Rename rustdoc/test -> rustdoc/doctest

This modules contains the implementation of doctests, and not the
tests of rustdoc itself. This name is confusing, so let's rename it to
doctest for clarity.

1 files changed, 1039 insertions, 0 deletions

diff --git a/src/librustdoc/doctest.rs b/src/librustdoc/doctest.rs
new file mode 100644
index 00000000000..7b7c152d8ab
--- /dev/null
+++ b/src/librustdoc/doctest.rs
@@ -0,0 +1,1039 @@
+use rustc_ast as ast;
+use rustc_data_structures::sync::Lrc;
+use rustc_errors::ErrorReported;
+use rustc_feature::UnstableFeatures;
+use rustc_hir as hir;
+use rustc_hir::intravisit;
+use rustc_hir::{HirId, CRATE_HIR_ID};
+use rustc_interface::interface;
+use rustc_middle::hir::map::Map;
+use rustc_middle::ty::TyCtxt;
+use rustc_session::config::{self, CrateType};
+use rustc_session::{lint, DiagnosticOutput, Session};
+use rustc_span::edition::Edition;
+use rustc_span::source_map::SourceMap;
+use rustc_span::symbol::sym;
+use rustc_span::{BytePos, FileName, Pos, Span, DUMMY_SP};
+use rustc_target::spec::TargetTriple;
+use tempfile::Builder as TempFileBuilder;
+
+use std::collections::HashMap;
+use std::env;
+use std::io::{self, Write};
+use std::panic;
+use std::path::PathBuf;
+use std::process::{self, Command, Stdio};
+use std::str;
+
+use crate::clean::Attributes;
+use crate::config::Options;
+use crate::core::init_lints;
+use crate::html::markdown::{self, ErrorCodes, Ignore, LangString};
+use crate::passes::span_of_attrs;
+
+#[derive(Clone, Default)]
+pub struct TestOptions {
+    /// Whether to disable the default `extern crate my_crate;` when creating doctests.
+    pub no_crate_inject: bool,
+    /// Whether to emit compilation warnings when compiling doctests. Setting this will suppress
+    /// the default `#![allow(unused)]`.
+    pub display_warnings: bool,
+    /// Additional crate-level attributes to add to doctests.
+    pub attrs: Vec<String>,
+}
+
+pub fn run(options: Options) -> Result<(), ErrorReported> {
+    let input = config::Input::File(options.input.clone());
+
+    let invalid_codeblock_attributes_name = rustc_lint::builtin::INVALID_CODEBLOCK_ATTRIBUTES.name;
+
+    // In addition to those specific lints, we also need to allow those given through
+    // command line, otherwise they'll get ignored and we don't want that.
+    let allowed_lints = vec![invalid_codeblock_attributes_name.to_owned()];
+
+    let (lint_opts, lint_caps) = init_lints(allowed_lints, options.lint_opts.clone(), |lint| {
+        if lint.name == invalid_codeblock_attributes_name {
+            None
+        } else {
+            Some((lint.name_lower(), lint::Allow))
+        }
+    });
+
+    let crate_types =
+        if options.proc_macro_crate { vec![CrateType::ProcMacro] } else { vec![CrateType::Rlib] };
+
+    let sessopts = config::Options {
+        maybe_sysroot: options.maybe_sysroot.clone(),
+        search_paths: options.libs.clone(),
+        crate_types,
+        lint_opts: if !options.display_warnings { lint_opts } else { vec![] },
+        lint_cap: Some(options.lint_cap.clone().unwrap_or_else(|| lint::Forbid)),
+        cg: options.codegen_options.clone(),
+        externs: options.externs.clone(),
+        unstable_features: UnstableFeatures::from_environment(),
+        actually_rustdoc: true,
+        debugging_opts: config::DebuggingOptions { ..config::basic_debugging_options() },
+        edition: options.edition,
+        target_triple: options.target.clone(),
+        ..config::Options::default()
+    };
+
+    let mut cfgs = options.cfgs.clone();
+    cfgs.push("doc".to_owned());
+    cfgs.push("doctest".to_owned());
+    let config = interface::Config {
+        opts: sessopts,
+        crate_cfg: interface::parse_cfgspecs(cfgs),
+        input,
+        input_path: None,
+        output_file: None,
+        output_dir: None,
+        file_loader: None,
+        diagnostic_output: DiagnosticOutput::Default,
+        stderr: None,
+        crate_name: options.crate_name.clone(),
+        lint_caps,
+        register_lints: None,
+        override_queries: None,
