From e39c3c05a472a7b4ecb2e3f93f1b7f299ea18664 Mon Sep 17 00:00:00 2001
From: Aman Arora <me@aman-arora.com>
Date: Mon, 8 Feb 2021 23:31:26 -0500
Subject: [PATCH] Handle restricting closure origin

---
 compiler/rustc_typeck/src/check/upvar.rs      |  5 +---
 .../closure-origin-array-diagnostics.rs       | 16 +++++++++++++
 .../closure-origin-array-diagnostics.stderr   | 23 +++++++++++++++++++
 3 files changed, 40 insertions(+), 4 deletions(-)
 create mode 100644 src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.rs
 create mode 100644 src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.stderr

diff --git a/compiler/rustc_typeck/src/check/upvar.rs b/compiler/rustc_typeck/src/check/upvar.rs
index 79c60ab3cfe..12eacdf25e2 100644
--- a/compiler/rustc_typeck/src/check/upvar.rs
+++ b/compiler/rustc_typeck/src/check/upvar.rs
@@ -206,11 +206,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // If we have an origin, store it.
             if let Some(origin) = delegate.current_origin.clone() {
                 let origin = if self.tcx.features().capture_disjoint_fields {
-                    origin
+                    (origin.0, restrict_capture_precision(origin.1))
                 } else {
-                    // FIXME(project-rfc-2229#31): Once the changes to support reborrowing are
-                    //                             made, make sure we are selecting and restricting
-                    //                             the origin correctly.
                     (origin.0, Place { projections: vec![], ..origin.1 })
                 };
 
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.rs b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.rs
new file mode 100644
index 00000000000..cd7c25620a7
--- /dev/null
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.rs
@@ -0,0 +1,16 @@
+#![feature(capture_disjoint_fields)]
+//~^ WARNING: the feature `capture_disjoint_fields` is incomplete
+//~| `#[warn(incomplete_features)]` on by default
+//~| see issue #53488 <https://github.com/rust-lang/rust/issues/53488>
+
+// Test that array access is not stored as part of closure kind origin
+
+fn expect_fn<F: Fn()>(_f: F) {}
+
+fn main() {
+    let s = [format!("s"), format!("s")];
+    let c = || { //~ ERROR expected a closure that implements the `Fn`
+        let [_, _s] = s;
+    };
+    expect_fn(c);
+}
diff --git a/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.stderr b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.stderr
new file mode 100644
index 00000000000..bd9428771f4
--- /dev/null
+++ b/src/test/ui/closures/2229_closure_analysis/diagnostics/closure-origin-array-diagnostics.stderr
@@ -0,0 +1,23 @@
+warning: the feature `capture_disjoint_fields` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/closure-origin-array-diagnostics.rs:1:12
+   |
+LL | #![feature(capture_disjoint_fields)]
+   |            ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+   = note: see issue #53488 <https://github.com/rust-lang/rust/issues/53488> for more information
+
+error[E0525]: expected a closure that implements the `Fn` trait, but this closure only implements `FnOnce`
+  --> $DIR/closure-origin-array-diagnostics.rs:12:13
+   |
+LL |     let c = || {
+   |             ^^ this closure implements `FnOnce`, not `Fn`
+LL |         let [_, _s] = s;
+   |                       - closure is `FnOnce` because it moves the variable `s` out of its environment
+LL |     };
+LL |     expect_fn(c);
+   |     --------- the requirement to implement `Fn` derives from here
+
+error: aborting due to previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0525`.