1 use std::collections::BTreeMap;
2 use std::convert::TryFrom;
5 use std::path::PathBuf;
8 use rustc_data_structures::fx::FxHashMap;
9 use rustc_session::config::{
10 self, parse_crate_types_from_list, parse_externs, parse_target_triple, CrateType,
12 use rustc_session::config::{get_cmd_lint_options, nightly_options};
13 use rustc_session::config::{CodegenOptions, DebuggingOptions, ErrorOutputType, Externs};
14 use rustc_session::getopts;
15 use rustc_session::lint::Level;
16 use rustc_session::search_paths::SearchPath;
17 use rustc_span::edition::Edition;
18 use rustc_target::spec::TargetTriple;
20 use crate::core::new_handler;
21 use crate::externalfiles::ExternalHtml;
23 use crate::html::markdown::IdMap;
24 use crate::html::render::StylePath;
25 use crate::html::static_files;
27 use crate::passes::{self, Condition};
28 use crate::scrape_examples::{AllCallLocations, ScrapeExamplesOptions};
31 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
32 crate enum OutputFormat {
37 impl Default for OutputFormat {
38 fn default() -> OutputFormat {
44 crate fn is_json(&self) -> bool {
45 matches!(self, OutputFormat::Json)
49 impl TryFrom<&str> for OutputFormat {
52 fn try_from(value: &str) -> Result<Self, Self::Error> {
54 "json" => Ok(OutputFormat::Json),
55 "html" => Ok(OutputFormat::Html),
56 _ => Err(format!("unknown output format `{}`", value)),
61 /// Configuration options for rustdoc.
63 crate struct Options {
64 // Basic options / Options passed directly to rustc
65 /// The crate root or Markdown file to load.
67 /// The name of the crate being documented.
68 crate crate_name: Option<String>,
69 /// Whether or not this is a proc-macro crate
70 crate proc_macro_crate: bool,
71 /// How to format errors and warnings.
72 crate error_format: ErrorOutputType,
73 /// Library search paths to hand to the compiler.
74 crate libs: Vec<SearchPath>,
75 /// Library search paths strings to hand to the compiler.
76 crate lib_strs: Vec<String>,
77 /// The list of external crates to link against.
78 crate externs: Externs,
79 /// The list of external crates strings to link against.
80 crate extern_strs: Vec<String>,
81 /// List of `cfg` flags to hand to the compiler. Always includes `rustdoc`.
82 crate cfgs: Vec<String>,
83 /// Codegen options to hand to the compiler.
84 crate codegen_options: CodegenOptions,
85 /// Codegen options strings to hand to the compiler.
86 crate codegen_options_strs: Vec<String>,
87 /// Debugging (`-Z`) options to pass to the compiler.
88 crate debugging_opts: DebuggingOptions,
89 /// Debugging (`-Z`) options strings to pass to the compiler.
90 crate debugging_opts_strs: Vec<String>,
91 /// The target used to compile the crate against.
92 crate target: TargetTriple,
93 /// Edition used when reading the crate. Defaults to "2015". Also used by default when
94 /// compiling doctests from the crate.
95 crate edition: Edition,
96 /// The path to the sysroot. Used during the compilation process.
97 crate maybe_sysroot: Option<PathBuf>,
98 /// Lint information passed over the command-line.
99 crate lint_opts: Vec<(String, Level)>,
100 /// Whether to ask rustc to describe the lints it knows.
101 crate describe_lints: bool,
102 /// What level to cap lints at.
103 crate lint_cap: Option<Level>,
105 // Options specific to running doctests
106 /// Whether we should run doctests instead of generating docs.
107 crate should_test: bool,
108 /// List of arguments to pass to the test harness, if running tests.
109 crate test_args: Vec<String>,
110 /// The working directory in which to run tests.
111 crate test_run_directory: Option<PathBuf>,
112 /// Optional path to persist the doctest executables to, defaults to a
113 /// temporary directory if not set.
114 crate persist_doctests: Option<PathBuf>,
115 /// Runtool to run doctests with
116 crate runtool: Option<String>,
117 /// Arguments to pass to the runtool
118 crate runtool_args: Vec<String>,
119 /// Whether to allow ignoring doctests on a per-target basis
120 /// For example, using ignore-foo to ignore running the doctest on any target that
121 /// contains "foo" as a substring
122 crate enable_per_target_ignores: bool,
123 /// Do not run doctests, compile them if should_test is active.
