This is sort of confusing "side step". All it does is to change the
representation of a skolemized region. but the source of that universe
index is not the inference context, which is what we eventually want,
but rather an internal counter in the region inference context.
We'll patch that up later. But doing this now ought to help with
confusing diffs later.
This gives each type inference variable a notion of universe but doesn't
do anything with it. We can always get the "current universe" from
infer_ctxt. This relies on the property of type variables that they can
never interact with siblings.
Treat generators as if they have an arbitrary destructor
Conservatively assume dropping a generator touches its upvars, via locals' destructors.
Fix#49918
rustc: return iterators from Terminator(Kind)::successors(_mut).
Minor cleanup (and potentially speedup) prompted by @nnethercote's `SmallVec` experiments.
This PR assumes `.count()` and `.nth(i)` on `iter::Chain<option::IntoIter, slice::Iter(Mut)>` are `O(1)`, but otherwise all of the uses appear to immediately iterate through the successors.
r? @nikomatsakis
This is meant to address rust-lang/rust#49918.
Review feedback: put back comment justifying skipping interior traversal.
Review feedback: dropck generators like trait objects: all their upvars must
outlive the generator itself, so just create a DtorckConstraint saying so.
Module experiments: Add one more prelude layer for extern crate names passed with `--extern`
Implements one item from https://internals.rust-lang.org/t/the-great-module-adventure-continues/6678/183
When some name is looked up in lexical scope (`name`, i.e. not module-relative scope `some_mod::name` or `::name`), it's searched roughly in the next order:
- local variables
- items in unnamed blocks
- items in the current module
- ✨ NEW! ✨ crate names passed with `--extern` ("extern prelude")
- standard library prelude (`Vec`, `drop`)
- language prelude (built-in types like `u8`, `str`, etc)
The last two layers contain a limited set of names controlled by us and not arbitrary user-defined names like upper layers. We want to be able to add new names into these two layers without breaking user code, so "extern prelude" names have higher priority than std prelude and built-in types.
This is a one-time breaking change, that's why it would be nice to run this through crater.
Practical impact is expected to be minimal though due to stylistic reasons (there are not many `Uppercase` crates) and due to the way how primitive types are resolved (https://github.com/rust-lang/rust/pull/32131).
This code is assuming that usize >= 32bits, but it is not the case on
16bit targets. It is producing a warning that will fail the compilation
on MSP430 if deny(warnings) is enabled.
It is very unlikely that someone would actually use this code on
a microcontroller, but since unicode was merged into libcore we
have compile it on 16bit targets.
When looking at any scope in scope chain A, we only need to look for
matches among scopes previously seen in scope chain B, and vice versa.
This halves the number of "seen before?" comparisons, speeding up some
runs of style-servo, clap-rs, and syn by 1--2%.
This reworks the force-frame-pointer PR to explicitly only consider the
value of the flag if it is provided, and use a target default otherwise.
Something that was tried but not kept was renaming the flag to
`frame-pointer`, because for flag `frame-pointer=no`, there is no
guarante, that LLVM will elide *all* the frame pointers; oposite of what
the literal reading of the flag would suggest.
We apparently used to generate bad/incomplete debug info causing
debuggers not to find symbols of stack allocated variables. This was
somehow worked around by having frame pointers.
With the current codegen, this seems no longer necessary, so we can
remove the code that force-enables frame pointers whenever debug info
is requested.
Since certain situations, like profiling code profit from having frame
pointers, we add a -Cforce-frame-pointers flag to always enable frame
pointers.
Fixes#11906
