Advise to put a :: prefix inside the ticks

clippy_lints/src/doc.rs

@@ -690,7 +690,16 @@ fn check_text(cx: &LateContext<'_>, valid_idents: &FxHashSet<String>, text: &str
         // Trim punctuation as in `some comment (see foo::bar).`
         //                                                   ^^
         // Or even as in `_foo bar_` which is emphasized.
-        let word = word.trim_matches(|c: char| !c.is_alphanumeric());
+        let word = {
+            let w = word.trim_matches(|c: char| !c.is_alphanumeric());
+            let offset = w.as_ptr() as usize - word.as_ptr() as usize;
+            // Preserve an initial `::` prefix, even as in `_::a::b_` which is emphasized.
+            if offset >= 2 && word.as_bytes()[offset - 2] == b':' && word.as_bytes()[offset - 1] == b':' {
+                &word[offset - 2..offset + w.len()]
+            } else {
+                w
+            }
+        };
 
         if valid_idents.contains(word) {
             continue;

tests/ui/doc/doc.rs

@@ -8,7 +8,7 @@
 /// The foo_bar function does _nothing_. See also foo::bar. (note the dot there)
 /// Markdown is _weird_. I mean _really weird_. This \_ is ok. So is `_`. But not Foo::some_fun
 /// which should be reported only once despite being __doubly bad__.
-/// Here be ::a::global:path.
+/// Here be ::a::global:path and _::another::global::path_.
 /// That's not code ~NotInCodeBlock~.
 /// be_sure_we_got_to_the_end_of_it
 fn foo_bar() {

tests/ui/doc/doc.stderr

@@ -18,11 +18,17 @@ error: you should put `Foo::some_fun` between ticks in the documentation
 LL | /// Markdown is _weird_. I mean _really weird_. This /_ is ok. So is `_`. But not Foo::some_fun
    |                                                                                   ^^^^^^^^^^^^^
 
-error: you should put `a::global:path` between ticks in the documentation
-  --> $DIR/doc.rs:11:15
+error: you should put `::a::global:path` between ticks in the documentation
+  --> $DIR/doc.rs:11:13
    |
-LL | /// Here be ::a::global:path.
-   |               ^^^^^^^^^^^^^^
+LL | /// Here be ::a::global:path and _::another::global::path_.
+   |             ^^^^^^^^^^^^^^^^
+
+error: you should put `::another::global::path` between ticks in the documentation
+  --> $DIR/doc.rs:11:35
+   |
+LL | /// Here be ::a::global:path and _::another::global::path_.
+   |                                   ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: you should put `NotInCodeBlock` between ticks in the documentation
   --> $DIR/doc.rs:12:22
@@ -186,5 +192,5 @@ error: you should put `mycrate::Collection` between ticks in the documentation
 LL | /// An iterator over mycrate::Collection's values.
    |                      ^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 31 previous errors
+error: aborting due to 32 previous errors