Rollup merge of rust-lang#83092 - petrochenkov:qspan, r=estebank

More precise spans for HIR paths

`Ty::assoc_item` is lowered to `<Ty>::assoc_item` in HIR, but `Ty` got span from the whole path.
This PR fixes that, and adjusts some diagnostic code that relied on `Ty` having the whole path span.

This is a pre-requisite for rust-lang#82868 (we cannot report suggestions like `Tr::assoc` -> `<dyn Tr>::assoc` with the current imprecise spans).
r? ````@estebank````

Author: JohnTitor

tests/ui/use_self.fixed

@@ -312,17 +312,18 @@ mod issue4140 {
         fn try_from(value: T) -> Result<Self, Error<Self::From, Self::To>>;
     }
 
-    impl<F, T> TryFrom<F> for T
-    where
-        T: From<F>,
-    {
-        type From = Self;
-        type To = Self;
-
-        fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
-            Ok(From::from(value))
-        }
-    }
+    // FIXME: Suggested fix results in infinite recursion.
+    // impl<F, T> TryFrom<F> for T
+    // where
+    //     T: From<F>,
+    // {
+    //     type From = Self::From;
+    //     type To = Self::To;
+
+    //     fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
+    //         Ok(From::from(value))
+    //     }
+    // }
 
     impl From<bool> for i64 {
         type From = bool;

tests/ui/use_self.rs

@@ -312,17 +312,18 @@ mod issue4140 {
         fn try_from(value: T) -> Result<Self, Error<Self::From, Self::To>>;
     }
 
-    impl<F, T> TryFrom<F> for T
-    where
-        T: From<F>,
-    {
-        type From = T::From;
-        type To = T::To;
-
-        fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
-            Ok(From::from(value))
-        }
-    }
+    // FIXME: Suggested fix results in infinite recursion.
+    // impl<F, T> TryFrom<F> for T
+    // where
+    //     T: From<F>,
+    // {
+    //     type From = Self::From;
+    //     type To = Self::To;
+
+    //     fn try_from(value: F) -> Result<Self, Error<Self::From, Self::To>> {
+    //         Ok(From::from(value))
+    //     }
+    // }
 
     impl From<bool> for i64 {
         type From = bool;

tests/ui/use_self.stderr

@@ -157,22 +157,10 @@ LL |             Foo { value }
    |             ^^^ help: use the applicable keyword: `Self`
 
 error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:319:21
-   |
-LL |         type From = T::From;
-   |                     ^^^^^^^ help: use the applicable keyword: `Self`
-
-error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:320:19
-   |
-LL |         type To = T::To;
-   |                   ^^^^^ help: use the applicable keyword: `Self`
-
-error: unnecessary structure name repetition
-  --> $DIR/use_self.rs:453:13
+  --> $DIR/use_self.rs:454:13
    |
 LL |             A::new::<submod::B>(submod::B {})
    |             ^ help: use the applicable keyword: `Self`
 
-error: aborting due to 29 previous errors
+error: aborting due to 27 previous errors
 

tests/ui/zero_sized_btreemap_values.stderr

@@ -83,7 +83,7 @@ error: map with zero-sized value type
   --> $DIR/zero_sized_btreemap_values.rs:64:35
    |
 LL |     let _: BTreeMap<String, ()> = BTreeMap::new();
-   |                                   ^^^^^^^^^^^^^
+   |                                   ^^^^^^^^
    |
    = help: consider using a set instead
 

tests/ui/zero_sized_hashmap_values.stderr

@@ -83,7 +83,7 @@ error: map with zero-sized value type
   --> $DIR/zero_sized_hashmap_values.rs:64:34
    |
 LL |     let _: HashMap<String, ()> = HashMap::new();
-   |                                  ^^^^^^^^^^^^
+   |                                  ^^^^^^^
    |
    = help: consider using a set instead