main.rs

#![forbid(unsafe_code)]
#![warn(rust_2018_idioms, single_use_lifetimes, unreachable_pub)]
#![warn(clippy::pedantic)]
#![allow(clippy::single_match_else, clippy::struct_excessive_bools)]

// Refs:
// - https://doc.rust-lang.org/nightly/rustc/instrument-coverage.html
// - https://llvm.org/docs/CommandGuide/llvm-profdata.html
// - https://llvm.org/docs/CommandGuide/llvm-cov.html

#[macro_use]
mod term;

#[macro_use]
mod process;

mod cargo;
mod clean;
mod cli;
mod config;
mod context;
mod demangler;
mod env;
mod fs;

use std::{
    collections::HashMap,
    ffi::{OsStr, OsString},
    fmt::Write as _,
    path::Path,
};

use anyhow::{Context as _, Result};
use camino::{Utf8Path, Utf8PathBuf};
use cargo_llvm_cov::json;
use clap::Parser;
use cli::{RunOptions, ShowEnvOptions};
use regex::Regex;
use walkdir::WalkDir;

use crate::{
    cli::{Args, Opts, Subcommand},
    config::StringOrArray,
    context::Context,
    json::LlvmCovJsonExport,
    process::ProcessBuilder,
    term::Coloring,
};

fn main() {
    if let Err(e) = try_main() {
        error!("{:#}", e);
    }
    if term::error()
        || term::warn()
            && env::var_os("CARGO_LLVM_COV_DENY_WARNINGS").filter(|v| v == "true").is_some()
    {
        std::process::exit(1)
    }
}

fn try_main() -> Result<()> {
    let Opts::LlvmCov(mut args) = Opts::parse();

    match args.subcommand.take() {
        Some(Subcommand::Demangle) => {
            demangler::run()?;
        }

        Some(Subcommand::Clean(options)) => {
            clean::run(options)?;
        }

        Some(Subcommand::Run(mut args)) => {
            let cx = &Context::new(
                args.build(),
                args.manifest(),
                args.cov(),
                &[],
                &[],
                false,
                false,
                false,
            )?;

            clean::clean_partial(cx)?;
            create_dirs(cx)?;

            run_run(cx, &args)?;

            if !cx.cov.no_report {
                generate_report(cx)?;
            }
        }

        Some(Subcommand::ShowEnv(options)) => {
            let cx = &context_from_args(&mut args, true)?;
            let writer = &mut ShowEnvWriter { target: std::io::stdout(), options };
            set_env(cx, writer);
            writer.set("CARGO_LLVM_COV_TARGET_DIR", cx.ws.metadata.target_directory.as_str());
        }

        Some(Subcommand::Nextest { passthrough_options }) => {
            let cx = &context_from_args(
                &mut Args::try_parse_from(
                    [
                        // fake argv[0] to help clap parse
                        "nextest".to_string(),
                    ]
                    .iter()
                    // real pass-through args
                    .chain(passthrough_options.iter()),
                )?,
                false,
            )?;

            clean::clean_partial(cx)?;
            create_dirs(cx)?;
            match (args.no_run, cx.cov.no_report) {
                (false, false) => {
                    run_nextest(cx, &args)?;
                    generate_report(cx)?;
                }
                (false, true) => {
                    run_nextest(cx, &args)?;
                }
                (true, false) => {
                    generate_report(cx)?;
                }
                (true, true) => unreachable!(),
            }
        }

        None => {
            let cx = &context_from_args(&mut args, false)?;
            let tmp = term::warn(); // The following warnings should not be promoted to an error.
            if args.doctests {
                warn!("--doctests option is unstable");
            }
            if args.doc {
                args.doctests = true;
                warn!("--doc option is unstable");
            }
            term::warn::set(tmp);

            clean::clean_partial(cx)?;
            create_dirs(cx)?;
            match (args.no_run, cx.cov.no_report) {
                (false, false) => {
                    run_test(cx, &args)?;
                    generate_report(cx)?;
                }
                (false, true) => {
                    run_test(cx, &args)?;
                }
                (true, false) => {
                    generate_report(cx)?;
                }
                (true, true) => unreachable!(),
            }
        }
    }
    Ok(())
}

fn context_from_args(args: &mut Args, show_env: bool) -> Result<Context> {
    Context::new(
        args.build(),
        args.manifest(),
        args.cov(),
        &args.exclude,
        &args.exclude_from_report,
        args.doctests,
        args.no_run,
        show_env,
    )
}

fn create_dirs(cx: &Context) -> Result<()> {
    fs::create_dir_all(&cx.ws.target_dir)?;

