Auto merge of #10594 - J-ZhengLi:issue9824, r=Jarcho

fix [`mem_replace_option_with_none`] not considering field variables

fixes: #9824

---

changelog: fix [`mem_replace_option_with_none`] not considering field variables

3 files changed, 93 insertions, 1 deletions

diff --git a/tests/ui/mem_replace.fixed b/tests/ui/mem_replace.fixed
index 874d5584330..7fd340173af 100644
--- a/tests/ui/mem_replace.fixed
+++ b/tests/ui/mem_replace.fixed
@@ -90,3 +90,37 @@ fn msrv_1_40() {
     let mut s = String::from("foo");
     let _ = std::mem::take(&mut s);
 }
+
+fn issue9824() {
+    struct Foo<'a>(Option<&'a str>);
+    impl<'a> std::ops::Deref for Foo<'a> {
+        type Target = Option<&'a str>;
+
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+    impl<'a> std::ops::DerefMut for Foo<'a> {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.0
+        }
+    }
+
+    struct Bar {
+        opt: Option<u8>,
+        val: String,
+    }
+
+    let mut f = Foo(Some("foo"));
+    let mut b = Bar {
+        opt: Some(1),
+        val: String::from("bar"),
+    };
+
+    // replace option with none
+    let _ = f.0.take();
+    let _ = (*f).take();
+    let _ = b.opt.take();
+    // replace with default
+    let _ = std::mem::take(&mut b.val);
+}
diff --git a/tests/ui/mem_replace.rs b/tests/ui/mem_replace.rs
index f4f3bff5144..fa2903addbc 100644
--- a/tests/ui/mem_replace.rs
+++ b/tests/ui/mem_replace.rs
@@ -90,3 +90,37 @@ fn msrv_1_40() {
     let mut s = String::from("foo");
     let _ = std::mem::replace(&mut s, String::default());
 }
+
+fn issue9824() {
+    struct Foo<'a>(Option<&'a str>);
+    impl<'a> std::ops::Deref for Foo<'a> {
+        type Target = Option<&'a str>;
+
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+    impl<'a> std::ops::DerefMut for Foo<'a> {
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            &mut self.0
+        }
+    }
+
+    struct Bar {
+        opt: Option<u8>,
+        val: String,
+    }
+
+    let mut f = Foo(Some("foo"));
+    let mut b = Bar {
+        opt: Some(1),
+        val: String::from("bar"),
+    };
+
+    // replace option with none
+    let _ = std::mem::replace(&mut f.0, None);
+    let _ = std::mem::replace(&mut *f, None);
+    let _ = std::mem::replace(&mut b.opt, None);
+    // replace with default
+    let _ = std::mem::replace(&mut b.val, String::default());
+}
diff --git a/tests/ui/mem_replace.stderr b/tests/ui/mem_replace.stderr
index caa127f76ee..58b57be7507 100644
--- a/tests/ui/mem_replace.stderr
+++ b/tests/ui/mem_replace.stderr
@@ -122,5 +122,29 @@ error: replacing a value of type `T` with `T::default()` is better expressed usi
 LL |     let _ = std::mem::replace(&mut s, String::default());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut s)`
 
-error: aborting due to 20 previous errors
+error: replacing an `Option` with `None`
+  --> $DIR/mem_replace.rs:121:13
+   |
+LL |     let _ = std::mem::replace(&mut f.0, None);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `f.0.take()`
+
+error: replacing an `Option` with `None`
+  --> $DIR/mem_replace.rs:122:13
+   |
+LL |     let _ = std::mem::replace(&mut *f, None);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `(*f).take()`
+
+error: replacing an `Option` with `None`
+  --> $DIR/mem_replace.rs:123:13
+   |
+LL |     let _ = std::mem::replace(&mut b.opt, None);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider `Option::take()` instead: `b.opt.take()`
+
+error: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
+  --> $DIR/mem_replace.rs:125:13
+   |
+LL |     let _ = std::mem::replace(&mut b.val, String::default());
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut b.val)`
+
+error: aborting due to 24 previous errors