Rollup merge of rust-lang#93217 - willcrichton:example-analyzer, r=GuillaumeGomez

Improve Rustdoc UI for scraped examples with multiline arguments, fix overflow in line numbers

This PR improves a few aspects of the scrape examples feature in Rustdoc.
* Only function names and not the full call expression are highlighted.
* For call-sites with multiline arguments, the minimized code viewer will scroll to the top of the call-site rather than the middle if the argument is larger than the viewer size, ensuring that the function name is visible.
* This fixes an issue where the line numbers column had a visible x-scroll bar.

r? `@GuillaumeGomez`

Author: Dylan-DPC

src/doc/rustdoc/src/SUMMARY.md

@@ -9,6 +9,7 @@
     - [Linking to items by name](write-documentation/linking-to-items-by-name.md)
     - [Documentation tests](write-documentation/documentation-tests.md)
 - [Rustdoc-specific lints](lints.md)
+- [Scraped examples](scraped-examples.md)
 - [Advanced features](advanced-features.md)
 - [Unstable features](unstable-features.md)
 - [Deprecated features](deprecated-features.md)

src/doc/rustdoc/src/scraped-examples.md

@@ -0,0 +1,55 @@
+# Scraped examples
+
+Rustdoc has an unstable feature where it can automatically scrape examples of items being documented from the `examples/` directory of a Cargo workspace. These examples will be included within the generated documentation for that item. For example, if your library contains a public function:
+
+```rust,ignore (needs-other-file)
+// a_crate/src/lib.rs
+pub fn a_func() {}
+```
+
+And you have an example calling this function:
+
+```rust,ignore (needs-other-file)
+// a_crate/examples/ex.rs
+fn main() {
+  a_crate::a_func();
+}
+```
+
+Then this code snippet will be included in the documentation for `a_func`. This documentation is inserted by Rustdoc and cannot be manually edited by the crate author.
+
+
+## How to use this feature
+
+This feature is unstable, so you can enable it by calling Rustdoc with the unstable `rustdoc-scrape-examples` flag:
+
+```bash
+cargo doc -Zunstable-options -Zrustdoc-scrape-examples=examples
+```
+
+To enable this feature on [docs.rs](https://docs.rs), add this to your Cargo.toml:
+
+```toml
+[package.metadata.docs.rs]
+cargo-args = ["-Zunstable-options", "-Zrustdoc-scrape-examples=examples"]
+```
+
+
+## How it works
+
+When you run `cargo doc`, Rustdoc will analyze all the crates that match Cargo's `--examples` filter for instances of items being documented. Then Rustdoc will include the source code of these instances in the generated documentation.
+
+Rustdoc has a few techniques to ensure these examples don't overwhelm documentation readers, and that it doesn't blow up the page size:
+
+1. For a given item, a maximum of 5 examples are included in the page. The remaining examples are just links to source code.
+2. Only one example is shown by default, and the remaining examples are hidden behind a toggle.
+3. For a given file that contains examples, only the item containing the examples will be included in the generated documentation.
+
+For a given item, Rustdoc sorts its examples based on the size of the example — smaller ones are shown first.
+
+
+## FAQ
+
+### My example is not showing up in the documentation
+
+This feature uses Cargo's convention for finding examples. You should ensure that `cargo check --examples` includes your example file.

src/librustdoc/html/render/context.rs

@@ -17,8 +17,8 @@ use super::print_item::{full_path, item_path, print_item};
 use super::search_index::build_index;
 use super::write_shared::write_shared;
 use super::{
-    collect_spans_and_sources, print_sidebar, settings, AllTypes, LinkFromSrc, NameDoc, StylePath,
-    BASIC_KEYWORDS,
+    collect_spans_and_sources, print_sidebar, scrape_examples_help, settings, AllTypes,
+    LinkFromSrc, NameDoc, StylePath, BASIC_KEYWORDS,
 };
 
 use crate::clean::{self, types::ExternalLocation, ExternalCrate};
@@ -551,6 +551,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         let crate_name = self.tcx().crate_name(LOCAL_CRATE);
         let final_file = self.dst.join(crate_name.as_str()).join("all.html");
         let settings_file = self.dst.join("settings.html");
+        let scrape_examples_help_file = self.dst.join("scrape-examples-help.html");
 
         let mut root_path = self.dst.to_str().expect("invalid path").to_owned();
         if !root_path.ends_with('/') {
@@ -606,6 +607,20 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
             &self.shared.style_files,
         );
         self.shared.fs.write(settings_file, v)?;
+
+        if self.shared.layout.scrape_examples_extension {
+            page.title = "About scraped examples";
+            page.description = "How the scraped examples feature works in Rustdoc";
+            let v = layout::render(
+                &self.shared.layout,
+                &page,
+                "",
+                scrape_examples_help(&*self.shared),
+                &self.shared.style_files,
+            );
+            self.shared.fs.write(scrape_examples_help_file, v)?;
+        }
+
         if let Some(ref redirections) = self.shared.redirections {
             if !redirections.borrow().is_empty() {
                 let redirect_map_path =