126 /// The path to a rustc-like binary to build tests with. If not set, we
127 /// default to loading from `$sysroot/bin/rustc`.
128 crate test_builder: Option<PathBuf>,
130 // Options that affect the documentation process
131 /// Whether to run the `calculate-doc-coverage` pass, which counts the number of public items
132 /// with and without documentation.
133 crate show_coverage: bool,
135 // Options that alter generated documentation pages
136 /// Crate version to note on the sidebar of generated docs.
137 crate crate_version: Option<String>,
138 /// Collected options specific to outputting final pages.
139 crate render_options: RenderOptions,
140 /// The format that we output when rendering.
142 /// Currently used only for the `--show-coverage` option.
143 crate output_format: OutputFormat,
144 /// If this option is set to `true`, rustdoc will only run checks and not generate
146 crate run_check: bool,
147 /// Whether doctests should emit unused externs
148 crate json_unused_externs: bool,
149 /// Whether to skip capturing stdout and stderr of tests.
150 crate nocapture: bool,
152 /// Configuration for scraping examples from the current crate. If this option is Some(..) then
153 /// the compiler will scrape examples and not generate documentation.
154 crate scrape_examples_options: Option<ScrapeExamplesOptions>,
157 impl fmt::Debug for Options {
158 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
159 struct FmtExterns<'a>(&'a Externs);
161 impl<'a> fmt::Debug for FmtExterns<'a> {
162 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
163 f.debug_map().entries(self.0.iter()).finish()
167 f.debug_struct("Options")
168 .field("input", &self.input)
169 .field("crate_name", &self.crate_name)
170 .field("proc_macro_crate", &self.proc_macro_crate)
171 .field("error_format", &self.error_format)
172 .field("libs", &self.libs)
173 .field("externs", &FmtExterns(&self.externs))
174 .field("cfgs", &self.cfgs)
175 .field("codegen_options", &"...")
176 .field("debugging_options", &"...")
177 .field("target", &self.target)
178 .field("edition", &self.edition)
179 .field("maybe_sysroot", &self.maybe_sysroot)
180 .field("lint_opts", &self.lint_opts)
181 .field("describe_lints", &self.describe_lints)
182 .field("lint_cap", &self.lint_cap)
183 .field("should_test", &self.should_test)
184 .field("test_args", &self.test_args)
185 .field("test_run_directory", &self.test_run_directory)
186 .field("persist_doctests", &self.persist_doctests)
187 .field("show_coverage", &self.show_coverage)
188 .field("crate_version", &self.crate_version)
189 .field("render_options", &self.render_options)
190 .field("runtool", &self.runtool)
191 .field("runtool_args", &self.runtool_args)
192 .field("enable-per-target-ignores", &self.enable_per_target_ignores)
193 .field("run_check", &self.run_check)
194 .field("no_run", &self.no_run)
195 .field("nocapture", &self.nocapture)
196 .field("scrape_examples_options", &self.scrape_examples_options)
201 /// Configuration options for the HTML page-creation process.
202 #[derive(Clone, Debug)]
203 crate struct RenderOptions {
204 /// Output directory to generate docs into. Defaults to `doc`.
205 crate output: PathBuf,
206 /// External files to insert into generated pages.
207 crate external_html: ExternalHtml,
208 /// A pre-populated `IdMap` with the default headings and any headings added by Markdown files
209 /// processed by `external_html`.
211 /// If present, playground URL to use in the "Run" button added to code samples.
213 /// Be aware: This option can come both from the CLI and from crate attributes!
214 crate playground_url: Option<String>,
215 /// Whether to sort modules alphabetically on a module page instead of using declaration order.
216 /// `true` by default.
218 // FIXME(misdreavus): the flag name is `--sort-modules-by-appearance` but the meaning is
219 // inverted once read.
220 crate sort_modules_alphabetically: bool,
221 /// List of themes to extend the docs with. Original argument name is included to assist in
222 /// displaying errors if it fails a theme check.
223 crate themes: Vec<StylePath>,
224 /// If present, CSS file that contains rules to add to the default CSS.
225 crate extension_css: Option<PathBuf>,
226 /// A map of crate names to the URL to use instead of querying the crate's `html_root_url`.
