Make is_importable stop rejecting assoc const and fn

compiler/rustc_resolve/src/imports.rs

@@ -829,33 +829,27 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     Err(Undetermined) => indeterminate_count += 1,
                     // Don't update the resolution, because it was never added.
                     Err(Determined) if target.name == kw::Underscore => {}
-                    Ok(binding)
-                        if binding.is_importable()
-                            || binding.is_assoc_const_or_fn()
-                                && this.tcx.features().import_trait_associated_functions() =>
-                    {
+                    Ok(binding) if binding.is_importable() => {
+                        if binding.is_assoc_const_or_fn()
+                            && !this.tcx.features().import_trait_associated_functions()
+                        {
+                            feature_err(
+                                this.tcx.sess,
+                                sym::import_trait_associated_functions,
+                                import.span,
+                                "`use` associated items of traits is unstable",
+                            )
+                            .emit();
+                        }
                         let imported_binding = this.import(binding, import);
                         target_bindings[ns].set(Some(imported_binding));
                         this.define(parent, target, ns, imported_binding);
                     }
                     source_binding @ (Ok(..) | Err(Determined)) => {
-                        if let Ok(binding) = source_binding {
-                            if binding.is_assoc_const_or_fn() {
-                                feature_err(
-                                    this.tcx.sess,
-                                    sym::import_trait_associated_functions,
-                                    import.span,
-                                    "`use` associated items of traits is unstable",
-                                )
+                        if source_binding.is_ok() {
+                            this.dcx()
+                                .create_err(IsNotDirectlyImportable { span: import.span, target })
                                 .emit();
-                            } else {
-                                this.dcx()
-                                    .create_err(IsNotDirectlyImportable {
-                                        span: import.span,
-                                        target,
-                                    })
-                                    .emit();
-                            }
                         }
                         let key = BindingKey::new(target, ns);
                         this.update_resolution(parent, key, false, |_, resolution| {

compiler/rustc_resolve/src/lib.rs

@@ -920,10 +920,7 @@ impl<'ra> NameBindingData<'ra> {
     }
 
     fn is_importable(&self) -> bool {
-        !matches!(
-            self.res(),
-            Res::Def(DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy, _)
-        )
+        !matches!(self.res(), Res::Def(DefKind::AssocTy, _))
     }
 
     fn is_assoc_const_or_fn(&self) -> bool {

tests/ui/associated-type-bounds/return-type-notation/not-a-method.stderr

@@ -15,6 +15,11 @@ error[E0576]: cannot find function `method` in this scope
    |
 LL |     method(..): Send,
    |     ^^^^^^ not found in this scope
+   |
+help: consider importing this associated function
+   |
+LL + use Tr::method;
+   |
 
 error[E0412]: cannot find type `method` in this scope
   --> $DIR/not-a-method.rs:36:5

tests/ui/delegation/bad-resolve.stderr

@@ -62,6 +62,11 @@ error[E0425]: cannot find function `foo` in this scope
    |
 LL |     reuse foo { &self.0 }
    |           ^^^ not found in this scope
+   |
+help: consider importing this associated function
+   |
+LL + use Trait::foo;
+   |
 
 error[E0425]: cannot find function `foo2` in trait `Trait`
   --> $DIR/bad-resolve.rs:37:18

tests/ui/delegation/explicit-paths.stderr

@@ -21,42 +21,58 @@ error[E0425]: cannot find function `foo4` in `S`
    |
 LL |     reuse S::foo4;
    |              ^^^^ not found in `S`
+   |
+note: associated function `trait_assoc_fn_to_other::Trait2::foo4` exists but is inaccessible
+  --> $DIR/explicit-paths.rs:65:9
+   |
+LL |         reuse F::foo4 { &F }
+   |         ^^^^^^^^^^^^^ not accessible
 
 error[E0425]: cannot find function `foo4` in `F`
   --> $DIR/explicit-paths.rs:38:18
    |
 LL |         reuse F::foo4 { &self.0 }
    |                  ^^^^ not found in `F`
    |
-note: function `fn_to_other::foo4` exists but is inaccessible
+note: these items exist but are inaccessible
   --> $DIR/explicit-paths.rs:27:5
    |
 LL |     reuse S::foo4;
-   |     ^^^^^^^^^^^^^^ not accessible
+   |     ^^^^^^^^^^^^^^ `fn_to_other::foo4`: not accessible
+...
+LL |         reuse F::foo4 { &F }
+   |         ^^^^^^^^^^^^^ `trait_assoc_fn_to_other::Trait2::foo4`: not accessible
 
 error[E0425]: cannot find function `foo4` in `F`
   --> $DIR/explicit-paths.rs:51:18
    |
 LL |         reuse F::foo4 { &self.0 }
    |                  ^^^^ not found in `F`
    |
-note: function `fn_to_other::foo4` exists but is inaccessible
+note: these items exist but are inaccessible
   --> $DIR/explicit-paths.rs:27:5
    |
 LL |     reuse S::foo4;
-   |     ^^^^^^^^^^^^^^ not accessible
+   |     ^^^^^^^^^^^^^^ `fn_to_other::foo4`: not accessible
+...
+LL |         reuse F::foo4 { &F }
+   |         ^^^^^^^^^^^^^ `trait_assoc_fn_to_other::Trait2::foo4`: not accessible
 
