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Merged
merged 3 commits into from
Apr 30, 2025
Merged

Warn on and ignore duplicate footnote definitions #2681

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1696f56
Move footnote expected HTML to a separate file
ehuss Apr 30, 2025
09d22e9
Add a test for duplicate footnote definitions
krishanjmistry Apr 29, 2025
7e9be8d
Warn on duplicate footnote definition and ignore subsequent definitions
krishanjmistry Apr 29, 2025
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22 changes: 18 additions & 4 deletions src/utils/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -235,10 +235,10 @@ pub fn render_markdown_with_path(
// `count` is the number of references to this footnote (used for multiple
// linkbacks, and checking for unused footnotes).
let mut footnote_numbers = HashMap::new();
// This is a list of (name, Vec<Event>)
// This is a map of name -> Vec<Event>
// `name` is the name of the footnote.
// The events list is the list of events needed to build the footnote definition.
let mut footnote_defs = Vec::new();
let mut footnote_defs = HashMap::new();

// The following are used when currently processing a footnote definition.
//
Expand Down Expand Up @@ -268,7 +268,16 @@ pub fn render_markdown_with_path(
Event::End(TagEnd::FootnoteDefinition) => {
let def_events = std::mem::take(&mut in_footnote);
let name = std::mem::take(&mut in_footnote_name);
footnote_defs.push((name, def_events));

if footnote_defs.contains_key(&name) {
log::warn!(
"footnote `{name}` in {} defined multiple times - \
not updating to new definition",
path.map_or_else(|| Cow::from("<unknown>"), |p| p.to_string_lossy())
);
} else {
footnote_defs.insert(name, def_events);
}
None
}
Event::FootnoteReference(name) => {
Expand Down Expand Up @@ -304,7 +313,12 @@ pub fn render_markdown_with_path(
html::push_html(&mut body, events);

if !footnote_defs.is_empty() {
add_footnote_defs(&mut body, path, footnote_defs, &footnote_numbers);
add_footnote_defs(
&mut body,
path,
footnote_defs.into_iter().collect(),
&footnote_numbers,
);
}

body
Expand Down
56 changes: 16 additions & 40 deletions tests/testsuite/markdown.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
//! Tests for special markdown rendering.

use crate::prelude::*;
use snapbox::file;

// Checks custom header id and classes.
#[test]
Expand All @@ -17,46 +18,21 @@ fn custom_header_attributes() {
#[test]
fn footnotes() {
BookTest::from_dir("markdown/footnotes")
.check_main_file("book/footnotes.html", str![[r##"
<h1 id="footnote-tests"><a class="header" href="#footnote-tests">Footnote tests</a></h1>
<p>Footnote example<sup class="footnote-reference" id="fr-1-1"><a href="#footnote-1">1</a></sup>, or with a word<sup class="footnote-reference" id="fr-word-1"><a href="#footnote-word">2</a></sup>.</p>
<p>There are multiple references to word<sup class="footnote-reference" id="fr-word-2"><a href="#footnote-word">2</a></sup>.</p>
<p>Footnote without a paragraph<sup class="footnote-reference" id="fr-para-1"><a href="#footnote-para">3</a></sup></p>
<p>Footnote with multiple paragraphs<sup class="footnote-reference" id="fr-multiple-1"><a href="#footnote-multiple">4</a></sup></p>
<p>Footnote name with wacky characters<sup class="footnote-reference" id="fr-&quot;wacky&quot;-1"><a href="#footnote-&quot;wacky&quot;">5</a></sup></p>
<p>Testing when referring to something earlier.<sup class="footnote-reference" id="fr-define-before-use-1"><a href="#footnote-define-before-use">6</a></sup></p>
<hr>
<ol class="footnote-definition"><li id="footnote-1">
<p>This is a footnote. <a href="#fr-1-1">↩</a> <a href="#fr-1-2">↩2</a></p>
</li>
<li id="footnote-word">
<p>A longer footnote.
With multiple lines. <a href="other.html">Link to other</a>.
With a reference inside.<sup class="footnote-reference" id="fr-1-2"><a href="#footnote-1">1</a></sup> <a href="#fr-word-1">↩</a> <a href="#fr-word-2">↩2</a></p>
</li>
<li id="footnote-para">
<ol>
<li>Item one
<ol>
<li>Sub-item</li>
</ol>
</li>
<li>Item two</li>
</ol>
<a href="#fr-para-1">↩</a></li>
<li id="footnote-multiple">
<p>One</p>
<p>Two</p>
<p>Three <a href="#fr-multiple-1">↩</a></p>
</li>
<li id="footnote-&quot;wacky&quot;">
<p>Testing footnote id with special characters. <a href="#fr-&quot;wacky&quot;-1">↩</a></p>
</li>
<li id="footnote-define-before-use">
<p>This is defined before it is referred to. <a href="#fr-define-before-use-1">↩</a></p>
</li>
</ol>
"##]]);
.run("build", |cmd| {
cmd.expect_stderr(str![[r#"
[TIMESTAMP] [INFO] (mdbook::book): Book building has started
[TIMESTAMP] [INFO] (mdbook::book): Running the html backend
[TIMESTAMP] [WARN] (mdbook::utils): footnote `multiple-definitions` in <unknown> defined multiple times - not updating to new definition
[TIMESTAMP] [WARN] (mdbook::utils): footnote `unused` in `<unknown>` is defined but not referenced
[TIMESTAMP] [WARN] (mdbook::utils): footnote `multiple-definitions` in footnotes.md defined multiple times - not updating to new definition
[TIMESTAMP] [WARN] (mdbook::utils): footnote `unused` in `footnotes.md` is defined but not referenced