227 crate extern_html_root_urls: BTreeMap<String, String>,
228 /// Whether to give precedence to `html_root_url` or `--exten-html-root-url`.
229 crate extern_html_root_takes_precedence: bool,
230 /// A map of the default settings (values are as for DOM storage API). Keys should lack the
231 /// `rustdoc-` prefix.
232 crate default_settings: FxHashMap<String, String>,
233 /// If present, suffix added to CSS/JavaScript files when referencing them in generated pages.
234 crate resource_suffix: String,
235 /// Whether to run the static CSS/JavaScript through a minifier when outputting them. `true` by
238 // FIXME(misdreavus): the flag name is `--disable-minification` but the meaning is inverted
240 crate enable_minification: bool,
241 /// Whether to create an index page in the root of the output directory. If this is true but
242 /// `enable_index_page` is None, generate a static listing of crates instead.
243 crate enable_index_page: bool,
244 /// A file to use as the index page at the root of the output directory. Overrides
245 /// `enable_index_page` to be true if set.
246 crate index_page: Option<PathBuf>,
247 /// An optional path to use as the location of static files. If not set, uses combinations of
248 /// `../` to reach the documentation root.
249 crate static_root_path: Option<String>,
251 // Options specific to reading standalone Markdown files
252 /// Whether to generate a table of contents on the output file when reading a standalone
254 crate markdown_no_toc: bool,
255 /// Additional CSS files to link in pages generated from standalone Markdown files.
256 crate markdown_css: Vec<String>,
257 /// If present, playground URL to use in the "Run" button added to code samples generated from
258 /// standalone Markdown files. If not present, `playground_url` is used.
259 crate markdown_playground_url: Option<String>,
260 /// If false, the `select` element to have search filtering by crates on rendered docs
261 /// won't be generated.
262 crate generate_search_filter: bool,
263 /// Document items that have lower than `pub` visibility.
264 crate document_private: bool,
265 /// Document items that have `doc(hidden)`.
266 crate document_hidden: bool,
267 /// If `true`, generate a JSON file in the crate folder instead of HTML redirection files.
268 crate generate_redirect_map: bool,
269 /// Show the memory layout of types in the docs.
270 crate show_type_layout: bool,
271 crate unstable_features: rustc_feature::UnstableFeatures,
272 crate emit: Vec<EmitType>,
273 /// If `true`, HTML source pages will generate links for items to their definition.
274 crate generate_link_to_definition: bool,
275 crate call_locations: AllCallLocations,
278 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
279 crate enum EmitType {
285 impl FromStr for EmitType {
288 fn from_str(s: &str) -> Result<Self, Self::Err> {
291 "unversioned-shared-resources" => Ok(Unversioned),
292 "toolchain-shared-resources" => Ok(Toolchain),
293 "invocation-specific" => Ok(InvocationSpecific),
300 crate fn should_emit_crate(&self) -> bool {
301 self.emit.is_empty() || self.emit.contains(&EmitType::InvocationSpecific)
306 /// Parses the given command-line for options. If an error message or other early-return has
307 /// been printed, returns `Err` with the exit code.
308 crate fn from_matches(matches: &getopts::Matches) -> Result<Options, i32> {
309 // Check for unstable options.
