304c8b1eda made the Session's one-time-diagnostics set take a
special-purpose `DiagnosticMessageId` enum rather than a LintID so that
it could support more than just lints, but the `diag_span_note_once` and
`diag_note_once` methods continued to take references to lints: for API
consistency, we now make these methods take a `DiagnosticMessageId`
while we add support for one-time span-suggestions.
This commit prepares to enable ThinLTO and multiple codegen units in release
mode by default. We've still got a debuginfo bug or two to sort out before
actually turning it on by default.
show macro backtrace with -Z flag
Fixes#39413 by adding a facility to restore the "old school" macro expansion backtraces (previously removed in 61865384b8).
The restored functionality is accessed through the flag `-Z external-macro-backtrace`. Errors showing the truncated backtraces will suggest this flag.
### Example
Code: <details>
`a/src/lib.rs`
```rust
#[macro_export]
macro_rules! a {
() => { a!(@) };
(@) => { a!(@@) };
(@@) => {
syntax error;
}
}
```
`b/src/main.rs`
```rust
#[macro_use] extern crate a;
macro_rules! b {
() => { b!(@) };
(@) => { b!(@@) };
(@@) => {
syntax error;
}
}
fn main() {
a!();
b!();
}
```
</details>
<br/><br/>
Running without env var (note: first error is from remote macro, second from local macro):
<details>
```
$ cargo +custom run
Compiling b v0.1.0
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:12:5
|
12 | a!();
| ^^^^^
| |
| expected one of 8 possible tokens here
| unexpected token
|
= note: this error originates in a macro outside of the current crate (run with RUST_MACRO_BACKTRACE=1 for more info)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:7:16
|
7 | syntax error;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
...
13 | b!();
| ----- in this macro invocation
error: aborting due to 2 previous errors
error: Could not compile `b`.
To learn more, run the command again with --verbose.
```
</details>
The output is the same as today, except for an addition to the note which aids discoverability of the new environment variable.
<br/><br/>
Running _with_ env var:
<details>
```
$ RUST_MACRO_BACKTRACE=1 cargo +custom run
Compiling b v0.1.0
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> <a macros>:1:72
|
1 | ( ) => { a ! ( @ ) } ; ( @ ) => { a ! ( @ @ ) } ; ( @ @ ) => { syntax error ;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
src/main.rs:12:5: 12:10 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:11: 1:20 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:36: 1:47 note: in this expansion of a! (defined in <a macros>)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:7:16
|
7 | syntax error;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
src/main.rs:12:5: 12:10 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:11: 1:20 note: in this expansion of a! (defined in <a macros>)
<a macros>:1:36: 1:47 note: in this expansion of a! (defined in <a macros>)
error: expected one of `!`, `.`, `::`, `;`, `?`, `{`, `}`, or an operator, found `error`
--> src/main.rs:7:16
|
7 | syntax error;
| -^^^^^ unexpected token
| |
| expected one of 8 possible tokens here
src/main.rs:13:5: 13:10 note: in this expansion of b! (defined in src/main.rs)
src/main.rs:4:13: 4:18 note: in this expansion of b! (defined in src/main.rs)
src/main.rs:5:14: 5:20 note: in this expansion of b! (defined in src/main.rs)
error: aborting due to 2 previous errors
error: Could not compile `b`.
To learn more, run the command again with --verbose.
```
</details>
The output is hard to read, but better than nothing (and it's exactly what we used to have before the infamous `fix_multispans_in_std_macros`).
<br/><br/>
Wishlist:
- Save the actual source of macros in crate metadata, not just AST, so the output can be improved
- Hopefully this would allow line numbers in the trace as well
- Show the actual macro invocations in the traces
r? @nrc
This commit adds a new target to the compiler: wasm32-unknown-unknown. This
target is a reimagining of what it looks like to generate WebAssembly code from
Rust. Instead of using Emscripten which can bring with it a weighty runtime this
instead is a target which uses only the LLVM backend for WebAssembly and a
"custom linker" for now which will hopefully one day be direct calls to lld.
