code-block directive should have a width option

[miglincit]

Is your feature request related to a problem? Please describe.
Code inside a code-block might be longer as the space available by the output format. On HTML this results in a horizontal scroll-bar, but on other formats, like PDF this is then truncated. The same is if from e.g. HTMLHELP a pdf is derived.

Describe the solution you'd like
There should be an option (e.g. :width: 60) which defines the maximum length of the generated output.
Along with it a character (e.g. :eolmark: ^) shall be definable which is then used to mark the virtual end of a line. The rest of the line shall be output beneath this line and intended by (e.g. 2 or tab-width?) spaces.
The reader is then enabled to understand that this line is longer and spans more than one line

Describe alternatives you've considered
none

[jfbu]

Hi, a remark only indirectly related to your query as you seem to refer to PDF obtained from HTML by some unspecified tool: what you are asking for in HTML is (for PDF) about exactly the implemented behavior of Sphinx for PDF via LaTeX since 1.4.2 (released May 29, 2016, #2343).

I am not telling people to produce their HTML via PDF though 😄