Suggest calling trait objects and parameters too, when possible

7 files changed, 93 insertions, 16 deletions

diff --git a/src/test/ui/associated-types/substs-ppaux.normal.stderr b/src/test/ui/associated-types/substs-ppaux.normal.stderr
index 501d2cfaa26..3f180cf4f1f 100644
--- a/src/test/ui/associated-types/substs-ppaux.normal.stderr
+++ b/src/test/ui/associated-types/substs-ppaux.normal.stderr
@@ -11,7 +11,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::bar::<'static, char>;
    |
    = note: expected unit type `()`
                 found fn item `fn() {<i8 as Foo<'static, 'static, u8>>::bar::<'static, char>}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::bar::<'static, char>();
    |                                                                         ++
@@ -29,7 +29,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>;
    |
    = note: expected unit type `()`
                 found fn item `fn() {<i8 as Foo<'static, 'static>>::bar::<'static, char>}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>();
    |                                                                          ++
@@ -47,7 +47,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::baz;
    |
    = note: expected unit type `()`
                 found fn item `fn() {<i8 as Foo<'static, 'static, u8>>::baz}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::baz();
    |                                                        ++
diff --git a/src/test/ui/associated-types/substs-ppaux.verbose.stderr b/src/test/ui/associated-types/substs-ppaux.verbose.stderr
index ae3e862dddd..16dd29de2c5 100644
--- a/src/test/ui/associated-types/substs-ppaux.verbose.stderr
+++ b/src/test/ui/associated-types/substs-ppaux.verbose.stderr
@@ -11,7 +11,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::bar::<'static, char>;
    |
    = note: expected unit type `()`
                 found fn item `fn() {<i8 as Foo<ReStatic, ReStatic, u8>>::bar::<ReStatic, char>}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::bar::<'static, char>();
    |                                                                         ++
@@ -29,7 +29,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>;
    |
    = note: expected unit type `()`
                 found fn item `fn() {<i8 as Foo<ReStatic, ReStatic>>::bar::<ReStatic, char>}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u32>>::bar::<'static, char>();
    |                                                                          ++
@@ -47,7 +47,7 @@ LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::baz;
    |
    = note: expected unit type `()`
                 found fn item `fn() {<i8 as Foo<ReStatic, ReStatic, u8>>::baz}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let x: () = <i8 as Foo<'static, 'static,  u8>>::baz();
    |                                                        ++
diff --git a/src/test/ui/fn/fn-trait-formatting.stderr b/src/test/ui/fn/fn-trait-formatting.stderr
index ea88e401bed..1d5e0a859a6 100644
--- a/src/test/ui/fn/fn-trait-formatting.stderr
+++ b/src/test/ui/fn/fn-trait-formatting.stderr
@@ -8,6 +8,10 @@ LL |     let _: () = Box::new(|_: isize| {}) as Box<dyn FnOnce(isize)>;
    |
    = note: expected unit type `()`
                  found struct `Box<dyn FnOnce(isize)>`
+help: use parentheses to call this trait object
+   |
+LL |     let _: () = (Box::new(|_: isize| {}) as Box<dyn FnOnce(isize)>)(_);
+   |                 +                                                 ++++
 
 error[E0308]: mismatched types
   --> $DIR/fn-trait-formatting.rs:10:17
@@ -19,6 +23,10 @@ LL |     let _: () = Box::new(|_: isize, isize| {}) as Box<dyn Fn(isize, isize)>
    |
    = note: expected unit type `()`
                  found struct `Box<dyn Fn(isize, isize)>`
+help: use parentheses to call this trait object
+   |
+LL |     let _: () = (Box::new(|_: isize, isize| {}) as Box<dyn Fn(isize, isize)>)(_, _);
+   |                 +                                                           +++++++
 
 error[E0308]: mismatched types
   --> $DIR/fn-trait-formatting.rs:14:17
diff --git a/src/test/ui/impl-trait/suggest-calling-rpit-closure.stderr b/src/test/ui/impl-trait/suggest-calling-rpit-closure.stderr
index 2a328a0e6f5..c10a856d83b 100644
--- a/src/test/ui/impl-trait/suggest-calling-rpit-closure.stderr
+++ b/src/test/ui/impl-trait/suggest-calling-rpit-closure.stderr
@@ -11,7 +11,7 @@ LL | fn opaque() -> impl Fn() -> i32 {
    |
    = note:     expected type `i32`
            found opaque type `impl Fn() -> i32`
-help: use parentheses to call this closure
+help: use parentheses to call this opaque type
    |
 LL |     opaque()()
    |             ++
diff --git a/src/test/ui/suggestions/call-on-missing.rs b/src/test/ui/suggestions/call-on-missing.rs
index 611b9d40f0f..25ced84dd37 100644
--- a/src/test/ui/suggestions/call-on-missing.rs
+++ b/src/test/ui/suggestions/call-on-missing.rs
@@ -16,4 +16,24 @@ fn main() {
     foo.i;
     //~^ ERROR no field `i`
     //~| HELP use parentheses to call this function
+
+    let callable = Box::new(|| Foo { i: 1 }) as Box<dyn Fn() -> Foo>;
+
+    callable.bar();
+    //~^ ERROR no method named `bar`
+    //~| HELP use parentheses to call this trait object
+
+    callable.i;
+    //~^ ERROR no field `i`
+    //~| HELP use parentheses to call this trait object
+}
+
+fn type_param<T: Fn() -> Foo>(t: T) {
+    t.bar();
+    //~^ ERROR no method named `bar`
+    //~| HELP use parentheses to call this type parameter
+
+    t.i;
+    //~^ ERROR no field `i`
+    //~| HELP use parentheses to call this type parameter
 }
diff --git a/src/test/ui/suggestions/call-on-missing.stderr b/src/test/ui/suggestions/call-on-missing.stderr
index d8070321e14..ca9abc7e906 100644
--- a/src/test/ui/suggestions/call-on-missing.stderr
+++ b/src/test/ui/suggestions/call-on-missing.stderr
@@ -20,7 +20,56 @@ help: use parentheses to call this function
 LL |     foo().i;
    |        ++
 
