Add new label to E0283

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -2014,6 +2014,21 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                 let subst = data.trait_ref.substs.iter().find(|s| s.has_infer_types_or_consts());
 
                 let mut err = if let Some(subst) = subst {
+                    if matches!(obligation.cause.code(), ObligationCauseCode::ItemObligation(..))
+                        && !obligation.param_env.is_const()
+                        && !self.is_tainted_by_errors()
+                    {
+                        let mut err = struct_span_err!(
+                            self.tcx.sess,
+                            span,
+                            E0283,
+                            "type annotations needed",
+                        );
+                        err.span_label(span, "cannot call trait method as a free function");
+                        err.emit();
+                        return;
+                    }
+
                     self.emit_inference_failure_err(body_id, span, subst, ErrorCode::E0283, true)
                 } else {
                     struct_span_err!(

src/test/ui/associated-types/associated-types-unconstrained.stderr

@@ -5,7 +5,7 @@ LL |     fn bar() -> isize;
    |     ------------------ `Foo::bar` defined here
 ...
 LL |     let x: isize = Foo::bar();
-   |                    ^^^^^^^^ cannot call associated function of trait
+   |                    ^^^^^^^^ cannot call trait method as a free function
 
 error: aborting due to previous error
 

src/test/ui/error-codes/E0283.stderr

@@ -5,31 +5,13 @@ LL |     fn create() -> u32;
    |     ------------------- `Generator::create` defined here
 ...
 LL |     let cont: u32 = Generator::create();
-   |                     ^^^^^^^^^^^^^^^^^ cannot call associated function of trait
-   |
-help: use a fully-qualified path to a specific available implementation (2 found)
-   |
-LL |     let cont: u32 = <::Impl as Generator>::create();
-   |                     ++++++++++          +
+   |                     ^^^^^^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/E0283.rs:35:24
    |
 LL |     let bar = foo_impl.into() * 1u32;
-   |                        ^^^^
-   |
-note: multiple `impl`s satisfying `Impl: Into<_>` found
-  --> $DIR/E0283.rs:17:1
-   |
-LL | impl Into<u32> for Impl {
-   | ^^^^^^^^^^^^^^^^^^^^^^^
-   = note: and another `impl` found in the `core` crate:
-           - impl<T, U> Into<U> for T
-             where U: From<T>;
-help: try using a fully qualified path to specify the expected types
-   |
-LL |     let bar = <Impl as Into<T>>::into(foo_impl) * 1u32;
-   |               ++++++++++++++++++++++++        ~
+   |                        ^^^^ cannot call trait method as a free function
 
 error: aborting due to 2 previous errors
 

src/test/ui/inference/issue-72690.stderr

@@ -2,11 +2,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:7:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:7:22
@@ -51,31 +47,17 @@ help: try using a fully qualified path to specify the expected types
 LL |     |x| String::from(<str as AsRef<T>>::as_ref("x"));
    |                      ++++++++++++++++++++++++++   ~
 
-error[E0283]: type annotations needed for `&T`
-  --> $DIR/issue-72690.rs:17:9
+error[E0283]: type annotations needed
+  --> $DIR/issue-72690.rs:17:17
    |
 LL |     let _ = "x".as_ref();
-   |         ^       ------ type must be known at this point
-   |
-   = note: multiple `impl`s satisfying `str: AsRef<_>` found in the following crates: `core`, `std`:
-           - impl AsRef<OsStr> for str;
-           - impl AsRef<Path> for str;
-           - impl AsRef<[u8]> for str;
-           - impl AsRef<str> for str;
-help: consider giving this pattern a type, where the type for type parameter `T` is specified
-   |
-LL |     let _: &T = "x".as_ref();
-   |          ++++
+   |                 ^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:21:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:21:22
@@ -97,11 +79,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:28:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:28:22
@@ -123,11 +101,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:37:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:37:22
@@ -149,11 +123,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:46:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:46:22
@@ -175,11 +145,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:53:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:53:22
@@ -201,11 +167,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:62:5
    |
 LL |     String::from("x".as_ref());
-   |     ^^^^^^^^^^^^ cannot infer type for reference `&_`
-   |
-   = note: multiple `impl`s satisfying `String: From<&_>` found in the `alloc` crate:
-           - impl<> From<&String> for String;
-           - impl<> From<&str> for String;
+   |     ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error[E0283]: type annotations needed
   --> $DIR/issue-72690.rs:62:22