+        registry: rustc_driver::diagnostics_registry(),
+    };
+
+    let mut test_args = options.test_args.clone();
+    let display_warnings = options.display_warnings;
+
+    let tests = interface::run_compiler(config, |compiler| {
+        compiler.enter(|queries| {
+            let lower_to_hir = queries.lower_to_hir()?;
+
+            let mut opts = scrape_test_config(lower_to_hir.peek().0);
+            opts.display_warnings |= options.display_warnings;
+            let enable_per_target_ignores = options.enable_per_target_ignores;
+            let mut collector = Collector::new(
+                queries.crate_name()?.peek().to_string(),
+                options,
+                false,
+                opts,
+                Some(compiler.session().parse_sess.clone_source_map()),
+                None,
+                enable_per_target_ignores,
+            );
+
+            let mut global_ctxt = queries.global_ctxt()?.take();
+
+            global_ctxt.enter(|tcx| {
+                let krate = tcx.hir().krate();
+
+                let mut hir_collector = HirCollector {
+                    sess: compiler.session(),
+                    collector: &mut collector,
+                    map: tcx.hir(),
+                    codes: ErrorCodes::from(
+                        compiler.session().opts.unstable_features.is_nightly_build(),
+                    ),
+                    tcx,
+                };
+                hir_collector.visit_testable(
+                    "".to_string(),
+                    &krate.item.attrs,
+                    CRATE_HIR_ID,
+                    krate.item.span,
+                    |this| {
+                        intravisit::walk_crate(this, krate);
+                    },
+                );
+            });
+            compiler.session().abort_if_errors();
+
+            let ret: Result<_, ErrorReported> = Ok(collector.tests);
+            ret
+        })
+    });
+    let tests = match tests {
+        Ok(tests) => tests,
+        Err(ErrorReported) => return Err(ErrorReported),
+    };
+
+    test_args.insert(0, "rustdoctest".to_string());
+
+    testing::test_main(
+        &test_args,
+        tests,
+        Some(testing::Options::new().display_output(display_warnings)),
+    );
+
+    Ok(())
+}
+
+// Look for `#![doc(test(no_crate_inject))]`, used by crates in the std facade.
+fn scrape_test_config(krate: &::rustc_hir::Crate<'_>) -> TestOptions {
+    use rustc_ast_pretty::pprust;
+
+    let mut opts =
+        TestOptions { no_crate_inject: false, display_warnings: false, attrs: Vec::new() };
+
+    let test_attrs: Vec<_> = krate
+        .item
+        .attrs
+        .iter()
+        .filter(|a| a.has_name(sym::doc))
+        .flat_map(|a| a.meta_item_list().unwrap_or_else(Vec::new))
+        .filter(|a| a.has_name(sym::test))
+        .collect();
+    let attrs = test_attrs.iter().flat_map(|a| a.meta_item_list().unwrap_or(&[]));
+
+    for attr in attrs {
+        if attr.has_name(sym::no_crate_inject) {
+            opts.no_crate_inject = true;
+        }
+        if attr.has_name(sym::attr) {
+            if let Some(l) = attr.meta_item_list() {
+                for item in l {
+                    opts.attrs.push(pprust::meta_list_item_to_string(item));
+                }
+            }
+        }
+    }
+
+    opts
+}
+
+/// Documentation test failure modes.
+enum TestFailure {
+    /// The test failed to compile.
+    CompileError,
+    /// The test is marked `compile_fail` but compiled successfully.
+    UnexpectedCompilePass,
+    /// The test failed to compile (as expected) but the compiler output did not contain all
+    /// expected error codes.
+    MissingErrorCodes(Vec<String>),
+    /// The test binary was unable to be executed.
+    ExecutionError(io::Error),
+    /// The test binary exited with a non-zero exit code.
+    ///
+    /// This typically means an assertion in the test failed or another form of panic occurred.
+    ExecutionFailure(process::Output),
+    /// The test is marked `should_panic` but the test binary executed successfully.
