The previous implementation of this function was overly conservative with
liberal usage of `Option` and `.unwrap()` which in theory never triggers. This
commit essentially removes the `Option`s in favor of unsafe implementations,
improving the code generation of the fast path for LLVM to see through what's
happening more clearly.
cc #34727
E0072 update error format
Part of #35233Fixes#35506
r? @jonathandturner
The bonus for this issue currently seems to be impossible to do reliably, as the compiler seems to lack span information for item names alone, like `Foo` in `struct Foo { ... }`. It would be possible to hack something together by computing span offsets, but that seems like a solution that would be begging for trouble.
A proper solution to this would, of course, be to add span information to the right place (seems to be `rustc::hir::Item::name` but I may be wrong).
Update E0038 to the new error format
Part of #35233
Addresses #35500
"r? @jonathandturner
This doesn't compile yet, and I need help. In my naive solution, adding the span label makes our error message a mutable `errors::DiagnosticBuilder` pointer.
```bash
python src/bootstrap/bootstrap.py --step check-cfail E0038 --stage 1
```
```
Building stage0 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Building stage0 test artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Building stage0 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Compiling rustc v0.0.0 (file:///home/nash/code/rust/src/librustc)
src/librustc/traits/error_reporting.rs:735:9: 735:12 error: mismatched types [E0308]
src/librustc/traits/error_reporting.rs:735 err
^~~
src/librustc/traits/error_reporting.rs:735:9: 735:12 help: run `rustc --explain E0308` to see a detailed explanation
src/librustc/traits/error_reporting.rs:735:9: 735:12 note: expected type `core::option::Option<errors::DiagnosticBuilder<'tcx>>`
src/librustc/traits/error_reporting.rs:735:9: 735:12 note: found type `core::option::Option<&mut errors::DiagnosticBuilder<'_>>`
error: aborting due to previous error
error: Could not compile `rustc`.
To learn more, run the command again with --verbose.
command did not execute successfully: "/home/nash/code/rust/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "-j" "4" "--target" "x86_64-unknown-linux-gnu" "--release" "--features" " jemalloc" "--manifest-path" "/home/nash/code/rust/src/rustc/Cargo.toml"
expected success, got: exit code: 101
```
Update e0017 to new format
Updated `span_err!` to use `struct_span_err!` and provide a `span_label` that describes the error in context.
Updated the test to look for the `span_label`s that are provided now.
refactor lvalue_ty to be method of lvalue
Currently `Mir` (and `MirContext`) implement a method `lvalue_ty` (and actually many more `foo_ty`). But this should be a method of `Lvalue`.
If you have an `lvalue` and you want to get its type, the natural thing to write is:
```
lvalue.ty()
```
Of course it needs context, but still:
```
lvalue.ty(mir, tcx)
```
Makes more sense than
```
mir.lvalue_ty(lvalue, tcx)
```
I actually think we should go a step farther and have traits so we could get the type of some value generically, but that's up for debate. The thing I'm running into a lot in the compiler is I have a value of type `Foo` and I know that there is some related type `Bar` which I can get through some combination of method calls, but it's often not as direct as I would imagine. Unless you already know the code, its not clear why you would look in `Mir` for a method to get the type of an `Lvalue`.
