line buffering in sage-logger causes "hang" due to invisible prompt when installing experimental packages

[mkoeppe]

(Observed on Mac OS X.)

As I reported in #20708 comment:8:

When installing an "experimental" package, Sage warns a lot and then prompts the user.
Because of line buffering, one does not see the prompt, but Sage just waits indefinitely.

sage -f latte_int
...
[latte_int-1.7.3] =========================== WARNING ===========================
[latte_int-1.7.3] You are about to download and install an experimental package.
[latte_int-1.7.3] This probably won't work at all for you! There is no guarantee
[latte_int-1.7.3] that it will build correctly, or behave as expected.
[latte_int-1.7.3] Use at your own risk!
[latte_int-1.7.3] ===============================================================

<--- This is where it asks "[latte_int-1.7.3] Are you sure you want to continue [Y/n]?" but this is line-buffered and not visible to the user.

CC: @jdemeyer @embray @vbraun @kcrisman @dimpase @videlec @novoselt

Component: build

Author: Matthias Koeppe

Branch: 6888a67

Reviewer: Leif Leonhardy, Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/20884

[vbraun]

comment:1

IMHO we just shouldn't ask questions here, a (potentially) parallel make session is just not an interactive process. Either do it or bail out and require a command line switch --experimental to opt-in.

[mkoeppe]

comment:2

I think so too.

[embray]

comment:3

+1, just keep the message.

[kcrisman]

comment:4

I also think it's fine for experimental packages to just run and fail. As long as there isn't any potential to mess up the rest of Sage (like with messed up runs of make).

[embray]

Author: Erik Bray

[embray]

Branch: u/embray/disable-exp-pkg-prompt

[embray]

comment:5

Here's a patch to remove the prompt entirely.

Might be good to find a fix to the underlying problem, since in principle there could be some other prompt somewhere that would be hidden in the same way. I'm not sure how best to fix this though--would have to disable line-buffering on such prompts somehow.

---

New commits:

ccff005

Disable the y/n prompt when installing experimental packages.

[embray]

Commit: ccff005

[mkoeppe]

comment:6

This would be fine with me. But it could be argued that this warning is too easy to overlook (and comes too late) and so the point of distinguishing between optional and experimental packages is lost.

[dimpase]

comment:10

I don't think simply removing this dialog is the right thing to do.

[embray]

comment:12

This would be fine with me. But it could be argued that this warning is too easy to overlook (and comes too late) and so the point of distinguishing between optional and experimental packages is lost.

I'm not sure what you suggest differently, other than moving the warning a little earlier?

But if someone doesn't read their build output it will be lost on them anyways. That's okay, because it's "merely" a warning.

[embray]

comment:13

Dima has a point that removing the prompt outright is potentially disruptive.

What if we moved the warning so that there's no prompt if running make <packagename> directly, as a package developer might do. But running ./sage -i for an experimental package both displays the warning and the prompt (before ever even running make, much less sage-logger).