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Rollup merge of #115355 - lqd:issue-115351, r=compiler-errors

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new solver: handle edge case of a recursion limit of 0

Apparently a recursion limit of 0 is possible/valid/useful/used/cute, the more you know 🌟 .

(It's somewhat interesting to me that the old solver seemingly handles this, and that the new solver currently requires a recursion limit of 2 here)

r? `@compiler-errors.`

Fixes #115351.
This commit is contained in:
Matthias Krüger 2023-08-30 07:18:13 +02:00 committed by GitHub
commit 36182f1f13
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3 changed files with 44 additions and 1 deletions
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6
compiler/rustc_trait_selection/src/solve/search_graph/mod.rs
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@ -51,9 +51,13 @@ pub(super) struct SearchGraph<'tcx> {
impl<'tcx> SearchGraph<'tcx> {
pub(super) fn new(tcx: TyCtxt<'tcx>, mode: SolverMode) -> SearchGraph<'tcx> {
let local_overflow_limit = {
let recursion_limit = tcx.recursion_limit().0;
if recursion_limit == 0 { 0 } else { recursion_limit.ilog2() as usize }
};
Self {
mode,
local_overflow_limit: tcx.recursion_limit().0.ilog2() as usize,
local_overflow_limit,
stack: Default::default(),
provisional_cache: ProvisionalCache::empty(),
}

12
tests/ui/traits/new-solver/overflow/recursion-limit-zero-issue-115351.rs Normal file
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@ -0,0 +1,12 @@
//~ ERROR overflow evaluating the requirement `Self well-formed`
//~| ERROR overflow evaluating the requirement `Self: Trait`
// This is a non-regression test for issue #115351, where a recursion limit of 0 caused an ICE.
// compile-flags: -Ztrait-solver=next --crate-type=lib
// check-fail
#![recursion_limit = "0"]
trait Trait {}
impl Trait for u32 {}
//~^ ERROR overflow evaluating the requirement `u32: Trait`
//~| ERROR overflow evaluating the requirement `u32 well-formed`

27
tests/ui/traits/new-solver/overflow/recursion-limit-zero-issue-115351.stderr Normal file
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@ -0,0 +1,27 @@
error[E0275]: overflow evaluating the requirement `Self: Trait`
|
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "2"]` attribute to your crate (`recursion_limit_zero_issue_115351`)
error[E0275]: overflow evaluating the requirement `Self well-formed`
|
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "2"]` attribute to your crate (`recursion_limit_zero_issue_115351`)
error[E0275]: overflow evaluating the requirement `u32: Trait`
--> $DIR/recursion-limit-zero-issue-115351.rs:10:16
|
LL | impl Trait for u32 {}
| ^^^
|
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "2"]` attribute to your crate (`recursion_limit_zero_issue_115351`)
error[E0275]: overflow evaluating the requirement `u32 well-formed`
--> $DIR/recursion-limit-zero-issue-115351.rs:10:16
|
LL | impl Trait for u32 {}
| ^^^
|
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "2"]` attribute to your crate (`recursion_limit_zero_issue_115351`)
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0275`.