Add test file

Add test file

Add changes & test results

Add stderr reference file

Move break to correct position. Failing test added from tests in ui

Update compiler/rustc_hir_typeck/src/method/suggest.rs

Co-authored-by: Esteban Kuber <estebank@users.noreply.github.com>

Update compiler/rustc_hir_typeck/src/method/suggest.rs

Co-authored-by: Esteban Kuber <estebank@users.noreply.github.com>

Match to find Error type: BadReturnType

Print info

whitespace

fmt

Use probe_name_for_many

Revert  probe.rs

Update .stderr

Update compiler/rustc_hir_typeck/src/method/suggest.rs

Add span.note - this pottlues other tests

span_labels

add span_label

Ignore candidtes beyond the scope of current context

Move check to end of function to filter out methods with better context errors

Whiteline

Format

Remove mutation check

Whitespace

Fmt again

Author: iSwapna

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -483,7 +483,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 );
                 probe.is_ok()
             });
-
             self.note_internal_mutation_in_method(
                 &mut err,
                 rcvr_expr,
@@ -1240,7 +1239,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
             }
         }
+        // Only if an appropriate error source is not found, check method chain for possible candiates
+        let error_source_not_found = unsatisfied_predicates.is_empty();
+        if error_source_not_found && let Mode::MethodCall = mode && let SelfSource::MethodCall(mut rcvr_expr) = source {
+        while let hir::ExprKind::MethodCall(_path_segment, parent_expr, _args, method_span) =
+        rcvr_expr.kind
+            {
+                let prev_ty = self.resolve_vars_if_possible(
+                    self.typeck_results
+                        .borrow()
+                        .expr_ty_adjusted_opt(parent_expr)
+                        .unwrap_or(Ty::new_misc_error(self.tcx)),);
+
+                for _matched_method in self.probe_for_name_many(
+                    Mode::MethodCall,
+                    item_name,
+                    None,
+                    IsSuggestion(true),
+                    prev_ty,
+                    rcvr_expr.hir_id,
+                    ProbeScope::TraitsInScope,) {
+                        err.span_label(method_span, format!("{item_kind} `{item_name}` is available on `{prev_ty}`"));
+                    }
+                    rcvr_expr = parent_expr;
 
+            }
+        }
         self.note_derefed_ty_has_method(&mut err, source, rcvr_ty, item_name, expected);
         return Some(err);
     }

tests/ui/structs/method-chain-expression-failure.rs

@@ -0,0 +1,26 @@
+struct A;
+struct B;
+struct C;
+struct D;
+
+impl A {
+    fn b(&self) -> B { B }
+}
+
+impl B {
+    fn c(&self) -> C { C }
+    fn foo(&self) {}
+}
+
+impl C {
+    fn d(&self) -> D { D }
+}
+
+impl D {
+    fn e(&self) {}
+}
+
+fn main() {
+    A.b().c().d().foo();
+//~^ ERROR no method named `foo` found for struct `D` in the current scope
+}

tests/ui/structs/method-chain-expression-failure.stderr

@@ -0,0 +1,14 @@
+error[E0599]: no method named `foo` found for struct `D` in the current scope
+  --> $DIR/method-chain-expression-failure.rs:24:19
+   |
+LL | struct D;
+   | -------- method `foo` not found for this struct
+...
+LL |     A.b().c().d().foo();
+   |           ---     ^^^ method not found in `D`
+   |           |
+   |           method `foo` is available on `&B`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0599`.

tests/ui/suggestions/chain-method-call-mutation-in-place.stderr

@@ -18,7 +18,10 @@ error[E0599]: no method named `sort` found for unit type `()` in the current sco
   --> $DIR/chain-method-call-mutation-in-place.rs:3:72
    |
 LL |     vec![1, 2, 3].into_iter().collect::<Vec<i32>>().sort_by_key(|i| i).sort();
-   |                                                                        ^^^^ method not found in `()`
+   |                   -----------                       ------------------ ^^^^ method not found in `()`
+   |                   |                                 |
+   |                   |                                 method `sort` is available on `&mut [i32]`
+   |                   method `sort` is available on `Vec<i32>`
    |
 note: method `sort_by_key` modifies its receiver in-place, it is not meant to be used in method chains.
   --> $DIR/chain-method-call-mutation-in-place.rs:3:53