 error[E0425]: cannot find function `foo4` in `F`
   --> $DIR/explicit-paths.rs:65:18
    |
 LL |         reuse F::foo4 { &F }
    |                  ^^^^ not found in `F`
    |
-note: function `fn_to_other::foo4` exists but is inaccessible
-  --> $DIR/explicit-paths.rs:27:5
+help: consider importing this associated function
+   |
+LL +     use trait_assoc_fn_to_other::Trait2::foo4;
+   |
+help: if you import `foo4`, refer to it directly
+   |
+LL -         reuse F::foo4 { &F }
+LL +         reuse foo4 { &F }
    |
-LL |     reuse S::foo4;
-   |     ^^^^^^^^^^^^^^ not accessible
 
 error[E0119]: conflicting implementations of trait `Trait` for type `S`
   --> $DIR/explicit-paths.rs:74:5

tests/ui/delegation/ice-issue-124342.stderr

@@ -3,6 +3,16 @@ error[E0425]: cannot find function `foo` in module `to_reuse`
    |
 LL |     reuse to_reuse::foo { foo }
    |                     ^^^ not found in `to_reuse`
+   |
+help: consider importing this associated function
+   |
+LL + use Trait::foo;
+   |
+help: if you import `foo`, refer to it directly
+   |
+LL -     reuse to_reuse::foo { foo }
+LL +     reuse foo { foo }
+   |
 
 error[E0425]: cannot find value `foo` in this scope
   --> $DIR/ice-issue-124342.rs:7:27
@@ -14,6 +24,10 @@ help: you might have meant to refer to the associated function
    |
 LL |     reuse to_reuse::foo { Self::foo }
    |                           ++++++
+help: consider importing this associated function
+   |
+LL + use Trait::foo;
+   |
 
 error: aborting due to 2 previous errors
 

tests/ui/imports/import-trait-method.rs

@@ -4,4 +4,4 @@ trait Foo {
 
 use Foo::foo; //~ ERROR `use` associated items of traits is unstable [E0658]
 
-fn main() { foo(); }
+fn main() { foo(); } //~ ERROR type annotations needed

tests/ui/imports/import-trait-method.stderr

@@ -8,6 +8,15 @@ LL | use Foo::foo;
    = help: add `#![feature(import_trait_associated_functions)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: aborting due to 1 previous error
+error[E0283]: type annotations needed
+  --> $DIR/import-trait-method.rs:7:13
+   |
+LL | fn main() { foo(); }
+   |             ^^^^^ cannot infer type
+   |
+   = note: cannot satisfy `_: Foo`
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0658`.
+Some errors have detailed explanations: E0283, E0658.
+For more information about an error, try `rustc --explain E0283`.

tests/ui/macros/rfc-3086-metavar-expr/syntax-errors.stderr

@@ -313,39 +313,26 @@ LL |     unknown_metavar!(a);
    |
    = note: this error originates in the macro `unknown_metavar` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0425]: cannot find value `i` in this scope
-  --> $DIR/syntax-errors.rs:23:36
+error[E0425]: cannot find function `count` in this scope
+  --> $DIR/syntax-errors.rs:23:30
    |
 LL |     ( $( $i:ident ),* ) => { count(i) };
-   |                                    ^ not found in this scope
+   |                              ^^^^^ not found in this scope
 ...
 LL |     no_curly__no_rhs_dollar__round!(a, b, c);
    |     ---------------------------------------- in this macro invocation
    |
    = note: this error originates in the macro `no_curly__no_rhs_dollar__round` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error[E0425]: cannot find value `i` in this scope
-  --> $DIR/syntax-errors.rs:30:29
-   |
-LL |     ( $i:ident ) => { count(i) };
-   |                             ^ not found in this scope
-...
-LL |     no_curly__no_rhs_dollar__no_round!(a);
-   |     ------------------------------------- in this macro invocation
+help: consider importing this associated function
    |
-   = note: this error originates in the macro `no_curly__no_rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error[E0425]: cannot find value `a` in this scope
-  --> $DIR/syntax-errors.rs:152:37
+LL + use std::iter::Iterator::count;
    |
-LL |     no_curly__rhs_dollar__no_round!(a);
-   |                                     ^ not found in this scope
 
