map_entry: don't suggest when {e.insert(_); None } would be required

tests/ui/entry.fixed

@@ -1,6 +1,6 @@
 //@needs-asm-support
 
-#![allow(unused, clippy::needless_pass_by_value, clippy::collapsible_if)]
+#![allow(clippy::needless_pass_by_value, clippy::collapsible_if)]
 #![warn(clippy::map_entry)]
 
 use std::arch::asm;

tests/ui/entry.rs

@@ -1,6 +1,6 @@
 //@needs-asm-support
 
-#![allow(unused, clippy::needless_pass_by_value, clippy::collapsible_if)]
+#![allow(clippy::needless_pass_by_value, clippy::collapsible_if)]
 #![warn(clippy::map_entry)]
 
 use std::arch::asm;

tests/ui/entry_btree.fixed

@@ -1,5 +1,4 @@
 #![warn(clippy::map_entry)]
-#![allow(dead_code)]
 
 use std::collections::BTreeMap;
 

tests/ui/entry_btree.rs

@@ -1,5 +1,4 @@
 #![warn(clippy::map_entry)]
-#![allow(dead_code)]
 
 use std::collections::BTreeMap;
 

tests/ui/entry_btree.stderr

@@ -1,5 +1,5 @@
 error: usage of `contains_key` followed by `insert` on a `BTreeMap`
-  --> tests/ui/entry_btree.rs:10:5
+  --> tests/ui/entry_btree.rs:9:5
    |
 LL | /     if !m.contains_key(&k) {
 LL | |

tests/ui/entry_unfixable.rs

@@ -14,40 +14,6 @@ macro_rules! insert {
     };
 }
 
-mod issue13306 {
-    use std::collections::HashMap;
-
-    struct Env {
-        enclosing: Option<Box<Env>>,
-        values: HashMap<String, usize>,
-    }
-
-    impl Env {
-        fn assign(&mut self, name: String, value: usize) -> bool {
-            if !self.values.contains_key(&name) {
-                //~^ map_entry
-                self.values.insert(name, value);
-                true
-            } else if let Some(enclosing) = &mut self.enclosing {
-                enclosing.assign(name, value)
-            } else {
-                false
-            }
-        }
-    }
-}
-
-fn issue9925(mut hm: HashMap<String, bool>) {
-    let key = "hello".to_string();
-    if hm.contains_key(&key) {
-        //~^ map_entry
-        let bval = hm.get_mut(&key).unwrap();
-        *bval = false;
-    } else {
-        hm.insert(key, true);
-    }
-}
-
 mod issue9470 {
     use std::collections::HashMap;
     use std::sync::Mutex;
@@ -90,4 +56,45 @@ mod issue9470 {
     }
 }
 
+fn issue9925(mut hm: HashMap<String, bool>) {
+    let key = "hello".to_string();
+    if hm.contains_key(&key) {
+        //~^ map_entry
+        let bval = hm.get_mut(&key).unwrap();
+        *bval = false;
+    } else {
+        hm.insert(key, true);
+    }
+}
+
+mod issue13306 {
+    use std::collections::HashMap;
+
+    struct Env {
+        enclosing: Option<Box<Env>>,
+        values: HashMap<String, usize>,
+    }
+
+    impl Env {
+        fn assign(&mut self, name: String, value: usize) -> bool {
+            if !self.values.contains_key(&name) {
+                //~^ map_entry
+                self.values.insert(name, value);
+                true
+            } else if let Some(enclosing) = &mut self.enclosing {
+                enclosing.assign(name, value)
+            } else {
+                false
+            }
+        }
+    }
+}
+
+fn issue15307<K: Eq + Hash, V>(mut m: HashMap<K, V>, k: K, v: V) {
+    if !m.contains_key(&k) {
+        //~^ map_entry
+        assert!(m.insert(k, v).is_none());
+    }
+}
+
 fn main() {}

tests/ui/entry_unfixable.stderr

@@ -1,12 +1,12 @@
 error: usage of `contains_key` followed by `insert` on a `HashMap`
-  --> tests/ui/entry_unfixable.rs:27:13
+  --> tests/ui/entry_unfixable.rs:46:13
    |
-LL | /             if !self.values.contains_key(&name) {
+LL | /             if self.globals.contains_key(&name) {
 LL | |
-LL | |                 self.values.insert(name, value);
-LL | |                 true
-...  |
-LL | |                 false
+LL | |                 self.globals.insert(name, value);
+LL | |             } else {
+LL | |                 let interner = INTERNER.lock().unwrap();
+LL | |                 return Err(interner.resolve(name).unwrap().to_owned());
 LL | |             }
    | |_____________^
    |
@@ -15,7 +15,7 @@ LL | |             }
    = help: to override `-D warnings` add `#[allow(clippy::map_entry)]`
 
 error: usage of `contains_key` followed by `insert` on a `HashMap`
-  --> tests/ui/entry_unfixable.rs:42:5
+  --> tests/ui/entry_unfixable.rs:61:5
    |
 LL | /     if hm.contains_key(&key) {
 LL | |
@@ -31,16 +31,27 @@ LL | |     }
 error: usage of `contains_key` followed by `insert` on a `HashMap`
   --> tests/ui/entry_unfixable.rs:80:13
    |
-LL | /             if self.globals.contains_key(&name) {
+LL | /             if !self.values.contains_key(&name) {
 LL | |
-LL | |                 self.globals.insert(name, value);
-LL | |             } else {
-LL | |                 let interner = INTERNER.lock().unwrap();
-LL | |                 return Err(interner.resolve(name).unwrap().to_owned());
+LL | |                 self.values.insert(name, value);
+LL | |                 true
+...  |
+LL | |                 false
 LL | |             }
    | |_____________^
    |
    = help: consider using the `Entry` API: https://doc.rust-lang.org/std/collections/struct.HashMap.html#entry-api
 
