Partial support for raw-dylib linkage
First cut of functionality for issue #58713: add support for `#[link(kind = "raw-dylib")]` on `extern` blocks in lib crates compiled to .rlib files. Does not yet support `#[link_name]` attributes on functions, or the `#[link_ordinal]` attribute, or `#[link(kind = "raw-dylib")]` on `extern` blocks in bin crates; I intend to publish subsequent PRs to fill those gaps. It's also not yet clear whether this works for functions in `extern "stdcall"` blocks; I also intend to investigate that shortly and make any necessary changes as a follow-on PR.
This implementation calls out to an LLVM function to construct the actual `.idata` sections as temporary `.lib` files on disk and then links those into the generated .rlib.
This does not yet support #[link_name] attributes on functions, the #[link_ordinal]
attribute, #[link(kind = "raw-dylib")] on extern blocks in bin crates, or
stdcall functions on 32-bit x86.
Restoring the `num_def_ids` function in the CStore API
## The context
I am the maintainer of https://github.com/hacspec/hacspec, an embedded Rust DSL aimed at cryptographic specifications. As it is normal for an embedded DSL, Hacspec's compiler relies on being plugged to the internal API of the Rust compiler, which is unstable and subject to changes.
## The problem
The Hacspec compiler features its own typechecker, that performs an additional, more restrictive typechecking pass over the Rust code of a crate. To complete this typechecking, the Hacspec compiler needs to retrieve the signature of functions defined in non-local imported crates. Rather than retrieving these signatures on-demand, the Hacspec compiler pre-populates its typechecking context with all the Hacspec-compatible symbols defined in non-local crates first. This requires having a way to iterate over all the definitions in a non-local crate.
I used to do this with `CrateMetadata::all_def_path_hashes_and_def_ids`, but this function was deleted in 908bf5a310. Then, I fellback on `CStore::num_def_ids`, exploiting the fact that all the `DefIds` for a crate have the same `krate_num` and range from `0` to `num_def_ids(krate_num)`. But `num_def_ids` was deleted in b6120bfb35.
I looked to the `Cstore::item_children_untracked` function to replicate the feature of traversing through all the `DefId` for a crate, using `CRATE_DEF_INDEX` as the root, but this does not work as recursive `Cstore::item_children_untracked` calls do not reach all the symbols I was able to reach using the two previous methods.
## Description of this PR
This PR simply restores in the public API of `CStore` the `num_def_ids` function, giving the size of the definition table for a given crate.
Remove unused feature gates
The first commit removes a usage of a feature gate, but I don't expect it to be controversial as the feature gate was only used to workaround a limitation of rust in the past. (closures never being `Clone`)
The second commit uses `#[allow_internal_unstable]` to avoid leaking the `trusted_step` feature gate usage from inside the index newtype macro. It didn't work for the `min_specialization` feature gate though.
The third commit removes (almost) all feature gates from the compiler that weren't used anyway.
Restored underlying num_def_ids_method
Update compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
Changed name to fit with naming convention
Co-authored-by: bjorn3 <bjorn3@users.noreply.github.com>
Update compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
Replace regular doc with Rustdoc comment
Co-authored-by: Joshua Nelson <jyn514@gmail.com>
Clarifies third-party use of num_def_ids_untracked
Remove CrateNum parameter for queries that only work on local crate
The pervasive `CrateNum` parameter is a remnant of the multi-crate rustc idea.
Using `()` as query key in those cases avoids having to worry about the validity of the query key.
Preserve `SyntaxContext` for invalid/dummy spans in crate metadata
Fixes#85197
We already preserved the `SyntaxContext` for invalid/dummy spans in the
incremental cache, but we weren't doing the same for crate metadata.
If an invalid (lo/hi from different files) span is written to the
incremental cache, we will decode it with a 'dummy' location, but keep
the original `SyntaxContext`. Since the crate metadata encoder was only
checking for `DUMMY_SP` (dummy location + root `SyntaxContext`),
the metadata encoder would treat it as a normal span, encoding the
`SyntaxContext`. As a result, the final span encoded to the metadata
would change across sessions, even if the crate itself was unchanged.
This could lead to an 'unstable fingerprint' ICE under the following conditions:
1. We compile a crate with an invalid span using incremental compilation. The metadata encoder discards the `SyntaxContext` since the span is invalid, while the incremental cache encoder preserves the `SyntaxContext`
2. From another crate, we execute a foreign query, decoding the invalid span from the metadata as `DUMMY_SP` (e.g. with `SyntaxContext::root()`). This span gets hashed into the query fingerprint. So far, this has always happened through the `optimized_mir` query.
3. We recompile the first crate using our populated incremental cache, without changing anything. We load the (previously) invalid span from our incremental cache - it gets converted to a span with a dummy (but valid) location, along with the original `SyntaxContext`. This span gets written out to the crate metadata - since it now has a valid location, we preserve its `SyntaxContext`.
