Implement constant support in MIR.
All of the intended features in `trans::consts` are now supported by `mir::constant`.
The implementation is considered a temporary measure until `miri` replaces it.
A `-Z orbit` bootstrap build will only translate LLVM IR from AST for `#[rustc_no_mir]` functions.
Furthermore, almost all checks of constant expressions have been moved to MIR.
In non-`const` functions, trees of temporaries are promoted, as per RFC 1414 (rvalue promotion).
Promotion before MIR borrowck would allow reasoning about promoted values' lifetimes.
The improved checking comes at the cost of four `[breaking-change]`s:
* repeat counts must contain a constant expression, e.g.:
`let arr = [0; { println!("foo"); 5 }];` used to be allowed (it behaved like `let arr = [0; 5];`)
* dereference of a reference to a `static` cannot be used in another `static`, e.g.:
`static X: [u8; 1] = [1]; static Y: u8 = (&X)[0];` was unintentionally allowed before
* the type of a `static` *must* be `Sync`, irrespective of the initializer, e.g.
`static FOO: *const T = &BAR;` worked as `&T` is `Sync`, but it shouldn't because `*const T` isn't
* a `static` cannot wrap `UnsafeCell` around a type that *may* need drop, e.g.
`static X: MakeSync<UnsafeCell<Option<String>>> = MakeSync(UnsafeCell::new(None));`
was previously allowed based on the fact `None` alone doesn't need drop, but in `UnsafeCell`
it can be later changed to `Some(String)` which *does* need dropping
The drop restrictions are relaxed by RFC 1440 (#33156), which is implemented, but feature-gated.
However, creating `UnsafeCell` from constants is unstable, so users can just enable the feature gate.
parser: do not try to continue with `unsafe` on foreign fns
The changed line makes it look like `unsafe` is allowed, but the first statement of `parse_item_foreign_fn` is:
```
self.expect_keyword(keywords::Fn)?;
```
So we get the strange "expected one of `fn`, `pub`, `static`, or `unsafe`, found `unsafe`".
Fixes: #27361
parser: fix suppression of syntax errors in range RHS
Invalid expressions on the RHS were just swallowed without generating an error. The new version more closely mirrors the code for parsing `..x` in the `parse_prefix_range_expr` method below, where no cancel is done either.
Fixes#33262.
Instead of finding aux-build files in `auxiliary`, we now search for an
`aux` directory relative to the test. So if your test is
`compile-fail/foo.rs`, we would look in `compile-fail/aux`. Similarly,
we ignore the `aux` directory when searching for tets.
debuginfo: Fix regression in namespace handling for struct types.
Fixes a small regression that has been introduced in recent refactorings.
Fixes#33193
r? @eddyb
Short-cut `T: Sized` trait selection for ADTs
Basically avoids all nested obligations when checking whether an ADT is sized - this speeds up typeck by ~15%
The refactoring fixed#32963, but I also want to make `Copy` not object-safe (will commit that soon).
Fixes#33201
r? @nikomatsakis
This requirement appears to be missing from RFC1214, but is clearly
necessary for translation. The last field of a tuple/enum remains in
a state of limbo, compiling but causing an ICE when it is used - we
should eventually fix that somehow.
this is a [breaking-change] - a soundness fix - and requires a
crater run.
rustdoc: HTML-escape Rust code (from constants)
Especially in cases like the one in the test file, this can blow up the rendering big time if string constants in the code contain HTML.
But also other constants can contain special chars (e.g. `&` as an operator in constant expressions).
rustdoc: fix inserting source code spans for constant values
This will go wrong when the constants partially result from macro expansion.
Instead, use the expressions and pretty-print them as Rust code.
Fixes: #33302
parser: change warning into an error on `T<A=B, C>`
part of #32214
This seems to be the obvious fix, and the error message is consistent with all the other parser errors ("expected x, found y").
resolve: print location of static for "static in pattern" error
The implementation mirrors the one for "constant defined here" annotation used for constant patterns in the irrefutable-pattern case.
Fixes: #23716
fix various const eval errors
These were found after const_evaluating arbitrary expressions and linting if the const evaluator failed
fixes#33275 (int -> float casts for negative ints)
fixes#33291 (int -> char casts (new! wasn't allowed in constants until this PR))
r? @eddyb
cc @bluss @japaric
Especially in cases like the one in the test file, this can blow
up the docs big time if string constants in the code contain HTML.
