resolve: disallow label use through closure/async

This commit modifies resolve to disallow `break`/`continue` to labels
through closures or async blocks. This doesn't make sense and should
have been prohibited anyway.

Signed-off-by: David Wood <david@davidtw.co>

2 files changed, 21 insertions, 0 deletions

diff --git a/src/test/ui/error-codes/E0767.rs b/src/test/ui/error-codes/E0767.rs
new file mode 100644
index 00000000000..6c6cb746e6c
--- /dev/null
+++ b/src/test/ui/error-codes/E0767.rs
@@ -0,0 +1,7 @@
+fn main () {
+    'a: loop {
+        || {
+            loop { break 'a; } //~ ERROR E0767
+        }
+    }
+}
diff --git a/src/test/ui/error-codes/E0767.stderr b/src/test/ui/error-codes/E0767.stderr
new file mode 100644
index 00000000000..2429823306b
--- /dev/null
+++ b/src/test/ui/error-codes/E0767.stderr
@@ -0,0 +1,14 @@
+error[E0767]: use of unreachable label `'a`
+  --> $DIR/E0767.rs:4:26
+   |
+LL |     'a: loop {
+   |     -- unreachable label defined here
+LL |         || {
+LL |             loop { break 'a; }
+   |                          ^^ unreachable label `'a`
+   |
+   = note: labels are unreachable through functions, closures, async blocks and modules
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0767`.