add third help hint to diagnostic error E0027

Author: duncpro

compiler/rustc_hir_typeck/src/pat.rs

@@ -2070,6 +2070,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 s = pluralize!(len),
                 them = if len == 1 { "it" } else { "them" },
             ),
+            format!(
+                "{}{}{}{}",
+                prefix,
+                unmentioned_fields
+                    .iter()
+                    .map(|(_, name)| {
+                        let field_name = name.to_string();
+                        format!("{field_name}: _")
+                    })
+                    .collect::<Vec<_>>()
+                    .join(", "),
+                if have_inaccessible_fields { ", .." } else { "" },
+                postfix,
+            ),
+            Applicability::MachineApplicable,
+        );
+        err.span_suggestion(
+            sp,
+            "or always ignore missing fields here",
             format!("{prefix}..{postfix}"),
             Applicability::MachineApplicable,
         );

tests/ui/destructuring-assignment/struct_destructure_fail.stderr

@@ -41,6 +41,10 @@ LL |     Struct { a, b } = Struct { a: 1, b: 2 };
    |               ~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     Struct { a, b: _ } = Struct { a: 1, b: 2 };
+   |               ~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     Struct { a, .. } = Struct { a: 1, b: 2 };
    |               ~~~~~~
 

tests/ui/error-codes/E0027.stderr

@@ -10,6 +10,10 @@ LL |         Dog { age: x, name } => {}
    |                     ~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Dog { age: x, name: _ } => {}
+   |                     ~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Dog { age: x, .. } => {}
    |                     ~~~~~~
 
@@ -25,6 +29,10 @@ LL |         Dog { name: x, age } => {}
    |                      ~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Dog { name: x, age: _ } => {}
+   |                      ~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Dog { name: x, .. } => {}
    |                      ~~~~~~
 
@@ -40,6 +48,10 @@ LL |         Dog { name: x, age } => {}
    |                      ~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Dog { name: x, age: _ } => {}
+   |                      ~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Dog { name: x, .. } => {}
    |                      ~~~~~~
 
@@ -55,6 +67,10 @@ LL |         Dog { name, age } => {}
    |             ~~~~~~~~~~~~~
 help: if you don't care about these missing fields, you can explicitly ignore them
    |
+LL |         Dog { name: _, age: _ } => {}
+   |             ~~~~~~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Dog { .. } => {}
    |             ~~~~~~
 

tests/ui/pattern/usefulness/doc-hidden-fields.stderr

@@ -21,6 +21,10 @@ LL |     let HiddenStruct { one, two, .. } = HiddenStruct::default();
    |                           ~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let HiddenStruct { one, two: _, .. } = HiddenStruct::default();
+   |                           ~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let HiddenStruct { one, .. } = HiddenStruct::default();
    |                           ~~~~~~
 
@@ -36,6 +40,10 @@ LL |     let HiddenStruct { one, hide, two } = HiddenStruct::default();
    |                                 ~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let HiddenStruct { one, hide, two: _ } = HiddenStruct::default();
+   |                                 ~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let HiddenStruct { one, hide, .. } = HiddenStruct::default();
    |                                 ~~~~~~
 
@@ -51,6 +59,10 @@ LL |     let InCrate { a, b, im_hidden } = InCrate { a: 0, b: false, im_hidden:
    |                       ~~~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let InCrate { a, b, im_hidden: _ } = InCrate { a: 0, b: false, im_hidden: 0 };
+   |                       ~~~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let InCrate { a, b, .. } = InCrate { a: 0, b: false, im_hidden: 0 };
    |                       ~~~~~~
 

tests/ui/pattern/usefulness/stable-gated-fields.stderr

@@ -10,6 +10,10 @@ LL |     let UnstableStruct { stable, stable2, .. } = UnstableStruct::default();
    |                                ~~~~~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let UnstableStruct { stable, stable2: _, .. } = UnstableStruct::default();
+   |                                ~~~~~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let UnstableStruct { stable, .. } = UnstableStruct::default();
    |                                ~~~~~~
 

tests/ui/pattern/usefulness/unstable-gated-fields.stderr

@@ -10,6 +10,10 @@ LL |     let UnstableStruct { stable, stable2, unstable } = UnstableStruct::defa
    |                                         ~~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let UnstableStruct { stable, stable2, unstable: _ } = UnstableStruct::default();
+   |                                         ~~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let UnstableStruct { stable, stable2, .. } = UnstableStruct::default();
    |                                         ~~~~~~
 