310 nightly_options::check_nightly_options(matches, &opts());
312 if matches.opt_present("h") || matches.opt_present("help") {
313 crate::usage("rustdoc");
315 } else if matches.opt_present("version") {
316 rustc_driver::version("rustdoc", matches);
320 let color = config::parse_color(matches);
321 let config::JsonConfig { json_rendered, json_unused_externs, .. } =
322 config::parse_json(matches);
323 let error_format = config::parse_error_format(matches, color, json_rendered);
325 let codegen_options = CodegenOptions::build(matches, error_format);
326 let debugging_opts = DebuggingOptions::build(matches, error_format);
328 let diag = new_handler(error_format, None, &debugging_opts);
330 // check for deprecated options
331 check_deprecated_options(matches, &diag);
333 if matches.opt_strs("passes") == ["list"] {
334 println!("Available passes for running rustdoc:");
335 for pass in passes::PASSES {
336 println!("{:>20} - {}", pass.name, pass.description);
338 println!("\nDefault passes for rustdoc:");
339 for p in passes::DEFAULT_PASSES {
340 print!("{:>20}", p.pass.name);
341 println_condition(p.condition);
344 if nightly_options::match_is_nightly_build(matches) {
345 println!("\nPasses run with `--show-coverage`:");
346 for p in passes::COVERAGE_PASSES {
347 print!("{:>20}", p.pass.name);
348 println_condition(p.condition);
352 fn println_condition(condition: Condition) {
355 Always => println!(),
356 WhenDocumentPrivate => println!(" (when --document-private-items)"),
357 WhenNotDocumentPrivate => println!(" (when not --document-private-items)"),
358 WhenNotDocumentHidden => println!(" (when not --document-hidden-items)"),
365 let mut emit = Vec::new();
366 for list in matches.opt_strs("emit") {
367 for kind in list.split(',') {
369 Ok(kind) => emit.push(kind),
371 diag.err(&format!("unrecognized emission type: {}", kind));
378 // check for `--output-format=json`
379 if !matches!(matches.opt_str("output-format").as_deref(), None | Some("html"))
380 && !matches.opt_present("show-coverage")
381 && !nightly_options::is_unstable_enabled(matches)
383 rustc_session::early_error(
385 "the -Z unstable-options flag must be passed to enable --output-format for documentation generation (see https://github.com/rust-lang/rust/issues/76578)",
389 let to_check = matches.opt_strs("check-theme");
390 if !to_check.is_empty() {
391 let paths = theme::load_css_paths(static_files::themes::LIGHT.as_bytes());
394 println!("rustdoc: [check-theme] Starting tests! (Ignoring all other arguments)");
395 for theme_file in to_check.iter() {
396 print!(" - Checking \"{}\"...", theme_file);
397 let (success, differences) = theme::test_theme_against(theme_file, &paths, &diag);
398 if !differences.is_empty() || !success {
401 if !differences.is_empty() {
402 println!("{}", differences.join("\n"));
414 if matches.free.is_empty() {
415 diag.struct_err("missing file operand").emit();
418 if matches.free.len() > 1 {
419 diag.struct_err("too many file operands").emit();
422 let input = PathBuf::from(&matches.free[0]);
427 .map(|s| SearchPath::from_cli_opt(s, error_format))
429 let externs = parse_externs(matches, &debugging_opts, error_format);
430 let extern_html_root_urls = match parse_extern_html_roots(matches) {
433 diag.struct_err(err).emit();
438 let default_settings: Vec<Vec<(String, String)>> = vec![
440 .opt_str("default-theme")
444 ("use-system-theme".to_string(), "false".to_string()),
445 ("theme".to_string(), theme.to_string()),
451 .opt_strs("default-setting")
453 .map(|s| match s.split_once('=') {
454 None => (s.clone(), "true".to_string()),
455 Some((k, v)) => (k.to_string(), v.to_string()),
459 let default_settings = default_settings
463 // The keys here become part of `data-` attribute names in the generated HTML. The
464 // browser does a strange mapping when converting them into attributes on the
465 // `dataset` property on the DOM HTML Node:
466 // https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/dataset
468 // The original key values we have are the same as the DOM storage API keys and the
469 // command line options, so contain `-`. Our Javascript needs to be able to look
470 // these values up both in `dataset` and in the storage API, so it needs to be able
471 // to convert the names back and forth. Despite doing this kebab-case to
472 // StudlyCaps transformation automatically, the JS DOM API does not provide a
473 // mechanism for doing the just transformation on a string. So we want to avoid
474 // the StudlyCaps representation in the `dataset` property.
476 // We solve this by replacing all the `-`s with `_`s. We do that here, when we
477 // generate the `data-` attributes, and in the JS, when we look them up. (See
478 // `getSettingValue` in `storage.js.`) Converting `-` to `_` is simple in JS.
480 // The values will be HTML-escaped by the default Tera escaping.
