1 files changed, 40 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0297.md b/compiler/rustc_error_codes/src/error_codes/E0297.md
new file mode 100644
index 000000000..66c31376d
--- /dev/null
+++ b/compiler/rustc_error_codes/src/error_codes/E0297.md
@@ -0,0 +1,40 @@
+#### Note: this error code is no longer emitted by the compiler.
+
+Patterns used to bind names must be irrefutable. That is, they must guarantee
+that a name will be extracted in all cases. Instead of pattern matching the
+loop variable, consider using a `match` or `if let` inside the loop body. For
+instance:
+
+```compile_fail,E0005
+let xs : Vec<Option<i32>> = vec![Some(1), None];
+
+// This fails because `None` is not covered.
+for Some(x) in xs {
+    // ...
+}
+```
+
+Match inside the loop instead:
+
+```
+let xs : Vec<Option<i32>> = vec![Some(1), None];
+
+for item in xs {
+    match item {
+        Some(x) => {},
+        None => {},
+    }
+}
+```
+
+Or use `if let`:
+
+```
+let xs : Vec<Option<i32>> = vec![Some(1), None];
+
+for item in xs {
+    if let Some(x) = item {
+        // ...
+    }
+}
+```