Issue-125323: ICE non-ADT in struct pattern when long time constant evaluation is in for loop
This PR fixes#125323
## Context
According to the issue, the ICE happens since #121206.
In the PR, some error methods were reorganized. For example, has_errors() was renamed to has_errors_exclude_lint_errors(). However, some codes which used the original has_errors() were not switched to has_errors_exclude_lint_errors(). I finally found that report_error() in writeback.rs causes this ICE. Currently the method uses tainted_by_errors() to get guar (ErrorGuaranteed), but originally it used dcx().has_errors() but it wasn't changed to has_errors_exclude_lint_errors() when changes in #121206 were merged. I don't think I fully understand how an error is propagated, but I suppose that the error from long time constant evaluation is unexpectedly propagated other parts (in this ICE, for loop), then cause the non-ADT in struct pattern ICE.
## Change
- Fix report_error() in writeback.rs: use dcx().has_errors_exclude_lint_errors() instead of tainted_by_errors() to prevent error propagation from constant evaluation.
- Add test for the ICE
- Modify some tests to align the change: Due to this fix, E0282 error happens (or not happen anymore) in some tests.
## NOTE
The 4th commit aims to revert the fix in #123516 because I confirmed that the ICE solved by the PR doesn't happen if I modify report_error(). I think the root cause of that ICE is the same as #125323 . But I can discard this commit since we can fix#125323 without it.
deduced_param_attrs: check Freeze on monomorphic types.
`deduced_param_attrs` currently checks `Freeze` bound on polymorphic MIR. This pessimizes the deduction, as generic types are not `Freeze` by default.
This moves the check to the ABI adjustment.
Simplify trivial constants in SimplifyConstCondition
After `InstSimplify-after-simplifycfg` with `-Zub_checks=false`, there are many of the following patterns.
```
_13 = const false;
assume(copy _13);
_12 = unreachable_unchecked::precondition_check() -> [return: bb1, unwind unreachable];
```
Simplifying them to unreachable early should make CFG simpler.
the `#[track_caller]` shim should not inherit `#[no_mangle]`
fixes https://github.com/rust-lang/rust/issues/143162
builds on https://github.com/rust-lang/rust/pull/143293 which introduced a mechanism to strip attributes from shims.
cc `@Jules-Bertholet` `@workingjubilee` `@bjorn3`
---
Summary:
This PR fixes an interaction between `#[track_caller]`, `#[no_mangle]`, and casting to a function pointer.
A function annotated with `#[track_caller]` internally has a hidden extra argument for the panic location. The `#[track_caller]` attribute is only allowed on `extern "Rust"` functions. When a function is annotated with both `#[no_mangle]` and `#[track_caller]`, the exported symbol has the signature that includes the extra panic location argument. This works on stable rust today:
```rust
extern "Rust" {
#[track_caller]
fn rust_track_caller_ffi_test_tracked() -> &'static Location<'static>;
}
mod provides {
use std::panic::Location;
#[track_caller] // UB if we did not have this!
#[no_mangle]
fn rust_track_caller_ffi_test_tracked() -> &'static Location<'static> {
Location::caller()
}
}
```
When a `#[track_caller]` function is converted to a function pointer, a shim is added to drop the additional argument. So this is a valid program:
```rust
#[track_caller]
fn foo() {}
fn main() {
let f = foo as fn();
f();
}
```
The issue arises when `foo` is additionally annotated with `#[no_mangle]`, the generated shim currently inherits this attribute, also exporting a symbol named `foo`, but one without the hidden panic location argument. The linker rightfully complains about a duplicate symbol.
The solution of this PR is to have the generated shim drop the `#[no_mangle]` attribute.
Limit impl_trait_header query to only trait impls
Changes `impl_trait_header` to panic on inherent impls intstead of returning None. A few downstream functions are split into option and non-option returning functions. This gets rid of a lot of unwraps where we know we have a trait impl, while there are still some cases where the Option is helpful.
Summary of changes to tcx methods:
* `impl_is_of_trait` (new)
* `impl_trait_header` -> `impl_trait_header`/`impl_opt_trait_header`
* `impl_trait_ref` -> `impl_trait_ref`/`impl_opt_trait_ref`
* `trait_id_of_impl` -> `impl_trait_id`/`impl_opt_trait_id`
Pre-compute MIR CFG caches for borrowck and other analyses
I was puzzled that https://github.com/rust-lang/rust/pull/142390 introduces additional computations of CFG traversals: borrowck computes them, right?
It turns out that borrowck clones the MIR body, so doesn't share its cache with other analyses.
This PR:
- forces the computation of all caches in `mir_promoted` query;
- modifies region renumbering to avoid dropping that cache.
error from const eval lint causes ICE at check_pat in late_lint, because the function expects the typeck result isn't tainted by error but it is.
