Account for `///` when rendering multiline spans

Don't consider `///` and `//!` docstrings to be empty for the purposes of multiline span rendering.

18 files changed, 144 insertions, 43 deletions

diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index 04b18b92a0c..ac2f91cdeb3 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -3050,13 +3050,17 @@ impl FileWithAnnotatedLines {
                 // We'll show up to 4 lines past the beginning of the multispan start.
                 // We will *not* include the tail of lines that are only whitespace, a comment or
                 // a bare delimiter.
+                let filter = |s: &str| {
+                    let s = s.trim();
+                    // Consider comments as empty, but don't consider docstrings to be empty.
+                    !(s.starts_with("//") && !(s.starts_with("///") || s.starts_with("//!")))
+                        // Consider lines with nothing but whitespace, a single delimiter as empty.
+                        && !["", "{", "}", "(", ")", "[", "]"].contains(&s)
+                };
                 let until = (ann.line_start..middle)
                     .rev()
                     .filter_map(|line| file.get_line(line - 1).map(|s| (line + 1, s)))
-                    .find(|(_, s)| {
-                        let s = s.trim();
-                        !["", "{", "}", "(", ")", "[", "]"].contains(&s) && !s.starts_with("//")
-                    })
+                    .find(|(_, s)| filter(s))
                     .map(|(line, _)| line)
                     .unwrap_or(ann.line_start);
                 for line in ann.line_start + 1..until {
@@ -3064,10 +3068,7 @@ impl FileWithAnnotatedLines {
                     add_annotation_to_file(&mut output, Lrc::clone(&file), line, ann.as_line());
                 }
                 let line_end = ann.line_end - 1;
-                let end_is_empty = file.get_line(line_end - 1).map_or(false, |s| {
-                    let s = s.trim();
-                    ["", "{", "}", "(", ")", "[", "]"].contains(&s) || s.starts_with("//")
-                });
+                let end_is_empty = file.get_line(line_end - 1).map_or(false, |s| !filter(&s));
                 if middle < line_end && !end_is_empty {
                     add_annotation_to_file(&mut output, Lrc::clone(&file), line_end, ann.as_line());
                 }
diff --git a/src/tools/clippy/tests/ui/doc/unbalanced_ticks.stderr b/src/tools/clippy/tests/ui/doc/unbalanced_ticks.stderr
index 3bcf65c4595..50324010e97 100644
--- a/src/tools/clippy/tests/ui/doc/unbalanced_ticks.stderr
+++ b/src/tools/clippy/tests/ui/doc/unbalanced_ticks.stderr
@@ -3,7 +3,9 @@ error: backticks are unbalanced
    |
 LL |   /// This is a doc comment with `unbalanced_tick marks and several words that
    |  _____^
-...  |
+LL | |
+LL | | /// should be `encompassed_by` tick marks because they `contain_underscores`.
+LL | | /// Because of the initial `unbalanced_tick` pair, the error message is
 LL | | /// very `confusing_and_misleading`.
    | |____________________________________^
    |
diff --git a/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr b/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr
index c4d4dde7f73..c5d5f3d3759 100644
--- a/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr
+++ b/src/tools/clippy/tests/ui/empty_line_after/doc_comments.stderr
@@ -96,6 +96,9 @@ error: empty lines after doc comment
   --> tests/ui/empty_line_after/doc_comments.rs:63:5
    |
 LL | /     /// for OldA
+LL | |     // struct OldA;
+LL | |
+LL | |     /// Docs
 ...  |
 LL | |
    | |_^
diff --git a/src/tools/clippy/tests/ui/needless_doc_main.stderr b/src/tools/clippy/tests/ui/needless_doc_main.stderr
