Add test for weird backticks placement

Author: camelid

src/test/rustdoc-ui/intra-doc/unknown-disambiguator.rs

@@ -1,10 +1,13 @@
+#![deny(warnings)]
+
 //! Linking to [foo@banana] and [`bar@banana!()`].
 //~^ ERROR unknown disambiguator `foo`
 //~| ERROR unknown disambiguator `bar`
 //! And to [no disambiguator](@nectarine) and [another](@apricot!()).
 //~^ ERROR unknown disambiguator ``
 //~| ERROR unknown disambiguator ``
-
-#![deny(warnings)]
+//! And with weird backticks: [``foo@hello``] [foo`@`hello].
+//~^ ERROR unknown disambiguator `foo`
+//~| ERROR unknown disambiguator `foo`
 
 fn main() {}

src/test/rustdoc-ui/intra-doc/unknown-disambiguator.stderr

@@ -1,33 +1,45 @@
 error: unknown disambiguator `foo`
-  --> $DIR/unknown-disambiguator.rs:1:17
+  --> $DIR/unknown-disambiguator.rs:3:17
    |
 LL | //! Linking to [foo@banana] and [`bar@banana!()`].
    |                 ^^^
    |
 note: the lint level is defined here
-  --> $DIR/unknown-disambiguator.rs:8:9
+  --> $DIR/unknown-disambiguator.rs:1:9
    |
 LL | #![deny(warnings)]
    |         ^^^^^^^^
    = note: `#[deny(rustdoc::broken_intra_doc_links)]` implied by `#[deny(warnings)]`
 
 error: unknown disambiguator `bar`
-  --> $DIR/unknown-disambiguator.rs:1:35
+  --> $DIR/unknown-disambiguator.rs:3:35
    |
 LL | //! Linking to [foo@banana] and [`bar@banana!()`].
    |                                   ^^^
 
+error: unknown disambiguator `foo`
+  --> $DIR/unknown-disambiguator.rs:9:34
+   |
+LL | //! And with weird backticks: [``foo@hello``] [foo`@`hello].
+   |                                  ^^^
+
+error: unknown disambiguator `foo`
+  --> $DIR/unknown-disambiguator.rs:9:48
+   |
+LL | //! And with weird backticks: [``foo@hello``] [foo`@`hello].
+   |                                                ^^^
+
 error: unknown disambiguator ``
-  --> $DIR/unknown-disambiguator.rs:4:31
+  --> $DIR/unknown-disambiguator.rs:6:31
    |
 LL | //! And to [no disambiguator](@nectarine) and [another](@apricot!()).
    |                               ^
 
 error: unknown disambiguator ``
-  --> $DIR/unknown-disambiguator.rs:4:57
+  --> $DIR/unknown-disambiguator.rs:6:57
    |
 LL | //! And to [no disambiguator](@nectarine) and [another](@apricot!()).
    |                                                         ^
 
-error: aborting due to 4 previous errors
+error: aborting due to 6 previous errors