481 |(k, v)| (k.replace('-', "_"), v),
485 let test_args = matches.opt_strs("test-args");
486 let test_args: Vec<String> =
487 test_args.iter().flat_map(|s| s.split_whitespace()).map(|s| s.to_string()).collect();
489 let should_test = matches.opt_present("test");
490 let no_run = matches.opt_present("no-run");
492 if !should_test && no_run {
493 diag.err("the `--test` flag must be passed to enable `--no-run`");
497 let out_dir = matches.opt_str("out-dir").map(|s| PathBuf::from(&s));
498 let output = matches.opt_str("output").map(|s| PathBuf::from(&s));
499 let output = match (out_dir, output) {
500 (Some(_), Some(_)) => {
501 diag.struct_err("cannot use both 'out-dir' and 'output' at once").emit();
504 (Some(out_dir), None) => out_dir,
505 (None, Some(output)) => output,
506 (None, None) => PathBuf::from("doc"),
509 let cfgs = matches.opt_strs("cfg");
511 let extension_css = matches.opt_str("e").map(|s| PathBuf::from(&s));
513 if let Some(ref p) = extension_css {
515 diag.struct_err("option --extend-css argument must be a file").emit();
520 let mut themes = Vec::new();
521 if matches.opt_present("theme") {
522 let paths = theme::load_css_paths(static_files::themes::LIGHT.as_bytes());
524 for (theme_file, theme_s) in
525 matches.opt_strs("theme").iter().map(|s| (PathBuf::from(&s), s.to_owned()))
527 if !theme_file.is_file() {
528 diag.struct_err(&format!("invalid argument: \"{}\"", theme_s))
529 .help("arguments to --theme must be files")
533 if theme_file.extension() != Some(OsStr::new("css")) {
534 diag.struct_err(&format!("invalid argument: \"{}\"", theme_s))
535 .help("arguments to --theme must have a .css extension")
539 let (success, ret) = theme::test_theme_against(&theme_file, &paths, &diag);
541 diag.struct_err(&format!("error loading theme file: \"{}\"", theme_s)).emit();
543 } else if !ret.is_empty() {
544 diag.struct_warn(&format!(
545 "theme file \"{}\" is missing CSS rules from the default theme",
548 .warn("the theme may appear incorrect when loaded")
550 "to see what rules are missing, call `rustdoc --check-theme \"{}\"`",
555 themes.push(StylePath { path: theme_file });
559 let edition = config::parse_crate_edition(matches);
561 let mut id_map = html::markdown::IdMap::new();
562 let external_html = match ExternalHtml::load(
563 &matches.opt_strs("html-in-header"),
564 &matches.opt_strs("html-before-content"),
565 &matches.opt_strs("html-after-content"),
566 &matches.opt_strs("markdown-before-content"),
567 &matches.opt_strs("markdown-after-content"),
568 nightly_options::match_is_nightly_build(matches),
575 None => return Err(3),
578 match matches.opt_str("r").as_deref() {
579 Some("rust") | None => {}
581 diag.struct_err(&format!("unknown input format: {}", s)).emit();
586 let index_page = matches.opt_str("index-page").map(|s| PathBuf::from(&s));
587 if let Some(ref index_page) = index_page {
588 if !index_page.is_file() {
589 diag.struct_err("option `--index-page` argument must be a file").emit();
594 let target = parse_target_triple(matches, error_format);
596 let show_coverage = matches.opt_present("show-coverage");
598 let crate_types = match parse_crate_types_from_list(matches.opt_strs("crate-type")) {
601 diag.struct_err(&format!("unknown crate type: {}", e)).emit();
606 let output_format = match matches.opt_str("output-format") {
607 Some(s) => match OutputFormat::try_from(s.as_str()) {
609 if !out_fmt.is_json() && show_coverage {
611 "html output format isn't supported for the --show-coverage option",
619 diag.struct_err(&e).emit();
623 None => OutputFormat::default(),
625 let crate_name = matches.opt_str("crate-name");
626 let proc_macro_crate = crate_types.contains(&CrateType::ProcMacro);
627 let playground_url = matches.opt_str("playground-url");
628 let maybe_sysroot = matches.opt_str("sysroot").map(PathBuf::from);
629 let sort_modules_alphabetically = !matches.opt_present("sort-modules-by-appearance");
630 let resource_suffix = matches.opt_str("resource-suffix").unwrap_or_default();
631 let enable_minification = !matches.opt_present("disable-minification");
632 let markdown_no_toc = matches.opt_present("markdown-no-toc");
633 let markdown_css = matches.opt_strs("markdown-css");
634 let markdown_playground_url = matches.opt_str("markdown-playground-url");