src/librustdoc/html/render/mod.rs

@@ -75,8 +75,10 @@ use crate::html::format::{
 use crate::html::highlight;
 use crate::html::markdown::{HeadingOffset, IdMap, Markdown, MarkdownHtml, MarkdownSummaryLine};
 use crate::html::sources;
+use crate::html::static_files::SCRAPE_EXAMPLES_HELP_MD;
 use crate::scrape_examples::{CallData, CallLocation};
 use crate::try_none;
+use crate::DOC_RUST_LANG_ORG_CHANNEL;
 
 /// A pair of name and its optional document.
 crate type NameDoc = (String, Option<String>);
@@ -460,6 +462,34 @@ fn settings(root_path: &str, suffix: &str, theme_names: Vec<String>) -> Result<S
     ))
 }
 
+fn scrape_examples_help(shared: &SharedContext<'_>) -> String {
+    let mut content = SCRAPE_EXAMPLES_HELP_MD.to_owned();
+    content.push_str(&format!(
+      "## More information\n\n\
+      If you want more information about this feature, please read the [corresponding chapter in the Rustdoc book]({}/rustdoc/scraped-examples.html).",
+      DOC_RUST_LANG_ORG_CHANNEL));
+
+    let mut ids = IdMap::default();
+    format!(
+        "<div class=\"main-heading\">\
+            <h1 class=\"fqn\">\
+                <span class=\"in-band\">About scraped examples</span>\
+            </h1>\
+        </div>\
+        <div>{}</div>",
+        Markdown {
+            content: &content,
+            links: &[],
+            ids: &mut ids,
+            error_codes: shared.codes,
+            edition: shared.edition(),
+            playground: &shared.playground,
+            heading_offset: HeadingOffset::H1
+        }
+        .into_string()
+    )
+}
+
 fn document(
     w: &mut Buffer,
     cx: &Context<'_>,
@@ -2743,7 +2773,9 @@ fn render_call_locations(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item) {
           <span></span>\
           <h5 id=\"{id}\">\
              <a href=\"#{id}\">Examples found in repository</a>\
+             <a class=\"scrape-help\" href=\"{root_path}scrape-examples-help.html\">?</a>\
           </h5>",
+        root_path = cx.root_path(),
         id = id
     );
 
@@ -2795,9 +2827,10 @@ fn render_call_locations(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item) {
             .locations
             .iter()
             .map(|loc| {
-                let (byte_lo, byte_hi) = loc.call_expr.byte_span;
+                let (byte_lo, byte_hi) = loc.call_ident.byte_span;
                 let (line_lo, line_hi) = loc.call_expr.line_span;
                 let byte_range = (byte_lo - byte_min, byte_hi - byte_min);
+
                 let line_range = (line_lo - line_min, line_hi - line_min);
                 let (line_url, line_title) = link_to_loc(call_data, loc);
 
@@ -2913,6 +2946,7 @@ fn render_call_locations(w: &mut Buffer, cx: &Context<'_>, item: &clean::Item) {
                   <summary class=\"hideme\">\
                      <span>More examples</span>\
                   </summary>\
+                  <div class=\"hide-more\">Hide additional examples</div>\
                   <div class=\"more-scraped-examples\">\
                     <div class=\"toggle-line\"><div class=\"toggle-line-inner\"></div></div>\
                     <div class=\"more-scraped-examples-inner\">"

src/librustdoc/html/static/css/rustdoc.css

@@ -618,7 +618,7 @@ h2.location a {
 	position: relative;
 }
 
-.docblock > :not(.information) {
+.docblock > :not(.information):not(.more-examples-toggle) {
 	max-width: 100%;
 	overflow-x: auto;
 }
@@ -840,8 +840,8 @@ h2.small-section-header > .anchor {
 	content: '§';
 }
 
-.docblock a:not(.srclink):not(.test-arrow):hover,
-.docblock-short a:not(.srclink):not(.test-arrow):hover, .item-info a {
+.docblock a:not(.srclink):not(.test-arrow):not(.scrape-help):hover,
+.docblock-short a:not(.srclink):not(.test-arrow):not(.scrape-help):hover, .item-info a {
 	text-decoration: underline;
 }
 
@@ -2038,21 +2038,45 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 
 /* Begin: styles for --scrape-examples feature */
 
