rustdoc: add - (stdin) support

src/librustdoc/config.rs

@@ -60,7 +60,7 @@ impl TryFrom<&str> for OutputFormat {
 pub(crate) struct Options {
     // Basic options / Options passed directly to rustc
     /// The crate root or Markdown file to load.
-    pub(crate) input: PathBuf,
+    pub(crate) input: String,
     /// The name of the crate being documented.
     pub(crate) crate_name: Option<String>,
     /// Whether or not this is a bin crate
@@ -450,15 +450,16 @@ impl Options {
 
         let (lint_opts, describe_lints, lint_cap) = get_cmd_lint_options(early_dcx, matches);
 
-        let input = PathBuf::from(if describe_lints {
+        let input = if describe_lints {
             "" // dummy, this won't be used
         } else if matches.free.is_empty() {
             dcx.fatal("missing file operand");
         } else if matches.free.len() > 1 {
             dcx.fatal("too many file operands");
         } else {
             &matches.free[0]
-        });
+        }
+        .to_string();
 
         let externs = parse_externs(early_dcx, matches, &unstable_opts);
         let extern_html_root_urls = match parse_extern_html_roots(matches) {
@@ -797,7 +798,7 @@ impl Options {
 
     /// Returns `true` if the file given as `self.input` is a Markdown file.
     pub(crate) fn markdown_input(&self) -> bool {
-        self.input.extension().is_some_and(|e| e == "md" || e == "markdown")
+        self.input.rsplit_once('.').is_some_and(|(_, e)| e == "md" || e == "markdown")
     }
 }
 

src/librustdoc/core.rs

@@ -15,13 +15,16 @@ use rustc_middle::hir::nested_filter;
 use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
 use rustc_session::config::{self, CrateType, ErrorOutputType, ResolveDocLinks};
 use rustc_session::lint;
+use rustc_session::EarlyDiagCtxt;
 use rustc_session::Session;
 use rustc_span::symbol::sym;
-use rustc_span::{source_map, Span};
+use rustc_span::{source_map, FileName, Span};
 
 use std::cell::RefCell;
 use std::io;
+use std::io::Read;
 use std::mem;
+use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::LazyLock;
 use std::sync::{atomic::AtomicBool, Arc};
@@ -174,10 +177,30 @@ pub(crate) fn new_dcx(
     rustc_errors::DiagCtxt::new(emitter).with_flags(unstable_opts.dcx_flags(true))
 }
 
+/// Create the input (string or file path)
+pub(crate) fn make_input(
+    early_dcx: &EarlyDiagCtxt,
+    input: &String,
+) -> Result<Input, ErrorGuaranteed> {
+    Ok(if input == "-" {
+        let mut src = String::new();
+        if io::stdin().read_to_string(&mut src).is_err() {
+            // Immediately stop compilation if there was an issue reading
+            // the input (for example if the input stream is not UTF-8).
+            let reported =
+                early_dcx.early_err("couldn't read from stdin, as it did not contain valid UTF-8");
+            return Err(reported);
+        }
+        Input::Str { name: FileName::anon_source_code(&src), input: src }
+    } else {
+        Input::File(PathBuf::from(input))
+    })
+}
+
 /// Parse, resolve, and typecheck the given crate.
 pub(crate) fn create_config(
     RustdocOptions {
-        input,
+        input: _,
         crate_name,
         proc_macro_crate,
         error_format,
@@ -199,13 +222,12 @@ pub(crate) fn create_config(
         ..
     }: RustdocOptions,
     RenderOptions { document_private, .. }: &RenderOptions,
+    input: Input,
     using_internal_features: Arc<AtomicBool>,
 ) -> rustc_interface::Config {
     // Add the doc cfg into the doc build.
     cfgs.push("doc".to_string());
 