+    UnexpectedRunPass,
+}
+
+enum DirState {
+    Temp(tempfile::TempDir),
+    Perm(PathBuf),
+}
+
+impl DirState {
+    fn path(&self) -> &std::path::Path {
+        match self {
+            DirState::Temp(t) => t.path(),
+            DirState::Perm(p) => p.as_path(),
+        }
+    }
+}
+
+fn run_test(
+    test: &str,
+    cratename: &str,
+    line: usize,
+    options: Options,
+    should_panic: bool,
+    no_run: bool,
+    as_test_harness: bool,
+    runtool: Option<String>,
+    runtool_args: Vec<String>,
+    target: TargetTriple,
+    compile_fail: bool,
+    mut error_codes: Vec<String>,
+    opts: &TestOptions,
+    edition: Edition,
+    outdir: DirState,
+    path: PathBuf,
+) -> Result<(), TestFailure> {
+    let (test, line_offset) = make_test(test, Some(cratename), as_test_harness, opts, edition);
+
+    let output_file = outdir.path().join("rust_out");
+
+    let rustc_binary = options
+        .test_builder
+        .as_deref()
+        .unwrap_or_else(|| rustc_interface::util::rustc_path().expect("found rustc"));
+    let mut compiler = Command::new(&rustc_binary);
+    compiler.arg("--crate-type").arg("bin");
+    for cfg in &options.cfgs {
+        compiler.arg("--cfg").arg(&cfg);
+    }
+    if let Some(sysroot) = options.maybe_sysroot {
+        compiler.arg("--sysroot").arg(sysroot);
+    }
+    compiler.arg("--edition").arg(&edition.to_string());
+    compiler.env("UNSTABLE_RUSTDOC_TEST_PATH", path);
+    compiler.env("UNSTABLE_RUSTDOC_TEST_LINE", format!("{}", line as isize - line_offset as isize));
+    compiler.arg("-o").arg(&output_file);
+    if as_test_harness {
+        compiler.arg("--test");
+    }
+    for lib_str in &options.lib_strs {
+        compiler.arg("-L").arg(&lib_str);
+    }
+    for extern_str in &options.extern_strs {
+        compiler.arg("--extern").arg(&extern_str);
+    }
+    compiler.arg("-Ccodegen-units=1");
+    for codegen_options_str in &options.codegen_options_strs {
+        compiler.arg("-C").arg(&codegen_options_str);
+    }
+    for debugging_option_str in &options.debugging_opts_strs {
+        compiler.arg("-Z").arg(&debugging_option_str);
+    }
+    if no_run && !compile_fail {
+        compiler.arg("--emit=metadata");
+    }
+    compiler.arg("--target").arg(match target {
+        TargetTriple::TargetTriple(s) => s,
+        TargetTriple::TargetPath(path) => {
+            path.to_str().expect("target path must be valid unicode").to_string()
+        }
+    });
+
+    compiler.arg("-");
+    compiler.stdin(Stdio::piped());
+    compiler.stderr(Stdio::piped());
+
+    let mut child = compiler.spawn().expect("Failed to spawn rustc process");
+    {
+        let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+        stdin.write_all(test.as_bytes()).expect("could write out test sources");
+    }
+    let output = child.wait_with_output().expect("Failed to read stdout");
+
+    struct Bomb<'a>(&'a str);
+    impl Drop for Bomb<'_> {
+        fn drop(&mut self) {
+            eprint!("{}", self.0);
+        }
+    }
+    let out = str::from_utf8(&output.stderr).unwrap();
+    let _bomb = Bomb(&out);
+    match (output.status.success(), compile_fail) {
+        (true, true) => {
+            return Err(TestFailure::UnexpectedCompilePass);
+        }
+        (true, false) => {}
+        (false, true) => {
+            if !error_codes.is_empty() {
+                error_codes.retain(|err| !out.contains(&format!("error[{}]: ", err)));
+
+                if !error_codes.is_empty() {
+                    return Err(TestFailure::MissingErrorCodes(error_codes));
+                }
+            }
+        }
+        (false, false) => {
+            return Err(TestFailure::CompileError);
+        }
+    }
+
+    if no_run {
+        return Ok(());
+    }
+
+    // Run the code!
+    let mut cmd;
+
+    if let Some(tool) = runtool {
+        cmd = Command::new(tool);
+        cmd.args(runtool_args);
+        cmd.arg(output_file);
+    } else {
+        cmd = Command::new(output_file);
+    }
+
+    match cmd.output() {
+        Err(e) => return Err(TestFailure::ExecutionError(e)),
+        Ok(out) => {
+            if should_panic && out.status.success() {
+                return Err(TestFailure::UnexpectedRunPass);
+            } else if !should_panic && !out.status.success() {
+                return Err(TestFailure::ExecutionFailure(out));
+            }
+        }
+    }
+
+    Ok(())
+}
+
+/// Transforms a test into code that can be compiled into a Rust binary, and returns the number of
+/// lines before the test code begins.
