When `allow_abbrev` was first added, disabling the abbreviation of
long options broke the grouping of short flags ([bpo-26967](https://bugs.python.org/issue26967)). As a fix,
b1e4d1b603 (contained in v3.8) ignores `allow_abbrev=False` for a
given argument string if the string does _not_ start with "--"
(i.e. it doesn't look like a long option).
This fix, however, doesn't take into account that long options can
start with alternative characters specified via `prefix_chars`,
introducing a regression: `allow_abbrev=False` has no effect on long
options that start with an alternative prefix character.
The most minimal fix would be to replace the "starts with --" check
with a "starts with two prefix_chars characters". But
`_get_option_tuples` already distinguishes between long and short
options, so let's instead piggyback off of that check by moving the
`allow_abbrev` condition into `_get_option_tuples`.
https://bugs.python.org/issue39546
BPO -16970: Adding error message for invalid args
Applied the patch argparse-v2 patch issue 16970, ran patch check and the test suite, test_argparse with 0 errors
https://bugs.python.org/issue16970
The `allow_abbrev` option for ArgumentParser is documented and intended to disable support for unique prefixes of --options, which may sometimes be ambiguous due to deferred parsing.
However, the initial implementation also broke parsing of grouped short flags, such as `-ab` meaning `-a -b` (or `-a=b`). Checking the argument for a leading `--` before rejecting it fixes this.
This was prompted by pytest-dev/pytest#5469, so a backport to at least 3.8 would be great 😄
And this is my first PR to CPython, so please let me know if I've missed anything!
https://bugs.python.org/issue26967
There is a possibility that someone (like me) accidentally will omit parentheses with `FileType` arguments after `FileType`, and parser will contain wrong file until someone will try to use it.
Example:
```python
parser = argparse.ArgumentParser()
parser.add_argument('-x', type=argparse.FileType)
```
https://bugs.python.org/issue37150
- bugfix and test for fragile metavar handling in argparse (see
bpo-24089, bpo-14046, bpo-25058, bpo-11874)
- also fixes some incorrect tests that did not make 1-element tuples correctly
bpo-26510 in 3.7.0a2 changed the behavior of argparse to make
subparsers required by default, returning to the behavior of 2.7
and 3.2. The behavior was changed in 3.3 to be no longer required.
While it might make more sense to have the default to required,
compatibility with 3.3 through 3.6 is probably less disruptive
than trying to reintroduce compatibility with 2.7 at this point.
This change restores the 3.6 behavior.
This adds support for parsing a command line where options and positionals are intermixed as is common in many unix commands. This is paul.j3's patch with a few tweaks.
