fix APITIT being treated as a normal generic parameter in suggestions

Author: Qelxiros

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -232,8 +232,7 @@ fn missing_items_err(
     };
 
     // Obtain the level of indentation ending in `sugg_sp`.
-    let padding =
-        tcx.sess.source_map().indentation_before(sugg_sp).unwrap_or_else(|| String::new());
+    let padding = tcx.sess.source_map().indentation_before(sugg_sp).unwrap_or_else(String::new);
     let (mut missing_trait_item, mut missing_trait_item_none, mut missing_trait_item_label) =
         (Vec::new(), Vec::new(), Vec::new());
 
@@ -356,6 +355,10 @@ fn bounds_from_generic_predicates<'tcx>(
     let mut types_str = vec![];
     for (ty, bounds) in types {
         if let ty::Param(_) = ty.kind() {
+            let ty_str = ty.to_string();
+            if ty_str.contains("impl ") {
+                continue;
+            }
             let mut bounds_str = vec![];
             for bound in bounds {
                 let mut projections_str = vec![];
@@ -376,9 +379,9 @@ fn bounds_from_generic_predicates<'tcx>(
                 }
             }
             if bounds_str.is_empty() {
-                types_str.push(ty.to_string());
+                types_str.push(ty_str);
             } else {
-                types_str.push(format!("{}: {}", ty, bounds_str.join(" + ")));
+                types_str.push(format!("{}: {}", ty_str, bounds_str.join(" + ")));
             }
         } else {
             // Avoid suggesting the following:
@@ -475,7 +478,7 @@ fn fn_sig_suggestion<'tcx>(
     let (generics, where_clauses) = bounds_from_generic_predicates(tcx, predicates);
 
     // FIXME: this is not entirely correct, as the lifetimes from borrowed params will
-    // not be present in the `fn` definition, not will we account for renamed
+    // not be present in the `fn` definition, nor will we account for renamed
     // lifetimes between the `impl` and the `trait`, but this should be good enough to
     // fill in a significant portion of the missing code, and other subsequent
     // suggestions can help the user fix the code.

tests/ui/suggestions/apitit-unimplemented-method.rs

@@ -0,0 +1,12 @@
+//@ aux-build:dep.rs
+
+extern crate dep;
+use dep::*;
+
+struct Local;
+impl Trait for Local {}
+//~^ ERROR not all trait items implemented
+//~| HELP implement the missing item: `fn foo(_: impl Sized) { todo!() }`
+//~| HELP implement the missing item: `fn bar<T>(_: impl Sized) { todo!() }`
+
+fn main() {}

tests/ui/suggestions/apitit-unimplemented-method.stderr

@@ -0,0 +1,12 @@
+error[E0046]: not all trait items implemented, missing: `foo`, `bar`
+  --> $DIR/apitit-unimplemented-method.rs:7:1
+   |
+LL | impl Trait for Local {}
+   | ^^^^^^^^^^^^^^^^^^^^ missing `foo`, `bar` in implementation
+   |
+   = help: implement the missing item: `fn foo(_: impl Sized) { todo!() }`
+   = help: implement the missing item: `fn bar<T>(_: impl Sized) { todo!() }`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0046`.

tests/ui/suggestions/auxiliary/dep.rs

@@ -0,0 +1,4 @@
+pub trait Trait {
+    fn foo(_: impl Sized);
+    fn bar<T>(_: impl Sized);
+}