4. We recompile the second crate, again using a populated incremental cache. We now re-run the foreign query `optimized_mir` - the foreign crate hash is unchanged, but we end up decoding a different span (it now ha a non-root `SyntaxContext`). This results in the fingerprint changing, resulting in an ICE.
This PR updates our encoding of spans in the crate metadata to mirror
the encoding of spans into the incremental cache. We now always encode a
`SyntaxContext`, and encode location information for spans with a
non-dummy location.
Fix diagnostic for cross crate private tuple struct constructors
Fixes#78708.
There was already some limited support for certain cross-crate scenarios but that didn't handle a tuple struct rexported from an inner module for example (e.g. the NonZero* types as seen in #85049).
```Rust
➜ cat bug.rs
fn main() {
let _x = std::num::NonZeroU32(12);
let n = std::num::NonZeroU32::new(1).unwrap();
match n {
std::num::NonZeroU32(i) => {},
}
}
```
**Before:**
<details>
```Rust
➜ rustc +nightly bug.rs
error[E0423]: expected function, tuple struct or tuple variant, found struct `std::num::NonZeroU32`
--> bug.rs:2:14
|
2 | let _x = std::num::NonZeroU32(12);
| ^^^^^^^^^^^^^^^^^^^^^^^^ help: use struct literal syntax instead: `std::num::NonZeroU32 { 0: val }`
|
::: /home/luqman/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/nonzero.rs:148:1
[snip]
error[E0532]: expected tuple struct or tuple variant, found struct `std::num::NonZeroU32`
--> bug.rs:5:9
|
5 | std::num::NonZeroU32(i) => {},
| ^^^^^^^^^^^^^^^^^^^^^^^ help: use struct pattern syntax instead: `std::num::NonZeroU32 { 0 }`
|
::: /home/luqman/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/num/nonzero.rs:148:1
[snip]
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0423, E0532.
For more information about an error, try `rustc --explain E0423`.
```
</details>
**After:**
<details>
```Rust
➜ /rust/build/x86_64-unknown-linux-gnu/stage1/bin/rustc bug.rs
error[E0423]: cannot initialize a tuple struct which contains private fields
--> bug.rs:2:14
|
2 | let _x = std::num::NonZeroU32(12);
| ^^^^^^^^^^^^^^^^^^^^
|
note: constructor is not visible here due to private fields
--> /rust/library/core/src/num/nonzero.rs:148:1
[snip]
error[E0532]: cannot match against a tuple struct which contains private fields
--> bug.rs:5:9
|
5 | std::num::NonZeroU32(i) => {},
| ^^^^^^^^^^^^^^^^^^^^
|
note: constructor is not visible here due to private fields
--> bug.rs:5:30
|
5 | std::num::NonZeroU32(i) => {},
| ^ private field
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0423, E0532.
For more information about an error, try `rustc --explain E0423`.
```
</details>
One question is if we should only collect the needed info for the cross-crate case after encountering an error instead of always doing it. Perf run perhaps to gauge the impact.
Fixes#85197
We already preserved the `SyntaxContext` for invalid/dummy spans in the
incremental cache, but we weren't doing the same for crate metadata.
If an invalid (lo/hi from different files) span is written to the
incremental cache, we will decode it with a 'dummy' location, but keep
the original `SyntaxContext`. Since the crate metadata encoder was only
checking for `DUMMY_SP` (dummy location + root `SyntaxContext`),
the metadata encoder would treat it as a normal span, encoding the
`SyntaxContext`. As a result, the final span encoded to the metadata
would change across sessions, even if the crate itself was unchanged.
This PR updates our encoding of spans in the crate metadata to mirror
the encoding of spans into the incremental cache. We now always encode a
`SyntaxContext`, and encode location information for spans with a
non-dummy location.
Fix `--remap-path-prefix` not correctly remapping `rust-src` component paths and unify handling of path mapping with virtualized paths
This PR fixes#73167 ("Binaries end up containing path to the rust-src component despite `--remap-path-prefix`") by preventing real local filesystem paths from reaching compilation output if the path is supposed to be remapped.
`RealFileName::Named` introduced in #72767 is now renamed as `LocalPath`, because this variant wraps a (most likely) valid local filesystem path.
`RealFileName::Devirtualized` is renamed as `Remapped` to be used for remapped path from a real path via `--remap-path-prefix` argument, as well as real path inferred from a virtualized (during compiler bootstrapping) `/rustc/...` path. The `local_path` field is now an `Option<PathBuf>`, as it will be set to `None` before serialisation, so it never reaches any build output. Attempting to serialise a non-`None` `local_path` will cause an assertion faliure.
When a path is remapped, a `RealFileName::Remapped` variant is created. The original path is preserved in `local_path` field and the remapped path is saved in `virtual_name` field. Previously, the `local_path` is directly modified which goes against its purpose of "suitable for reading from the file system on the local host".
