Provide structured suggestion for `hashmap[idx] = val`

5 files changed, 36 insertions, 10 deletions

diff --git a/src/test/ui/borrowck/index-mut-help.rs b/src/test/ui/borrowck/index-mut-help.rs
index d57ef975d96..35266e113a6 100644
--- a/src/test/ui/borrowck/index-mut-help.rs
+++ b/src/test/ui/borrowck/index-mut-help.rs
@@ -1,10 +1,9 @@
 // When mutably indexing a type that implements `Index` but not `IndexMut`, a
 // special 'help' message is added to the output.
+use std::collections::HashMap;
 
 
 fn main() {
-    use std::collections::HashMap;
-
     let mut map = HashMap::new();
     map.insert("peter", "23".to_string());
 
diff --git a/src/test/ui/borrowck/index-mut-help.stderr b/src/test/ui/borrowck/index-mut-help.stderr
index 0ce60e3eb1d..f42d7e01554 100644
--- a/src/test/ui/borrowck/index-mut-help.stderr
+++ b/src/test/ui/borrowck/index-mut-help.stderr
@@ -1,23 +1,33 @@
 error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutable
-  --> $DIR/index-mut-help.rs:11:5
+  --> $DIR/index-mut-help.rs:10:5
    |
 LL |     map["peter"].clear();
    |     ^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>`
-   = help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<&str, String>` use `.get_mut()`
+   |
+LL |     map.get_mut("peter").map(|val| val.clear());
+   |        ~~~~~~~~~       ~~~~~~~~~~~~~~~        +
 
 error[E0594]: cannot assign to data in an index of `HashMap<&str, String>`
-  --> $DIR/index-mut-help.rs:12:5
+  --> $DIR/index-mut-help.rs:11:5
    |
 LL |     map["peter"] = "0".to_string();
    |     ^^^^^^^^^^^^ cannot assign
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>`
-   = help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API
+   |
+LL |     map.insert("peter", "0".to_string());
+   |        ~~~~~~~~       ~                +
+LL |     map.get_mut("peter").map(|val| { *val = "0".to_string(); });
+   |        ~~~~~~~~~       ~~~~~~~~~~~~~~~~~~                  ++++
+LL |     let val = map.entry("peter").or_insert("0".to_string());
+   |     +++++++++    ~~~~~~~       ~~~~~~~~~~~~               +
 
 error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutable
-  --> $DIR/index-mut-help.rs:13:13
+  --> $DIR/index-mut-help.rs:12:13
    |
 LL |     let _ = &mut map["peter"];
    |             ^^^^^^^^^^^^^^^^^ cannot borrow as mutable
diff --git a/src/test/ui/btreemap/btreemap-index-mut.stderr b/src/test/ui/btreemap/btreemap-index-mut.stderr
index 260f7100074..26f2a4c4b29 100644
--- a/src/test/ui/btreemap/btreemap-index-mut.stderr
+++ b/src/test/ui/btreemap/btreemap-index-mut.stderr
@@ -5,7 +5,14 @@ LL |     map[&0] = 1;
    |     ^^^^^^^^^^^ cannot assign
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `BTreeMap<u32, u32>`
-   = help: to modify a `BTreeMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `BTreeMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+   |
+LL |     map.insert(&0, 1);
+   |        ~~~~~~~~  ~  +
+LL |     map.get_mut(&0).map(|val| { *val = 1; });
+   |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |     let val = map.entry(&0).or_insert(1);
+   |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/hashmap/hashmap-index-mut.stderr b/src/test/ui/hashmap/hashmap-index-mut.stderr
index c72b380f466..c1948ab6271 100644
--- a/src/test/ui/hashmap/hashmap-index-mut.stderr
+++ b/src/test/ui/hashmap/hashmap-index-mut.stderr
@@ -5,7 +5,14 @@ LL |     map[&0] = 1;
    |     ^^^^^^^^^^^ cannot assign
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<u32, u32>`
-   = help: to modify a `HashMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
+   |
+LL |     map.insert(&0, 1);
+   |        ~~~~~~~~  ~  +
+LL |     map.get_mut(&0).map(|val| { *val = 1; });
+   |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |     let val = map.entry(&0).or_insert(1);
+   |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-41726.stderr b/src/test/ui/issues/issue-41726.stderr
index 9c70ab7d971..b05c1fb14ef 100644
--- a/src/test/ui/issues/issue-41726.stderr
+++ b/src/test/ui/issues/issue-41726.stderr
@@ -5,7 +5,10 @@ LL |         things[src.as_str()].sort();
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot borrow as mutable
    |
    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<String, Vec<String>>`
-   = help: to modify a `HashMap<String, Vec<String>>`, use `.get_mut()`, `.insert()` or the entry API
+help: to modify a `HashMap<String, Vec<String>>` use `.get_mut()`
+   |
+LL |         things.get_mut(src.as_str()).map(|val| val.sort());
+   |               ~~~~~~~~~            ~~~~~~~~~~~~~~~       +
 
 error: aborting due to previous error