-error[E0425]: cannot find function `count` in this scope
-  --> $DIR/syntax-errors.rs:23:30
+error[E0425]: cannot find value `i` in this scope
+  --> $DIR/syntax-errors.rs:23:36
    |
 LL |     ( $( $i:ident ),* ) => { count(i) };
-   |                              ^^^^^ not found in this scope
+   |                                    ^ not found in this scope
 ...
 LL |     no_curly__no_rhs_dollar__round!(a, b, c);
    |     ---------------------------------------- in this macro invocation
@@ -358,6 +345,21 @@ error[E0425]: cannot find function `count` in this scope
 LL |     ( $i:ident ) => { count(i) };
    |                       ^^^^^ not found in this scope
 ...
+LL |     no_curly__no_rhs_dollar__no_round!(a);
+   |     ------------------------------------- in this macro invocation
+   |
+   = note: this error originates in the macro `no_curly__no_rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this associated function
+   |
+LL + use std::iter::Iterator::count;
+   |
+
+error[E0425]: cannot find value `i` in this scope
+  --> $DIR/syntax-errors.rs:30:29
+   |
+LL |     ( $i:ident ) => { count(i) };
+   |                             ^ not found in this scope
+...
 LL |     no_curly__no_rhs_dollar__no_round!(a);
    |     ------------------------------------- in this macro invocation
    |
@@ -373,6 +375,16 @@ LL |     no_curly__rhs_dollar__no_round!(a);
    |     ---------------------------------- in this macro invocation
    |
    = note: this error originates in the macro `no_curly__rhs_dollar__no_round` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider importing this associated function
+   |
+LL + use std::iter::Iterator::count;
+   |
+
+error[E0425]: cannot find value `a` in this scope
+  --> $DIR/syntax-errors.rs:152:37
+   |
+LL |     no_curly__rhs_dollar__no_round!(a);
+   |                                     ^ not found in this scope
 
 error: aborting due to 39 previous errors
 

tests/ui/methods/suggest-method-on-call-for-ambig-receiver.stderr

@@ -3,6 +3,11 @@ error[E0425]: cannot find function `consume` in this scope
    |
 LL |             consume(right);
    |             ^^^^^^^ not found in this scope
+   |
+help: consider importing this associated function
+   |
+LL + use std::io::BufRead::consume;
+   |
 
 error: aborting due to 1 previous error
 

tests/ui/methods/suggest-method-on-call-with-macro-rcvr.stderr

@@ -4,10 +4,9 @@ error[E0425]: cannot find function `len` in this scope
 LL |     let hello = len(vec![]);
    |                 ^^^ not found in this scope
    |
-help: use the `.` operator to call the method `len` on `&Vec<_>`
+help: consider importing this associated function
    |
-LL -     let hello = len(vec![]);
-LL +     let hello = vec![].len();
+LL + use std::iter::ExactSizeIterator::len;
    |
 
 error: aborting due to 1 previous error

tests/ui/resolve/associated-fn-called-as-fn.rs

@@ -1,29 +1,32 @@
 struct S;
+//~^ HELP consider importing one of these associated functions
+//~| HELP consider importing one of these associated functions
+
 impl Foo for S {
-    fn parse(s:&str) {
+    fn parse(s: &str) {
         for c in s.chars() {
             match c {
                 '0'..='9' => collect_primary(&c), //~ ERROR cannot find function `collect_primary`
                 //~^ HELP you might have meant to call the associated function
                 '+' | '-' => println!("We got a sign: {}", c),
-                _ => println!("Not a number!")
+                _ => println!("Not a number!"),
             }
         }
     }
 }
 trait Foo {
-    fn collect_primary(ch:&char) { }
-    fn parse(s:&str);
+    fn collect_primary(ch: &char) {}
+    fn parse(s: &str);
 }
 trait Bar {
-    fn collect_primary(ch:&char) { }
-    fn parse(s:&str) {
+    fn collect_primary(ch: &char) {}
+    fn parse(s: &str) {
         for c in s.chars() {
             match c {
                 '0'..='9' => collect_primary(&c), //~ ERROR cannot find function `collect_primary`
                 //~^ HELP you might have meant to call the associated function
                 '+' | '-' => println!("We got a sign: {}", c),
-                _ => println!("Not a number!")
+                _ => println!("Not a number!"),
             }
         }
     }

tests/ui/resolve/associated-fn-called-as-fn.stderr

@@ -1,5 +1,5 @@
 error[E0425]: cannot find function `collect_primary` in this scope
-  --> $DIR/associated-fn-called-as-fn.rs:6:30
+  --> $DIR/associated-fn-called-as-fn.rs:9:30
    |
 LL |                 '0'..='9' => collect_primary(&c),
    |                              ^^^^^^^^^^^^^^^
@@ -8,9 +8,15 @@ help: you might have meant to call the associated function
    |
 LL |                 '0'..='9' => Self::collect_primary(&c),
    |                              ++++++
+help: consider importing one of these associated functions
+   |
+LL + use Bar::collect_primary;
+   |
+LL + use Foo::collect_primary;
+   |
 
 error[E0425]: cannot find function `collect_primary` in this scope
-  --> $DIR/associated-fn-called-as-fn.rs:23:30
+  --> $DIR/associated-fn-called-as-fn.rs:26:30
    |
 LL |                 '0'..='9' => collect_primary(&c),
    |                              ^^^^^^^^^^^^^^^
@@ -19,6 +25,12 @@ help: you might have meant to call the associated function
    |
 LL |                 '0'..='9' => Self::collect_primary(&c),
    |                              ++++++
+help: consider importing one of these associated functions
+   |
+LL + use Bar::collect_primary;
+   |
+LL + use Foo::collect_primary;
+   |
 
 error: aborting due to 2 previous errors