index cfb389801db..7e362cf377c 100644
--- a/src/tools/clippy/tests/ui/needless_doc_main.stderr
+++ b/src/tools/clippy/tests/ui/needless_doc_main.stderr
@@ -3,7 +3,9 @@ error: needless `fn main` in doctest
    |
 LL |   /// fn main() {
    |  _____^
-...  |
+LL | |
+LL | |
+LL | | ///     unimplemented!();
 LL | | /// }
    | |_____^
    |
@@ -15,7 +17,8 @@ error: needless `fn main` in doctest
    |
 LL |   /// fn main() -> () {
    |  _____^
-...  |
+LL | |
+LL | | ///     unimplemented!();
 LL | | /// }
    | |_____^
 
@@ -24,7 +27,8 @@ error: needless `fn main` in doctest
    |
 LL |   /// fn main() {
    |  _____^
-...  |
+LL | |
+LL | | ///     unimplemented!();
 LL | | /// }
    | |_____^
 
@@ -33,7 +37,9 @@ error: needless `fn main` in doctest
    |
 LL |   /// // the fn is not always the first line
    |  _____^
-...  |
+LL | |
+LL | | /// fn main() {
+LL | | ///     unimplemented!();
 LL | | /// }
    | |_____^
 
diff --git a/src/tools/clippy/tests/ui/suspicious_doc_comments_unfixable.stderr b/src/tools/clippy/tests/ui/suspicious_doc_comments_unfixable.stderr
index 2209a63d2c0..d15f16f7c50 100644
--- a/src/tools/clippy/tests/ui/suspicious_doc_comments_unfixable.stderr
+++ b/src/tools/clippy/tests/ui/suspicious_doc_comments_unfixable.stderr
@@ -2,7 +2,10 @@ error: this is an outer doc comment and does not apply to the parent module or c
   --> tests/ui/suspicious_doc_comments_unfixable.rs:4:1
    |
 LL | / ///! a
-...  |
+LL | |
+LL | |
+LL | | ///! b
+LL | | /// c
 LL | | ///! d
    | |______^
    |
@@ -22,7 +25,9 @@ error: this is an outer doc comment and does not apply to the parent module or c
   --> tests/ui/suspicious_doc_comments_unfixable.rs:12:1
    |
 LL | / ///! a
-...  |
+LL | |
+LL | | ///! b
+LL | | /// c
 LL | | ///! d
    | |______^
    |
diff --git a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr
index 5925d2f902a..6ef333f0cfd 100644
--- a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr
+++ b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph-fix.stderr
@@ -2,7 +2,9 @@ error: first doc comment paragraph is too long
   --> tests/ui/too_long_first_doc_paragraph-fix.rs:3:1
    |
 LL | / /// A very short summary.
-...  |
+LL | | /// A much longer explanation that goes into a lot more detail about
+LL | | /// how the thing works, possibly with doclinks and so one,
+LL | | /// and probably spanning a many rows. Blablabla, it needs to be over
 LL | | /// 200 characters so I needed to write something longeeeeeeer.
    | |_^
    |
diff --git a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr
index c40ee2fcb48..95f42349b9b 100644
--- a/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr
+++ b/src/tools/clippy/tests/ui/too_long_first_doc_paragraph.stderr
@@ -2,7 +2,9 @@ error: first doc comment paragraph is too long
   --> tests/ui/too_long_first_doc_paragraph.rs:8:5
    |
 LL | /     //! A very short summary.
-...  |
+LL | |     //! A much longer explanation that goes into a lot more detail about
+LL | |     //! how the thing works, possibly with doclinks and so one,
+LL | |     //! and probably spanning a many rows. Blablabla, it needs to be over
 LL | |     //! 200 characters so I needed to write something longeeeeeeer.
    | |____^
    |
@@ -27,7 +29,8 @@ error: first doc comment paragraph is too long
   --> tests/ui/too_long_first_doc_paragraph.rs:36:1
    |
 LL | / /// Lorem
-...  |
+LL | | /// ipsum dolor sit amet, consectetur adipiscing elit. Nunc turpis nunc, lacinia
+LL | | /// a dolor in, pellentesque aliquet enim. Cras nec maximus sem. Mauris arcu libero,
 LL | | /// gravida non lacinia at, rhoncus eu lacus.
