rustc: Implement custom panic runtimes
This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.
[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md
Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.
With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.
Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).
Closes#32837
This commit is an implementation of [RFC 1513] which allows applications to
alter the behavior of panics at compile time. A new compiler flag, `-C panic`,
is added and accepts the values `unwind` or `panic`, with the default being
`unwind`. This model affects how code is generated for the local crate, skipping
generation of landing pads with `-C panic=abort`.
[RFC 1513]: https://github.com/rust-lang/rfcs/blob/master/text/1513-less-unwinding.md
Panic implementations are then provided by crates tagged with
`#![panic_runtime]` and lazily required by crates with
`#![needs_panic_runtime]`. The panic strategy (`-C panic` value) of the panic
runtime must match the final product, and if the panic strategy is not `abort`
then the entire DAG must have the same panic strategy.
With the `-C panic=abort` strategy, users can expect a stable method to disable
generation of landing pads, improving optimization in niche scenarios,
decreasing compile time, and decreasing output binary size. With the `-C
panic=unwind` strategy users can expect the existing ability to isolate failure
in Rust code from the outside world.
Organizationally, this commit dismantles the `sys_common::unwind` module in
favor of some bits moving part of it to `libpanic_unwind` and the rest into the
`panicking` module in libstd. The custom panic runtime support is pretty similar
to the custom allocator support with the only major difference being how the
panic runtime is injected (takes the `-C panic` flag into account).
Overhaul borrowck error messages and compiler error formatting generally
This is a major overhaul of how the compiler reports errors. The primary goal is to be able to give many spans within the same overall context, such as this:
```
./borrow-errors.rs:73:17: 73:20: error: cannot borrow `*vec` as immutable because previous closure requires unique access [E0501]
70 let append = |e| {
~~~ closure construction occurs here
71 vec.push(e)
~~~ previous borrow occurs due to use of `vec` in closure
72 };
73 let data = &vec[3];
~~~ borrow occurs here
74 }
~ borrow from closure ends here
```
However, in the process we made a number of other changes:
- Removed the repetitive filenames from snippets and just give the line number.
- Color the line numbers blue so they "fade away"
- Remove the file name and line number from the error code suggestions since they don't seem to fit anymore. (This should probably happen in more places, like existing notes.)
- Newlines in between errors to help group them better.
This PR is not quite ready to land, but we thought it made sense to stop here and get some feedback from people at large. It'd be great if people can check out the branch and play with it. We'd be especially interested in hearing about cases that don't look good with the new formatting (I suspect they exist).
Here is a checklist of some pending work items for this PR. Some of them may be best left for follow-up PRs:
- [x] Accommodate multiple files in a `MultiSpan` (this should be easy)
- In this case, we want to print filenames though.
- [x] Remove duplicate E0500 code.
- [x] Make the header message bold, rather than current hack that makes all errors/warnings bold
- [x] Update warning text color (yellow is hard to read w/ a white background)
Moved numerous follow-ups to: https://github.com/rust-lang/rust/issues/33240
Joint work with @jonathandturner.
Fixes https://github.com/rust-lang/rust/issues/3533
Major changes:
- Remove old snippet rendering code and use the new stuff.
- Introduce `span_label` method to add a label
- Remove EndSpan mode and replace with a fn to get the last
character of a span.
- Stop using `Option<MultiSpan>` and just use an empty `MultiSpan`
- and probably a bunch of other stuff :)
rustc_driver: Allow running the compiler with a FileLoader
cc @nrc. I chose to implement this in such a way that it doesn't break anything. Please let me know if you want me to change anything.
In fact, we make JSOn the default and add an option for save-analysis-csv for the legacy behaviour.
We also rename some bits and pieces `dxr` -> `save-analysis`
Compute `target_feature` from LLVM
This is a work-in-progress fix for #31662.
The logic that computes the target features from the command line has been replaced with queries to the `TargetMachine`.
List possible keys of the -L rustc option.
