add a panic-strategy field to the target specification
Now a target can define its panic strategy in its specification. If a
user doesn't specify a panic strategy via the command line, i.e. '-C
panic', then the compiler will use the panic strategy defined by the
target specification.
Custom targets can pick their panic strategy via the "panic-strategy"
field of their target specification JSON file. If omitted in the
specification, the strategy defaults to "unwind".
closes#36647
---
I checked that compiling an executable for a custom target with "panic-strategy" set to "abort" doesn't need the "eh_personality" lang item and also that standard crates compiled for that custom target didn't contained undefined symbols to _Unwind_Resume. But this needs an actual unit test, any suggestion on how to test this?
Most of the noise in the diff is due to moving `PanicStrategy` from the `rustc` to the `rustc_back` crate.
r? @alexcrichton
cc @phil-opp
Now a target can define its panic strategy in its specification. If a
user doesn't specify a panic strategy via the command line, i.e. '-C
panic', then the compiler will use the panic strategy defined by the
target specification.
Custom targets can pick their panic strategy via the "panic-strategy"
field of their target specification JSON file. If omitted in the
specification, the strategy defaults to "unwind".
closes#36647
incr. comp.: Take spans into account for ICH
This PR makes the ICH (incr. comp. hash) take spans into account when debuginfo is enabled.
A side-effect of this is that the SVH (which is based on the ICHs of all items in the crate) becomes sensitive to the tiniest change in a code base if debuginfo is enabled. Since we are not trying to model ABI compatibility via the SVH anymore (this is done via the crate disambiguator now), this should be not be a problem.
Fixes#33888.
Fixes#32753.
This commit is an implementation of [RFC 1681] which adds support to the
compiler for first-class user-define custom `#[derive]` modes with a far more
stable API than plugins have today.
[RFC 1681]: https://github.com/rust-lang/rfcs/blob/master/text/1681-macros-1.1.md
The main features added by this commit are:
* A new `rustc-macro` crate-type. This crate type represents one which will
provide custom `derive` implementations and perhaps eventually flower into the
implementation of macros 2.0 as well.
* A new `rustc_macro` crate in the standard distribution. This crate will
provide the runtime interface between macro crates and the compiler. The API
here is particularly conservative right now but has quite a bit of room to
expand into any manner of APIs required by macro authors.
* The ability to load new derive modes through the `#[macro_use]` annotations on
other crates.
All support added here is gated behind the `rustc_macro` feature gate, both for
the library support (the `rustc_macro` crate) as well as the language features.
There are a few minor differences from the implementation outlined in the RFC,
such as the `rustc_macro` crate being available as a dylib and all symbols are
`dlsym`'d directly instead of having a shim compiled. These should only affect
the implementation, however, not the public interface.
This commit also ended up touching a lot of code related to `#[derive]`, making
a few notable changes:
* Recognized derive attributes are no longer desugared to `derive_Foo`. Wasn't
sure how to keep this behavior and *not* expose it to custom derive.
* Derive attributes no longer have access to unstable features by default, they
have to opt in on a granular level.
* The `derive(Copy,Clone)` optimization is now done through another "obscure
attribute" which is just intended to ferry along in the compiler that such an
optimization is possible. The `derive(PartialEq,Eq)` optimization was also
updated to do something similar.
---
One part of this PR which needs to be improved before stabilizing are the errors
and exact interfaces here. The error messages are relatively poor quality and
there are surprising spects of this such as `#[derive(PartialEq, Eq, MyTrait)]`
not working by default. The custom attributes added by the compiler end up
becoming unstable again when going through a custom impl.
Hopefully though this is enough to start allowing experimentation on crates.io!
syntax-[breaking-change]
Commandline arguments influence whether incremental compilation
can use its compilation cache and thus their changes relative to
previous compilation sessions need to be taking into account. This
commit makes sure that one has to specify for every commandline
argument whether it influences incremental compilation or not.
We used to use `Name`, but the session outlives the tokenizer, which
means that attempts to read this field after trans has complete
otherwise panic. All reads want an `InternedString` anyhow.
This is a spiritual succesor to #34268/8531d581, in which we replaced a
number of matches of None to the unit value with `if let` conditionals
where it was judged that this made for clearer/simpler code (as would be
recommended by Manishearth/rust-clippy's `single_match` lint). The same
rationale applies to matches of None to the empty block.
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).
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 :)
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`.
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.
... 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.
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.
