This patch changes the type of byte string literals from `&[u8]` to `&[u8; N]`.
It also implements some necessary traits (`IntoBytes`, `Seek`, `Read`, `BufRead`) for fixed-size arrays (also related to #21725) and adds test for #17233, which seems to be resolved.
Fixes#18465
[breaking-change]
When matching against strings/slices, we call the comparison function
for strings, which takes two string slices by value. The slices are
passed in memory, and currently we just pass in a pointer to the
original slice. That can cause misoptimizations because we emit a call
to llvm.lifetime.end for all by-value arguments at the end of a
function, which in this case marks the original slice as dead.
So we need to properly create copies of the slices to pass them to the
comparison function.
Fixes#22008
When matching against strings/slices, we call the comparison function
for strings, which takes two string slices by value. The slices are
passed in memory, and currently we just pass in a pointer to the
original slice. That can cause misoptimizations because we emit a call
to llvm.lifetime.end for all by-value arguments at the end of a
function, which in this case marks the original slice as dead.
So we need to properly create copies of the slices to pass them to the
comparison function.
Fixes#22008
Currently \"k / 2\" generates one (k: uint) or two (k: int) \"br false,
...\" instructions and the corresponding basic blocks, producing quite
some noise and making the code unnecessarily hard to read.
Additionally we can skip translation if the code would end up
unreachable anyway.
Currently "k / 2" generates one (k: uint) or two (k: int) "br false,
..." instructions and the corresponding basic blocks, producing quite
some noise and making the code unnecessarily hard to read.
Additionally we can skip translation if the code would end up
unreachable anyway.
So far, the source location an LLVM instruction was linked to was controlled by
`debuginfo::set_source_location()` and `debuginfo::clear_source_location()`.
This interface mimicked how LLVM's `IRBuilder` handles debug location
assignment. While this interface has some theoretical performance benefits, it
also makes things terribly unstable: One sets some quasi-global state and then
hopes that it is still correct when a given instruction is emitted---an
assumption that has been proven to not hold a bit too often.
This patch requires the debug source location to be passed to the actual
instruction emitting function. This makes source location assignment explicit
and will prevent future changes to `trans` from accidentally breaking things in
the majority of cases.
This patch does not yet implement the new principle for all instruction kinds
but the stepping experience should have improved significantly nonetheless
already.
There are two places left where we used to only know the byte
size of/offset into an array and had to cast to i8 and back to get the
right addresses. But by now, we always know the sizes in terms of the
number of elements in the array. In fact we have to add an extra Mul
instruction so we can use the weird cast-to-u8 code. So we should really
just embrace our new knowledge and use simple GEPs to do the address
calculations.
Fixes#3729
There are two places left where we used to only know the byte
size of/offset into an array and had to cast to i8 and back to get the
right addresses. But by now, we always know the sizes in terms of the
number of elements in the array. In fact we have to add an extra Mul
instruction so we can use the weird cast-to-u8 code. So we should really
just embrace our new knowledge and use simple GEPs to do the address
calculations.
Additionally, the pointer calculations in bind_subslice_pat don't handle
zero-sized types correctly, producing slices that point outside the
array that is being matched against. Using GEP fixes that as well.
Fixes#3729
fmt::Show is for debugging, and can and should be implemented for
all public types. This trait is used with `{:?}` syntax. There still
exists #[derive(Show)].
fmt::String is for types that faithfully be represented as a String.
Because of this, there is no way to derive fmt::String, all
implementations must be purposeful. It is used by the default format
syntax, `{}`.
This will break most instances of `{}`, since that now requires the type
to impl fmt::String. In most cases, replacing `{}` with `{:?}` is the
correct fix. Types that were being printed specifically for users should
receive a fmt::String implementation to fix this.
Part of #20013
[breaking-change]
This implements RFC 179 by making the pattern `&<pat>` require matching
against a variable of type `&T`, and introducing the pattern `&mut
<pat>` which only works with variables of type `&mut T`.
The pattern `&mut x` currently parses as `&(mut x)` i.e. a pattern match
through a `&T` or a `&mut T` that binds the variable `x` to have type
`T` and to be mutable. This should be rewritten as follows, for example,
for &mut x in slice.iter() {
becomes
for &x in slice.iter() {
let mut x = x;
Due to this, this is a
[breaking-change]
Closes#20496.
`UnboxedClosureTyper`. This requires adding a `tcx` field to
`ParameterEnvironment` but generally simplifies everything since we
only need to pass along an `UnboxedClosureTyper` or `Typer`.