    if let Some(output_dir) = &cx.cov.output_dir {
        fs::create_dir_all(output_dir)?;
        if cx.cov.html {
            fs::create_dir_all(output_dir.join("html"))?;
        }
        if cx.cov.text {
            fs::create_dir_all(output_dir.join("text"))?;
        }
    }

    if cx.doctests {
        fs::create_dir_all(&cx.ws.doctests_dir)?;
    }
    Ok(())
}

trait EnvTarget {
    fn set(&mut self, key: &str, value: &str);
}

impl EnvTarget for ProcessBuilder {
    fn set(&mut self, key: &str, value: &str) {
        self.env(key, value);
    }
}

struct ShowEnvWriter<W: std::io::Write> {
    target: W,
    options: ShowEnvOptions,
}

impl<W: std::io::Write> EnvTarget for ShowEnvWriter<W> {
    fn set(&mut self, key: &str, value: &str) {
        writeln!(
            self.target,
            r#"{prefix}{key}="{value}""#,
            prefix = if self.options.export_prefix { "export " } else { "" },
            key = key,
            value = value,
        )
        .expect("failed to write to stdout");
    }
}

fn set_env(cx: &Context, target: &mut impl EnvTarget) {
    let llvm_profile_file = cx.ws.target_dir.join(format!("{}-%m.profraw", cx.ws.name));

    let rustflags = &mut cx.ws.config.rustflags().unwrap_or_default();
    if cx.ws.stable_coverage {
        rustflags.push_str(" -C instrument-coverage");
    } else {
        // TODO: drop support for `-Z instrument-coverage` in the future major release.
        rustflags.push_str(" -Z instrument-coverage");
        if cfg!(windows) {
            // `-C codegen-units=1` is needed to work around link error on windows
            // https://github.com/rust-lang/rust/issues/85461
            // https://github.com/microsoft/windows-rs/issues/1006#issuecomment-887789950
            // This has been fixed in https://github.com/rust-lang/rust/pull/91470,
            // but old nightly compilers still need this.
            rustflags.push_str(" -C codegen-units=1");
        }
    }
    if cx.build.remap_path_prefix {
        let _ = write!(rustflags, " --remap-path-prefix {}/=", cx.ws.metadata.workspace_root);
    }
    if !cx.cov.no_cfg_coverage {
        rustflags.push_str(" --cfg coverage");
    }
    if cx.ws.nightly && !cx.cov.no_cfg_coverage_nightly {
        rustflags.push_str(" --cfg coverage_nightly");
    }
    if cx.build.target.is_none() {
        // https://github.com/dtolnay/trybuild/pull/121
        // https://github.com/dtolnay/trybuild/issues/122
        // https://github.com/dtolnay/trybuild/pull/123
        rustflags.push_str(" --cfg trybuild_no_target");
    }

    // https://doc.rust-lang.org/nightly/rustc/instrument-coverage.html#including-doc-tests
    let rustdocflags = &mut cx.ws.config.rustdocflags();
    if cx.doctests {
        let rustdocflags = rustdocflags.get_or_insert_with(String::new);
        if cx.ws.stable_coverage {
            rustdocflags.push_str(" -C instrument-coverage");
        } else {
            // TODO: drop support for `-Z instrument-coverage` in the future major release.
            rustdocflags.push_str(" -Z instrument-coverage");
        }
        let _ =
            write!(rustdocflags, " -Z unstable-options --persist-doctests {}", cx.ws.doctests_dir);
        if cfg!(windows) {
            rustdocflags.push_str(" -C codegen-units=1");
        }
        if !cx.cov.no_cfg_coverage {
            rustdocflags.push_str(" --cfg coverage");
        }
        if cx.ws.nightly && !cx.cov.no_cfg_coverage_nightly {
            rustdocflags.push_str(" --cfg coverage_nightly");
        }
    }

    match (cx.build.coverage_target_only, &cx.build.target) {
        (true, Some(coverage_target)) => target.set(
            &format!("CARGO_TARGET_{}_RUSTFLAGS", coverage_target.to_uppercase().replace('-', "_")),
            rustflags,
        ),
        _ => target.set("RUSTFLAGS", rustflags),
    }

    if let Some(rustdocflags) = rustdocflags {
        target.set("RUSTDOCFLAGS", rustdocflags);
    }
    target.set("LLVM_PROFILE_FILE", llvm_profile_file.as_str());
    target.set("CARGO_INCREMENTAL", "0");
    // Workaround for https://github.com/rust-lang/rust/issues/91092
    target.set("RUST_TEST_THREADS", "1");
}

fn has_z_flag(args: &Args, name: &str) -> bool {
    args.unstable_flags.iter().any(|f| f == name)
}

fn run_test(cx: &Context, args: &Args) -> Result<()> {
    let mut cargo = cx.cargo();