+pub fn make_test(
+    s: &str,
+    cratename: Option<&str>,
+    dont_insert_main: bool,
+    opts: &TestOptions,
+    edition: Edition,
+) -> (String, usize) {
+    let (crate_attrs, everything_else, crates) = partition_source(s);
+    let everything_else = everything_else.trim();
+    let mut line_offset = 0;
+    let mut prog = String::new();
+
+    if opts.attrs.is_empty() && !opts.display_warnings {
+        // If there aren't any attributes supplied by #![doc(test(attr(...)))], then allow some
+        // lints that are commonly triggered in doctests. The crate-level test attributes are
+        // commonly used to make tests fail in case they trigger warnings, so having this there in
+        // that case may cause some tests to pass when they shouldn't have.
+        prog.push_str("#![allow(unused)]\n");
+        line_offset += 1;
+    }
+
+    // Next, any attributes that came from the crate root via #![doc(test(attr(...)))].
+    for attr in &opts.attrs {
+        prog.push_str(&format!("#![{}]\n", attr));
+        line_offset += 1;
+    }
+
+    // Now push any outer attributes from the example, assuming they
+    // are intended to be crate attributes.
+    prog.push_str(&crate_attrs);
+    prog.push_str(&crates);
+
+    // Uses librustc_ast to parse the doctest and find if there's a main fn and the extern
+    // crate already is included.
+    let result = rustc_driver::catch_fatal_errors(|| {
+        rustc_span::with_session_globals(edition, || {
+            use rustc_errors::emitter::EmitterWriter;
+            use rustc_errors::Handler;
+            use rustc_parse::maybe_new_parser_from_source_str;
+            use rustc_session::parse::ParseSess;
+            use rustc_span::source_map::FilePathMapping;
+
+            let filename = FileName::anon_source_code(s);
+            let source = crates + everything_else;
+
+            // Any errors in parsing should also appear when the doctest is compiled for real, so just
+            // send all the errors that librustc_ast emits directly into a `Sink` instead of stderr.
+            let sm = Lrc::new(SourceMap::new(FilePathMapping::empty()));
+            let emitter =
+                EmitterWriter::new(box io::sink(), None, false, false, false, None, false);
+            // FIXME(misdreavus): pass `-Z treat-err-as-bug` to the doctest parser
+            let handler = Handler::with_emitter(false, None, box emitter);
+            let sess = ParseSess::with_span_handler(handler, sm);
+
+            let mut found_main = false;
+            let mut found_extern_crate = cratename.is_none();
+            let mut found_macro = false;
+
+            let mut parser = match maybe_new_parser_from_source_str(&sess, filename, source) {
+                Ok(p) => p,
+                Err(errs) => {
+                    for mut err in errs {
+                        err.cancel();
+                    }
+
+                    return (found_main, found_extern_crate, found_macro);
+                }
+            };
+
+            loop {
+                match parser.parse_item() {
+                    Ok(Some(item)) => {
+                        if !found_main {
+                            if let ast::ItemKind::Fn(..) = item.kind {
+                                if item.ident.name == sym::main {
+                                    found_main = true;
+                                }
+                            }
+                        }
+
+                        if !found_extern_crate {
+                            if let ast::ItemKind::ExternCrate(original) = item.kind {
+                                // This code will never be reached if `cratename` is none because
+                                // `found_extern_crate` is initialized to `true` if it is none.
+                                let cratename = cratename.unwrap();
+
+                                match original {
+                                    Some(name) => found_extern_crate = name.as_str() == cratename,
+                                    None => found_extern_crate = item.ident.as_str() == cratename,
+                                }
+                            }
+                        }
+
+                        if !found_macro {
+                            if let ast::ItemKind::MacCall(..) = item.kind {
+                                found_macro = true;
+                            }
+                        }
+
+                        if found_main && found_extern_crate {
+                            break;
+                        }
+                    }
+                    Ok(None) => break,
+                    Err(mut e) => {
+                        e.cancel();
+                        break;
+                    }
+                }
+            }
+
+            (found_main, found_extern_crate, found_macro)
+        })
+    });
+    let (already_has_main, already_has_extern_crate, found_macro) = match result {
+        Ok(result) => result,
+        Err(ErrorReported) => {
+            // If the parser panicked due to a fatal error, pass the test code through unchanged.
+            // The error will be reported during compilation.
+            return (s.to_owned(), 0);
+        }
+    };
+
+    // If a doctest's `fn main` is being masked by a wrapper macro, the parsing loop above won't
+    // see it. In that case, run the old text-based scan to see if they at least have a main
+    // function written inside a macro invocation. See
+    // https://github.com/rust-lang/rust/issues/56898
+    let already_has_main = if found_macro && !already_has_main {
+        s.lines()
+            .map(|line| {
+                let comment = line.find("//");
+                if let Some(comment_begins) = comment { &line[0..comment_begins] } else { line }
+            })
+            .any(|code| code.contains("fn main"))
+    } else {
+        already_has_main
+    };
+
+    // Don't inject `extern crate std` because it's already injected by the
+    // compiler.
