rustc: support impl's in PrintCx::parameterized.

Author: eddyb

src/librustc/util/ppaux.rs

@@ -352,6 +352,22 @@ impl PrintCx<'a, 'gcx, 'tcx> {
 
             write!(f, "::{}", key.disambiguated_data.data.as_interned_str())?;
         } else {
+            // Try to print `impl`s more like how you'd refer to their associated items.
+            if let DefPathData::Impl = key.disambiguated_data.data {
+                if let Some(trait_ref) = self.tcx.impl_trait_ref(def_id) {
+                    // HACK(eddyb) this is in lieu of more specific disambiguation.
+                    print!(f, self, write("{}", self.tcx.item_path_str(def_id)))?;
+
+                    let trait_ref = trait_ref.subst(self.tcx, substs);
+                    print!(f, self, print_debug(trait_ref))?;
+                } else {
+                    let self_ty = self.tcx.type_of(def_id).subst(self.tcx, substs);
+                    // FIXME(eddyb) omit the <> where possible.
+                    print!(f, self, write("<"), print(self_ty), write(">"))?;
+                }
+                return Ok(());
+            }
+
             print!(f, self, write("{}", self.tcx.item_path_str(def_id)))?;
         }
 

src/test/ui/hygiene/impl_items.rs

@@ -9,7 +9,7 @@ mod foo {
     }
 
     pub macro m() {
-        let _: () = S.f(); //~ ERROR type `for<'r> fn(&'r foo::S) {foo::S::f}` is private
+        let _: () = S.f(); //~ ERROR type `for<'r> fn(&'r foo::S) {<foo::S>::f}` is private
     }
 }
 

src/test/ui/hygiene/impl_items.stderr

@@ -1,7 +1,7 @@
-error: type `for<'r> fn(&'r foo::S) {foo::S::f}` is private
+error: type `for<'r> fn(&'r foo::S) {<foo::S>::f}` is private
   --> $DIR/impl_items.rs:12:23
    |
-LL |         let _: () = S.f(); //~ ERROR type `for<'r> fn(&'r foo::S) {foo::S::f}` is private
+LL |         let _: () = S.f(); //~ ERROR type `for<'r> fn(&'r foo::S) {<foo::S>::f}` is private
    |                       ^
 ...
 LL |     foo::m!();

src/test/ui/issues/issue-22638.rs

@@ -50,7 +50,7 @@ struct D (Box<A>);
 
 impl D {
     pub fn matches<F: Fn()>(&self, f: &F) {
-        //~^ ERROR reached the type-length limit while instantiating `D::matches::<[closure
+        //~^ ERROR reached the type-length limit while instantiating `<D>::matches::<[closure
         let &D(ref a) = self;
         a.matches(f)
     }

src/test/ui/issues/issue-22638.stderr

@@ -1,8 +1,8 @@
-error: reached the type-length limit while instantiating `D::matches::$CLOSURE`
+error: reached the type-length limit while instantiating `<D>::matches::$CLOSURE`
   --> $DIR/issue-22638.rs:52:5
    |
 LL | /     pub fn matches<F: Fn()>(&self, f: &F) {
-LL | |         //~^ ERROR reached the type-length limit while instantiating `D::matches::<[closure
+LL | |         //~^ ERROR reached the type-length limit while instantiating `<D>::matches::<[closure
 LL | |         let &D(ref a) = self;
 LL | |         a.matches(f)
 LL | |     }

src/test/ui/issues/issue-24322.stderr

@@ -5,7 +5,7 @@ LL |     let x: &fn(&B) -> u32 = &B::func; //~ ERROR mismatched types
    |                             ^^^^^^^^ expected fn pointer, found fn item
    |
    = note: expected type `&for<'r> fn(&'r B) -> u32`
-              found type `&for<'r> fn(&'r B) -> u32 {B::func}`
+              found type `&for<'r> fn(&'r B) -> u32 {<B>::func}`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-29124.rs

@@ -13,7 +13,7 @@ fn func() -> Ret {
 
 fn main() {
     Obj::func.x();
-    //~^ ERROR no method named `x` found for type `fn() -> Ret {Obj::func}` in the current scope
+    //~^ ERROR no method named `x` found for type `fn() -> Ret {<Obj>::func}` in the current scope
     func.x();
     //~^ ERROR no method named `x` found for type `fn() -> Ret {func}` in the current scope
 }

src/test/ui/issues/issue-29124.stderr

@@ -1,4 +1,4 @@
-error[E0599]: no method named `x` found for type `fn() -> Ret {Obj::func}` in the current scope
+error[E0599]: no method named `x` found for type `fn() -> Ret {<Obj>::func}` in the current scope
   --> $DIR/issue-29124.rs:15:15
    |
 LL |     Obj::func.x();

src/test/ui/issues/issue-39559-2.stderr

@@ -8,7 +8,7 @@ error[E0080]: evaluation of constant value failed
   --> $DIR/issue-39559-2.rs:14:24
    |
 LL |     let array: [usize; Dim3::dim()]
-   |                        ^^^^^^^^^^^ calling non-const function `<Dim3 as Dim>::dim`
+   |                        ^^^^^^^^^^^ calling non-const function `<Dim3 as Dim><Dim3 as Dim>::dim`
 
 error[E0015]: calls in constants are limited to constant functions, tuple structs and tuple variants
   --> $DIR/issue-39559-2.rs:17:15
@@ -20,7 +20,7 @@ error[E0080]: evaluation of constant value failed
   --> $DIR/issue-39559-2.rs:17:15
    |
 LL |         = [0; Dim3::dim()];
-   |               ^^^^^^^^^^^ calling non-const function `<Dim3 as Dim>::dim`
+   |               ^^^^^^^^^^^ calling non-const function `<Dim3 as Dim><Dim3 as Dim>::dim`
 
 error: aborting due to 4 previous errors
 

src/test/ui/privacy/associated-item-privacy-inherent.rs

@@ -11,11 +11,11 @@ mod priv_nominal {
 
     pub macro mac() {
         let value = Pub::method;
-        //~^ ERROR type `for<'r> fn(&'r priv_nominal::Pub) {priv_nominal::Pub::method}` is private
+        //~^ ERROR type `for<'r> fn(&'r priv_nominal::Pub) {<priv_nominal::Pub>::method}` is private
         value;
-        //~^ ERROR type `for<'r> fn(&'r priv_nominal::Pub) {priv_nominal::Pub::method}` is private
+        //~^ ERROR type `for<'r> fn(&'r priv_nominal::Pub) {<priv_nominal::Pub>::method}` is private
         Pub.method();
-        //~^ ERROR type `for<'r> fn(&'r priv_nominal::Pub) {priv_nominal::Pub::method}` is private
+        //~^ ERROR type `for<'r> fn(&'r priv_nominal::Pub) {<priv_nominal::Pub>::method}` is private
         Pub::CONST;
         //~^ ERROR associated constant `CONST` is private
         // let _: Pub::AssocTy;