To avoid the ICE, check_pat returns earlier if the typeck_result is tainted.
check_mod_deathness also has an issue from the same reason. visit_body for making live symbols expects the typeck result has no error.
So this commit adds a check in visit_nested_body to avoid the ICE.
However, if visit_nested_body just returns without doing anything, all codes with the error are marked as dead, because live_symbols is empty.
To avoid this side effect, visit_nested_body and other visit_* functions in MarkSymbolVistior should return appropriate error.
If a function returns ControlFlow::Break, live_symbols_and_ignore_derived_traits returns earlier with error,
then check_mod_deathness, the caller of the function returns earlier without pushing everything into dead_codes.
Guard HIR lowered contracts with `contract_checks`
Refactor contract HIR lowering to ensure no contract code is executed when contract-checks are disabled.
The call to `contract_checks` is moved to inside the lowered fn body, and contract closures are built conditionally, ensuring no side-effects present in contracts occur when those are disabled. This partially addresses rust-lang/rust#139548, i.e. the bad behavior no longer happens with contract checks disabled (`-Zcontract-checks=no`).
The change is made in preparation for adding contract variable declarations - variables declared before the `requires` assertion, and accessible from both `requires` and `ensures`, but not in the function body (PR rust-lang/rust#144444). As those declarations may also have side-effects, it's good to guard them with `contract_checks` - the new lowering approach allows for this to be done easily.
Contracts tracking issue: rust-lang/rust#128044
**Known limiatations**:
- It is still possible to early return from the *function* from within a contract, e.g.
```rust
#[ensures({if x > 0 { return 0 }; |_| true})]
fn foo(x: u32) -> i32 {
42
}
```
When `foo` is called with an argument greater than 0, instead of `42`, `0` will be returned.
As this is not a regression, it is not addressed in this PR. However, it may be worth revisiting later down the line, as users may expect a form of early return from *contract specifications*, and so returning from the entire *function* could cause confusion.
- ~Contracts are still not optimised out when disabled. Currently, even when contracts are disabled, the code generated causes existing optimisations to fail, meaning even disabled contracts could impact runtime performance. This issue is blocking rust-lang/rust#136578, and has not been addressed in this PR, i.e. the `mir-opt` and `codegen` tests that fail in rust-lang/rust#136578 still fail with these new HIR lowering changes.~ Contracts should now be optimised out when disabled, however some regressions tests still need to be added to be sure that is indeed the case.
Rollup of 11 pull requests
Successful merges:
- rust-lang/rust#143191 (Stabilize `rwlock_downgrade` library feature)
- rust-lang/rust#147444 (Allow printing a fully-qualified path in `def_path_str`)
- rust-lang/rust#147527 (Update t-compiler beta nomination Zulip msg)
- rust-lang/rust#147670 (some `ErrorGuaranteed` cleanups)
- rust-lang/rust#147676 (Return spans out of `is_doc_comment` to reduce reliance on `.span()` on attributes)
- rust-lang/rust#147708 (const `mem::drop`)
- rust-lang/rust#147710 (Fix ICE when using contracts on async functions)
- rust-lang/rust#147716 (Fix some comments)
- rust-lang/rust#147718 (miri: use allocator_shim_contents codegen helper)
- rust-lang/rust#147729 (ignore boring locals when explaining why a borrow contains a point due to drop of a live local under polonius)
- rust-lang/rust#147742 (Revert unintentional whitespace changes to rustfmt-excluded file)
r? `@ghost`
`@rustbot` modify labels: rollup
Allow printing a fully-qualified path in `def_path_str`
Previously, the local crate would always be printed as a leading `crate::`. Allow resolving it to the crate name instead.
This allows printing a fully qualified path with:
```rust
let qualified_name = with_no_visible_paths!(with_resolve_crate_name!(
with_no_trimmed_paths!(tcx.def_path_str(def_id))
));
```
I found this useful for an out-of-tree rustc-driver. I do not currently have a usecase in mind upstream; I'm ok if you don't want this PR for that reason. See [#t-compiler/help > print a fully qualified path name? @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/182449-t-compiler.2Fhelp/topic/print.20a.20fully.20qualified.20path.20name.3F/near/541560961) for additional context.
This does not currently have tests. I am not aware of an easy way to test def-id printing, since it requires having access to a TyCtxt.
For sizedness, default and auto trait predicates, now prefer non-param
candidates if any exist. As these traits do not have generic parameters,
it never makes sense to prefer an non-alias candidate, as there can
never be a more permissive candidate.
Assert that non-extended temporaries and `super let` bindings have scopes
This PR clarifies a point of confusion in the compiler: all bodies have an outer temporary drop scope, including `static` and `const` item bodies[^1]. Whenever a temporary should be dropped in its enclosing temporary scope, it should have a temporary scope to be dropped in so that its drop can be scheduled[^2]. As such, I've updated some relevant comments and made `ScopeTree::default_temporary_scope` and `RvalueScopes::temporary_scope` panic when an enclosing temporary scope isn't found instead of allowing potential bugs where potentially-drop-sensitive temporaries are effectively given static lifetimes.
