Compiler panics should be rare - when they do occur, we want the report
filed by the user to contain as much information as possible. This is
especially important when the panic is due to an incremental compilation
bug, since we may not have enough information to reproduce it.
This PR sets `RUST_BACKTRACE=full` inside `rustc` if the user has not
explicitly set `RUST_BACKTRACE`. This is more verbose than
`RUST_BACKTRACE=1`, but this may make it easier to debug incremental
compilation issues. Users who find this too verbose can still manually
set `RUST_BACKTRACE` before invoking the compiler.
This only affects `rustc` (and any tool using `rustc_driver::install_ice_hook`).
It does *not* affect any user crates or the standard library -
backtraces will continue to be off by default in any application
*compiled* by rustc.
Make dead code check a query.
Dead code check is run for each invocation of the compiler, even if no modifications were involved.
This PR makes dead code check a query keyed on the module. This allows to skip the check when a module has not changed.
To perform this, a query `live_symbols_and_ignored_derived_traits` is introduced to encapsulate the global analysis of finding live symbols. The second query `check_mod_deathness` outputs diagnostics for each module based on this first query's results.
Currently, it can be `None` if the conversion from `OsString` fails, in
which case all searches will skip over the `SearchPathFile`.
The commit changes things so that the `SearchPathFile` just doesn't get
created in the first place. Same behaviour, but slightly simpler code.
Continue work on associated const equality
This actually implements some more complex logic for assigning associated consts to values.
Inside of projection candidates, it now defers to a separate function for either consts or
types. To reduce amount of code, projections are now generic over T, where T is either a Type or
a Const. I can add some comments back later, but this was the fastest way to implement it.
It also now finds the correct type of consts in type_of.
---
The current main TODO is finding the const of the def id for the LeafDef.
Right now it works if the function isn't called, but once you use the trait impl with the bound it fails inside projection.
I was hoping to get some help in getting the `&'tcx ty::Const<'tcx>`, in addition to a bunch of other `todo!()`s which I think may not be hit.
r? `@oli-obk`
Updates #92827
This code and comment appear to be out of date.
`CrateLocator::find_library_crate` is the only caller of this function
and it handles rlib vs dylib overlap itself (see
`CrateLocator::extract_lib`) after inspecting all the files present, so
it doesn't need to see them in any particular order.
Format `if_chain` invocations in clippy_utils
Not realizing it was [already obsolete](https://github.com/rust-lang/rust-clippy/pull/8360), I built a [tool to format inside `if_chain` invocations](https://crates.io/crates/rustfmt_if_chain).
This PR applies the tool to clippy_utils. (If you apply it to clippy_lints, the changes are extensive.)
Anyway, I'm making it known here in case anyone wants to use it while `if-let` chain support is developed for `rustfmt`. (There could be a few Clippy PRs between now and then, and IMHO, the code looks better with the `if_chain` invocations formatted.)
Cheers.
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changelog: none
Change Termination::report return type to ExitCode
Related to https://github.com/rust-lang/rust/issues/43301
The goal of this change is to minimize the forward compatibility risks in stabilizing Termination. By using the opaque type `ExitCode` instead of an `i32` we leave room for us to evolve the API over time to provide what cross-platform consistency we can / minimize footguns when working with exit codes, where as stabilizing on `i32` would limit what changes we could make in the future in how we represent and construct exit codes.
Implement `RawWaker` and `Waker` getters for underlying pointers
implement #87021
New APIs:
- `RawWaker::data(&self) -> *const ()`
- `RawWaker::vtable(&self) -> &'static RawWakerVTable`
- ~`Waker::as_raw_waker(&self) -> &RawWaker`~ `Waker::as_raw(&self) -> &RawWaker`
This third one is an auxiliary function to make the two APIs above more useful. Since we can only get `&Waker` in `Future::poll`, without this, we need to `transmute` it into `&RawWaker` (relying on `repr(transparent)`) in order to access its data/vtable pointers.
~Not sure if it should be named `as_raw` or `as_raw_waker`. Seems we always use `as_<something-raw>` instead of just `as_raw`. But `as_raw_waker` seems not quite consistent with `Waker::from_raw`.~ As suggested in https://github.com/rust-lang/rust/pull/91828#discussion_r770729837, use `as_raw`.