-error: aborting due to 3 previous errors
+error: usage of `contains_key` followed by `insert` on a `HashMap`
+  --> tests/ui/entry_unfixable.rs:94:5
+   |
+LL | /     if !m.contains_key(&k) {
+LL | |
+LL | |         assert!(m.insert(k, v).is_none());
+LL | |     }
+   | |_____^
+   |
+   = help: consider using the `Entry` API: https://doc.rust-lang.org/std/collections/struct.HashMap.html#entry-api
+
+error: aborting due to 4 previous errors
 

tests/ui/entry_with_else.fixed

@@ -1,4 +1,4 @@
-#![allow(unused, clippy::needless_pass_by_value, clippy::collapsible_if)]
+#![allow(clippy::needless_pass_by_value, clippy::collapsible_if)]
 #![warn(clippy::map_entry)]
 
 use std::collections::{BTreeMap, HashMap};
@@ -55,17 +55,6 @@ fn insert_if_absent0<K: Eq + Hash + Copy, V: Copy>(m: &mut HashMap<K, V>, k: K,
         }
     }
 
-    match m.entry(k) {
-        std::collections::hash_map::Entry::Occupied(mut e) => {
-            //~^ map_entry
-            if true { Some(e.insert(v)) } else { Some(e.insert(v2)) }
-        }
-        std::collections::hash_map::Entry::Vacant(e) => {
-            e.insert(v);
-            None
-        }
-    };
-
     if let std::collections::hash_map::Entry::Occupied(mut e) = m.entry(k) {
         //~^ map_entry
         foo();

tests/ui/entry_with_else.rs

@@ -1,4 +1,4 @@
-#![allow(unused, clippy::needless_pass_by_value, clippy::collapsible_if)]
+#![allow(clippy::needless_pass_by_value, clippy::collapsible_if)]
 #![warn(clippy::map_entry)]
 
 use std::collections::{BTreeMap, HashMap};
@@ -46,13 +46,6 @@ fn insert_if_absent0<K: Eq + Hash + Copy, V: Copy>(m: &mut HashMap<K, V>, k: K,
         m.insert(k, v2);
     }
 
-    if m.contains_key(&k) {
-        //~^ map_entry
-        if true { m.insert(k, v) } else { m.insert(k, v2) }
-    } else {
-        m.insert(k, v)
-    };
-
     if m.contains_key(&k) {
         //~^ map_entry
         foo();

tests/ui/entry_with_else.stderr

@@ -119,31 +119,6 @@ error: usage of `contains_key` followed by `insert` on a `HashMap`
    |
 LL | /     if m.contains_key(&k) {
 LL | |
-LL | |         if true { m.insert(k, v) } else { m.insert(k, v2) }
-LL | |     } else {
-LL | |         m.insert(k, v)
-LL | |     };
-   | |_____^
-   |
-help: try
-   |
-LL ~     match m.entry(k) {
-LL +         std::collections::hash_map::Entry::Occupied(mut e) => {
-LL +
-LL +             if true { Some(e.insert(v)) } else { Some(e.insert(v2)) }
-LL +         }
-LL +         std::collections::hash_map::Entry::Vacant(e) => {
-LL +             e.insert(v);
-LL +             None
-LL +         }
-LL ~     };
-   |
-
-error: usage of `contains_key` followed by `insert` on a `HashMap`
-  --> tests/ui/entry_with_else.rs:56:5
-   |
-LL | /     if m.contains_key(&k) {
-LL | |
 LL | |         foo();
 LL | |         m.insert(k, v)
 LL | |     } else {
@@ -162,5 +137,5 @@ LL +         None
 LL ~     };
    |
 
-error: aborting due to 7 previous errors
+error: aborting due to 6 previous errors
 

tests/ui/entry_with_else_unfixable.rs

@@ -0,0 +1,16 @@
+//@no-rustfix
+#![warn(clippy::map_entry)]
+
+use std::collections::HashMap;
+use std::hash::Hash;
+
+fn foo() {}
+
+fn insert_if_absent0<K: Eq + Hash + Copy, V: Copy>(m: &mut HashMap<K, V>, k: K, v: V, v2: V) {
+    if m.contains_key(&k) {
+        //~^ map_entry
+        if true { m.insert(k, v) } else { m.insert(k, v2) }
+    } else {
+        m.insert(k, v)
+    };
+}

tests/ui/entry_with_else_unfixable.stderr

@@ -0,0 +1,17 @@
+error: usage of `contains_key` followed by `insert` on a `HashMap`
+  --> tests/ui/entry_with_else_unfixable.rs:10:5
+   |
+LL | /     if m.contains_key(&k) {
+LL | |
+LL | |         if true { m.insert(k, v) } else { m.insert(k, v2) }
+LL | |     } else {
+LL | |         m.insert(k, v)
+LL | |     };
+   | |_____^
+   |
+   = help: consider using the `Entry` API: https://doc.rust-lang.org/std/collections/struct.HashMap.html#entry-api
+   = note: `-D clippy::map-entry` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::map_entry)]`
+
+error: aborting due to 1 previous error
+