rustc_codegen_llvm: replace the first argument early in FnType::new_vtable.
Fixes#51907 by removing the vtable pointer before the `ArgType` is even created.
This allows any ABI to support trait object method calls, regardless of how it passes `*dyn Trait`.
r? @nikomatsakis
hygiene: Decouple transparencies from expansion IDs
And remove fallback to parent modules during resolution of names in scope.
This is a breaking change for users of unstable macros 2.0 (both procedural and declarative), code like this:
```rust
#![feature(decl_macro)]
macro m($S: ident) {
struct $S;
mod m {
type A = $S;
}
}
fn main() {
m!(S);
}
```
or equivalent
```rust
#![feature(decl_macro)]
macro m($S: ident) {
mod m {
type A = $S;
}
}
fn main() {
struct S;
m!(S);
}
```
stops working due to module boundaries being properly enforced.
For proc macro derives this is still reported as a compatibility warning to give `actix_derive`, `diesel_derives` and `palette_derive` time to fix their issues.
Fixes https://github.com/rust-lang/rust/issues/50504 in accordance with [this comment](https://github.com/rust-lang/rust/issues/50504#issuecomment-399764767).
Upgrade to LLVM's master branch (LLVM 7)
### Current status
~~Blocked on a [performance regression](https://github.com/rust-lang/rust/pull/51966#issuecomment-402320576). The performance regression has an [upstream LLVM issue](https://bugs.llvm.org/show_bug.cgi?id=38047) and has also [been bisected](https://reviews.llvm.org/D44282) to an LLVM revision.~~
Ready to merge!
---
This commit upgrades the main LLVM submodule to LLVM's current master branch.
The LLD submodule is updated in tandem as well as compiler-builtins.
Along the way support was also added for LLVM 7's new features. This primarily
includes the support for custom section concatenation natively in LLD so we now
add wasm custom sections in LLVM IR rather than having custom support in rustc
itself for doing so.
Some other miscellaneous changes are:
* We now pass `--gc-sections` to `wasm-ld`
* The optimization level is now passed to `wasm-ld`
* A `--stack-first` option is passed to LLD to have stack overflow always cause
a trap instead of corrupting static data
* The wasm target for LLVM switched to `wasm32-unknown-unknown`.
* The syntax for aligned pointers has changed in LLVM IR and tests are updated
to reflect this.
* ~~The `thumbv6m-none-eabi` target is disabled due to an [LLVM bug][llbug]~~
Nowadays we've been mostly only upgrading whenever there's a major release of
LLVM but enough changes have been happening on the wasm target that there's been
growing motivation for quite some time now to upgrade out version of LLD. To
upgrade LLD, however, we need to upgrade LLVM to avoid needing to build yet
another version of LLVM on the builders.
The revision of LLVM in use here is arbitrarily chosen. We will likely need to
continue to update it over time if and when we discover bugs. Once LLVM 7 is
fully released we can switch to that channel as well.
[llbug]: https://bugs.llvm.org/show_bug.cgi?id=37382
cc #50543
This commit upgrades the main LLVM submodule to LLVM's current master branch.
The LLD submodule is updated in tandem as well as compiler-builtins.
Along the way support was also added for LLVM 7's new features. This primarily
includes the support for custom section concatenation natively in LLD so we now
add wasm custom sections in LLVM IR rather than having custom support in rustc
itself for doing so.
Some other miscellaneous changes are:
* We now pass `--gc-sections` to `wasm-ld`
* The optimization level is now passed to `wasm-ld`
* A `--stack-first` option is passed to LLD to have stack overflow always cause
a trap instead of corrupting static data
* The wasm target for LLVM switched to `wasm32-unknown-unknown`.
* The syntax for aligned pointers has changed in LLVM IR and tests are updated
to reflect this.
* The `thumbv6m-none-eabi` target is disabled due to an [LLVM bug][llbug]
Nowadays we've been mostly only upgrading whenever there's a major release of
LLVM but enough changes have been happening on the wasm target that there's been
growing motivation for quite some time now to upgrade out version of LLD. To
upgrade LLD, however, we need to upgrade LLVM to avoid needing to build yet
another version of LLVM on the builders.
The revision of LLVM in use here is arbitrarily chosen. We will likely need to
continue to update it over time if and when we discover bugs. Once LLVM 7 is
fully released we can switch to that channel as well.
[llbug]: https://bugs.llvm.org/show_bug.cgi?id=37382
Implement #[alloc_error_handler]
This to-be-stable attribute is equivalent to `#[lang = "oom"]`. It is required when using the `alloc` crate without the `std` crate. It is called by `handle_alloc_error`, which is in turned called by "infallible" allocations APIs such as `Vec::push`.
