending in, for example
>>"<< " or possibly "<<E", but certainly NOT just "<<".
>>
>> Further, emacs does something outright wrong: An attempt to fix the
>>situation by inserting another '<' between the "<<" and "EOF" +results
>>in ANOTHER pair of "EOF" being inserted in a syntactically invalid way.
>
> I fixed the second problem, but I don't see any easy way to solve the
> first one.
>
> (The difficulty of fixing the first bug is illustrative of the problems
> with individual major modes rolling their own "electric" completion
> facilities.  It might be nice to have a minor mode that provides a
> unified framework for this kind of functionality; which may also need
> built-in support.)

Just a note that I've reproduced the original problem in Emacs 25, so it
appears to be unfixed at present.