Auto merge of #121870 - matthiaskrgr:rollup-mfpa3jx, r=matthiaskrgr

Rollup of 11 pull requests

Successful merges:

 - #111505 (Made `INVALID_DOC_ATTRIBUTES` lint deny by default)
 - #120305 (Delete line if suggestion would replace it with an empty line)
 - #121153 (Suggest removing superfluous semicolon when statements used as expression)
 - #121497 (`-Znext-solver=coherence`: suggest increasing recursion limit)
 - #121634 (Clarify behavior of slice prefix/suffix operations in case of equality)
 - #121706 (match lowering: Remove hacky branch in sort_candidate)
 - #121730 (Add profiling support to AIX)
 - #121750 (match lowering: Separate the `bool` case from other integers in `TestKind`)
 - #121803 (Never say "`Trait` is implemented for `{type error}`")
 - #121811 (Move sanitizer ui tests to sanitizer directory)
 - #121824 (Implement missing ABI structures in StableMIR)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 20 insertions, 10 deletions

diff --git a/compiler/rustc_middle/src/traits/solve.rs b/compiler/rustc_middle/src/traits/solve.rs
index 048df367bd6..0dc65126011 100644
--- a/compiler/rustc_middle/src/traits/solve.rs
+++ b/compiler/rustc_middle/src/traits/solve.rs
@@ -60,7 +60,6 @@ pub enum Certainty {
 
 impl Certainty {
     pub const AMBIGUOUS: Certainty = Certainty::Maybe(MaybeCause::Ambiguity);
-    pub const OVERFLOW: Certainty = Certainty::Maybe(MaybeCause::Overflow);
 
     /// Use this function to merge the certainty of multiple nested subgoals.
     ///
@@ -79,16 +78,13 @@ impl Certainty {
             (Certainty::Yes, Certainty::Yes) => Certainty::Yes,
             (Certainty::Yes, Certainty::Maybe(_)) => other,
             (Certainty::Maybe(_), Certainty::Yes) => self,
-            (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(MaybeCause::Ambiguity)) => {
-                Certainty::Maybe(MaybeCause::Ambiguity)
-            }
-            (Certainty::Maybe(MaybeCause::Ambiguity), Certainty::Maybe(MaybeCause::Overflow))
-            | (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Ambiguity))
-            | (Certainty::Maybe(MaybeCause::Overflow), Certainty::Maybe(MaybeCause::Overflow)) => {
-                Certainty::Maybe(MaybeCause::Overflow)
-            }
+            (Certainty::Maybe(a), Certainty::Maybe(b)) => Certainty::Maybe(a.unify_with(b)),
         }
     }
+
+    pub const fn overflow(suggest_increasing_limit: bool) -> Certainty {
+        Certainty::Maybe(MaybeCause::Overflow { suggest_increasing_limit })
+    }
 }
 
 /// Why we failed to evaluate a goal.
@@ -99,7 +95,21 @@ pub enum MaybeCause {
     /// or we hit a case where we just don't bother, e.g. `?x: Trait` goals.
     Ambiguity,
     /// We gave up due to an overflow, most often by hitting the recursion limit.
-    Overflow,
+    Overflow { suggest_increasing_limit: bool },
+}
+
+impl MaybeCause {
+    fn unify_with(self, other: MaybeCause) -> MaybeCause {
+        match (self, other) {
+            (MaybeCause::Ambiguity, MaybeCause::Ambiguity) => MaybeCause::Ambiguity,
+            (MaybeCause::Ambiguity, MaybeCause::Overflow { .. }) => other,
+            (MaybeCause::Overflow { .. }, MaybeCause::Ambiguity) => self,
+            (
+                MaybeCause::Overflow { suggest_increasing_limit: a },
+                MaybeCause::Overflow { suggest_increasing_limit: b },
+            ) => MaybeCause::Overflow { suggest_increasing_limit: a || b },
+        }
+    }
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, HashStable, TypeFoldable, TypeVisitable)]