<ostream>: When is setting badbit a bad thing to do?

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#283 opened on Nov 9, 2019 0 comments 0 reactions 0 assignees View on GitHub

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bug

Dominant language: C++
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Description

We appear to be inconsistent about our behavior after constructing a sentry. Usually, we just test it:

https://github.com/microsoft/STL/blob/f9b1dccd121b5f8bb76d06adb0c85aac3f766326/stl/inc/ostream#L266-L270

But sometimes, we set badbit. I believe I've found Standardese justifying two of these occurrences, but there are several more.

Here are the occurrences that I can't find Standardese for - is this a bug? The difference appears to be that the badbit setters above are unformatted output functions, while the occurrences below are formatted output functions.

All of these lead to https://eel.is/c++draft/ostream.formatted.reqmts#1 .

(Standardese citations as of WG21-N4835.)

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Research direction

Start with the listed badbit handling in stl/inc/ostream, stl/inc/iomanip, and stl/inc/xstring, then compare each occurrence with the cited WG21-N4835 clauses. Determine whether the formatted-output cases conform to the referenced Standardese and identify the correct behavior for each location. Done means reaching a justified conformance decision for all five cases.

Written by the indexing model from the issue text.

Assessment

Tech stack: cpp
Domain: tooling
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Stale
Clarity: Mostly clear
Newbie friendliness: 35/100