-    let input = Input::File(input);
-
     // By default, rustdoc ignores all lints.
     // Specifically unblock lints relevant to documentation or the lint machinery itself.
     let mut lints_to_show = vec![

src/librustdoc/doctest.rs

@@ -12,6 +12,7 @@ use rustc_middle::ty::TyCtxt;
 use rustc_parse::maybe_new_parser_from_source_str;
 use rustc_parse::parser::attr::InnerAttrPolicy;
 use rustc_resolve::rustdoc::span_of_fragments;
+use rustc_session::config::Input;
 use rustc_session::config::{self, CrateType, ErrorOutputType};
 use rustc_session::parse::ParseSess;
 use rustc_session::{lint, Session};
@@ -92,9 +93,8 @@ fn get_doctest_dir() -> io::Result<TempDir> {
 pub(crate) fn run(
     dcx: &rustc_errors::DiagCtxt,
     options: RustdocOptions,
+    input: Input,
 ) -> Result<(), ErrorGuaranteed> {
-    let input = config::Input::File(options.input.clone());
-
     let invalid_codeblock_attributes_name = crate::lint::INVALID_CODEBLOCK_ATTRIBUTES.name;
 
     // See core::create_config for what's going on here.

src/librustdoc/lib.rs

@@ -729,13 +729,21 @@ fn main_args(
     let diag =
         core::new_dcx(options.error_format, None, options.diagnostic_width, &options.unstable_opts);
 
+    let input = core::make_input(early_dcx, &options.input)?;
+
     match (options.should_test, options.markdown_input()) {
         (true, true) => return wrap_return(&diag, markdown::test(options)),
-        (true, false) => return doctest::run(&diag, options),
+        (true, false) => return doctest::run(&diag, options, input),
         (false, true) => {
-            let input = options.input.clone();
             let edition = options.edition;
-            let config = core::create_config(options, &render_options, using_internal_features);
+            let config =
+                core::create_config(options, &render_options, input, using_internal_features);
+
+            use rustc_session::config::Input;
+            let input = match &config.input {
+                Input::File(path) => path.clone(),
+                Input::Str { .. } => unreachable!("only path to markdown are supported"),
+            };
 
             // `markdown::render` can invoke `doctest::make_test`, which
             // requires session globals and a thread pool, so we use
@@ -768,7 +776,7 @@ fn main_args(
     let scrape_examples_options = options.scrape_examples_options.clone();
     let bin_crate = options.bin_crate;
 
-    let config = core::create_config(options, &render_options, using_internal_features);
+    let config = core::create_config(options, &render_options, input, using_internal_features);
 
     interface::run_compiler(config, |compiler| {
         let sess = &compiler.sess;

src/librustdoc/markdown.rs

@@ -1,7 +1,7 @@
 use std::fmt::Write as _;
 use std::fs::{create_dir_all, read_to_string, File};
 use std::io::prelude::*;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 
 use tempfile::tempdir;
 
@@ -145,7 +145,7 @@ pub(crate) fn render<P: AsRef<Path>>(
 /// Runs any tests/code examples in the markdown file `input`.
 pub(crate) fn test(options: Options) -> Result<(), String> {
     let input_str = read_to_string(&options.input)
-        .map_err(|err| format!("{input}: {err}", input = options.input.display()))?;
+        .map_err(|err| format!("{input}: {err}", input = options.input))?;
     let mut opts = GlobalTestOptions::default();
     opts.no_crate_inject = true;
 
@@ -155,12 +155,12 @@ pub(crate) fn test(options: Options) -> Result<(), String> {
     generate_args_file(&file_path, &options)?;
 
     let mut collector = Collector::new(
-        options.input.display().to_string(),
+        options.input.clone(),
         options.clone(),
         true,
         opts,
         None,
-        Some(options.input),
+        Some(PathBuf::from(options.input)),
         options.enable_per_target_ignores,
         file_path,
     );

tests/run-make/stdin-rustdoc/rmake.rs

@@ -0,0 +1,27 @@
+//! This test checks rustdoc `-` (stdin) handling
+
+extern crate run_make_support;
+
+use run_make_support::{rustdoc, tmp_dir};
+
+const INPUT: &str = r#"
+//! ```
+//! dbg!(());
+//! ```
+pub struct F;
+"#;
+
+fn main() {
+    let tmp_dir = tmp_dir();
+    let out_dir = tmp_dir.join("doc");
+
+    // rustdoc -
+    rustdoc().arg("-").out_dir(&out_dir).run_with_stdin(INPUT);
+    assert!(out_dir.join("rust_out/struct.F.html").try_exists().unwrap());
+
+    // rustdoc --test -
+    rustdoc().arg("--test").arg("-").run_with_stdin(INPUT);
+
+    // rustdoc file.rs -
+    rustdoc().arg("file.rs").arg("-").run_fail();
+}