Since `rustc --help -v` does not describe it, only *rustc.1* man page, but there is no man for Windows.
r? @alexcrichton
cc @steveklabnik
This commit applies all stabilizations, renamings, and deprecations that the
library team has decided on for the upcoming 1.9 release. All tracking issues
have gone through a cycle-long "final comment period" and the specific APIs
stabilized/deprecated are:
Stable
* `std::panic`
* `std::panic::catch_unwind` (renamed from `recover`)
* `std::panic::resume_unwind` (renamed from `propagate`)
* `std::panic::AssertUnwindSafe` (renamed from `AssertRecoverSafe`)
* `std::panic::UnwindSafe` (renamed from `RecoverSafe`)
* `str::is_char_boundary`
* `<*const T>::as_ref`
* `<*mut T>::as_ref`
* `<*mut T>::as_mut`
* `AsciiExt::make_ascii_uppercase`
* `AsciiExt::make_ascii_lowercase`
* `char::decode_utf16`
* `char::DecodeUtf16`
* `char::DecodeUtf16Error`
* `char::DecodeUtf16Error::unpaired_surrogate`
* `BTreeSet::take`
* `BTreeSet::replace`
* `BTreeSet::get`
* `HashSet::take`
* `HashSet::replace`
* `HashSet::get`
* `OsString::with_capacity`
* `OsString::clear`
* `OsString::capacity`
* `OsString::reserve`
* `OsString::reserve_exact`
* `OsStr::is_empty`
* `OsStr::len`
* `std::os::unix::thread`
* `RawPthread`
* `JoinHandleExt`
* `JoinHandleExt::as_pthread_t`
* `JoinHandleExt::into_pthread_t`
* `HashSet::hasher`
* `HashMap::hasher`
* `CommandExt::exec`
* `File::try_clone`
* `SocketAddr::set_ip`
* `SocketAddr::set_port`
* `SocketAddrV4::set_ip`
* `SocketAddrV4::set_port`
* `SocketAddrV6::set_ip`
* `SocketAddrV6::set_port`
* `SocketAddrV6::set_flowinfo`
* `SocketAddrV6::set_scope_id`
* `<[T]>::copy_from_slice`
* `ptr::read_volatile`
* `ptr::write_volatile`
* The `#[deprecated]` attribute
* `OpenOptions::create_new`
Deprecated
* `std::raw::Slice` - use raw parts of `slice` module instead
* `std::raw::Repr` - use raw parts of `slice` module instead
* `str::char_range_at` - use slicing plus `chars()` plus `len_utf8`
* `str::char_range_at_reverse` - use slicing plus `chars().rev()` plus `len_utf8`
* `str::char_at` - use slicing plus `chars()`
* `str::char_at_reverse` - use slicing plus `chars().rev()`
* `str::slice_shift_char` - use `chars()` plus `Chars::as_str`
* `CommandExt::session_leader` - use `before_exec` instead.
Closes#27719
cc #27751 (deprecating the `Slice` bits)
Closes#27754Closes#27780Closes#27809Closes#27811Closes#27830Closes#28050Closes#29453Closes#29791Closes#29935Closes#30014Closes#30752Closes#31262
cc #31398 (still need to deal with `before_exec`)
Closes#31405Closes#31572Closes#31755Closes#31756
Extract the code that performs the initialization of the LLVM backend
and invoke it before computing the available features. The
initialization is required to happen before the features are added to
the configuration, because they are computed by LLVM, therefore is is
now performed when creating the `Session` object.
Save/load incremental compilation dep graph
Contains the code to serialize/deserialize the dep graph to disk between executions. We also hash the item contents and compare to the new hashes. Also includes a unit test harness. There are definitely some known limitations, such as https://github.com/rust-lang/rust/issues/32014 and https://github.com/rust-lang/rust/issues/32015, but I am leaving those for follow-up work.
Note that this PR builds on https://github.com/rust-lang/rust/pull/32007, so the overlapping commits can be excluded from review.
r? @michaelwoerister
You can now pass `-Z incremental=dir` as well as saying `-Z
query-dep-graph` if you want to enable queries for some other
purpose. Accessor functions take the place of computed boolean flags.
... as single "internal compiler error" entry point.
The macros pass `file!()`, `line!()` and `format_args!(...)` on to a
cold, never-inlined function, ultimately calling `bug()` or `span_bug()`
on the `Handler` from `session::diagnostic()` via the tcx in tls or,
failing that, panicking directly.
