rustc: Lower link args to `@`-files on Windows more
When spawning a linker rustc has historically been known to blow OS limits for
the command line being too large, notably on Windows. This is especially true of
incremental compilation where there can be dozens of object files per
compilation. The compiler currently has logic for detecting a failure to spawn
and instead passing arguments via a file instead, but this failure detection
only triggers if a process actually fails to spawn.
Unfortunately on Windows we've got something else to worry about which is
`cmd.exe`. The compiler may be running a linker through `cmd.exe` where
`cmd.exe` has a limit of 8192 on the command line vs 32k on `CreateProcess`.
Moreso rustc actually succeeds in spawning `cmd.exe` today, it's just that after
it's running `cmd.exe` fails to spawn its child, which rustc doesn't currently
detect.
Consequently this commit updates the logic for the spawning the linker on
Windows to instead have a heuristic to see if we need to pass arguments via a
file. This heuristic is an overly pessimistic and "inaccurate" calculation which
just calls `len` on a bunch of `OsString` instances (where `len` is not
precisely the length in u16 elements). This number, when exceeding the 6k
threshold, will force rustc to always pass arguments through a file.
This strategy should avoid us trying to parse the output on Windows of the
linker to see if it successfully spawned yet failed to actually sub-spawn the
linker. We may just be passing arguments through files a little more commonly
now...
The motivation for this commit was a recent bug in Gecko [1] when beta testing,
notably when incremental compilation was enabled it blew out the limit on
`cmd.exe`. This commit will also fix#46999 as well though as emscripten uses a
bat script as well (and we're blowing the limit there).
[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1430886Closes#46999
When encountering a method call for an ADT that doesn't have any
implementation of it, we search for traits that could be implemented
that do have that method. Filter out private non-local traits that would
not be able to be implemented.
This doesn't account for public traits that are in a private scope, but
works as a first approximation and is a more correct behavior than the
current one.
renumber regions in generators
This fixes#47189, but I think we still have to double check various things around how to treat generators in MIR type check + borrow check (e.g., what borrows should be invalidated by a `Suspend`? What consistency properties should type check be enforcing anyway around the "interior" type?)
Also fixes#47587 thanks to @spastorino's commit.
r? @pnkfelix
While attempting to reproduce rust-lang/rust#47086 I noticed the
following warning:
```shell
> rustc /dev/null --crate-type proc-macro
warning: unused variable: `registrar`
--> /dev/null:0:1
```
As there are no macros to register the automatically generated registrar
function for the crate has no body. As a result its `registrar` argument
is unused triggering the above warning.
The warning is confusing and not easily actionable by the developer. It
could also be triggered legitimately by e.g. having all of the macros in
a crate #[cfg]'ed out.
Fix by naming the generated argument `_registrar` inside
`mk_registrar()`. This suppresses the unused variable warning.
Implement repr(transparent)
r? @eddyb for the functional changes. The bulk of the PR is error messages and docs, might be good to have a doc person look over those.
cc #43036
cc @nox
Custom error when moving arg outside of its closure
When given the following code:
```rust
fn give_any<F: for<'r> FnOnce(&'r ())>(f: F) {
f(&());
}
fn main() {
let mut x = None;
give_any(|y| x = Some(y));
}
```
provide a custom error:
```
error: borrowed data cannot be moved outside of its closure
--> file.rs:7:27
|
6 | let mut x = None;
| ----- borrowed data cannot be moved into here...
7 | give_any(|y| x = Some(y));
| --- ^ cannot be moved outside of its closure
| |
| ...because it cannot outlive this closure
```
instead of the generic lifetime error:
```
error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
--> file.rs:7:27
|
7 | give_any(|y| x = Some(y));
| ^
|
note: first, the lifetime cannot outlive the anonymous lifetime #2 defined on the body at 7:14...
--> file.rs:7:14
|
7 | give_any(|y| x = Some(y));
| ^^^^^^^^^^^^^^^
note: ...so that expression is assignable (expected &(), found &())
--> file.rs:7:27
|
7 | give_any(|y| x = Some(y));
| ^
note: but, the lifetime must be valid for the block suffix following statement 0 at 6:5...
--> file.rs:6:5
|
6 | / let mut x = None;
7 | | give_any(|y| x = Some(y));
8 | | }
| |_^
note: ...so that variable is valid at time of its declaration
--> file.rs:6:9
|
6 | let mut x = None;
| ^^^^^
```
Fix#45983.
When spawning a linker rustc has historically been known to blow OS limits for
the command line being too large, notably on Windows. This is especially true of
incremental compilation where there can be dozens of object files per
compilation. The compiler currently has logic for detecting a failure to spawn
and instead passing arguments via a file instead, but this failure detection
only triggers if a process actually fails to spawn.
Unfortunately on Windows we've got something else to worry about which is
`cmd.exe`. The compiler may be running a linker through `cmd.exe` where
`cmd.exe` has a limit of 8192 on the command line vs 32k on `CreateProcess`.
Moreso rustc actually succeeds in spawning `cmd.exe` today, it's just that after
it's running `cmd.exe` fails to spawn its child, which rustc doesn't currently
detect.
Consequently this commit updates the logic for the spawning the linker on
Windows to instead have a heuristic to see if we need to pass arguments via a
file. This heuristic is an overly pessimistic and "inaccurate" calculation which
just calls `len` on a bunch of `OsString` instances (where `len` is not
precisely the length in u16 elements). This number, when exceeding the 6k
threshold, will force rustc to always pass arguments through a file.
This strategy should avoid us trying to parse the output on Windows of the
linker to see if it successfully spawned yet failed to actually sub-spawn the
linker. We may just be passing arguments through files a little more commonly
now...
The motivation for this commit was a recent bug in Gecko [1] when beta testing,
notably when incremental compilation was enabled it blew out the limit on
`cmd.exe`. This commit will also fix#46999 as well though as emscripten uses a
bat script as well (and we're blowing the limit there).
[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1430886Closes#46999
Tweaks to invalid ctor messages
- Do not suggest using a constructor that isn't accessible
- Suggest the appropriate syntax (`()`/`{}` as appropriate)
- Add note when trying to use `Self` as a ctor
CC #22488, fix#47085.
check_match: fix handling of privately uninhabited types
the match-checking code used to use TyErr for signaling "unknown,
inhabited" types for a long time. It had been switched to using the
exact type in #38069, to handle uninhabited types.
However, in #39980, we discovered that we still needed the "unknown
inhabited" logic, but I used `()` instead of `TyErr` to handle that.
Revert to using `TyErr` to fix that problem.
Fixes#46964.
r? @nikomatsakis
remove bogus assertion and comments
The code (incorrectly) assumed that constants could not have generics
in scope, but it's not really a problem if they do.
Fixes#47153
r? @pnkfelix
Closure argument mismatch tweaks
- use consistent phrasing for expected and found arguments
- suggest changing arguments to tuple if possible
- suggest changing single tuple argument to arguments if possible
Fix#44150.
Add transpose conversions for nested Option and Result
These impls are useful when working with combinator
methods that expect an option or a result, but you
have a `Result<Option<T>, E>` instead of an `Option<Result<T, E>>`
or vice versa.
It is currently allowed to perform such assignments when not making use
of NLL. NLL already does this right, but let's add a test in place to
ensure it never regresses.
Thew `_raw` prefix is included because the fact that `Box`’s ownership
semantics are "dissolved" or recreated seem more important than the exact
parameter type or return type.
- use consistent phrasing for expected and found arguments
- suggest changing arugments to tuple if possible
- suggest changing single tuple argument to arguments if possible
