borrow checker and generalize what moves are allowed. Fixes a nasty
bug or two in the pattern move checking code. Unifies dataflow code
used for initialization and other things. First step towards
once fns. Everybody wins.
Fixes#4384. Fixes#4715. cc once fns (#2202), optimizing local moves (#5016).
This adds a lint mode for detecting unnecessary allocations on the heap. This isn't super fancy, currently it only has two rules
1. For a function's arguments, if you allocate a `[~|@]str` literal, when the type of the argument is a `&str`, emit a warning.
2. For the same case, emit warnings for boxed vectors when slices are required.
After adding the lint, I rampaged through the libraries and removed all the unnecessary allocations I could find.
signature. In a nutshell, the idea is to (1) report an error if, for
a region pointer `'a T`, the lifetime `'a` is longer than any
lifetimes that appear in `T` (in other words, if a borrowed pointer
outlives any portion of its contents) and then (2) use this to assume
that in a function like `fn(self: &'a &'b T)`, the relationship `'a <=
'b` holds. This is needed for #5656. Fixes#5728.
The basic idea is that we add a new kind of adjustment, AutoAddEnv, that pads
an extern fn into a closure by adding the extra NULL word. Then there are a few
misc changes in trans to get the LLVM types to match up.
Fixes#4808.
LinearMap is quite a bit faster, and is fully owned/sendable without
requiring copies. The older std::map also doesn't use explicit self and
relies on mutable fields.
Changes:
- Refactor move mode computation
- Removes move mode arguments, unary move, capture clauses
(though they still parse for backwards compatibility)
- Simplify how moves are handled in trans
- Fix a number of illegal copies that cropped up
- Workaround for bug involving def-ids in params
(see details below)
Future work (I'll open bugs for these...):
- Improve error messages for moves that are due
to bindings
- Add support for moving owned content like a.b.c
to borrow check, test in trans (but I think it'll
"just work")
- Proper fix for def-ids in params
Def ids in params:
Move captures into a map instead of recomputing.
This is a workaround for a larger bug having to do with the def-ids associated
with ty_params, which are not always properly preserved when inlining. I am
not sure of my preferred fix for the larger bug yet. This current fix removes
the only code in trans that I know of which relies on ty_param def-ids, but
feels fragile.
"Dual impls" are impls that are both type implementations and trait
implementations. They can lead to ambiguity and so this patch removes them
from the language.
This also enforces coherence rules. Without this patch, records can implement
traits not defined in the current crate. This patch fixes this, and updates
all of rustc to adhere to the new enforcement. Most of this patch is fixing
rustc to obey the coherence rules, which involves converting a bunch of records
to structs.
