rustdoc: use descriptive tooltip if doctest is conditionally ignored

fixes https://github.com/rust-lang/rust/issues/141092

src/librustdoc/html/highlight.rs

@@ -6,7 +6,7 @@
 //! Use the `render_with_highlighting` to highlight some rust code.
 
 use std::collections::VecDeque;
-use std::fmt::{Display, Write};
+use std::fmt::{self, Display, Write};
 
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_lexer::{Cursor, FrontmatterAllowed, LiteralKind, TokenKind};
@@ -36,9 +36,10 @@ pub(crate) struct HrefContext<'a, 'tcx> {
 #[derive(Default)]
 pub(crate) struct DecorationInfo(pub(crate) FxIndexMap<&'static str, Vec<(u32, u32)>>);
 
-#[derive(Eq, PartialEq, Clone, Copy)]
+#[derive(Eq, PartialEq, Clone)]
 pub(crate) enum Tooltip {
-    Ignore,
+    IgnoreAll,
+    IgnoreSome(Vec<String>),
     CompileFail,
     ShouldPanic,
     Edition(Edition),
@@ -70,7 +71,7 @@ fn write_header(
         format_args!(
             "<div class=\"example-wrap{}\">",
             match tooltip {
-                Tooltip::Ignore => " ignore",
+                Tooltip::IgnoreAll | Tooltip::IgnoreSome(_) => " ignore",
                 Tooltip::CompileFail => " compile_fail",
                 Tooltip::ShouldPanic => " should_panic",
                 Tooltip::Edition(_) => " edition",
@@ -80,18 +81,46 @@ fn write_header(
     );
 
     if tooltip != Tooltip::None {
-        let edition_code;
+        // variable for extending lifetimes of temporaries
+        let tmp;
         write_str(
             out,
             format_args!(
                 "<a href=\"#\" class=\"tooltip\" title=\"{}\">ⓘ</a>",
                 match tooltip {
-                    Tooltip::Ignore => "This example is not tested",
+                    Tooltip::IgnoreAll => "This example is not tested",
+                    Tooltip::IgnoreSome(platforms) => {
+                        tmp = format!(
+                            "This example is not tested on {}",
+                            fmt::from_fn(|f| {
+                                match platforms.len() {
+                                    0 => unreachable!(),
+                                    1 => f.write_str(&platforms[0]),
+                                    2 => write!(f, "{} or {}", &platforms[0], &platforms[1]),
+                                    _ => {
+                                        for (i, plat) in platforms.iter().enumerate() {
+                                            match (platforms.len() - 2).cmp(&i) {
+                                                std::cmp::Ordering::Greater => {
+                                                    write!(f, "{}, ", plat)?
+                                                }
+                                                std::cmp::Ordering::Equal => {
+                                                    write!(f, "{}, or ", plat)?
+                                                }
+                                                std::cmp::Ordering::Less => f.write_str(&plat)?,
+                                            }
+                                        }
+                                        Ok(())
+                                    }
+                                }
+                            })
+                        );
+                        &tmp
+                    }
                     Tooltip::CompileFail => "This example deliberately fails to compile",
                     Tooltip::ShouldPanic => "This example panics",
                     Tooltip::Edition(edition) => {
-                        edition_code = format!("This example runs with edition {edition}");
-                        &edition_code
+                        tmp = format!("This example runs with edition {edition}");
+                        &tmp
                     }
                     Tooltip::None => unreachable!(),
                 }

src/librustdoc/html/markdown.rs

@@ -320,8 +320,10 @@ impl<'a, I: Iterator<Item = Event<'a>>> Iterator for CodeBlocks<'_, 'a, I> {
             ))
         });
 
-        let tooltip = if ignore != Ignore::None {
-            highlight::Tooltip::Ignore
+        let tooltip = if ignore == Ignore::All {
+            highlight::Tooltip::IgnoreAll
+        } else if let Ignore::Some(platforms) = ignore {
+            highlight::Tooltip::IgnoreSome(platforms)
         } else if compile_fail {
             highlight::Tooltip::CompileFail
         } else if should_panic {

tests/rustdoc/doctest/ignore-sometimes.rs

@@ -0,0 +1,23 @@
+#![crate_name = "foo"]
+
+// test for https://github.com/rust-lang/rust/issues/141092
+
+//@ has 'foo/fn.f.html' '//a[@title="This example is not tested on wasm"]' 'ⓘ'
+/// Example
+///
+/// ```ignore-wasm
+/// let x = 1;
+/// ```
+pub fn f() {}
+
+//@ has 'foo/fn.g.html' '//a[@title="This example is not tested on wasm or windows"]' 'ⓘ'
+/// ```ignore-wasm,ignore-windows
+/// let x = 1;
+/// ```
+pub fn g() {}
+
+//@ has 'foo/fn.h.html' '//a[@title="This example is not tested on wasm, windows, or unix"]' 'ⓘ'
+/// ```ignore-wasm,ignore-windows,ignore-unix
+/// let x = 1;
+/// ```
+pub fn h() {}