Since non-extended `super let` bindings are dropped in their block's enclosing temporary scope, this applies to them as well: the enclosing temporary scope should exist.
[^1]: See https://github.com/rust-lang/rust/blob/master/compiler/rustc_hir_analysis/src/check/region.rs#L773-L778 for non-`fn`/closure bodies. The `this.cx.var_parent = None;` enables [lifetime extension to `'static` lifetimes](https://doc.rust-lang.org/stable/reference/destructors.html#r-destructors.scope.lifetime-extension.static) and the `ScopeData::Destruction` scope ensures non-extended temporaries are dropped in the body expression's scope.
[^2]: For certain borrowed temporaries, drops that don't require running destructors may later be removed by constant promotion. That is unrelated to this PR.
Fix normalization overflow ICEs in monomorphization
Fixesrust-lang/rust#92004Fixesrust-lang/rust#92470Fixesrust-lang/rust#95134Fixesrust-lang/rust#105275Fixesrust-lang/rust#105937
Fixes rust-lang/rust#117696-2
Fixesrust-lang/rust#118590Fixesrust-lang/rust#122823Fixesrust-lang/rust#131342Fixesrust-lang/rust#139659
## Analysis:
The causes of these issues are similar. They contain generic recursive functions that can be instantiated with different args infinitely at monomorphization stage.
Ideally this should be caught by the [`check_recursion_limit`](c0bb3b98bb/compiler/rustc_monomorphize/src/collector.rs (L468)) function. The reality is that normalization can reach recursion limit earlier than monomorphization's check because they calculate depths in different ways.
Since normalization is called everywhere, ICEs appear in different locations.
## Fix:
If we abort on overflow with `TypingMode::PostAnalysis` in the trait solver, it would also catch these errors.
The main challenge is providing good diagnostics for them. So it's quite natural to put the check right before these normalization happening.
I first tried to check the whole MIR body's normalization and `references_error`. (As elaborate_drop handles normalization failure by [returning `ty::Error`](c0bb3b98bb/compiler/rustc_mir_transform/src/elaborate_drop.rs (L514-L519)).)
It turns out that checking all `Local`s seems sufficient.
These types are gonna be normalized anyway. So with cache, these checks shouldn't be expensive.
This fixes these ICEs for both the next and old solver, though I'm not sure the change I made to the old solver is proper. Its overflow handling looks convoluted thus I didn't try to fix it more "upstream".
Perform unused assignment and unused variables lints on MIR.
Rebase of https://github.com/rust-lang/rust/pull/101500
Fixes https://github.com/rust-lang/rust/issues/51003.
The first commit moves detection of uninhabited types from the current liveness pass to MIR building.
In order to keep the same level of diagnostics, I had to instrument MIR a little more:
- keep for which original local a guard local is created;
- store in the `VarBindingForm` the list of introducer places and whether this was a shorthand pattern.
I am not very proud of the handling of self-assignments. The proposed scheme is in two parts: first detect probable self-assignments, by pattern matching on MIR, and second treat them specially during dataflow analysis. I welcome ideas.
Please review carefully the changes in tests. There are many small changes to behaviour, and I'm not sure all of them are desirable.
Extract most code from `define_feedable!`
This PR extracts most of the non-trivial code from the `define_feedable!` macro (which defines the `TyCtxtFeed::$query` methods), and moves it to a helper function `query_feed_inner` written in ordinary non-macro code.
Doing so should make that code easier to read and modify, because it now gets proper IDE support and has explicit trait bounds.
---
There should be no change in compiler behaviour.
I've structured the commits so that the actual extraction part is mostly just whitespace changes, making it easier to review individually with whitespace changes hidden.
Validate CopyForDeref and DerefTemps better and remove them from runtime MIR
(split from my WIP rust-lang/rust#145344)
This PR:
- Removes `Rvalue::CopyForDeref` and `LocalInfo::DerefTemp` from runtime MIR
- Using a new mir pass `EraseDerefTemps`
- `CopyForDeref(x)` is turned into `Use(Copy(x))`
- `DerefTemp` is turned into `Boring`
- Not sure if this part is actually necessary, it made more sense in rust-lang/rust#145344 with `DerefTemp` storing actual data that I wanted to keep from having to be kept in sync with the rest of the body in runtime MIR
- Checks in validation that `CopyForDeref` and `DerefTemp` are only used together
- Removes special handling for `CopyForDeref` from many places
- Removes `CopyForDeref` from `custom_mir` reverting rust-lang/rust#111587
- In runtime MIR simple copies can be used instead
- In post cleanup analysis MIR it was already wrong to use due to the lack of support for creating `DerefTemp` locals
- Possibly this should be its own PR?