"#]]);
})
.check_main_file(
"book/footnotes.html",
file!["markdown/footnotes/expected/footnotes.html"],
);
}

// Basic table test.
Expand Down
46 changes: 46 additions & 0 deletions tests/testsuite/markdown/footnotes/expected/footnotes.html
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Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
<h1 id="footnote-tests"><a class="header" href="#footnote-tests">Footnote tests</a></h1>
<p>Footnote example<sup class="footnote-reference" id="fr-1-1"><a href="#footnote-1">1</a></sup>, or with a word<sup class="footnote-reference" id="fr-word-1"><a href="#footnote-word">2</a></sup>.</p>
<p>There are multiple references to word<sup class="footnote-reference" id="fr-word-2"><a href="#footnote-word">2</a></sup>.</p>
<p>Footnote without a paragraph<sup class="footnote-reference" id="fr-para-1"><a href="#footnote-para">3</a></sup></p>
<p>Footnote with multiple paragraphs<sup class="footnote-reference" id="fr-multiple-1"><a href="#footnote-multiple">4</a></sup></p>
<p>Footnote name with wacky characters<sup class="footnote-reference" id="fr-&quot;wacky&quot;-1"><a href="#footnote-&quot;wacky&quot;">5</a></sup></p>
<p>Testing when referring to something earlier.<sup class="footnote-reference" id="fr-define-before-use-1"><a href="#footnote-define-before-use">6</a></sup></p>
<p>Footnote that is defined multiple times.<sup class="footnote-reference" id="fr-multiple-definitions-1"><a href="#footnote-multiple-definitions">7</a></sup></p>
<p>And another<sup class="footnote-reference" id="fr-in-between-1"><a href="#footnote-in-between">8</a></sup> that references the duplicate again.<sup class="footnote-reference" id="fr-multiple-definitions-2"><a href="#footnote-multiple-definitions">7</a></sup></p>
<hr>
<ol class="footnote-definition"><li id="footnote-1">
<p>This is a footnote. <a href="#fr-1-1">↩</a> <a href="#fr-1-2">↩2</a></p>
</li>
<li id="footnote-word">
<p>A longer footnote.
With multiple lines. <a href="other.html">Link to other</a>.
With a reference inside.<sup class="footnote-reference" id="fr-1-2"><a href="#footnote-1">1</a></sup> <a href="#fr-word-1">↩</a> <a href="#fr-word-2">↩2</a></p>
</li>
<li id="footnote-para">
<ol>
<li>Item one
<ol>
<li>Sub-item</li>
</ol>
</li>
<li>Item two</li>
</ol>
<a href="#fr-para-1">↩</a></li>
<li id="footnote-multiple">
<p>One</p>
<p>Two</p>
<p>Three <a href="#fr-multiple-1">↩</a></p>
</li>
<li id="footnote-&quot;wacky&quot;">
<p>Testing footnote id with special characters. <a href="#fr-&quot;wacky&quot;-1">↩</a></p>
</li>
<li id="footnote-define-before-use">
<p>This is defined before it is referred to. <a href="#fr-define-before-use-1">↩</a></p>
</li>
<li id="footnote-multiple-definitions">
<p>This is the first definition of the footnote with tag multiple-definitions <a href="#fr-multiple-definitions-1">↩</a> <a href="#fr-multiple-definitions-2">↩2</a></p>
</li>
<li id="footnote-in-between">
<p>Footnote between duplicates. <a href="#fr-in-between-1">↩</a></p>
</li>
</ol>
10 changes: 10 additions & 0 deletions tests/testsuite/markdown/footnotes/src/footnotes.md
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Expand Up @@ -35,3 +35,13 @@ Footnote name with wacky characters[^"wacky"]
[^"wacky"]: Testing footnote id with special characters.

Testing when referring to something earlier.[^define-before-use]

Footnote that is defined multiple times.[^multiple-definitions]

[^multiple-definitions]: This is the first definition of the footnote with tag multiple-definitions

And another[^in-between] that references the duplicate again.[^multiple-definitions]

[^in-between]: Footnote between duplicates.

[^multiple-definitions]: This is the second definition of the footnote with tag multiple-definitions