635 let crate_version = matches.opt_str("crate-version");
636 let enable_index_page = matches.opt_present("enable-index-page") || index_page.is_some();
637 let static_root_path = matches.opt_str("static-root-path");
638 let generate_search_filter = !matches.opt_present("disable-per-crate-search");
639 let test_run_directory = matches.opt_str("test-run-directory").map(PathBuf::from);
640 let persist_doctests = matches.opt_str("persist-doctests").map(PathBuf::from);
641 let test_builder = matches.opt_str("test-builder").map(PathBuf::from);
642 let codegen_options_strs = matches.opt_strs("C");
643 let debugging_opts_strs = matches.opt_strs("Z");
644 let lib_strs = matches.opt_strs("L");
645 let extern_strs = matches.opt_strs("extern");
646 let runtool = matches.opt_str("runtool");
647 let runtool_args = matches.opt_strs("runtool-arg");
648 let enable_per_target_ignores = matches.opt_present("enable-per-target-ignores");
649 let document_private = matches.opt_present("document-private-items");
650 let document_hidden = matches.opt_present("document-hidden-items");
651 let run_check = matches.opt_present("check");
652 let generate_redirect_map = matches.opt_present("generate-redirect-map");
653 let show_type_layout = matches.opt_present("show-type-layout");
654 let nocapture = matches.opt_present("nocapture");
655 let generate_link_to_definition = matches.opt_present("generate-link-to-definition");
656 let extern_html_root_takes_precedence =
657 matches.opt_present("extern-html-root-takes-precedence");
659 if generate_link_to_definition && (show_coverage || output_format != OutputFormat::Html) {
661 "--generate-link-to-definition option can only be used with HTML output format",
667 let scrape_examples_options = ScrapeExamplesOptions::new(&matches, &diag)?;
668 let with_examples = matches.opt_strs("with-examples");
669 let call_locations = crate::scrape_examples::load_call_locations(with_examples, &diag)?;
671 let (lint_opts, describe_lints, lint_cap) = get_cmd_lint_options(matches, error_format);
683 codegen_options_strs,
700 enable_per_target_ignores,
705 render_options: RenderOptions {
710 sort_modules_alphabetically,
713 extern_html_root_urls,
714 extern_html_root_takes_precedence,
723 markdown_playground_url,
724 generate_search_filter,
727 generate_redirect_map,
729 unstable_features: rustc_feature::UnstableFeatures::from_environment(
730 crate_name.as_deref(),
733 generate_link_to_definition,
739 scrape_examples_options,
743 /// Returns `true` if the file given as `self.input` is a Markdown file.
744 crate fn markdown_input(&self) -> bool {
745 self.input.extension().map_or(false, |e| e == "md" || e == "markdown")
749 /// Prints deprecation warnings for deprecated options
750 fn check_deprecated_options(matches: &getopts::Matches, diag: &rustc_errors::Handler) {
751 let deprecated_flags = [];
753 for &flag in deprecated_flags.iter() {
754 if matches.opt_present(flag) {
755 diag.struct_warn(&format!("the `{}` flag is deprecated", flag))
757 "see issue #44136 <https://github.com/rust-lang/rust/issues/44136> \
758 for more information",
764 let removed_flags = ["plugins", "plugin-path", "no-defaults", "passes", "input-format"];
766 for &flag in removed_flags.iter() {
767 if matches.opt_present(flag) {
768 let mut err = diag.struct_warn(&format!("the `{}` flag no longer functions", flag));
770 "see issue #44136 <https://github.com/rust-lang/rust/issues/44136> \
771 for more information",
774 if flag == "no-defaults" || flag == "passes" {
775 err.help("you may want to use --document-private-items");
776 } else if flag == "plugins" || flag == "plugin-path" {
777 err.warn("see CVE-2018-1000622");
785 /// Extracts `--extern-html-root-url` arguments from `matches` and returns a map of crate names to
786 /// the given URLs. If an `--extern-html-root-url` argument was ill-formed, returns an error
787 /// describing the issue.
788 fn parse_extern_html_roots(
789 matches: &getopts::Matches,
790 ) -> Result<BTreeMap<String, String>, &'static str> {
791 let mut externs = BTreeMap::new();
792 for arg in &matches.opt_strs("extern-html-root-url") {
794 arg.split_once('=').ok_or("--extern-html-root-url must be of the form name=url")?;
795 externs.insert(name.to_string(), url.to_string());