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rust-cpython: mark all PyLeaked methods as unsafe...
rust-cpython: mark all PyLeaked methods as unsafe Unfortunately, these methods can be abused to obtain the inner 'static reference. The simplest (pseudo-code) example is: let leaked: PyLeaked<&'static _> = shared.leak_immutable(); let static_ref: &'static _ = &*leaked.try_borrow(py)?; // PyLeakedRef::deref() tries to bound the lifetime to itself, but // the underlying data is a &'static reference, so the returned // reference can be &'static. This problem can be easily fixed by coercing the lifetime, but there are many other ways to achieve that, and there wouldn't be a generic solution: let leaked: PyLeaked<&'static [_]> = shared.leak_immutable(); let leaked_iter: PyLeaked<slice::Iter<'static, _>> = unsafe { leaked.map(|v| v.iter()) }; let static_slice: &'static [_] = leaked_iter.try_borrow(py)?.as_slice(); So basically I failed to design the safe borrowing interface. Maybe we'll instead have to add much more restricted interface on top of the unsafe PyLeaked methods? For instance, Iterator::next() could be implemented if its Item type is not &'a (where 'a may be cheated.) Anyway, this seems not an easy issue, so it's probably better to leave the current interface as unsafe, and get broader comments while upstreaming this feature.
Matt Harbison - - Load All Authors

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flags.txt
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Most Mercurial commands accept various flags.
Flag names
==========
Flags for each command are listed in :hg:`help` for that command.
Additionally, some flags, such as --repository, are global and can be used with
any command - those are seen in :hg:`help -v`, and can be specified before or
after the command.
Every flag has at least a long name, such as --repository. Some flags may also
have a short one-letter name, such as the equivalent -R. Using the short or long
name is equivalent and has the same effect.
Flags that have a short name can also be bundled together - for instance, to
specify both --edit (short -e) and --interactive (short -i), one could use::
hg commit -ei
If any of the bundled flags takes a value (i.e. is not a boolean), it must be
last, followed by the value::
hg commit -im 'Message'
Flag types
==========
Mercurial command-line flags can be strings, numbers, booleans, or lists of
strings.
Specifying flag values
======================
The following syntaxes are allowed, assuming a flag 'flagname' with short name
'f'::
--flagname=foo
--flagname foo
-f foo
-ffoo
This syntax applies to all non-boolean flags (strings, numbers or lists).
Specifying boolean flags
========================
Boolean flags do not take a value parameter. To specify a boolean, use the flag
name to set it to true, or the same name prefixed with 'no-' to set it to
false::
hg commit --interactive
hg commit --no-interactive
Specifying list flags
=====================
List flags take multiple values. To specify them, pass the flag multiple times::
hg files --include mercurial --include tests
Setting flag defaults
=====================
In order to set a default value for a flag in an hgrc file, it is recommended to
use aliases::
[alias]
commit = commit --interactive
For more information on hgrc files, see :hg:`help config`.
Overriding flags on the command line
====================================
If the same non-list flag is specified multiple times on the command line, the
latest specification is used::
hg commit -m "Ignored value" -m "Used value"
This includes the use of aliases - e.g., if one has::
[alias]
committemp = commit -m "Ignored value"
then the following command will override that -m::
hg committemp -m "Used value"
Overriding flag defaults
========================
Every flag has a default value, and you may also set your own defaults in hgrc
as described above.
Except for list flags, defaults can be overridden on the command line simply by
specifying the flag in that location.
Hidden flags
============
Some flags are not shown in a command's help by default - specifically, those
that are deemed to be experimental, deprecated or advanced. To show all flags,
add the --verbose flag for the help command::
hg help --verbose commit