+    if !already_has_extern_crate && !opts.no_crate_inject && cratename != Some("std") {
+        if let Some(cratename) = cratename {
+            // Make sure its actually used if not included.
+            if s.contains(cratename) {
+                prog.push_str(&format!("extern crate {};\n", cratename));
+                line_offset += 1;
+            }
+        }
+    }
+
+    // FIXME: This code cannot yet handle no_std test cases yet
+    if dont_insert_main || already_has_main || prog.contains("![no_std]") {
+        prog.push_str(everything_else);
+    } else {
+        let returns_result = everything_else.trim_end().ends_with("(())");
+        let (main_pre, main_post) = if returns_result {
+            (
+                "fn main() { fn _inner() -> Result<(), impl core::fmt::Debug> {",
+                "}\n_inner().unwrap() }",
+            )
+        } else {
+            ("fn main() {\n", "\n}")
+        };
+        prog.extend([main_pre, everything_else, main_post].iter().cloned());
+        line_offset += 1;
+    }
+
+    debug!("final doctest:\n{}", prog);
+
+    (prog, line_offset)
+}
+
+// FIXME(aburka): use a real parser to deal with multiline attributes
+fn partition_source(s: &str) -> (String, String, String) {
+    #[derive(Copy, Clone, PartialEq)]
+    enum PartitionState {
+        Attrs,
+        Crates,
+        Other,
+    }
+    let mut state = PartitionState::Attrs;
+    let mut before = String::new();
+    let mut crates = String::new();
+    let mut after = String::new();
+
+    for line in s.lines() {
+        let trimline = line.trim();
+
+        // FIXME(misdreavus): if a doc comment is placed on an extern crate statement, it will be
+        // shunted into "everything else"
+        match state {
+            PartitionState::Attrs => {
+                state = if trimline.starts_with("#![")
+                    || trimline.chars().all(|c| c.is_whitespace())
+                    || (trimline.starts_with("//") && !trimline.starts_with("///"))
+                {
+                    PartitionState::Attrs
+                } else if trimline.starts_with("extern crate")
+                    || trimline.starts_with("#[macro_use] extern crate")
+                {
+                    PartitionState::Crates
+                } else {
+                    PartitionState::Other
+                };
+            }
+            PartitionState::Crates => {
+                state = if trimline.starts_with("extern crate")
+                    || trimline.starts_with("#[macro_use] extern crate")
+                    || trimline.chars().all(|c| c.is_whitespace())
+                    || (trimline.starts_with("//") && !trimline.starts_with("///"))
+                {
+                    PartitionState::Crates
+                } else {
+                    PartitionState::Other
+                };
+            }
+            PartitionState::Other => {}
+        }
+
+        match state {
+            PartitionState::Attrs => {
+                before.push_str(line);
+                before.push_str("\n");
+            }
+            PartitionState::Crates => {
+                crates.push_str(line);
+                crates.push_str("\n");
+            }
+            PartitionState::Other => {
+                after.push_str(line);
+                after.push_str("\n");
+            }
+        }
+    }
+
+    debug!("before:\n{}", before);
+    debug!("crates:\n{}", crates);
+    debug!("after:\n{}", after);
+
+    (before, after, crates)
+}
+
+pub trait Tester {
+    fn add_test(&mut self, test: String, config: LangString, line: usize);
+    fn get_line(&self) -> usize {
+        0
+    }
+    fn register_header(&mut self, _name: &str, _level: u32) {}
+}
+
+pub struct Collector {
+    pub tests: Vec<testing::TestDescAndFn>,
+
+    // The name of the test displayed to the user, separated by `::`.
+    //
+    // In tests from Rust source, this is the path to the item
+    // e.g., `["std", "vec", "Vec", "push"]`.
+    //
+    // In tests from a markdown file, this is the titles of all headers (h1~h6)
+    // of the sections that contain the code block, e.g., if the markdown file is
+    // written as:
+    //
+    // ``````markdown
+    // # Title
+    //
+    // ## Subtitle
+    //
+    // ```rust
+    // assert!(true);
+    // ```
+    // ``````
+    //
+    // the `names` vector of that test will be `["Title", "Subtitle"]`.