Enable combining `+crt-static` and `relocation-model=pic` on `x86_64-unknown-linux-gnu`
Modern `gcc` versions support `-static-pie`, and `rustc` will already fall-back to `-static` if the local `gcc` is too old (and hence this change is optimistic rather than absolute). This brings the `-musl` and `-gnu` targets to feature compatibility (albeit with different default settings).
Of note a `-static` or `-static-pie` binary based on glibc that uses NSS-backed functions (`gethostbyname` or `getpwuid` etc.) need to have access to the `libnss_X.so.2` libraries and any of their dynamic dependencies.
I wasn't sure about the `# only`/`# ignore` changes (I've not got a `gnux32` toolchain to test with hence not also enabling `-static-pie` there).
Disable drop range analysis
The previous PR, #93165, still performed the drop range analysis despite ignoring the results. Unfortunately, there were ICEs in the analysis as well, so some packages failed to build (see the issue #93197 for an example). This change further disables the analysis and just provides dummy results in that case.
Carefully remove bounds checks from some chunk iterator functions
So, I was writing code that requires the equivalent of `rchunks(N).rev()` (which isn't the same as forward `chunks(N)` — in particular, if the buffer length is not a multiple of `N`, I must handle the "remainder" first).
I happened to look at the codegen output of the function (I was actually interested in whether or not a nested loop was being unrolled — it was), and noticed that in the outer `rchunks(n).rev()` loop, LLVM seemed to be unable to remove the bounds checks from the iteration: https://rust.godbolt.org/z/Tnz4MYY8f (this panic was from the split_at in `RChunks::next_back`).
After doing some experimentation, it seems all of the `next_back` in the non-exact chunk iterators have the issue: (`Chunks::next_back`, `RChunks::next_back`, `ChunksMut::next_back`, and `RChunksMut::next_back`)...
Even worse, the forward `rchunks` iterators sometimes have the issue as well (... but only sometimes). For example https://rust.godbolt.org/z/oGhbqv53r has bounds checks, but if I uncomment the loop body, it manages to remove the check (which is bizarre, since I'd expect the opposite...). I suspect it's highly dependent on the surrounding code, so I decided to remove the bounds checks from them anyway. Overall, this change includes:
- All `next_back` functions on the non-`Exact` iterators (e.g. `R?Chunks(Mut)?`).
- All `next` functions on the non-exact rchunks iterators (e.g. `RChunks(Mut)?`).
I wasn't able to catch any of the other chunk iterators failing to remove the bounds checks (I checked iterations over `r?chunks(_exact)?(_mut)?` with constant chunk sizes under `-O3`, `-Os`, and `-Oz`), which makes sense, since these were the cases where it was harder to prove the bounds check correct to remove...
In fact, it took quite a bit of thinking to convince myself that using unchecked_ here was valid — so I'm not really surprised that LLVM had trouble (although compilers are slightly better at this sort of reasoning than humans). A consequence of that is the fact that the `// SAFETY` comment for these are... kinda long...
---
I didn't do this for, or even think about it for, any of the other iteration methods; just `next` and `next_back` (where it mattered). If this PR is accepted, I'll file a follow up for someone (possibly me) to look at the others later (in particular, `nth`/`nth_back` looked like they had similar logic), but I wanted to do this now, as IMO `next`/`next_back` are the most important here, since they're what gets used by the iteration protocol.
---
Note: While I don't expect this to impact performance directly, the panic is a side effect, which would otherwise not exist in these loops. That is, this could prevent the compiler from being able to move/remove/otherwise rework a loop over these iterators (as an example, it could not delete the code for a loop whose body computes a value which doesn't get used).
Also, some like to be able to have confidence this code has no panicking branches in the optimized code, and "no bounds checks" is kinda part of the selling point of Rust's iterators anyway.
Before this change, closure/generator environments coming from different
instantiations of the same generic function were all assigned the same
name even though they were distinct types with potentially different data
layout. Now we append the generic arguments of the originating function
to the type name.
This commit also emits '{closure_env#0}' as the name of these types in
order to disambiguate them from the accompanying closure function
'{closure#0}'. Previously both were assigned the same name.
