On partial uninit error point at where we need init
When a binding is declared without a value, borrowck verifies that all
codepaths have *one* assignment to them to initialize them fully. If
there are any cases where a condition can be met that leaves the binding
uninitialized or we attempt to initialize a field of an uninitialized
binding, we emit E0381.
We now look at all the statements that initialize the binding, and use
them to explore branching code paths that *don't* and point at them. If
we find *no* potential places where an assignment to the binding might
be missing, we display the spans of all the existing initializers to
provide some context.
Fix https://github.com/rust-lang/rust/issues/97956.
When a binding is declared without a value, borrowck verifies that all
codepaths have *one* assignment to them to initialize them fully. If
there are any cases where a condition can be met that leaves the binding
uninitialized or we attempt to initialize a field of an unitialized
binding, we emit E0381.
We now look at all the statements that initialize the binding, and use
them to explore branching code paths that *don't* and point at them. If
we find *no* potential places where an assignment to the binding might
be missing, we display the spans of all the existing initializers to
provide some context.
interpret: use AllocRange in UninitByteAccess
also use nice new format string syntax in `interpret/error.rs`, and use the `#` flag to add `0x` prefixes where applicable.
r? ``@oli-obk``
interpret: remove support for unsized_locals
I added support for unsized_locals in https://github.com/rust-lang/rust/pull/59780 but the current implementation is a crude hack and IMO definitely not the right way to have unsized locals in MIR. It also [causes problems](https://rust-lang.zulipchat.com/#narrow/stream/146212-t-compiler.2Fconst-eval/topic/Missing.20Layout.20Check.20in.20.60interpret.2Foperand.2Ers.60.3F). and what codegen does is unsound and has been for years since clearly nobody cares (so I hope nobody actually relies on that implementation and I'll be happy if Miri ensures they do not). I think if we want to have unsized locals in Miri/MIR we should add them properly, either by having a `StorageLive` that takes metadata or by having an `alloca` that returns a pointer (making the ptr indirection explicit) or something like that.
So, this PR removes the `LocalValue::Unallocated` hack. It adds `Immediate::Uninit`, for several reasons:
- This lets us still do fairly little work in `push_stack_frame`, in particular we do not actually have to create any allocations.
- If/when I remove `ScalarMaybeUninit`, we will need something like this to have an "optimized" representation of uninitialized locals. Without this we'd have to put uninitialized integers into the heap!
- const-prop needs some way to indicate "I don't know the value of this local'; it used to use `LocalValue::Unallocated` for that, now it can use `Immediate::Uninit`.
There is still a fundamental difference between `LocalValue::Unallocated` and `Immediate::Uninit`: the latter is considered a regular local that you can read from and write to, it just has a more optimized representation when compared with an actual `Allocation` that is fully uninit. In contrast, `LocalValue::Unallocated` had this really odd behavior where you would write to it but not read from it. (This is in fact what caused the problems mentioned above.)
While at it I also did two drive-by cleanups/improvements:
- In `pop_stack_frame`, do the return value copying and local deallocation while the frame is still on the stack. This leads to better error locations being reported. The old errors were [sometimes rather confusing](https://rust-lang.zulipchat.com/#narrow/stream/269128-miri/topic/Cron.20Job.20Failure.202022-06-24/near/287445522).
- Deduplicate `copy_op` and `copy_op_transmute`.
r? `@oli-obk`
fix typo in note about multiple inaccessible type aliases
Mainly intended as a small typo fix ("aliass" -> "aliases") for the case where a type cannot be found in scope but there are multiple inaccessible type aliases that match the missing type.
In general this change would use the correct plural form in this scenario for base words that end with 's'.
Mainly intended as a small typo fix ("aliass" -> "aliases") for
the case where a type cannot be found in scope, and there are
multiple inaccessible type aliases that match the missing type.
In general this change would use the correct plural form in
this scenario for words that end with 's'.
Fix repr(align) enum handling
`enum`, for better or worse, supports `repr(align)`. That has already caused a bug in https://github.com/rust-lang/rust/issues/92464, which was "fixed" in https://github.com/rust-lang/rust/pull/92932, but it turns out that that fix is wrong and caused https://github.com/rust-lang/rust/issues/96185.
So this reverts #92932 (which fixes#96185), and attempts another strategy for fixing #92464: special-case enums when doing a cast, re-using the code to load the discriminant rather than assuming that the enum has scalar layout. This works fine for the interpreter.
However, #92464 contained another testcase that was previously not in the test suite -- and after adding it, it ICEs again. This is not surprising; codegen needs the same patch that I did in the interpreter. Probably this has to happen [around here](d32ce37a17/compiler/rustc_codegen_ssa/src/mir/rvalue.rs (L276)). Unfortunately I don't know how to do that -- the interpreter can load a discriminant from an operand, but codegen can only do that from a place. `@oli-obk` `@eddyb` `@bjorn3` any idea?
lints: mostly translatable diagnostics
As lints are created slightly differently than other diagnostics, intended to try make them translatable first and then look into the applicability of diagnostic structs but ended up just making most of the diagnostics in the crate translatable (which will still be useful if I do make a lot of them structs later anyway).
r? ``@compiler-errors``
more `need_type_info` improvements
this now deals with macros in suggestions and the source cost computation does what I want for `channel` 🎉
r? ``@estebank``
