bug#34969: 26.2; `emacs -Q` unable to copy \200's eight-bit detail buffer

[Eli Zaretskii]

> From: Van L <van@scratch.space>
> Date: Tue, 26 Mar 2019 10:46:12 +1100
> Cc: 34969@debbugs.gnu.org
> 
> Copy and paste within the one Emacs is being interfered with if what you 
> suggest is true.

When you paste, and there's stuff in the clipboard, Emacs checks
whether Emacs itself is the owner of that stuff.  If it is, we yank
from the kill ring instead of accessing the clipboard, because yanking
is both faster and doesn't need any decoding.

So I'm guessing that some software on your system takes ownership of
the text in the clipboard, and Emacs then accesses that via the
window-system selections, and fails to decode raw bytes due to
character encoding issues.

> > Section A just gives a single sequence, but it doesn't tell how to do
> > that several times, i.e. what exactly is repeated N times.
> 
> a. run Emacs
> b. goto *scratch* buffer
> c. create new frame
> d. lookup keybindings for *scratch* buffer
> e. find `self`
> f. for the two variants of \200 copy and paste details buffer to *scratch*
> 
> Repeat the above a-f steps 7 times as listed in the bug-report for those 
> platforms detailed.

We are miscommunicating, I think.  Each one of the 7 instances in your
report says something like this, for example:

> : 4
> : [has problem the second time]
> : GNU Emacs 26.2 (build 1, x86_64-apple-darwin15.6.0, X toolkit)
> : of 2019-03-21

I'm asking what exactly does "second time" mean here.  Did you start
this version of Emacs twice, or did you start it only once and
performed the steps b-f above twice one after the other in the same
Emacs session?

> >>> What happens if you set interprogram-cut-function and
> >>> interprogram-paste-function to nil?
> >> 
> >> Will do the next time I get a chance.
> > 
> > If I'm right, the problem will disappear.
> 
> I am inside the one Emacs's copy and paste, and not going out of the Emacs.

I don't think I understand what this alludes to.  Is it a response to
my sentence that starts with "If I'm right"?

> >>> (And why do your symlink targets include \200 characters?)
> >> 
> >> I used `C-x 8 RET horizontal ellipsis` the email program was unable to 
> >> process.
> >> The \200 was what the email program used as substitute.
> > 
> > Strange email program: \200 is an unassigned codepoint.
> 
> That was the emacs-bug-report mechanism in Emacs that did that.

If you sent the report via mailclient, then this is probably the same
problem which causes the issue with pasting that we are discussing.