-error: aborting due to 2 previous errors
+error[E0599]: no method named `bar` found for struct `Box<dyn Fn() -> Foo>` in the current scope
+  --> $DIR/call-on-missing.rs:22:14
+   |
+LL |     callable.bar();
+   |              ^^^ method not found in `Box<dyn Fn() -> Foo>`
+   |
+help: use parentheses to call this trait object
+   |
+LL |     callable().bar();
+   |             ++
+
+error[E0609]: no field `i` on type `Box<dyn Fn() -> Foo>`
+  --> $DIR/call-on-missing.rs:26:14
+   |
+LL |     callable.i;
+   |              ^ unknown field
+   |
+help: use parentheses to call this trait object
+   |
+LL |     callable().i;
+   |             ++
+
+error[E0599]: no method named `bar` found for type parameter `T` in the current scope
+  --> $DIR/call-on-missing.rs:32:7
+   |
+LL | fn type_param<T: Fn() -> Foo>(t: T) {
+   |               - method `bar` not found for this type parameter
+LL |     t.bar();
+   |       ^^^ method not found in `T`
+   |
+help: use parentheses to call this type parameter
+   |
+LL |     t().bar();
+   |      ++
+
+error[E0609]: no field `i` on type `T`
+  --> $DIR/call-on-missing.rs:36:7
+   |
+LL | fn type_param<T: Fn() -> Foo>(t: T) {
+   |               - type parameter 'T' declared here
+...
+LL |     t.i;
+   |       ^
+   |
+help: use parentheses to call this type parameter
+   |
+LL |     t().i;
+   |      ++
+
+error: aborting due to 6 previous errors
 
 Some errors have detailed explanations: E0599, E0609.
 For more information about an error, try `rustc --explain E0599`.
diff --git a/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr b/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr
index e75ce0da82e..ba710bfa746 100644
--- a/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr
+++ b/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr
@@ -103,7 +103,7 @@ LL |     let _: usize = T::baz;
    |
    = note: expected type `usize`
            found fn item `fn(usize, usize) -> usize {<_ as T>::baz}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = T::baz(_, _);
    |                          ++++++
@@ -121,7 +121,7 @@ LL |     let _: usize = T::bat;
    |
    = note: expected type `usize`
            found fn item `fn(usize) -> usize {<_ as T>::bat}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = T::bat(_);
    |                          +++
@@ -157,7 +157,7 @@ LL |     let _: usize = X::baz;
    |
    = note: expected type `usize`
            found fn item `fn(usize, usize) -> usize {<X as T>::baz}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = X::baz(_, _);
    |                          ++++++
@@ -175,7 +175,7 @@ LL |     let _: usize = X::bat;
    |
    = note: expected type `usize`
            found fn item `fn(usize) -> usize {<X as T>::bat}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = X::bat(_);
    |                          +++
@@ -193,7 +193,7 @@ LL |     let _: usize = X::bax;
    |
    = note: expected type `usize`
            found fn item `fn(usize) -> usize {<X as T>::bax}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = X::bax(_);
    |                          +++
@@ -211,7 +211,7 @@ LL |     let _: usize = X::bach;
    |
    = note: expected type `usize`
            found fn item `fn(usize) -> usize {<X as T>::bach}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = X::bach(_);
    |                           +++
@@ -229,7 +229,7 @@ LL |     let _: usize = X::ban;
    |
    = note: expected type `usize`
            found fn item `for<'r> fn(&'r X) -> usize {<X as T>::ban}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = X::ban(_);
    |                          +++
@@ -247,7 +247,7 @@ LL |     let _: usize = X::bal;
    |
    = note: expected type `usize`
            found fn item `for<'r> fn(&'r X) -> usize {<X as T>::bal}`
-help: use parentheses to call this function
+help: use parentheses to call this associated function
    |
 LL |     let _: usize = X::bal(_);
    |                          +++