correct suggestion for `drain_collect` in a `no_std` environment

3 files changed, 27 insertions, 0 deletions

diff --git a/tests/ui/drain_collect_nostd.fixed b/tests/ui/drain_collect_nostd.fixed
new file mode 100644
index 00000000000..a4ab2956f2a
--- /dev/null
+++ b/tests/ui/drain_collect_nostd.fixed
@@ -0,0 +1,8 @@
+#![warn(clippy::drain_collect)]
+#![no_std]
+extern crate alloc;
+use alloc::vec::Vec;
+
+fn remove_all(v: &mut Vec<i32>) -> Vec<i32> {
+    core::mem::take(v)
+}
diff --git a/tests/ui/drain_collect_nostd.rs b/tests/ui/drain_collect_nostd.rs
new file mode 100644
index 00000000000..a8be1ce6bbd
--- /dev/null
+++ b/tests/ui/drain_collect_nostd.rs
@@ -0,0 +1,8 @@
+#![warn(clippy::drain_collect)]
+#![no_std]
+extern crate alloc;
+use alloc::vec::Vec;
+
+fn remove_all(v: &mut Vec<i32>) -> Vec<i32> {
+    v.drain(..).collect()
+}
diff --git a/tests/ui/drain_collect_nostd.stderr b/tests/ui/drain_collect_nostd.stderr
new file mode 100644
index 00000000000..91b38932fee
--- /dev/null
+++ b/tests/ui/drain_collect_nostd.stderr
@@ -0,0 +1,11 @@
+error: you seem to be trying to move all elements into a new `Vec`
+  --> tests/ui/drain_collect_nostd.rs:7:5
+   |
+LL |     v.drain(..).collect()
+   |     ^^^^^^^^^^^^^^^^^^^^^ help: consider using `mem::take`: `core::mem::take(v)`
+   |
+   = note: `-D clippy::drain-collect` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::drain_collect)]`
+
+error: aborting due to 1 previous error
+