    | |_^
 
diff --git a/tests/rustdoc-ui/custom_code_classes_in_docs-warning3.stderr b/tests/rustdoc-ui/custom_code_classes_in_docs-warning3.stderr
index a72e21fed85..385b2ccacc1 100644
--- a/tests/rustdoc-ui/custom_code_classes_in_docs-warning3.stderr
+++ b/tests/rustdoc-ui/custom_code_classes_in_docs-warning3.stderr
@@ -2,7 +2,10 @@ error: unclosed quote string `"`
   --> $DIR/custom_code_classes_in_docs-warning3.rs:8:1
    |
 LL | / /// ```{class="}
+LL | | /// main;
+LL | | /// ```
 ...  |
+LL | | /// main;
 LL | | /// ```
    | |_______^
    |
@@ -17,7 +20,10 @@ error: unclosed quote string `"`
   --> $DIR/custom_code_classes_in_docs-warning3.rs:8:1
    |
 LL | / /// ```{class="}
+LL | | /// main;
+LL | | /// ```
 ...  |
+LL | | /// main;
 LL | | /// ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/doctest/check-attr-test.stderr b/tests/rustdoc-ui/doctest/check-attr-test.stderr
index 2703885b184..257136d1633 100644
--- a/tests/rustdoc-ui/doctest/check-attr-test.stderr
+++ b/tests/rustdoc-ui/doctest/check-attr-test.stderr
@@ -2,7 +2,9 @@ error: unknown attribute `compile-fail`
  --> $DIR/check-attr-test.rs:5:1
   |
 5 | / /// foo
-... |
+6 | | ///
+7 | | /// ```compile-fail,compilefail,comPile_fail
+8 | | /// boo
 9 | | /// ```
   | |_______^
   |
@@ -18,7 +20,9 @@ error: unknown attribute `compilefail`
  --> $DIR/check-attr-test.rs:5:1
   |
 5 | / /// foo
-... |
+6 | | ///
+7 | | /// ```compile-fail,compilefail,comPile_fail
+8 | | /// boo
 9 | | /// ```
   | |_______^
   |
@@ -29,7 +33,9 @@ error: unknown attribute `comPile_fail`
  --> $DIR/check-attr-test.rs:5:1
   |
 5 | / /// foo
-... |
+6 | | ///
+7 | | /// ```compile-fail,compilefail,comPile_fail
+8 | | /// boo
 9 | | /// ```
   | |_______^
   |
@@ -40,7 +46,9 @@ error: unknown attribute `should-panic`
   --> $DIR/check-attr-test.rs:12:1
    |
 12 | / /// bar
-...  |
+13 | | ///
+14 | | /// ```should-panic,shouldpanic,shOuld_panic
+15 | | /// boo
 16 | | /// ```
    | |_______^
    |
@@ -51,7 +59,9 @@ error: unknown attribute `shouldpanic`
   --> $DIR/check-attr-test.rs:12:1
    |
 12 | / /// bar
-...  |
+13 | | ///
+14 | | /// ```should-panic,shouldpanic,shOuld_panic
+15 | | /// boo
 16 | | /// ```
    | |_______^
    |
@@ -62,7 +72,9 @@ error: unknown attribute `shOuld_panic`
   --> $DIR/check-attr-test.rs:12:1
    |
 12 | / /// bar
-...  |
+13 | | ///
+14 | | /// ```should-panic,shouldpanic,shOuld_panic
+15 | | /// boo
 16 | | /// ```
    | |_______^
    |
@@ -73,7 +85,9 @@ error: unknown attribute `no-run`
   --> $DIR/check-attr-test.rs:19:1
    |
 19 | / /// foobar
-...  |
+20 | | ///
+21 | | /// ```no-run,norun,nO_run
+22 | | /// boo
 23 | | /// ```
    | |_______^
    |
@@ -84,7 +98,9 @@ error: unknown attribute `norun`
   --> $DIR/check-attr-test.rs:19:1
    |
 19 | / /// foobar
-...  |
+20 | | ///
+21 | | /// ```no-run,norun,nO_run
+22 | | /// boo
 23 | | /// ```
    | |_______^
    |
@@ -95,7 +111,9 @@ error: unknown attribute `nO_run`
   --> $DIR/check-attr-test.rs:19:1
    |
 19 | / /// foobar
-...  |
+20 | | ///
+21 | | /// ```no-run,norun,nO_run
+22 | | /// boo
 23 | | /// ```
    | |_______^
    |
@@ -106,7 +124,9 @@ error: unknown attribute `test-harness`
   --> $DIR/check-attr-test.rs:26:1
    |
 26 | / /// b
-...  |
+27 | | ///
+28 | | /// ```test-harness,testharness,tesT_harness
+29 | | /// boo
 30 | | /// ```
    | |_______^
    |
@@ -117,7 +137,9 @@ error: unknown attribute `testharness`
   --> $DIR/check-attr-test.rs:26:1
    |
 26 | / /// b
-...  |
+27 | | ///
+28 | | /// ```test-harness,testharness,tesT_harness
+29 | | /// boo
 30 | | /// ```
    | |_______^
    |
@@ -128,7 +150,9 @@ error: unknown attribute `tesT_harness`
   --> $DIR/check-attr-test.rs:26:1
    |
 26 | / /// b
-...  |
+27 | | ///
+28 | | /// ```test-harness,testharness,tesT_harness
+29 | | /// boo
 30 | | /// ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/doctest/private-item-doc-test.stderr b/tests/rustdoc-ui/doctest/private-item-doc-test.stderr