+    names: Vec<String>,
+
+    options: Options,
+    use_headers: bool,
+    enable_per_target_ignores: bool,
+    cratename: String,
+    opts: TestOptions,
+    position: Span,
+    source_map: Option<Lrc<SourceMap>>,
+    filename: Option<PathBuf>,
+    visited_tests: HashMap<(String, usize), usize>,
+}
+
+impl Collector {
+    pub fn new(
+        cratename: String,
+        options: Options,
+        use_headers: bool,
+        opts: TestOptions,
+        source_map: Option<Lrc<SourceMap>>,
+        filename: Option<PathBuf>,
+        enable_per_target_ignores: bool,
+    ) -> Collector {
+        Collector {
+            tests: Vec::new(),
+            names: Vec::new(),
+            options,
+            use_headers,
+            enable_per_target_ignores,
+            cratename,
+            opts,
+            position: DUMMY_SP,
+            source_map,
+            filename,
+            visited_tests: HashMap::new(),
+        }
+    }
+
+    fn generate_name(&self, line: usize, filename: &FileName) -> String {
+        let mut item_path = self.names.join("::");
+        if !item_path.is_empty() {
+            item_path.push(' ');
+        }
+        format!("{} - {}(line {})", filename, item_path, line)
+    }
+
+    pub fn set_position(&mut self, position: Span) {
+        self.position = position;
+    }
+
+    fn get_filename(&self) -> FileName {
+        if let Some(ref source_map) = self.source_map {
+            let filename = source_map.span_to_filename(self.position);
+            if let FileName::Real(ref filename) = filename {
+                if let Ok(cur_dir) = env::current_dir() {
+                    if let Ok(path) = filename.local_path().strip_prefix(&cur_dir) {
+                        return path.to_owned().into();
+                    }
+                }
+            }
+            filename
+        } else if let Some(ref filename) = self.filename {
+            filename.clone().into()
+        } else {
+            FileName::Custom("input".to_owned())
+        }
+    }
+}
+
+impl Tester for Collector {
+    fn add_test(&mut self, test: String, config: LangString, line: usize) {
+        let filename = self.get_filename();
+        let name = self.generate_name(line, &filename);
+        let cratename = self.cratename.to_string();
+        let opts = self.opts.clone();
+        let edition = config.edition.unwrap_or(self.options.edition);
+        let options = self.options.clone();
+        let runtool = self.options.runtool.clone();
+        let runtool_args = self.options.runtool_args.clone();
+        let target = self.options.target.clone();
+        let target_str = target.to_string();
+
+        // FIXME(#44940): if doctests ever support path remapping, then this filename
+        // needs to be the result of `SourceMap::span_to_unmapped_path`.
+        let path = match &filename {
+            FileName::Real(path) => path.local_path().to_path_buf(),
+            _ => PathBuf::from(r"doctest.rs"),
+        };
+
+        let outdir = if let Some(mut path) = options.persist_doctests.clone() {
+            // For example `module/file.rs` would become `module_file_rs`
+            let folder_name = filename
+                .to_string()
+                .chars()
+                .map(|c| if c == '/' || c == '.' { '_' } else { c })
+                .collect::<String>();
+
+            path.push(format!(
+                "{name}_{line}_{number}",
+                name = folder_name,
+                number = {
+                    // Increases the current test number, if this file already
+                    // exists or it creates a new entry with a test number of 0.