Gate parser recovery via debugflag
Gate parser recovery via debugflag
Put in `-Z continue_parse_after_error`
This works by adding a method, `fn abort_if_no_parse_recovery`, to the
diagnostic handler in `syntax::errors`, and calling it after each
error is emitted in the parser.
(We might consider adding a debugflag to do such aborts in other
places where we are currently attempting recovery, such as resolve,
but I think the parser is the really important case to handle in the
face of #31994 and the parser bugs of varying degrees that were
injected by parse error recovery.)
r? @nikomatsakis
This works by adding a boolean flag, `continue_after_error`, to
`syntax::errors::Handler` that can be imperatively set to `true` or
`false` via a new `fn set_continue_after_error`.
The flag starts off true (since we generally try to recover from
compiler errors, and `Handler` is shared across all phases).
Then, during the `phase_1_parse_input`, we consult the setting of the
`-Z continue-parse-after-error` debug flag to determine whether we
should leave the flag set to `true` or should change it to `false`.
----
(We might consider adding a debugflag to do such aborts in other
places where we are currently attempting recovery, such as resolve,
but I think the parser is the really important case to handle in the
face of #31994 and the parser bugs of varying degrees that were
injected by parse error recovery.)
melt the ICE when lowering an impossible range
Emit a fatal error instead of panicking when HIR lowering encounters a range with no `end` point.
This involved adding a method to wire up `LoweringContext::span_fatal`.
Fixes#32245 (cc @nodakai).
r? @nrc
Restrict constants in patterns
This implements [RFC 1445](https://github.com/rust-lang/rfcs/blob/master/text/1445-restrict-constants-in-patterns.md). The primary change is to limit the types of constants used in patterns to those that *derive* `Eq` (note that implementing `Eq` is not sufficient). This has two main effects:
1. Floating point constants are linted, and will eventually be disallowed. This is because floating point constants do not implement `Eq` but only `PartialEq`. This check replaces the existing special case code that aimed to detect the use of `NaN`.
2. Structs and enums must derive `Eq` to be usable within a match.
This is a [breaking-change]: if you encounter a problem, you are most likely using a constant in an expression where the type of the constant is some struct that does not currently implement
`Eq`. Something like the following:
```rust
struct SomeType { ... }
const SOME_CONST: SomeType = ...;
match foo {
SOME_CONST => ...
}
```
The easiest and most future compatible fix is to annotate the type in question with `#[derive(Eq)]` (note that merely *implementing* `Eq` is not enough, it must be *derived*):
```rust
struct SomeType { ... }
const SOME_CONST: SomeType = ...;
match foo {
SOME_CONST => ...
}
```
Another good option is to rewrite the match arm to use an `if` condition (this is also particularly good for floating point types, which implement `PartialEq` but not `Eq`):
```rust
match foo {
c if c == SOME_CONST => ...
}
```
Finally, a third alternative is to tag the type with `#[structural_match]`; but this is not recommended, as the attribute is never expected to be stabilized. Please see RFC #1445 for more details.
cc https://github.com/rust-lang/rust/issues/31434
r? @pnkfelix
End-less ranges (`a...`) don't parse but bad syntax extensions could
conceivably produce them. Unbounded ranges (`...`) do parse and are
caught here.
The other panics in HIR lowering are all for unexpanded macros, which
cannot be constructed by bad syntax extensions.
This commit adds support for *truly* unstable options in the compiler, as well
as adding warnings for the start of the deprecation path of
unstable-but-not-really options. Specifically, the following behavior is now in
place for handling unstable options:
* As before, an unconditional error is emitted if an unstable option is passed
and the `-Z unstable-options` flag is not present. Note that passing another
`-Z` flag does not require passing `-Z unstable-options` as well.
* New flags added to the compiler will be in the `Unstable` category as opposed
to the `UnstableButNotReally` category which means they will unconditionally
emit an error when used on stable.
* All current flags are in a category where they will emit warnings when used
that the option will soon be a hard error.
Also as before, it is intended that `-Z` is akin to `#![feature]` in a crate
where it is required to unlock unstable functionality. A nightly compiler which
is used without any `-Z` flags should only be exercising stable behavior.
