warnings writes the full source line instead of the truncated one

[AZero13]

Bug report

Bug description:

It should read the truncated line

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-143201: warnings writes the full source line instead of the truncated one #143202

[picnixz]

What's the difference? can you show an example? and why do you believe we should report the truncated one?

[terryjreedy]

The truncated line appears to have initial whitespace stripped. In Python instead of C. would use str.lstrip.
EDIT. 'dedented' would be a better var name than 'truncated'.

The only purpose of calculating 'truncated' could be to print it.

Perhaps a test should be added.