Notable features of this target include:
* There is zero runtime footprint. The target assumes nothing exists other than
the wasm32 instruction set.
* There is zero toolchain footprint beyond adding the target. No custom linker
is needed, rustc contains everything.
* Very small wasm modules can be generated directly from Rust code using this
target.
* Most of the standard library is stubbed out to return an error, but anything
related to allocation works (aka `HashMap`, `Vec`, etc).
* Naturally, any `#[no_std]` crate should be 100% compatible with this new
target.
This target is currently somewhat janky due to how linking works. The "linking"
is currently unconditional whole program LTO (aka LLVM is being used as a
linker). Naturally that means compiling programs is pretty slow! Eventually
though this target should have a linker.
This target is also intended to be quite experimental. I'm hoping that this can
act as a catalyst for further experimentation in Rust with WebAssembly. Breaking
changes are very likely to land to this target, so it's not recommended to rely
on it in any critical capacity yet. We'll let you know when it's "production
ready".
---
Currently testing-wise this target is looking pretty good but isn't complete.
I've got almost the entire `run-pass` test suite working with this target (lots
of tests ignored, but many passing as well). The `core` test suite is still
getting LLVM bugs fixed to get that working and will take some time. Relatively
simple programs all seem to work though!
---
It's worth nothing that you may not immediately see the "smallest possible wasm
module" for the input you feed to rustc. For various reasons it's very difficult
to get rid of the final "bloat" in vanilla rustc (again, a real linker should
fix all this). For now what you'll have to do is:
cargo install --git https://github.com/alexcrichton/wasm-gc
wasm-gc foo.wasm bar.wasm
And then `bar.wasm` should be the smallest we can get it!
---
In any case for now I'd love feedback on this, particularly on the various
integration points if you've got better ideas of how to approach them!
The `ErrorId` variant takes a u16 so that `DiagnosticMessageId` can retain
its `Copy` status (the present author's first choice having been the "EXXX"
code as a string).
The duplicated "type mismatch resolving `{}`" literal is unfortunate, but
the `struct_span_err!` macro (which we want to mark that error code as
used) is fussy about taking a literal, and the one-time-diagnostics set
needs an owned string.
This is concerning #33941 and probably #45805!
Avoid repetition on “use of unstable library feature 'rustc_private'”
This PR fixes the error by only emitting it when the span contains a real file (is not inside a macro) - and making sure it's emitted only once per span.
The first check was needed because spans-within-macros seem to differ a lot and "fixing" them to the real location is not trivial (and the method that does this is private to another module). It also feels like there always will be an error on import, with the real file name, so not sure there's a point to re-emit the same error at macro use.
Fix#44953.
rustc: Allow target-specific default cgus
Some targets, like msp430 and nvptx, don't work with multiple codegen units
right now for bugs or fundamental reasons. To expose this allow targets to
express a default.
Closes#45000
Some targets, like msp430 and nvptx, don't work with multiple codegen units
right now for bugs or fundamental reasons. To expose this allow targets to
express a default.
Closes#45000
Make `-Z borrowck-mir` imply that `EndRegion`'s should be emitted.
Before this change, the `-Z borrowck-mir` flag is useless if you do not also pass `-Z emit-end-regions`.
So, in the same spirit as f2892ad281, make `-Z borrowck-mir` also emit `EndRegion` statements. (This will hopefully avoid some initial speed bumps for new-comers helping out with NLL.)
This boolean field on the error `Handler` is toggled to silence
warnings when `-A warnings` is passed. (This is actually a separate
mechanism from the global lint level—whether there's some redundancy
to be factored away here is an important question, but not one we
concern ourselves with in this commit.) But the same rationale
applies for `--cap-lints allow`. In particular, this makes the "soft"
feature-gate warning introduced in 8492ad24 (which is not a lint, but
just calls `struct_span_warn`) not pollute the builds of dependent
crates.
Thanks to @kennytm for pointing out the potential of
`can_emit_warnings` for this purpose.
Resolves#44213.
This commit removes the `dep_graph` field from the `Session` type according to
issue #44390. Most of the fallout here was relatively straightforward and the
`prepare_session_directory` function was rejiggered a bit to reuse the results
in the later-called `load_dep_graph` function.
