E0034: provide disambiguated syntax for candidates #38168

estebank · 2016-12-05T02:15:19Z

For a given file

trait A { fn foo(&self) {} }
trait B : A { fn foo(&self) {} }

fn bar<T: B>(a: &T) {
  a.foo()
}

provide the following output

error[E0034]: multiple applicable items in scope
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^ multiple `foo` found
  |
note: candidate #1 is defined in the trait `A`
 --> file.rs:2:11
  |
2 | trait A { fn foo(&self, a: usize) {} }
  |           ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to use it here write `A::foo(&a, 1)` instead
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^
note: candidate #2 is defined in the trait `B`
 --> file.rs:3:15
  |
3 | trait B : A { fn foo(&self, a: usize) {} }
  |               ^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to use it here write `B::foo(&a, 1)` instead
 --> file.rs:6:5
  |
6 |   a.foo(1)
  |     ^^^

Fix #37767.

rust-highfive · 2016-12-05T02:15:31Z

r? @nrc

(rust_highfive has picked a reviewer for you, use r? to override)

GuillaumeGomez · 2016-12-07T08:25:33Z

Seems good to me. I'll just wait for someone else's opinion.

cc @jonathandturner

nrc · 2016-12-19T00:02:23Z

src/librustc_typeck/check/method/suggest.rs

@@ -70,7 +70,8 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                               rcvr_ty: Ty<'tcx>,
                               item_name: ast::Name,
                               rcvr_expr: Option<&hir::Expr>,
-                               error: MethodError<'tcx>) {
+                               error: MethodError<'tcx>,
+                               args: Option<&'gcx [hir::Expr]>) {


In the None case here, could you pass an empty slice, and then not require Option<...>? If not, you should add a comment, explaining when and why to use None.

nrc · 2016-12-19T00:03:05Z

src/librustc_typeck/check/method/suggest.rs

@@ -130,6 +131,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                   "candidate #{} is defined in the trait `{}`",
                                   idx + 1,
                                   self.tcx.item_path_str(trait_did));
+                        err.span_help(span,


I would make this a non-span help, since the span is already part of the error, I don't think it is necessary to show the span twice.

nrc · 2016-12-19T00:03:40Z

src/librustc_typeck/check/method/suggest.rs

+                                      &format!("to use it here write `{}::{}({}{})` instead",
+                                               self.tcx.item_path_str(trait_did),
+                                               item_name,
+                                               if rcvr_ty.is_region_ptr() { "&" } else { "" },


Do you need to check for &mut here?

nrc · 2016-12-19T00:04:57Z

src/librustc_typeck/check/mod.rs

@@ -4075,7 +4079,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                    _ => Def::Err,
                };
                if item_name != keywords::Invalid.name() {
-                    self.report_method_error(span, ty, item_name, None, error);
+                    self.report_method_error(span, ty, item_name, None, error, None);


Why are there no args here? Is it just that we don't have access to them, or are they inappropriate?

If the former, then I'd prefer to output foo(...) rather than foo()

If the former, then I'd prefer to output foo(...) rather than foo()

This is the case now.

nrc · 2016-12-19T00:06:20Z

src/librustc_typeck/check/method/suggest.rs

@@ -130,6 +131,15 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                   "candidate #{} is defined in the trait `{}`",
                                   idx + 1,
                                   self.tcx.item_path_str(trait_did));
+                        err.span_help(span,
+                                      &format!("to use it here write `{}::{}({}{})` instead",


I would change the text to "to disambiguate the method call, write ..."

nrc · 2016-12-20T19:14:24Z

src/librustc/ty/sty.rs

@@ -1088,6 +1088,17 @@ impl<'a, 'gcx, 'tcx> TyS<'tcx> {
        }
    }

+    pub fn is_mutable(&self) -> bool {


This might be better named is_mutable_pointer

nrc · 2017-01-11T18:40:44Z

r=me, but failing tests

For a given file ```rust trait A { fn foo(&self) {} } trait B : A { fn foo(&self) {} } fn bar<T: B>(a: &T) { a.foo() } ``` provide the following output ``` error[E0034]: multiple applicable items in scope --> file.rs:6:5 | 6 | a.foo(1) | ^^^ multiple `foo` found | note: candidate rust-lang#1 is defined in the trait `A` --> file.rs:2:11 | 2 | trait A { fn foo(&self, a: usize) {} } | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: to use it here write `A::foo(&a, 1)` instead --> file.rs:6:5 | 6 | a.foo(1) | ^^^ note: candidate rust-lang#2 is defined in the trait `B` --> file.rs:3:15 | 3 | trait B : A { fn foo(&self, a: usize) {} } | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: to use it here write `B::foo(&a, 1)` instead --> file.rs:6:5 | 6 | a.foo(1) | ^^^ ```