- Adds an argument to `deref_finder` to avoid creating new `DerefTemp`s and `CopyForDeref` in runtime MIR.
- Ideally we would just avoid making intermediate derefs instead of fixing it at the end of a pass / during shim building
- Removes some usages of `deref_finder` that I found out don't actually do anything
r? oli-obk
Refactor contract HIR lowering to ensure no contract code is
executed when contract-checks are disabled.
The call to contract_checks is moved to inside the lowered fn
body, and contract closures are built conditionally, ensuring
no side-effects present in contracts occur when those are disabled.
Remove StatementKind::Deinit.
It is a remnant from the time we deaggreated MIR.
Now, it is only constructed by the `LargeEnums` MIR pass, which is disabled by default.
Prefer to use repeat_n over repeat().take()
More from https://github.com/rust-lang/rust/pull/147464, but batch processed with `ast-grep` to find and replace.
second commit add notes for library: affaf532f9
r? ``@RalfJung``
clarify wording of match ergonomics diagnostics (`rust_2024_incompatible_pat` lint and error)
Partially addresses rust-lang/rust#143557:
- Uses different wording than the Edition Guide chapter, to hopefully stand alone a bit better. Instead of referring to the "default binding mode", it now talks about what can't be written "within elided reference patterns". I ended up going with "elided" instead of "implicit" in hope that it reads bit less like it should behave the same as an explicit reference pattern, but I'm not totally happy with that wording.
- The explanatory note still points to where the default binding mode was introduced, but only refers to its effect, not what we call it. How that relates to the rest of the diagnostic may still be a bit of a puzzle, but hopefully it isn't too much of one? It also doesn't make sense anymore for the case of `&` written under a by-ref binding mode, so I've left the note out in that case (but kept the label). It's more cramped, but talking about binding modes would feel like a non-sequitur for the error about `&` patterns without further explanation.
- Links to the stable version of the Edition Guide instead of the nightly version. It looks like almost every link to the Edition Guide in diagnostics is to the nightly version, presumably for the same reason as here: the diagnostics were added before the new Edition was stabilized, then never updated. I'll make a separate PR to clean up the others.
This only changes the diagnostic messages, not the code suggestion or the Edition Guide.
r? `@Nadrieril` or reassign
Previously, the local crate would always be printed as a leading `crate::`.
Allow resolving it to the crate name instead.
This allows printing a fully qualified path with:
```rust
let qualified_name = with_no_visible_paths!(with_resolve_crate_name!(
with_no_trimmed_paths!(tcx.def_path_str(def_id))
));
```
I found this useful for an out-of-tree rustc-driver. I do not currently
have a usecase in mind upstream; I'm ok if you don't want this PR for
that reason.
This does not currently have tests. I am not aware of an easy way to
test def-id printing, since it requires having access to a TyCtxt.
Rollup of 8 pull requests
Successful merges:
- rust-lang/rust#146865 (kcfi: only reify trait methods when dyn-compatible)
- rust-lang/rust#147205 (Add a new `wasm32-wasip3` target to Rust)
- rust-lang/rust#147322 (cg_llvm: Consistently import `llvm::Type` and `llvm::Value`)
- rust-lang/rust#147398 (Fix; correct placement of type inference error for method calls)
- rust-lang/rust#147410 (Update `S-waiting-on-team` refs to new `S-waiting-on-{team}` labels)
- rust-lang/rust#147422 (collect-license-metadata: Print a diff of the expected output)
- rust-lang/rust#147431 (compiletest: Read the whole test file before parsing directives)
- rust-lang/rust#147433 (Fix doc comment)
Failed merges:
- rust-lang/rust#147390 (Use globals instead of metadata for std::autodiff)
r? `@ghost`
`@rustbot` modify labels: rollup
kcfi: only reify trait methods when dyn-compatible
fixes https://github.com/rust-lang/rust/issues/146853
Only generate a `ReifyShim` for trait method calls if the trait is dyn-compatible.
Until now kcfi would generate a `ReifyShim` whenever a trait method was cast to a function pointer. But technically the shim is only needed for dyn-compatible traits (where the method might end up in a vtable).
Up to this point that was only slightly inefficient, but in combination with c-variadic trait methods it is wrong. For c-variadic trait methods the generated shim is incorrect, and that is why c-variadic methods make a trait no longer dyn-compatible: we should simply never generate a `ReifyShim` that is c-variadic.
With this change the documentation on `ReifyReason` is now actually correct:
> If KCFI is enabled, creating a function pointer from a method on a dyn-compatible trait. This includes the case of converting `::call`-like methods on closure-likes to function pointers.
cc ```@maurer``` ```@workingjubilee```
r? ```@rcvalle```
