Add FAQ for NLL migration

[rust.git] / src / test / ui / issues / issue-49824.stderr

diff --git a/src/test/ui/issues/issue-49824.stderr b/src/test/ui/issues/issue-49824.stderr
index 4ad537f3eb5d8ea84093bba14bc57038d5d4bece..d5f1af88e133a002acc3de6855887de669f1bdcc 100644 (file)
--- a/src/test/ui/issues/issue-49824.stderr
+++ b/src/test/ui/issues/issue-49824.stderr
@@ -1,5 +1,24 @@
+warning: captured variable cannot escape `FnMut` closure body
+  --> $DIR/issue-49824.rs:10:9
+   |
+LL |       || {
+   |        - inferred to be a `FnMut` closure
+LL | /         || {
+LL | |
+LL | |
+LL | |
+LL | |             let _y = &mut x;
+LL | |         }
+   | |_________^ returns a closure that contains a reference to a captured variable, which then escapes the closure body
+   |
+   = note: `FnMut` closures only have access to their captured variables while they are executing...
+   = note: ...therefore, they cannot allow references to captured variables to escape
+   = warning: this error has been downgraded to a warning for backwards compatibility with previous releases
+   = warning: this represents potential undefined behavior in your code and this warning will become a hard error in the future
+   = note: for more information, try `rustc --explain E0729`
+
 error: compilation successful
-  --> $DIR/issue-49824.rs:8:1
+  --> $DIR/issue-49824.rs:6:1
    |
 LL | / fn main() {
 LL | |