Loosened rules involving statics mentioning other statics
Before this PR, trying to mention a static in any way other than taking a reference to it caused a compile-time error. So, while
```rust
static A: u32 = 42;
static B: &u32 = &A;
```
compiles successfully,
```rust
static A: u32 = 42;
static B: u32 = A; // error
```
and
```rust
static A: u32 = 42;
static B: u32 = *&A; // error
```
are not possible to express in Rust. On the other hand, introducing an intermediate `const fn` can presently allow one to do just that:
```rust
static A: u32 = 42;
static B: u32 = foo(&A); // success!
const fn foo(a: &u32) -> u32 {
*a
}
```
Preventing `const fn` from allowing to work around the ban on reading from statics would cripple `const fn` almost into uselessness.
Additionally, the limitation for reading from statics comes from the old const evaluator(s) and is not shared by `miri`.
This PR loosens the rules around use of statics to allow statics to evaluate other statics by value, allowing all of the above examples to compile and run successfully.
Reads from extern (foreign) statics are however still disallowed by miri, because there is no compile-time value to be read.
```rust
extern static A: u32;
static B: u32 = A; // error
```
This opens up a new avenue of potential issues, as a static can now not just refer to other statics or read from other statics, but even contain references that point into itself.
While it might seem like this could cause subtle bugs like allowing a static to be initialized by its own value, this is inherently impossible in miri.
Reading from a static causes the `const_eval` query for that static to be invoked. Calling the `const_eval` query for a static while already inside the `const_eval` query of said static will cause cycle errors.
It is not possible to accidentally create a bug in miri that would enable initializing a static with itself, because the memory of the static *does not exist* while being initialized.
The memory is not uninitialized, it is not there. Thus any change that would accidentally allow reading from a not yet initialized static would cause ICEs.
Tests have been modified according to the new rules, and new tests have been added for writing to `static mut`s within definitions of statics (which needs to fail), and incremental compilation with complex/interlinking static definitions.
Note that incremental compilation did not need to be adjusted, because all of this was already possible before with workarounds (like intermediate `const fn`s) and the encoding/decoding already supports all the possible cases.
r? @eddyb
Speed up compilation of large constant arrays
This is a different approach to #51672 as suggested by @oli-obk. Rather
than write each repeated value one-by-one, we write the first one and
then copy its value directly into the remaining memory.
With this change, the [toy program](c2f4744d2d/src/test/run-pass/mir_heavy_promoted.rs) goes from 63 seconds to 19 seconds on my machine.
Edit: Inlining `Size::bytes()` saves an additional 6 seconds dropping the total time to 13 seconds on my machine.
Edit2: Now down to 2.8 seconds.
r? @oli-obk
cc @nnethercote @eddyb
Do not allow LLVM to increase a TLS's alignment on macOS.
This addresses the various TLS segfault on macOS 10.10.
Fix#51794.
Fix#51758.
Fix#50867.
Fix#48866.
Fix#46355.
Fix#44056.
Add a compiletest header for edition
r? @nikomatsakis
Are the `-Zunstable-options` options needed in these tests? It looks like they aren't. If not, I can remove them.
`Self` in where clauses may not be object safe
Needs crater, virtually certain to cause regressions.
In #50781 it was discovered that our object safety rules are not sound because we allow `Self` in where clauses without restrain. This PR is a direct fix to the rules so that we disallow methods with unsound where clauses.
This currently uses hard error to measure impact, but we will want to downgrade it to a future compat error.
Part of #50781.
r? @nikomatsakis
This is virtually certain to cause regressions, needs crater.
In #50781 it was discovered that our object safety rules are not sound because we allow `Self` in where clauses without restrain. This PR is a direct fix to the rules so that we disallow methods with unsound where clauses.
This currently uses hard error to measure impact, but we will want to downgrade it to a future compat error.
Fixes#50781.
r? @nikomatsakis
The acronym is not descriptive unless one has seen it before.
* Rename the `oom` function to `handle_alloc_error`. It was **stabilized in 1.28**, so if we do this at all we need to land it this cycle.
* Rename `set_oom_hook` to `set_alloc_error_hook`
* Rename `take_oom_hook` to `take_alloc_error_hook`
Bikeshed: `alloc` v.s. `allocator`, `error` v.s. `failure`
Add existential type definitions
Note: this does not allow creating named existential types, it just desugars `impl Trait` to a less (but still very) hacky version of actual `existential type` items.
r? @nikomatsakis