src/test/ui/issues/issue-29147.stderr

@@ -2,15 +2,7 @@ error[E0283]: type annotations needed
   --> $DIR/issue-29147.rs:21:13
    |
 LL |     let _ = <S5<_>>::xxx;
-   |             ^^^^^^^^^^^^ cannot infer type for struct `S5<_>`
-   |
-note: multiple `impl`s satisfying `S5<_>: Foo` found
-  --> $DIR/issue-29147.rs:17:1
-   |
-LL | impl Foo for S5<u32> { fn xxx(&self) {} }
-   | ^^^^^^^^^^^^^^^^^^^^
-LL | impl Foo for S5<u64> { fn xxx(&self) {} }
-   | ^^^^^^^^^^^^^^^^^^^^
+   |             ^^^^^^^^^^^^ cannot call trait method as a free function
 
 error: aborting due to previous error
 

src/test/ui/traits/issue-77982.stderr

@@ -37,59 +37,22 @@ LL |     opts.get::<Q>(opt.as_ref());
    |             +++++
 
 error[E0283]: type annotations needed
-  --> $DIR/issue-77982.rs:13:59
+  --> $DIR/issue-77982.rs:13:44
    |
 LL |     let ips: Vec<_> = (0..100_000).map(|_| u32::from(0u32.into())).collect();
-   |                                            ---------      ^^^^
-   |                                            |
-   |                                            type must be known at this point
-   |
-   = note: multiple `impl`s satisfying `u32: From<_>` found in the following crates: `core`, `std`:
-           - impl From<Ipv4Addr> for u32;
-           - impl From<NonZeroU32> for u32;
-           - impl From<bool> for u32;
-           - impl From<char> for u32;
-           and 3 more
-help: try using a fully qualified path to specify the expected types
-   |
-LL |     let ips: Vec<_> = (0..100_000).map(|_| u32::from(<u32 as Into<T>>::into(0u32))).collect();
-   |                                                      +++++++++++++++++++++++    ~
+   |                                            ^^^^^^^^^ cannot call trait method as a free function
 
-error[E0283]: type annotations needed for `Box<T>`
-  --> $DIR/issue-77982.rs:36:9
+error[E0283]: type annotations needed
+  --> $DIR/issue-77982.rs:36:16
    |
 LL |     let _ = ().foo();
-   |         ^      --- type must be known at this point
-   |
-note: multiple `impl`s satisfying `(): Foo<'_, _>` found
-  --> $DIR/issue-77982.rs:29:1
-   |
-LL | impl Foo<'static, u32> for () {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL | impl<'a> Foo<'a, i16> for () {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: consider giving this pattern a type, where the type for type parameter `T` is specified
-   |
-LL |     let _: Box<T> = ().foo();
-   |          ++++++++
+   |                ^^^ cannot call trait method as a free function
 
-error[E0283]: type annotations needed for `Box<T>`
-  --> $DIR/issue-77982.rs:40:9
+error[E0283]: type annotations needed
+  --> $DIR/issue-77982.rs:40:19
    |
 LL |     let _ = (&()).bar();
-   |         ^         --- type must be known at this point
-   |
-note: multiple `impl`s satisfying `&(): Bar<'_, _>` found
-  --> $DIR/issue-77982.rs:32:1
-   |
-LL | impl<'a> Bar<'static, u32> for &'a () {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL | impl<'a> Bar<'a, i16> for &'a () {}
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-help: consider giving this pattern a type, where the type for type parameter `T` is specified
-   |
-LL |     let _: Box<T> = (&()).bar();
-   |          ++++++++
+   |                   ^^^ cannot call trait method as a free function
 
 error: aborting due to 5 previous errors
 

src/test/ui/traits/issue-98938.rs

@@ -0,0 +1,10 @@
+trait Foo {
+    fn bar() {}
+}
+
+fn main() {
+    Foo::bar();
+    //~^ ERROR type annotations needed
+
+    <_ as Foo>::bar();
+}

src/test/ui/traits/issue-98938.stderr

@@ -0,0 +1,9 @@
+error[E0283]: type annotations needed
+  --> $DIR/issue-98938.rs:6:5
+   |
+LL |     Foo::bar();
+   |     ^^^^^^^^ cannot call trait method as a free function
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0283`.

src/test/ui/traits/static-method-generic-inference.stderr

@@ -5,12 +5,7 @@ LL |         fn new() -> T;
    |         -------------- `HasNew::new` defined here
 ...
 LL |     let _f: base::Foo = base::HasNew::new();
-   |                         ^^^^^^^^^^^^^^^^^ cannot call associated function of trait
-   |
-help: use the fully-qualified path to the only available implementation
-   |
-LL |     let _f: base::Foo = base::<::base::Foo as HasNew>::new();
-   |                               +++++++++++++++       +
+   |                         ^^^^^^^^^^^^^^^^^ cannot call trait method as a free function
 
 error: aborting due to previous error