Rollup merge of #89248 - hkmatsumoto:suggest-similarly-named-assoc-items, r=estebank

Suggest similarly named associated items in trait impls

Fix #85942

Previously, the compiler didn't suggest similarly named associated items unlike we do in many situations. This patch adds such diagnostics for associated functions, types, and constants.

2 files changed, 122 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/suggest-trait-items.rs b/src/test/ui/suggestions/suggest-trait-items.rs
new file mode 100644
index 00000000000..9d42a734260
--- /dev/null
+++ b/src/test/ui/suggestions/suggest-trait-items.rs
@@ -0,0 +1,48 @@
+trait Foo {
+    type Type;
+
+    fn foo();
+    fn bar();
+    fn qux();
+}
+
+struct A;
+
+impl Foo for A {
+//~^ ERROR not all trait items implemented
+    type Typ = ();
+    //~^ ERROR type `Typ` is not a member of trait
+    //~| HELP there is an associated type with a similar name
+
+    fn fooo() {}
+    //~^ ERROR method `fooo` is not a member of trait
+    //~| HELP there is an associated function with a similar name
+
+    fn barr() {}
+    //~^ ERROR method `barr` is not a member of trait
+    //~| HELP there is an associated function with a similar name
+
+    fn quux() {}
+    //~^ ERROR method `quux` is not a member of trait
+    //~| HELP there is an associated function with a similar name
+}
+//~^ HELP implement the missing item
+//~| HELP implement the missing item
+//~| HELP implement the missing item
+//~| HELP implement the missing item
+
+trait Bar {
+    const Const: i32;
+}
+
+struct B;
+
+impl Bar for B {
+//~^ ERROR not all trait items implemented
+    const Cnst: i32 = 0;
+    //~^ ERROR const `Cnst` is not a member of trait
+    //~| HELP there is an associated constant with a similar name
+}
+//~^ HELP implement the missing item
+
+fn main() {}
diff --git a/src/test/ui/suggestions/suggest-trait-items.stderr b/src/test/ui/suggestions/suggest-trait-items.stderr
new file mode 100644
index 00000000000..151bae7d1b9
--- /dev/null
+++ b/src/test/ui/suggestions/suggest-trait-items.stderr
@@ -0,0 +1,74 @@
+error[E0437]: type `Typ` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:13:5
+   |
+LL |     type Typ = ();
+   |     ^^^^^---^^^^^^
+   |     |    |
+   |     |    help: there is an associated type with a similar name: `Type`
+   |     not a member of trait `Foo`
+
+error[E0407]: method `fooo` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:17:5
+   |
+LL |     fn fooo() {}
+   |     ^^^----^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `foo`
+   |     not a member of trait `Foo`
+
+error[E0407]: method `barr` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:21:5
+   |
+LL |     fn barr() {}
+   |     ^^^----^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `bar`
+   |     not a member of trait `Foo`
+
+error[E0407]: method `quux` is not a member of trait `Foo`
+  --> $DIR/suggest-trait-items.rs:25:5
+   |
+LL |     fn quux() {}
+   |     ^^^----^^^^^
+   |     |  |
+   |     |  help: there is an associated function with a similar name: `qux`
+   |     not a member of trait `Foo`
+
+error[E0438]: const `Cnst` is not a member of trait `Bar`
+  --> $DIR/suggest-trait-items.rs:42:5
+   |
+LL |     const Cnst: i32 = 0;
+   |     ^^^^^^----^^^^^^^^^^
+   |     |     |
+   |     |     help: there is an associated constant with a similar name: `Const`
+   |     not a member of trait `Bar`
+
+error[E0046]: not all trait items implemented, missing: `Type`, `foo`, `bar`, `qux`
+  --> $DIR/suggest-trait-items.rs:11:1
+   |
+LL |     type Type;
+   |     ---------- `Type` from trait
+LL | 
+LL |     fn foo();
+   |     --------- `foo` from trait
+LL |     fn bar();
+   |     --------- `bar` from trait
+LL |     fn qux();
+   |     --------- `qux` from trait
+...
+LL | impl Foo for A {
+   | ^^^^^^^^^^^^^^ missing `Type`, `foo`, `bar`, `qux` in implementation
+
+error[E0046]: not all trait items implemented, missing: `Const`
+  --> $DIR/suggest-trait-items.rs:40:1
+   |
+LL |     const Const: i32;
+   |     ----------------- `Const` from trait
+...
+LL | impl Bar for B {
+   | ^^^^^^^^^^^^^^ missing `Const` in implementation
+
+error: aborting due to 7 previous errors
+
+Some errors have detailed explanations: E0046, E0407, E0437, E0438.
+For more information about an error, try `rustc --explain E0046`.