index 7ce1f031499..5177057c728 100644
--- a/tests/rustdoc-ui/doctest/private-item-doc-test.stderr
+++ b/tests/rustdoc-ui/doctest/private-item-doc-test.stderr
@@ -2,7 +2,9 @@ error: documentation test in private item
   --> $DIR/private-item-doc-test.rs:4:5
    |
 LL | /     /// private doc test
-...  |
+LL | |     ///
+LL | |     /// ```
+LL | |     /// assert!(false);
 LL | |     /// ```
    | |___________^
    |
diff --git a/tests/rustdoc-ui/doctest/private-public-item-doc-test.stderr b/tests/rustdoc-ui/doctest/private-public-item-doc-test.stderr
index aa01f39314c..38b8dd652d3 100644
--- a/tests/rustdoc-ui/doctest/private-public-item-doc-test.stderr
+++ b/tests/rustdoc-ui/doctest/private-public-item-doc-test.stderr
@@ -2,7 +2,9 @@ error: documentation test in private item
   --> $DIR/private-public-item-doc-test.rs:4:5
    |
 LL | /     /// private doc test
-...  |
+LL | |     ///
+LL | |     /// ```
+LL | |     /// assert!(false);
 LL | |     /// ```
    | |___________^
    |
diff --git a/tests/rustdoc-ui/doctest/standalone-warning-2024.stderr b/tests/rustdoc-ui/doctest/standalone-warning-2024.stderr
index 662f07f3a4c..bfc1e919404 100644
--- a/tests/rustdoc-ui/doctest/standalone-warning-2024.stderr
+++ b/tests/rustdoc-ui/doctest/standalone-warning-2024.stderr
@@ -2,7 +2,11 @@ error: unknown attribute `standalone`
   --> $DIR/standalone-warning-2024.rs:11:1
    |
 11 | / //! ```standalone
-...  |
+12 | | //! bla
+13 | | //! ```
+14 | | //!
+15 | | //! ```standalone-crate
+16 | | //! bla
 17 | | //! ```
    | |_______^
    |
@@ -19,7 +23,11 @@ error: unknown attribute `standalone-crate`
   --> $DIR/standalone-warning-2024.rs:11:1
    |
 11 | / //! ```standalone
-...  |
+12 | | //! bla
+13 | | //! ```
+14 | | //!
+15 | | //! ```standalone-crate
+16 | | //! bla
 17 | | //! ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/invalid-syntax.stderr b/tests/rustdoc-ui/invalid-syntax.stderr
index f30660017d9..c6e1f6fd413 100644
--- a/tests/rustdoc-ui/invalid-syntax.stderr
+++ b/tests/rustdoc-ui/invalid-syntax.stderr
@@ -21,7 +21,9 @@ warning: could not parse code block as Rust code
    |
 LL |   /// ```
    |  _____^
-...  |
+LL | | ///    |
+LL | | /// LL | use foobar::Baz;
+LL | | ///    |     ^^^^^^ did you mean `baz::foobar`?
 LL | | /// ```
    | |_______^
    |
@@ -112,7 +114,8 @@ warning: Rust code block is empty
    |
 LL |   /// ```
    |  _____^
-...  |
+LL | | ///
+LL | | ///
 LL | | /// ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/lints/check-attr.stderr b/tests/rustdoc-ui/lints/check-attr.stderr
index 4576dea79cb..3366c021727 100644
--- a/tests/rustdoc-ui/lints/check-attr.stderr
+++ b/tests/rustdoc-ui/lints/check-attr.stderr
@@ -3,6 +3,7 @@ error: unknown attribute `compile-fail`
    |
 LL | / /// foo
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -19,6 +20,7 @@ error: unknown attribute `compilefail`
    |
 LL | / /// foo
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -30,6 +32,7 @@ error: unknown attribute `comPile_fail`
    |
 LL | / /// foo
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -41,6 +44,7 @@ error: unknown attribute `should-panic`
    |
 LL | / /// bar
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -52,6 +56,7 @@ error: unknown attribute `shouldpanic`
    |
 LL | / /// bar
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -63,6 +68,7 @@ error: unknown attribute `sHould_panic`
    |
 LL | / /// bar
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -74,6 +80,7 @@ error: unknown attribute `no-run`
    |
 LL | / /// foobar
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -85,6 +92,7 @@ error: unknown attribute `norun`
    |
 LL | / /// foobar
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -96,6 +104,7 @@ error: unknown attribute `no_Run`
    |
 LL | / /// foobar
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -107,6 +116,7 @@ error: unknown attribute `test-harness`
    |
 LL | / /// b