+.scraped-example-list .scrape-help {
+	margin-left: 10px;
+	padding: 0 4px;
+	font-weight: normal;
+	font-size: 12px;
+	position: relative;
+	bottom: 1px;
+	background: transparent;
+	border-width: 1px;
+	border-style: solid;
+	border-radius: 50px;
+}
+
 .scraped-example-title {
 	font-family: 'Fira Sans';
 }
 
-.scraped-example:not(.expanded) .code-wrapper pre.line-numbers {
-	overflow: hidden;
+.scraped-example .code-wrapper {
+	position: relative;
+	display: flex;
+	flex-direction: row;
+	flex-wrap: wrap;
+	width: 100%;
+}
+
+.scraped-example:not(.expanded) .code-wrapper {
 	max-height: 240px;
 }
 
-.scraped-example:not(.expanded) .code-wrapper .example-wrap pre.rust {
+.scraped-example:not(.expanded) .code-wrapper pre {
 	overflow-y: hidden;
 	max-height: 240px;
 	padding-bottom: 0;
 }
 
+.scraped-example:not(.expanded) .code-wrapper pre.line-numbers {
+	overflow-x: hidden;
+}
+
 .scraped-example .code-wrapper .prev {
 	position: absolute;
 	top: 0.25em;
@@ -2077,22 +2101,13 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	cursor: pointer;
 }
 
-.scraped-example .code-wrapper {
-	position: relative;
-	display: flex;
-	flex-direction: row;
-	flex-wrap: wrap;
-	width: 100%;
-}
-
 .scraped-example:not(.expanded) .code-wrapper:before {
 	content: " ";
 	width: 100%;
 	height: 5px;
 	position: absolute;
 	z-index: 100;
 	top: 0;
-	background: linear-gradient(to bottom, rgba(255, 255, 255, 1), rgba(255, 255, 255, 0));
 }
 
 .scraped-example:not(.expanded) .code-wrapper:after {
@@ -2102,12 +2117,6 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	position: absolute;
 	z-index: 100;
 	bottom: 0;
-	background: linear-gradient(to top, rgba(255, 255, 255, 1), rgba(255, 255, 255, 0));
-}
-
-.scraped-example:not(.expanded) .code-wrapper {
-	overflow: hidden;
-	max-height: 240px;
 }
 
 .scraped-example .code-wrapper .line-numbers {
@@ -2126,34 +2135,37 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	margin-bottom: 0;
 }
 
+.scraped-example:not(.expanded) .code-wrapper .example-wrap {
+	overflow-x: hidden;
+}
+
 .scraped-example .code-wrapper .example-wrap pre.rust {
 	overflow-x: inherit;
 	width: inherit;
 	overflow-y: hidden;
 }
 
-.scraped-example .example-wrap .rust span.highlight {
-	background: #fcffd6;
-}
-
-.scraped-example .example-wrap .rust span.highlight.focus {
-	background: #f6fdb0;
-}
 
 .more-examples-toggle {
+	max-width: calc(100% + 25px);
 	margin-top: 10px;
+	margin-left: -25px;
+}
+
+.more-examples-toggle .hide-more {
+	margin-left: 25px;
+	margin-bottom: 5px;
+	cursor: pointer;
 }
 
-.more-examples-toggle summary {
-	color: #999;
+.more-examples-toggle summary, .more-examples-toggle .hide-more {
 	font-family: 'Fira Sans';
 }
 
 .more-scraped-examples {
-	margin-left: 25px;
+	margin-left: 5px;
 	display: flex;
 	flex-direction: row;
-	width: calc(100% - 25px);
 }
 
 .more-scraped-examples-inner {
@@ -2169,13 +2181,8 @@ details.rustdoc-toggle[open] > summary.hideme::after {
 	cursor: pointer;
 }
 
-.toggle-line:hover .toggle-line-inner {
-	background: #aaa;
-}
-
 .toggle-line-inner {
 	min-width: 2px;
-	background: #ddd;
 	height: 100%;
 }
 

src/librustdoc/html/static/css/themes/ayu.css

@@ -611,6 +611,18 @@ input:checked + .slider {
 	background-color: #ffb454 !important;
 }
 
+
+.scraped-example-list .scrape-help {
+	border-color: #aaa;
+	color: #eee;
+}
+.scraped-example-list .scrape-help:hover {
+	border-color: white;
+	color: white;
+}
+.more-examples-toggle summary, .more-examples-toggle .hide-more {
+	color: #999;
+}
 .scraped-example .example-wrap .rust span.highlight {
 	background: rgb(91, 59, 1);
 }
@@ -624,8 +636,8 @@ input:checked + .slider {
 	background: linear-gradient(to top, rgba(15, 20, 25, 1), rgba(15, 20, 25, 0));
 }
 .toggle-line-inner {
-	background: #616161;
+	background: #999;
 }
 .toggle-line:hover .toggle-line-inner {
-	background: #898989;
+	background: #c5c5c5;
 }