+                    self.visited_tests
+                        .entry((folder_name.clone(), line))
+                        .and_modify(|v| *v += 1)
+                        .or_insert(0)
+                },
+                line = line,
+            ));
+
+            std::fs::create_dir_all(&path)
+                .expect("Couldn't create directory for doctest executables");
+
+            DirState::Perm(path)
+        } else {
+            DirState::Temp(
+                TempFileBuilder::new()
+                    .prefix("rustdoctest")
+                    .tempdir()
+                    .expect("rustdoc needs a tempdir"),
+            )
+        };
+
+        debug!("creating test {}: {}", name, test);
+        self.tests.push(testing::TestDescAndFn {
+            desc: testing::TestDesc {
+                name: testing::DynTestName(name),
+                ignore: match config.ignore {
+                    Ignore::All => true,
+                    Ignore::None => false,
+                    Ignore::Some(ref ignores) => ignores.iter().any(|s| target_str.contains(s)),
+                },
+                // compiler failures are test failures
+                should_panic: testing::ShouldPanic::No,
+                allow_fail: config.allow_fail,
+                test_type: testing::TestType::DocTest,
+            },
+            testfn: testing::DynTestFn(box move || {
+                let res = run_test(
+                    &test,
+                    &cratename,
+                    line,
+                    options,
+                    config.should_panic,
+                    config.no_run,
+                    config.test_harness,
+                    runtool,
+                    runtool_args,
+                    target,
+                    config.compile_fail,
+                    config.error_codes,
+                    &opts,
+                    edition,
+                    outdir,
+                    path,
+                );
+
+                if let Err(err) = res {
+                    match err {
+                        TestFailure::CompileError => {
+                            eprint!("Couldn't compile the test.");
+                        }
+                        TestFailure::UnexpectedCompilePass => {
+                            eprint!("Test compiled successfully, but it's marked `compile_fail`.");
+                        }
+                        TestFailure::UnexpectedRunPass => {
+                            eprint!("Test executable succeeded, but it's marked `should_panic`.");
+                        }
+                        TestFailure::MissingErrorCodes(codes) => {
+                            eprint!("Some expected error codes were not found: {:?}", codes);
+                        }
+                        TestFailure::ExecutionError(err) => {
+                            eprint!("Couldn't run the test: {}", err);
+                            if err.kind() == io::ErrorKind::PermissionDenied {
+                                eprint!(" - maybe your tempdir is mounted with noexec?");
+                            }
+                        }
+                        TestFailure::ExecutionFailure(out) => {
+                            let reason = if let Some(code) = out.status.code() {
+                                format!("exit code {}", code)
+                            } else {
+                                String::from("terminated by signal")
+                            };
+
+                            eprintln!("Test executable failed ({}).", reason);
+
+                            // FIXME(#12309): An unfortunate side-effect of capturing the test
+                            // executable's output is that the relative ordering between the test's
+                            // stdout and stderr is lost. However, this is better than the
+                            // alternative: if the test executable inherited the parent's I/O
+                            // handles the output wouldn't be captured at all, even on success.
+                            //
+                            // The ordering could be preserved if the test process' stderr was
+                            // redirected to stdout, but that functionality does not exist in the
+                            // standard library, so it may not be portable enough.
+                            let stdout = str::from_utf8(&out.stdout).unwrap_or_default();
+                            let stderr = str::from_utf8(&out.stderr).unwrap_or_default();
+
+                            if !stdout.is_empty() || !stderr.is_empty() {
+                                eprintln!();
+
+                                if !stdout.is_empty() {
+                                    eprintln!("stdout:\n{}", stdout);
+                                }
+
+                                if !stderr.is_empty() {
+                                    eprintln!("stderr:\n{}", stderr);
+                                }
+                            }
+                        }
+                    }
+
+                    panic::resume_unwind(box ());
+                }
+            }),
+        });
+    }
+
+    fn get_line(&self) -> usize {
+        if let Some(ref source_map) = self.source_map {
+            let line = self.position.lo().to_usize();
+            let line = source_map.lookup_char_pos(BytePos(line as u32)).line;
+            if line > 0 { line - 1 } else { line }
+        } else {
+            0
+        }
+    }
+
+    fn register_header(&mut self, name: &str, level: u32) {
+        if self.use_headers {
+            // We use these headings as test names, so it's good if
+            // they're valid identifiers.
+            let name = name
+                .chars()
+                .enumerate()
+                .map(|(i, c)| {
+                    if (i == 0 && rustc_lexer::is_id_start(c))
+                        || (i != 0 && rustc_lexer::is_id_continue(c))
+                    {
+                        c
+                    } else {
+                        '_'
+                    }
+                })
+                .collect::<String>();
+
+            // Here we try to efficiently assemble the header titles into the
+            // test name in the form of `h1::h2::h3::h4::h5::h6`.
+            //
+            // Suppose that originally `self.names` contains `[h1, h2, h3]`...
+            let level = level as usize;
+            if level <= self.names.len() {
+                // ... Consider `level == 2`. All headers in the lower levels
+                // are irrelevant in this new level. So we should reset
+                // `self.names` to contain headers until <h2>, and replace that
+                // slot with the new name: `[h1, name]`.
+                self.names.truncate(level);
+                self.names[level - 1] = name;
+            } else {
+                // ... On the other hand, consider `level == 5`. This means we
+                // need to extend `self.names` to contain five headers. We fill
+                // in the missing level (<h4>) with `_`. Thus `self.names` will
+                // become `[h1, h2, h3, "_", name]`.