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -118,6 +128,7 @@ error: unknown attribute `testharness`
    |
 LL | / /// b
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -129,6 +140,7 @@ error: unknown attribute `teSt_harness`
    |
 LL | / /// b
 ...  |
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -139,7 +151,10 @@ error: unknown attribute `rust2018`
   --> $DIR/check-attr.rs:43:1
    |
 LL | / /// b
-...  |
+LL | |
+LL | | ///
+LL | | /// ```rust2018
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -149,7 +164,11 @@ error: unknown attribute `rust2018`
   --> $DIR/check-attr.rs:51:1
    |
 LL | / /// b
-...  |
+LL | |
+LL | |
+LL | | ///
+LL | | /// ```rust2018 shouldpanic
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
@@ -159,7 +178,11 @@ error: unknown attribute `shouldpanic`
   --> $DIR/check-attr.rs:51:1
    |
 LL | / /// b
-...  |
+LL | |
+LL | |
+LL | | ///
+LL | | /// ```rust2018 shouldpanic
+LL | | /// boo
 LL | | /// ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/lints/check-fail.stderr b/tests/rustdoc-ui/lints/check-fail.stderr
index f021f0c42e5..2eb9496e5dc 100644
--- a/tests/rustdoc-ui/lints/check-fail.stderr
+++ b/tests/rustdoc-ui/lints/check-fail.stderr
@@ -26,7 +26,8 @@ error: unknown attribute `testharness`
   --> $DIR/check-fail.rs:8:1
    |
 LL | / //! ```rust,testharness
-...  |
+LL | |
+LL | | //! let x = 12;
 LL | | //! ```
    | |_______^
    |
@@ -43,7 +44,10 @@ error: unknown attribute `testharness`
   --> $DIR/check-fail.rs:17:1
    |
 LL | / /// hello
-...  |
+LL | |
+LL | | ///
+LL | | /// ```rust,testharness
+LL | | /// let x = 12;
 LL | | /// ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/lints/lint-group.stderr b/tests/rustdoc-ui/lints/lint-group.stderr
index 4b5b64c4378..7ff09fcc45a 100644
--- a/tests/rustdoc-ui/lints/lint-group.stderr
+++ b/tests/rustdoc-ui/lints/lint-group.stderr
@@ -14,7 +14,9 @@ error: documentation test in private item
   --> $DIR/lint-group.rs:22:1
    |
 LL | / /// wait, this *does* have a doctest?
-...  |
+LL | | ///
+LL | | /// ```
+LL | | /// println!("sup");
 LL | | /// ```
    | |_______^
    |
diff --git a/tests/rustdoc-ui/unescaped_backticks.stderr b/tests/rustdoc-ui/unescaped_backticks.stderr
index 01b2fd1fa27..d93aaf5f3ca 100644
--- a/tests/rustdoc-ui/unescaped_backticks.stderr
+++ b/tests/rustdoc-ui/unescaped_backticks.stderr
@@ -272,6 +272,7 @@ error: unescaped backtick
    |
 LL | /     /// The Subscriber` may be accessed by calling [`WeakDispatch::upgrade`],
 ...  |
+LL | |     /// [`rebuild_interest_cache`][rebuild] is called after the value of the max
 LL | |     /// level changes.
    | |______________________^
    |
@@ -287,6 +288,7 @@ error: unescaped backtick
    |
 LL | /     /// The Subscriber` may be accessed by calling [`WeakDispatch::upgrade`],
 ...  |
+LL | |     /// [`rebuild_interest_cache`][rebuild] is called after the value of the max
 LL | |     /// level changes.
    | |______________________^
    |
@@ -300,6 +302,7 @@ error: unescaped backtick
    |
 LL | /     /// The Subscriber` may be accessed by calling [`WeakDispatch::upgrade`],
 ...  |
+LL | |     /// [`rebuild_interest_cache`][rebuild] is called after the value of the max
 LL | |     /// level changes.
    | |______________________^
    |
@@ -315,6 +318,7 @@ error: unescaped backtick
    |
 LL | /     /// The Subscriber` may be accessed by calling [`WeakDispatch::upgrade`],
 ...  |
+LL | |     /// [`rebuild_interest_cache`][rebuild] is called after the value of the max
 LL | |     /// level changes.
    | |______________________^
    |
diff --git a/tests/ui/macros/issue-112342-1.stderr b/tests/ui/macros/issue-112342-1.stderr
index 73a7fe3a127..f2d82bf599e 100644
--- a/tests/ui/macros/issue-112342-1.stderr
+++ b/tests/ui/macros/issue-112342-1.stderr
@@ -55,7 +55,8 @@ error: repetition matches empty token tree
    |
 LL |           $(
    |  __________^
-...  |
+LL | |             ///
+LL | |             ///
 LL | |         )*
    | |_________^