@@ -25,6 +29,10 @@ LL |     let UnstableStruct { stable, unstable, stable2 } = UnstableStruct::defa
    |                                          ~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let UnstableStruct { stable, unstable, stable2: _ } = UnstableStruct::default();
+   |                                          ~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let UnstableStruct { stable, unstable, .. } = UnstableStruct::default();
    |                                          ~~~~~~
 

tests/ui/structs/struct-field-cfg.stderr

@@ -24,6 +24,10 @@ LL |     let Foo { present } = foo;
    |             ~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let Foo { present: _ } = foo;
+   |             ~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let Foo { .. } = foo;
    |             ~~~~~~
 

tests/ui/structs/struct-pat-derived-error.stderr

@@ -27,6 +27,10 @@ LL |         let A { x, y, b, c } = self.d;
    |                     ~~~~~~~~
 help: if you don't care about these missing fields, you can explicitly ignore them
    |
+LL |         let A { x, y, b: _, c: _ } = self.d;
+   |                     ~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         let A { x, y, .. } = self.d;
    |                     ~~~~~~
 

tests/ui/structs/struct-tuple-field-names.stderr

@@ -32,6 +32,10 @@ LL |     if let E::S { 0: a, 1: _ } = x {
    |                       ~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     if let E::S { 0: a, 1: _ } = x {
+   |                       ~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     if let E::S { 0: a, .. } = x {
    |                       ~~~~~~
 

tests/ui/structs/suggest-replacing-field-when-specifying-same-type.stderr

@@ -19,6 +19,10 @@ LL |         Foo::Bar { a, aa: 1, c, b } => (),
    |                               ~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Foo::Bar { a, aa: 1, c, b: _ } => (),
+   |                               ~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Foo::Bar { a, aa: 1, c, .. } => (),
    |                               ~~~~~~
 
@@ -43,6 +47,10 @@ LL |         Foo::Baz { bb: 1.0, a } => (),
    |                           ~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Foo::Baz { bb: 1.0, a: _ } => (),
+   |                           ~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Foo::Baz { bb: 1.0, .. } => (),
    |                           ~~~~~~
 
@@ -64,6 +72,10 @@ LL |         Foo::Bar { a, aa: "", c, b } => (),
    |                                ~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Foo::Bar { a, aa: "", c, b: _ } => (),
+   |                                ~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Foo::Bar { a, aa: "", c, .. } => (),
    |                                ~~~~~~
 
@@ -85,6 +97,10 @@ LL |         Foo::Baz { bb: "", a } => (),
    |                          ~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |         Foo::Baz { bb: "", a: _ } => (),
+   |                          ~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |         Foo::Baz { bb: "", .. } => (),
    |                          ~~~~~~
 

tests/ui/typeck/issue-87872-missing-inaccessible-field-pattern.stderr

@@ -10,6 +10,10 @@ LL |     let foo::Foo { visible, .. } = foo::Foo::default();
    |                  ~~~~~~~~~~~~~~~
 help: if you don't care about this missing field, you can explicitly ignore it
    |
+LL |     let foo::Foo { visible: _, .. } = foo::Foo::default();
+   |                  ~~~~~~~~~~~~~~~~~~
+help: or always ignore missing fields here
+   |
 LL |     let foo::Foo { .. } = foo::Foo::default();
    |                  ~~~~~~