+                if level - 1 > self.names.len() {
+                    self.names.resize(level - 1, "_".to_owned());
+                }
+                self.names.push(name);
+            }
+        }
+    }
+}
+
+struct HirCollector<'a, 'hir, 'tcx> {
+    sess: &'a Session,
+    collector: &'a mut Collector,
+    map: Map<'hir>,
+    codes: ErrorCodes,
+    tcx: TyCtxt<'tcx>,
+}
+
+impl<'a, 'hir, 'tcx> HirCollector<'a, 'hir, 'tcx> {
+    fn visit_testable<F: FnOnce(&mut Self)>(
+        &mut self,
+        name: String,
+        attrs: &[ast::Attribute],
+        hir_id: HirId,
+        sp: Span,
+        nested: F,
+    ) {
+        let mut attrs = Attributes::from_ast(self.sess.diagnostic(), attrs);
+        if let Some(ref cfg) = attrs.cfg {
+            if !cfg.matches(&self.sess.parse_sess, Some(&self.sess.features_untracked())) {
+                return;
+            }
+        }
+
+        let has_name = !name.is_empty();
+        if has_name {
+            self.collector.names.push(name);
+        }
+
+        attrs.collapse_doc_comments();
+        attrs.unindent_doc_comments();
+        // The collapse-docs pass won't combine sugared/raw doc attributes, or included files with
+        // anything else, this will combine them for us.
+        if let Some(doc) = attrs.collapsed_doc_value() {
+            // Use the outermost invocation, so that doctest names come from where the docs were written.
+            let span = attrs
+                .span
+                .map(|span| span.ctxt().outer_expn().expansion_cause().unwrap_or(span))
+                .unwrap_or(DUMMY_SP);
+            self.collector.set_position(span);
+            markdown::find_testable_code(
+                &doc,
+                self.collector,
+                self.codes,
+                self.collector.enable_per_target_ignores,
+                Some(&crate::html::markdown::ExtraInfo::new(
+                    &self.tcx,
+                    hir_id,
+                    span_of_attrs(&attrs).unwrap_or(sp),
+                )),
+            );
+        }
+
+        nested(self);
+
+        if has_name {
+            self.collector.names.pop();
+        }
+    }
+}
+
+impl<'a, 'hir, 'tcx> intravisit::Visitor<'hir> for HirCollector<'a, 'hir, 'tcx> {
+    type Map = Map<'hir>;
+
+    fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
+        intravisit::NestedVisitorMap::All(self.map)
+    }
+
+    fn visit_item(&mut self, item: &'hir hir::Item<'_>) {
+        let name = if let hir::ItemKind::Impl { ref self_ty, .. } = item.kind {
+            rustc_hir_pretty::id_to_string(&self.map, self_ty.hir_id)
+        } else {
+            item.ident.to_string()
+        };
+
+        self.visit_testable(name, &item.attrs, item.hir_id, item.span, |this| {
+            intravisit::walk_item(this, item);
+        });
+    }
+
+    fn visit_trait_item(&mut self, item: &'hir hir::TraitItem<'_>) {
+        self.visit_testable(item.ident.to_string(), &item.attrs, item.hir_id, item.span, |this| {
+            intravisit::walk_trait_item(this, item);
+        });
+    }
+
+    fn visit_impl_item(&mut self, item: &'hir hir::ImplItem<'_>) {
+        self.visit_testable(item.ident.to_string(), &item.attrs, item.hir_id, item.span, |this| {
+            intravisit::walk_impl_item(this, item);
+        });
+    }
+
+    fn visit_foreign_item(&mut self, item: &'hir hir::ForeignItem<'_>) {
+        self.visit_testable(item.ident.to_string(), &item.attrs, item.hir_id, item.span, |this| {
+            intravisit::walk_foreign_item(this, item);
+        });
+    }
+
+    fn visit_variant(
+        &mut self,
+        v: &'hir hir::Variant<'_>,
+        g: &'hir hir::Generics<'_>,
+        item_id: hir::HirId,
+    ) {
+        self.visit_testable(v.ident.to_string(), &v.attrs, v.id, v.span, |this| {
+            intravisit::walk_variant(this, v, g, item_id);
+        });
+    }
+
+    fn visit_struct_field(&mut self, f: &'hir hir::StructField<'_>) {
+        self.visit_testable(f.ident.to_string(), &f.attrs, f.hir_id, f.span, |this| {
+            intravisit::walk_struct_field(this, f);
+        });
+    }
+
+    fn visit_macro_def(&mut self, macro_def: &'hir hir::MacroDef<'_>) {
+        self.visit_testable(
+            macro_def.ident.to_string(),
+            &macro_def.attrs,
+            macro_def.hir_id,
+            macro_def.span,
+            |_| (),
+        );
+    }
+}
+
+#[cfg(test)]
+mod tests;