interpret: clobber return place when calling function
Makes sure the callee cannot observe the previous contents of the return place, and the caller cannot read any of the old return place contents even if the function unwinds.
I don't think we can test for this though, that would require some strange hand-written MIR.
r? `````@oli-obk`````
feed resolver_for_lowering instead of storing it in a field
r? `@cjgillot`
opening this as
* a discussion for `no_hash` + `feedable` queries. I think we'll want those, but I don't quite understand why they are rejected beyond a double check of the stable hashes for situations where the query is fed but also read from incremental caches.
* and a discussion on removing all untracked fields from TyCtxt and setting it up so that they are fed queries instead
Given that attributes is stored in a separate BTreeMap, it's not necessary
to pass it in when constructing `hir::Expr`. We can just construct
`hir::Expr` and then call `self.lower_attrs` later if it needs attributes.
As most desugaring code don't use attributes, this allows some code cleanup.
Disable top down MIR inlining
The current MIR inliner has exponential behavior in some cases: <https://godbolt.org/z/7jnWah4fE>. The cause of this is top-down inlining, where we repeatedly do inlining like `call_a() => { call_b(); call_b(); }`. Each decision on its own seems to make sense, but the result is exponential.
Disabling top-down inlining fundamentally prevents this. Each call site in the original, unoptimized source code is now considered for inlining exactly one time, which means that the total growth in MIR size is limited to number of call sites * inlining threshold.
Top down inlining may be worth re-introducing at some point, but it needs to be accompanied with a principled way to prevent this kind of behavior.
This ensures that the error is printed even for unused variables,
as well as unifying the handling between the LLVM and GCC backends.
This also fixes unusual behavior around exported Rust-defined variables
with linkage attributes. With the previous behavior, it appears to be
impossible to define such a variable such that it can actually be imported
and used by another crate. This is because on the importing side, the
variable is required to be a pointer, but on the exporting side, the
type checker rejects static variables of pointer type because they do
not implement `Sync`. Even if it were possible to import such a type, it
appears that code generation on the importing side would add an unexpected
additional level of pointer indirection, which would break type safety.
This highlighted that the semantics of linkage on Rust-defined variables
is different to linkage on foreign items. As such, we now model the
difference with two different codegen attributes: linkage for Rust-defined
variables, and import_linkage for foreign items.
This change gives semantics to the test
src/test/ui/linkage-attr/auxiliary/def_illtyped_external.rs which was
previously expected to fail to compile. Therefore, convert it into a
test that is expected to successfully compile.
The update to the GCC backend is speculative and untested.
`EarlyContextAndPass` wraps a single early lint pass. We aggregate
multiple passes into that single pass by using `EarlyLintPassObjects`.
This commit removes `EarlyLintPassObjects` by changing
`EarlyContextAndPass` into `EarlyContextAndPasses`. I.e. it just removes
a level of indirection. This makes the code simpler and slightly faster.
The commit does likewise for late lints.
It has a single call site in the HIR pretty printer, where the resulting
token lit is immediately converted to a string.
This commit replaces `LitKind::synthesize_token_lit` with a `Display`
impl for `LitKind`, which can be used by the HIR pretty printer.
These two methods both produce a `MetaItemLit`, and then some of the
call sites convert the `MetaItemLit` to a `token::Lit` with
`as_token_lit`.
This commit parameterises these two methods with a `mk_lit_char`
closure, which can be used to produce either `MetaItemLit` or
`token::Lit` directly as necessary.
Avoid some `InferCtxt::build` calls
Either because we're inside of an `InferCtxt` already, or because we're not in a place where we'd ever see inference vars.
r? types
There are better ways to create the meta items.
- In the rustdoc tests, the commit adds `dummy_meta_item_name_value`,
which matches the existing `dummy_meta_item_word` function and
`dummy_meta_item_list` macro.
- In `types.rs` the commit clones the existing meta item and then
modifies the clone.
Make sure async constructs do not `impl Generator`
Async lowering turns async functions and blocks into generators internally.
Though these special kinds of generators should not `impl Generator` themselves.
The other way around, normal generators should not `impl Future`.
This was discovered in https://github.com/rust-lang/rust/pull/105082#issuecomment-1332210907 and is a regression from https://github.com/rust-lang/rust/pull/104321.
r? `@compiler-errors`
rustc_codegen_ssa: Fix for codegen_get_discr
When doing the optimized implementation of getting the discriminant, the arithmetic needs to be done in the tag type so wrapping behavior works correctly.
Fixes#104519
Rollup of 6 pull requests
Successful merges:
- #101975 (Suggest to use . instead of :: when accessing a method of an object)
- #105141 (Fix ICE on invalid variable declarations in macro calls)
- #105224 (Properly substitute inherent associated types.)
- #105236 (Add regression test for #47814)
- #105247 (Use parent function WfCheckingContext to check RPITIT.)
- #105253 (Update a couple of rustbuild deps)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Fix ICE on invalid variable declarations in macro calls
This fixes ICE that happens with invalid variable declarations in macro calls like:
```rust
macro_rules! m { ($s:stmt) => {} }
m! { var x }
m! { auto x }
m! { mut x }
```
Found this is because of not collecting tokens on recovery, so I changed to force collect them.
Fixes https://github.com/rust-lang/rust/issues/103529.
Remove drop order twist of && and || and make them associative
Previously a short circuiting binop chain (chain of && or ||s) would drop the temporaries created by the first element after all the other elements, and otherwise follow evaluation order. So `f(1).g() && f(2).g() && f(3).g() && f(4).g()` would drop the temporaries in the order `2,3,4,1`. This made `&&` and `||` non-associative regarding drop order. In other words, adding ()'s to the expression would change drop order: `f(1).g() && (f(2).g() && f(3).g()) && f(4).g()` for example would drop in the order `3,2,4,1`.
As, except for the bool result, there is no data returned by the sub-expressions of the short circuiting binops, we can safely discard of any temporaries created by the sub-expr. Previously, code was already putting the rhs's into terminating scopes, but missed it for the lhs's.
This commit addresses this "twist". We now also put the lhs into a terminating scope. The drop order of the above expressions becomes `1,2,3,4`.
There might be code relying on the current order, and therefore I'd recommend doing a crater run to gauge the impact. I'd argue that such code is already quite wonky as it is one `foo() &&` addition away from breaking. ~~For the impact, I don't expect any *build* failures, as the compiler gets strictly more tolerant: shortening the lifetime of temporaries only expands the list of programs the compiler accepts as valid. There might be *runtime* failures caused by this change however.~~ Edit: both build and runtime failures are possible, e.g. see the example provided by dtolnay [below](https://github.com/rust-lang/rust/pull/103293#issuecomment-1285341113). Edit2: the crater run has finished and [results](https://github.com/rust-lang/rust/pull/103293#issuecomment-1292275203) are that there is only one build failure which is easy to fix with a +/- 1 line diff.
I've included a testcase that now compiles thanks to this patch.
The breakage is also limited to drop order relative to conditionals in the && chain: that is, in code like this:
```Rust
let hello = foo().hi() && bar().world();
println!("hi");
```
we already drop the temporaries of `foo().hi()` before we reach "hi".
I'd ideally have this PR merged before let chains are stabilized. If this PR is taking too long, I'd love to have a more restricted version of this change limited to `&&`'s in let chains: the `&&`'s of such chains are quite special anyways as they accept `let` bindings, in there the `&&` is therefore more a part of the "if let chain" construct than a construct of its own.
Fixes#103107
Status: waiting on [this accepted FCP](https://github.com/rust-lang/rust/pull/103293#issuecomment-1293411354) finishing.