But also other constants can contain special chars (e.g. `&` as an
operator in constant expressions).
This will go wrong when the constants partially result from macro expansion.
Instead, use the expressions and pretty-print them as Rust code.
Fixes: #33302
typeck: remove confusing suggestion for calling a fn type
* It is not clear what a "base function" is.
* The suggestion just adds parens, so suggests calling without args.
The second point could be fixed with e.g. `(...)` instead of `()`,
but the preceding "note: X is a function, perhaps you wish to call it"
should already be clear enough.
Fixes: #31341
match check: note "catchall" patterns in unreachable error
Caught as catchall patterns are:
* unconditional name bindings
* references to them
* tuple bindings with catchall elements
Fixes#31221.
Overhaul borrowck error messages and compiler error formatting generally
This is a major overhaul of how the compiler reports errors. The primary goal is to be able to give many spans within the same overall context, such as this:
```
./borrow-errors.rs:73:17: 73:20: error: cannot borrow `*vec` as immutable because previous closure requires unique access [E0501]
70 let append = |e| {
~~~ closure construction occurs here
71 vec.push(e)
~~~ previous borrow occurs due to use of `vec` in closure
72 };
73 let data = &vec[3];
~~~ borrow occurs here
74 }
~ borrow from closure ends here
```
However, in the process we made a number of other changes:
- Removed the repetitive filenames from snippets and just give the line number.
- Color the line numbers blue so they "fade away"
- Remove the file name and line number from the error code suggestions since they don't seem to fit anymore. (This should probably happen in more places, like existing notes.)
- Newlines in between errors to help group them better.
This PR is not quite ready to land, but we thought it made sense to stop here and get some feedback from people at large. It'd be great if people can check out the branch and play with it. We'd be especially interested in hearing about cases that don't look good with the new formatting (I suspect they exist).
Here is a checklist of some pending work items for this PR. Some of them may be best left for follow-up PRs:
- [x] Accommodate multiple files in a `MultiSpan` (this should be easy)
- In this case, we want to print filenames though.
- [x] Remove duplicate E0500 code.
- [x] Make the header message bold, rather than current hack that makes all errors/warnings bold
- [x] Update warning text color (yellow is hard to read w/ a white background)
Moved numerous follow-ups to: https://github.com/rust-lang/rust/issues/33240
Joint work with @jonathandturner.
Fixes https://github.com/rust-lang/rust/issues/3533
Overhaul borrowck error messages and compiler error formatting generally
This is a major overhaul of how the compiler reports errors. The primary goal is to be able to give many spans within the same overall context, such as this:
```
./borrow-errors.rs:73:17: 73:20: error: cannot borrow `*vec` as immutable because previous closure requires unique access [E0501]
70 let append = |e| {
~~~ closure construction occurs here
71 vec.push(e)
~~~ previous borrow occurs due to use of `vec` in closure
72 };
73 let data = &vec[3];
~~~ borrow occurs here
74 }
~ borrow from closure ends here
```
However, in the process we made a number of other changes:
- Removed the repetitive filenames from snippets and just give the line number.
- Color the line numbers blue so they "fade away"
- Remove the file name and line number from the error code suggestions since they don't seem to fit anymore. (This should probably happen in more places, like existing notes.)
- Newlines in between errors to help group them better.
This PR is not quite ready to land, but we thought it made sense to stop here and get some feedback from people at large. It'd be great if people can check out the branch and play with it. We'd be especially interested in hearing about cases that don't look good with the new formatting (I suspect they exist).
Here is a checklist of some pending work items for this PR. Some of them may be best left for follow-up PRs:
- [x] Accommodate multiple files in a `MultiSpan` (this should be easy)
- In this case, we want to print filenames though.
- [x] Remove duplicate E0500 code.
- [x] Make the header message bold, rather than current hack that makes all errors/warnings bold
- [x] Update warning text color (yellow is hard to read w/ a white background)
Moved numerous follow-ups to: https://github.com/rust-lang/rust/issues/33240
Joint work with @jonathandturner.
Fixes https://github.com/rust-lang/rust/issues/3533
Add CodeGen options to optimize for size.
Add CodeGen options to annotate functions with the attributes OptimizeSize and/or MinSize used by LLVM to reduce .text size.
Closes#32296