`rustc_span::SourceFile`'s fields `unmapped_path` (introduced by #44940) and `name_was_remapped` (introduced by #41508 when `--remap-path-prefix` feature originally added) are removed, as these two pieces of information can be inferred from the `name` field: if it's anything other than a `FileName::Real(_)`, or if it is a `FileName::Real(RealFileName::LocalPath(_))`, then clearly `name_was_remapped` would've been false and `unmapped_path` would've been `None`. If it is a `FileName::Real(RealFileName::Remapped{local_path, virtual_name})`, then `name_was_remapped` would've been true and `unmapped_path` would've been `Some(local_path)`.
cc `@eddyb` who implemented `/rustc/...` path devirtualisation
This PR implements span quoting, allowing proc-macros to produce spans
pointing *into their own crate*. This is used by the unstable
`proc_macro::quote!` macro, allowing us to get error messages like this:
```
error[E0412]: cannot find type `MissingType` in this scope
--> $DIR/auxiliary/span-from-proc-macro.rs:37:20
|
LL | pub fn error_from_attribute(_args: TokenStream, _input: TokenStream) -> TokenStream {
| ----------------------------------------------------------------------------------- in this expansion of procedural macro `#[error_from_attribute]`
...
LL | field: MissingType
| ^^^^^^^^^^^ not found in this scope
|
::: $DIR/span-from-proc-macro.rs:8:1
|
LL | #[error_from_attribute]
| ----------------------- in this macro invocation
```
Here, `MissingType` occurs inside the implementation of the proc-macro
`#[error_from_attribute]`. Previosuly, this would always result in a
span pointing at `#[error_from_attribute]`
This will make many proc-macro-related error message much more useful -
when a proc-macro generates code containing an error, users will get an
error message pointing directly at that code (within the macro
definition), instead of always getting a span pointing at the macro
invocation site.
This is implemented as follows:
* When a proc-macro crate is being *compiled*, it causes the `quote!`
macro to get run. This saves all of the sapns in the input to `quote!`
into the metadata of *the proc-macro-crate* (which we are currently
compiling). The `quote!` macro then expands to a call to
`proc_macro::Span::recover_proc_macro_span(id)`, where `id` is an
opaque identifier for the span in the crate metadata.
* When the same proc-macro crate is *run* (e.g. it is loaded from disk
and invoked by some consumer crate), the call to
`proc_macro::Span::recover_proc_macro_span` causes us to load the span
from the proc-macro crate's metadata. The proc-macro then produces a
`TokenStream` containing a `Span` pointing into the proc-macro crate
itself.
The recursive nature of 'quote!' can be difficult to understand at
first. The file `src/test/ui/proc-macro/quote-debug.stdout` shows
the output of the `quote!` macro, which should make this eaier to
understand.
This PR also supports custom quoting spans in custom quote macros (e.g.
the `quote` crate). All span quoting goes through the
`proc_macro::quote_span` method, which can be called by a custom quote
macro to perform span quoting. An example of this usage is provided in
`src/test/ui/proc-macro/auxiliary/custom-quote.rs`
Custom quoting currently has a few limitations:
In order to quote a span, we need to generate a call to
`proc_macro::Span::recover_proc_macro_span`. However, proc-macros
support renaming the `proc_macro` crate, so we can't simply hardcode
this path. Previously, the `quote_span` method used the path
`crate::Span` - however, this only works when it is called by the
builtin `quote!` macro in the same crate. To support being called from
arbitrary crates, we need access to the name of the `proc_macro` crate
to generate a path. This PR adds an additional argument to `quote_span`
to specify the name of the `proc_macro` crate. Howver, this feels kind
of hacky, and we may want to change this before stabilizing anything
quote-related.
Additionally, using `quote_span` currently requires enabling the
`proc_macro_internals` feature. The builtin `quote!` macro
has an `#[allow_internal_unstable]` attribute, but this won't work for
custom quote implementations. This will likely require some additional
tricks to apply `allow_internal_unstable` to the span of
`proc_macro::Span::recover_proc_macro_span`.
This commit implements both the native linking modifiers infrastructure
as well as an initial attempt at the individual modifiers from the RFC.
It also introduces a feature flag for the general syntax along with
individual feature flags for each modifier.
Give a better error when `std` or `core` are missing
- Suggest using `rustup target add` if `RUSTUP_HOME` is set. I don't know if there's any precedent for doing this, but it seems harmless enough and it will be a big help.
- On nightly, suggest using `cargo build -Z build-std` if `CARGO` is set
- Add a note about `#![no_std]` if `std` is missing but not core
- Add a note that std may be unsupported if `std` is missing but not core
Fixes https://github.com/rust-lang/rust/issues/84418.
r? `@petrochenkov`
