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diff --git a/src/tools/clippy/src/docs/len_without_is_empty.txt b/src/tools/clippy/src/docs/len_without_is_empty.txt
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+### What it does
+Checks for items that implement `.len()` but not
+`.is_empty()`.
+
+### Why is this bad?
+It is good custom to have both methods, because for
+some data structures, asking about the length will be a costly operation,
+whereas `.is_empty()` can usually answer in constant time. Also it used to
+lead to false positives on the [`len_zero`](#len_zero) lint – currently that
+lint will ignore such entities.
+
+### Example
+```
+impl X {
+    pub fn len(&self) -> usize {
+        ..
+    }
+}
+```
+\ No newline at end of file