    set_env(cx, &mut cargo);

    cargo.arg("test");
    if cx.doctests && !has_z_flag(args, "doctest-in-workspace") {
        // https://github.com/rust-lang/cargo/issues/9427
        cargo.arg("-Z");
        cargo.arg("doctest-in-workspace");
    }

    if args.ignore_run_fail {
        let mut cargo_no_run = cargo.clone();
        if !args.no_run {
            cargo_no_run.arg("--no-run");
        }
        cargo::test_args(cx, args, &mut cargo_no_run);
        if term::verbose() {
            status!("Running", "{}", cargo_no_run);
            cargo_no_run.stdout_to_stderr().run()?;
        } else {
            // Capture output to prevent duplicate warnings from appearing in two runs.
            cargo_no_run.run_with_output()?;
        }
        drop(cargo_no_run);

        cargo.arg("--no-fail-fast");
        cargo::test_args(cx, args, &mut cargo);
        if term::verbose() {
            status!("Running", "{}", cargo);
        }
        if let Err(e) = cargo.stdout_to_stderr().run() {
            warn!("{}", e);
        }
    } else {
        cargo::test_args(cx, args, &mut cargo);
        if term::verbose() {
            status!("Running", "{}", cargo);
        }
        cargo.stdout_to_stderr().run()?;
    }

    Ok(())
}

fn run_nextest(cx: &Context, args: &Args) -> Result<()> {
    let mut cargo = cx.cargo();

    set_env(cx, &mut cargo);

    cargo.arg("nextest").arg("run");

    if cx.doctests {
        return Err(anyhow::anyhow!("doctest is not supported for nextest"));
    }

    cargo::test_args(cx, args, &mut cargo);

    if term::verbose() {
        status!("Running", "{}", cargo);
    }
    cargo.stdout_to_stderr().run()?;
    Ok(())
}

fn run_run(cx: &Context, args: &RunOptions) -> Result<()> {
    let mut cargo = cx.cargo();

    set_env(cx, &mut cargo);

    cargo.arg("run");
    cargo::run_args(cx, args, &mut cargo);

    if term::verbose() {
        status!("Running", "{}", cargo);
    }
    cargo.stdout_to_stderr().run()?;
    Ok(())
}

fn generate_report(cx: &Context) -> Result<()> {
    merge_profraw(cx).context("failed to merge profile data")?;

    let object_files = object_files(cx).context("failed to collect object files")?;
    let ignore_filename_regex = ignore_filename_regex(cx);
    for format in Format::from_args(cx) {
        format
            .generate_report(cx, &object_files, ignore_filename_regex.as_ref())
            .context("failed to generate report")?;
    }

    if cx.cov.fail_under_lines.is_some()
        || cx.cov.fail_uncovered_functions.is_some()
        || cx.cov.fail_uncovered_lines.is_some()
        || cx.cov.fail_uncovered_regions.is_some()
        || cx.cov.show_missing_lines
    {
        let format = Format::Json;
        let json = format
            .get_json(cx, &object_files, ignore_filename_regex.as_ref())
            .context("failed to get json")?;

        if let Some(fail_under_lines) = cx.cov.fail_under_lines {
            // Handle --fail-under-lines.
            let lines_percent = json.get_lines_percent().context("failed to get line coverage")?;
            if lines_percent < fail_under_lines {
                term::error::set(true);
            }
        }

        if let Some(fail_uncovered_functions) = cx.cov.fail_uncovered_functions {
            // Handle --fail-uncovered-functions.
            let uncovered =
                json.count_uncovered_functions().context("failed to count uncovered functions")?;
            if uncovered > fail_uncovered_functions {
                term::error::set(true);
            }
        }
        if let Some(fail_uncovered_lines) = cx.cov.fail_uncovered_lines {
            // Handle --fail-uncovered-lines.
            let uncovered =
                json.count_uncovered_lines().context("failed to count uncovered lines")?;
            if uncovered > fail_uncovered_lines {
                term::error::set(true);
            }
        }
        if let Some(fail_uncovered_regions) = cx.cov.fail_uncovered_regions {
            // Handle --fail-uncovered-regions.
            let uncovered =
                json.count_uncovered_regions().context("failed to count uncovered regions")?;
            if uncovered > fail_uncovered_regions {
                term::error::set(true);
            }
        }

        if cx.cov.show_missing_lines {
            // Handle --show-missing-lines.
            let uncovered_files = json.get_uncovered_lines(&ignore_filename_regex);
            if !uncovered_files.is_empty() {
                println!("Uncovered Lines:");
            }
            for (file, lines) in &uncovered_files {
                let lines: Vec<_> = lines.iter().map(ToString::to_string).collect();
                println!("{}: {}", file, lines.join(", "));
            }
        }
    }

