Rollup merge of #104697 - dingxiangfei2009:fix-euv-control-flow, r=oli-obk

Restore control flow on error in EUV

cc `@Nilstrieb`

Fix #104649

Since #98574 refactored a piece of scrutinee memory categorization out as a subroutine, there is a subtle change in handling match arms especially when the categorization process faults and bails. In the correct case, it is not supposed to continue to process the arms any more. This PR restores the original control flow in EUV.

I promise to add a compile-fail test to demonstrate that this indeed fixes the issue after coming back from a nap.

4 files changed, 58 insertions, 7 deletions

diff --git a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
index 275f7d12148..e5e798f4b93 100644
--- a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
+++ b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
@@ -252,11 +252,11 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
             hir::ExprKind::Match(ref discr, arms, _) => {
                 let discr_place = return_if_err!(self.mc.cat_expr(discr));
-                self.maybe_read_scrutinee(
+                return_if_err!(self.maybe_read_scrutinee(
                     discr,
                     discr_place.clone(),
                     arms.iter().map(|arm| arm.pat),
-                );
+                ));
 
                 // treatment of the discriminant is handled while walking the arms.
                 for arm in arms {
@@ -390,7 +390,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         discr: &Expr<'_>,
         discr_place: PlaceWithHirId<'tcx>,
         pats: impl Iterator<Item = &'t hir::Pat<'t>>,
-    ) {
+    ) -> Result<(), ()> {
         // Matching should not always be considered a use of the place, hence
         // discr does not necessarily need to be borrowed.
         // We only want to borrow discr if the pattern contain something other
@@ -398,7 +398,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         let ExprUseVisitor { ref mc, body_owner: _, delegate: _ } = *self;
         let mut needs_to_be_read = false;
         for pat in pats {
-            return_if_err!(mc.cat_pattern(discr_place.clone(), pat, |place, pat| {
+            mc.cat_pattern(discr_place.clone(), pat, |place, pat| {
                 match &pat.kind {
                     PatKind::Binding(.., opt_sub_pat) => {
                         // If the opt_sub_pat is None, than the binding does not count as
@@ -453,7 +453,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                         // examined
                     }
                 }
-            }));
+            })?
         }
 
         if needs_to_be_read {
@@ -474,6 +474,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
             // that the discriminant has been initialized.
             self.walk_expr(discr);
         }
+        Ok(())
     }
 
     fn walk_local<F>(
@@ -490,7 +491,11 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         f(self);
         if let Some(els) = els {
             // borrowing because we need to test the discriminant
-            self.maybe_read_scrutinee(expr, expr_place.clone(), from_ref(pat).iter());
+            return_if_err!(self.maybe_read_scrutinee(
+                expr,
+                expr_place.clone(),
+                from_ref(pat).iter()
+            ));
             self.walk_block(els)
         }
         self.walk_irrefutable_pat(&expr_place, &pat);
diff --git a/compiler/rustc_hir_typeck/src/upvar.rs b/compiler/rustc_hir_typeck/src/upvar.rs
index 68f119adc7a..0f46972019e 100644
--- a/compiler/rustc_hir_typeck/src/upvar.rs
+++ b/compiler/rustc_hir_typeck/src/upvar.rs
@@ -2168,7 +2168,7 @@ fn determine_place_ancestry_relation<'tcx>(
     place_a: &Place<'tcx>,
     place_b: &Place<'tcx>,
 ) -> PlaceAncestryRelation {
-    // If Place A and Place B, don't start off from the same root variable, they are divergent.
+    // If Place A and Place B don't start off from the same root variable, they are divergent.
     if place_a.base != place_b.base {
         return PlaceAncestryRelation::Divergent;
     }
diff --git a/src/test/ui/inference/issue-104649.rs b/src/test/ui/inference/issue-104649.rs
new file mode 100644
index 00000000000..4637b884d44
--- /dev/null
+++ b/src/test/ui/inference/issue-104649.rs
@@ -0,0 +1,32 @@
+type Result<T, E = Error> = ::std::result::Result<T, E>;
+struct Error;
+
+trait ForEach {
+    type Input;
+    fn for_each<F, U>(self, f: F)
+    where
+        F: FnOnce(Self::Input) -> U;
+}
+
+impl<T> ForEach for A<T> {
+    type Input = T;
+    fn for_each<F, U>(self, f: F)
+    where
+        F: FnOnce(Self::Input) -> U,
+    {
+        todo!()
+    }
+}
+
+struct A<T>(T);
+
+fn main() {
+    let a = A(Result::Ok(Result::Ok(()))); //~ ERROR type annotations needed
+    a.for_each(|a: Result<_>| {
+        let f = || match a {
+            Ok(Ok(a)) => {}
+            Ok(Err(a)) => {}
+            Err(a) => {}
+        };
+    });
+}
diff --git a/src/test/ui/inference/issue-104649.stderr b/src/test/ui/inference/issue-104649.stderr
new file mode 100644
index 00000000000..4962b21f9fd
--- /dev/null
+++ b/src/test/ui/inference/issue-104649.stderr
@@ -0,0 +1,14 @@
+error[E0282]: type annotations needed for `A<std::result::Result<std::result::Result<(), E>, Error>>`
+  --> $DIR/issue-104649.rs:24:9
+   |
+LL |     let a = A(Result::Ok(Result::Ok(())));
+   |         ^
+   |
+help: consider giving `a` an explicit type, where the type for type parameter `E` is specified
+   |
+LL |     let a: A<std::result::Result<std::result::Result<(), E>, Error>> = A(Result::Ok(Result::Ok(())));
+   |          +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.