estebank · 2017-01-13T19:27:06Z

@nrc tests fixed after rebase/squash.

nrc · 2017-01-18T00:45:20Z

@bors: r+

bors · 2017-01-18T00:45:21Z

📌 Commit f595ea2 has been approved by nrc

bors · 2017-01-18T04:44:51Z

⌛ Testing commit f595ea2 with merge c8af93f...

E0034: provide disambiguated syntax for candidates For a given file ```rust trait A { fn foo(&self) {} } trait B : A { fn foo(&self) {} } fn bar<T: B>(a: &T) { a.foo() } ``` provide the following output ``` error[E0034]: multiple applicable items in scope --> file.rs:6:5 | 6 | a.foo(1) | ^^^ multiple `foo` found | note: candidate #1 is defined in the trait `A` --> file.rs:2:11 | 2 | trait A { fn foo(&self, a: usize) {} } | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: to use it here write `A::foo(&a, 1)` instead --> file.rs:6:5 | 6 | a.foo(1) | ^^^ note: candidate #2 is defined in the trait `B` --> file.rs:3:15 | 3 | trait B : A { fn foo(&self, a: usize) {} } | ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: to use it here write `B::foo(&a, 1)` instead --> file.rs:6:5 | 6 | a.foo(1) | ^^^ ``` Fix #37767.

bors · 2017-01-18T08:55:51Z

☀️ Test successful - status-appveyor, status-travis
Approved by: nrc
Pushing c8af93f to master...

rust-highfive assigned nrc Dec 5, 2016

estebank force-pushed the help-E0034 branch from d135320 to b34f860 Compare December 5, 2016 02:23

nrc suggested changes Dec 19, 2016

View reviewed changes

nrc reviewed Dec 20, 2016

View reviewed changes

estebank force-pushed the help-E0034 branch 3 times, most recently from 6b5df90 to e32f042 Compare January 10, 2017 20:15

nrc approved these changes Jan 11, 2017

View reviewed changes

estebank force-pushed the help-E0034 branch from e32f042 to 01c88b7 Compare January 11, 2017 20:58

estebank force-pushed the help-E0034 branch from 01c88b7 to f595ea2 Compare January 12, 2017 22:54

bors merged commit f595ea2 into rust-lang:master Jan 18, 2017

estebank deleted the help-E0034 branch November 9, 2023 05:27

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

E0034: provide disambiguated syntax for candidates #38168

E0034: provide disambiguated syntax for candidates #38168

estebank commented Dec 5, 2016

rust-highfive commented Dec 5, 2016

GuillaumeGomez commented Dec 7, 2016

nrc Dec 19, 2016

nrc Dec 19, 2016

nrc Dec 19, 2016

nrc Dec 19, 2016

nrc Dec 19, 2016

estebank Jan 10, 2017

nrc Dec 19, 2016

nrc Dec 20, 2016

estebank Jan 10, 2017

nrc commented Jan 11, 2017

estebank commented Jan 13, 2017

nrc commented Jan 18, 2017

bors commented Jan 18, 2017

bors commented Jan 18, 2017

bors commented Jan 18, 2017

E0034: provide disambiguated syntax for candidates #38168

E0034: provide disambiguated syntax for candidates #38168

Conversation

estebank commented Dec 5, 2016

rust-highfive commented Dec 5, 2016

GuillaumeGomez commented Dec 7, 2016

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

nrc commented Jan 11, 2017

estebank commented Jan 13, 2017

nrc commented Jan 18, 2017

bors commented Jan 18, 2017

bors commented Jan 18, 2017

bors commented Jan 18, 2017