Use if-let in structured suggestion instead of Option::map

Author: compiler-errors

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -575,7 +575,8 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         // ---------- place
                         self.err.multipart_suggestions(
                             format!(
-                                "use `.insert()` to insert a value into a `{}`, `.get_mut()` to modify it, or the entry API for more flexibility",
+                                "use `.insert()` to insert a value into a `{}`, `.get_mut()` \
+                                to modify it, or the entry API for more flexibility",
                                 self.ty,
                             ),
                             vec![
@@ -592,16 +593,17 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                                     (rv.span.shrink_to_hi(), ")".to_string()),
                                 ],
                                 vec![
-                                    // val.get_mut(index).map(|v| { *v = rv; });
+                                    // if let Some(v) = val.get_mut(index) { *v = rv; }
+                                    (val.span.shrink_to_lo(), "if let Some(val) = ".to_string()),
                                     (
                                         val.span.shrink_to_hi().with_hi(index.span.lo()),
                                         ".get_mut(".to_string(),
                                     ),
                                     (
                                         index.span.shrink_to_hi().with_hi(place.span.hi()),
-                                        ").map(|val| { *val".to_string(),
+                                        ") { *val".to_string(),
                                     ),
-                                    (rv.span.shrink_to_hi(), "; })".to_string()),
+                                    (rv.span.shrink_to_hi(), "; }".to_string()),
                                 ],
                                 vec![
                                     // let x = val.entry(index).or_insert(rv);
@@ -628,15 +630,16 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         self.err.multipart_suggestion(
                             format!("to modify a `{}` use `.get_mut()`", self.ty),
                             vec![
+                                (val.span.shrink_to_lo(), "if let Some(val) = ".to_string()),
                                 (
                                     val.span.shrink_to_hi().with_hi(index.span.lo()),
                                     ".get_mut(".to_string(),
                                 ),
                                 (
                                     index.span.shrink_to_hi().with_hi(receiver.span.hi()),
-                                    ").map(|val| val".to_string(),
+                                    ") { val".to_string(),
                                 ),
-                                (sp.shrink_to_hi(), ")".to_string()),
+                                (sp.shrink_to_hi(), "); }".to_string()),
                             ],
                             Applicability::MachineApplicable,
                         );

tests/ui/borrowck/index-mut-help.stderr

@@ -18,8 +18,8 @@ help: use `.insert()` to insert a value into a `HashMap<&str, String>`, `.get_mu
    |
 LL |     map.insert("peter", "0".to_string());
    |        ~~~~~~~~       ~                +
-LL |     map.get_mut("peter").map(|val| { *val = "0".to_string(); });
-   |        ~~~~~~~~~       ~~~~~~~~~~~~~~~~~~                  ++++
+LL |     if let Some(val) = map.get_mut("peter") { *val = "0".to_string(); };
+   |     ++++++++++++++++++    ~~~~~~~~~       ~~~~~~~~                  +++
 LL |     let val = map.entry("peter").or_insert("0".to_string());
    |     +++++++++    ~~~~~~~       ~~~~~~~~~~~~               +
 

tests/ui/btreemap/btreemap-index-mut-2.stderr

@@ -9,8 +9,8 @@ help: use `.insert()` to insert a value into a `BTreeMap<u32, u32>`, `.get_mut()
    |
 LL |         map.insert(&0, 1);
    |            ~~~~~~~~  ~  +
-LL |         map.get_mut(&0).map(|val| { *val = 1; });
-   |            ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |         if let Some(val) = map.get_mut(&0) { *val = 1; };
+   |         ++++++++++++++++++    ~~~~~~~~~  ~~~~~~~~    +++
 LL |         let val = map.entry(&0).or_insert(1);
    |         +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
 

tests/ui/btreemap/btreemap-index-mut.stderr

@@ -9,8 +9,8 @@ help: use `.insert()` to insert a value into a `BTreeMap<u32, u32>`, `.get_mut()
    |
 LL |     map.insert(&0, 1);
    |        ~~~~~~~~  ~  +
-LL |     map.get_mut(&0).map(|val| { *val = 1; });
-   |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |     if let Some(val) = map.get_mut(&0) { *val = 1; };
+   |     ++++++++++++++++++    ~~~~~~~~~  ~~~~~~~~    +++
 LL |     let val = map.entry(&0).or_insert(1);
    |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
 

tests/ui/hashmap/hashmap-index-mut.stderr

@@ -9,8 +9,8 @@ help: use `.insert()` to insert a value into a `HashMap<u32, u32>`, `.get_mut()`
    |
 LL |     map.insert(&0, 1);
    |        ~~~~~~~~  ~  +
-LL |     map.get_mut(&0).map(|val| { *val = 1; });
-   |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
+LL |     if let Some(val) = map.get_mut(&0) { *val = 1; };
+   |     ++++++++++++++++++    ~~~~~~~~~  ~~~~~~~~    +++
 LL |     let val = map.entry(&0).or_insert(1);
    |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +