Add regression test for rust-lang#105737

Author: GuillaumeGomez

src/test/rustdoc-ui/issue-105737.rs

@@ -0,0 +1,4 @@
+impl Vec<lol> {}
+//~^ ERROR
+
+pub fn lol() {}

src/test/rustdoc-ui/issue-105737.stderr

@@ -0,0 +1,12 @@
+error[E0747]: constant provided when a type was expected
+  --> $DIR/issue-105737.rs:1:10
+   |
+LL | impl Vec<lol> {}
+   |          ^^^
+   |
+   = help: `lol` is a function item, not a type
+   = help: function item types cannot be named directly
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0747`.