Closes#44390
This feature allows targets to opt in to full support of the crt-static
feature. Currently, crt-static is allowed on all targets, even those
that really can't or really shouldn't support it. This works because it
is very loose in the specification of its effects. Changing the behavior
of crt-static to be more strict in how it chooses libraries and links
executables would likely cause compilation to fail on these platforms.
To avoid breaking existing uses of crt-static, whitelist targets that
support the new, stricter behavior. For all other targets, this changes
crt-static from being "mostly a no-op" to "explicitly a no-op".
In preparation for incremental compilation this commit refactors the lint
handling infrastructure in the compiler to be more "eager" and overall more
incremental-friendly. Many passes of the compiler can emit lints at various
points but before this commit all lints were buffered in a table to be emitted
at the very end of compilation. This commit changes these lints to be emitted
immediately during compilation using pre-calculated lint level-related data
structures.
Linting today is split into two phases, one set of "early" lints run on the
`syntax::ast` and a "late" set of lints run on the HIR. This commit moves the
"early" lints to running as late as possible in compilation, just before HIR
lowering. This notably means that we're catching resolve-related lints just
before HIR lowering. The early linting remains a pass very similar to how it was
before, maintaining context of the current lint level as it walks the tree.
Post-HIR, however, linting is structured as a method on the `TyCtxt` which
transitively executes a query to calculate lint levels. Each request to lint on
a `TyCtxt` will query the entire crate's 'lint level data structure' and then go
from there about whether the lint should be emitted or not.
The query depends on the entire HIR crate but should be very quick to calculate
(just a quick walk of the HIR) and the red-green system should notice that the
lint level data structure rarely changes, and should hopefully preserve
incrementality.
Overall this resulted in a pretty big change to the test suite now that lints
are emitted much earlier in compilation (on-demand vs only at the end). This in
turn necessitated the addition of many `#![allow(warnings)]` directives
throughout the compile-fail test suite and a number of updates to the UI test
suite.
This PR is an implementation of [RFC 1974] which specifies a new method of
defining a global allocator for a program. This obsoletes the old
`#![allocator]` attribute and also removes support for it.
[RFC 1974]: https://github.com/rust-lang/rfcs/pull/197
The new `#[global_allocator]` attribute solves many issues encountered with the
`#![allocator]` attribute such as composition and restrictions on the crate
graph itself. The compiler now has much more control over the ABI of the
allocator and how it's implemented, allowing much more freedom in terms of how
this feature is implemented.
cc #27389
Prior to this PR, when we aborted because a "critical pass" failed, we
displayed the number of errors from that critical pass. While that's the
number of errors that caused compilation to abort in *that place*,
that's not what people really want to know. Instead, always report the
total number of errors, and don't bother to track the number of errors
from the last pass that failed.
This changes the compiler driver API to handle errors more smoothly,
and therefore is a compiler-api-[breaking-change].
Fixes#42793.
This commit integrates the `jobserver` crate into the compiler. The crate was
previously integrated in to Cargo as part of rust-lang/cargo#4110. The purpose
here is to two-fold:
* Primarily the compiler can cooperate with Cargo on parallelism. When you run
`cargo build -j4` then this'll make sure that the entire build process between
Cargo/rustc won't use more than 4 cores, whereas today you'd get 4 rustc
instances which may all try to spawn lots of threads.
* Secondarily rustc/Cargo can now integrate with a foreign GNU `make` jobserver.
This means that if you call cargo/rustc from `make` or another
jobserver-compatible implementation it'll use foreign parallelism settings
instead of creating new ones locally.
As the number of parallel codegen instances in the compiler continues to grow
over time with the advent of incremental compilation it's expected that this'll
become more of a problem, so this is intended to nip concurrent concerns in the
bud by having all the tools to cooperate!
Note that while rustc has support for itself creating a jobserver it's far more
likely that rustc will always use the jobserver configured by Cargo. Cargo today
will now set a jobserver unconditionally for rustc to use.