    if cx.cov.open {
        let path = &cx.cov.output_dir.as_ref().unwrap().join("html/index.html");
        status!("Opening", "{}", path);
        open_report(cx, path)?;
    }
    Ok(())
}

fn open_report(cx: &Context, path: &Utf8Path) -> Result<()> {
    let browser = cx.ws.config.doc.browser.as_ref().and_then(StringOrArray::path_and_args);

    match browser {
        Some((browser, initial_args)) => {
            cmd!(browser).args(initial_args).arg(path).run().with_context(|| {
                format!("couldn't open report with {}", browser.to_string_lossy())
            })?;
        }
        None => opener::open(path).context("couldn't open report")?,
    }
    Ok(())
}

fn merge_profraw(cx: &Context) -> Result<()> {
    // Convert raw profile data.
    let mut cmd = cx.process(&cx.llvm_profdata);
    cmd.args(["merge", "-sparse"])
        .args(
            glob::glob(cx.ws.target_dir.join(format!("{}-*.profraw", cx.ws.name)).as_str())?
                .filter_map(Result::ok),
        )
        .arg("-o")
        .arg(&cx.ws.profdata_file);
    if let Some(mode) = &cx.cov.failure_mode {
        cmd.arg(format!("-failure-mode={}", mode));
    }
    if let Some(jobs) = cx.build.jobs {
        cmd.arg(format!("-num-threads={}", jobs));
    }
    if let Some(flags) = &cx.cargo_llvm_profdata_flags {
        cmd.args(flags.split(' ').filter(|s| !s.trim().is_empty()));
    }
    if term::verbose() {
        status!("Running", "{}", cmd);
    }
    cmd.stdout_to_stderr().run()?;
    Ok(())
}

fn object_files(cx: &Context) -> Result<Vec<OsString>> {
    fn walk_target_dir<'a>(
        cx: &'a Context,
        target_dir: &Utf8Path,
    ) -> impl Iterator<Item = walkdir::DirEntry> + 'a {
        WalkDir::new(target_dir)
            .into_iter()
            .filter_entry(move |e| {
                let p = e.path();
                if p.is_dir() {
                    if p.file_name()
                        .map_or(false, |f| f == "incremental" || f == ".fingerprint" || f == "out")
                    {
                        return false;
                    }
                } else if let Some(stem) = p.file_stem() {
                    let stem = stem.to_string_lossy();
                    if stem == "build-script-build" || stem.starts_with("build_script_build-") {
                        let p = p.parent().unwrap();
                        if p.parent().unwrap().file_name().unwrap() == "build" {
                            if cx.cov.include_build_script {
                                let dir = p.file_name().unwrap().to_string_lossy();
                                if !cx.build_script_re.is_match(&dir) {
                                    return false;
                                }
                            } else {
                                return false;
                            }
                        }
                    }
                }
                true
            })
            .filter_map(Result::ok)
    }

    let mut files = vec![];
    // To support testing binary crate like tests that use the CARGO_BIN_EXE
    // environment variable, pass all compiled executables.
    // This is not the ideal way, but the way unstable book says it is cannot support them.
    // https://doc.rust-lang.org/nightly/rustc/instrument-coverage.html#tips-for-listing-the-binaries-automatically
    let mut target_dir = cx.ws.target_dir.clone();
    // https://doc.rust-lang.org/nightly/cargo/guide/build-cache.html
    if let Some(target) = &cx.build.target {
        target_dir.push(target);
    }
    // https://doc.rust-lang.org/nightly/cargo/reference/profiles.html#custom-profiles
    let profile = match cx.build.profile.as_deref() {
        None if cx.build.release => "release",
        None => "debug",
        Some(p) if matches!(p, "release" | "bench") => "release",
        Some(p) if matches!(p, "dev" | "test") => "debug",
        Some(p) => p,
    };
    target_dir.push(profile);
    for f in walk_target_dir(cx, &target_dir) {
        let f = f.path();
        if is_executable::is_executable(&f) {
            files.push(make_relative(cx, f).to_owned().into_os_string());
        }
    }
    if cx.doctests {
        for f in glob::glob(cx.ws.doctests_dir.join("*/rust_out").as_str())?.filter_map(Result::ok)
        {
            if is_executable::is_executable(&f) {
                files.push(make_relative(cx, &f).to_owned().into_os_string());
            }
        }
    }

    // trybuild
    let trybuild_dir = &cx.ws.metadata.target_directory.join("tests");
    let mut trybuild_target = trybuild_dir.join("target");
    if let Some(target) = &cx.build.target {
        trybuild_target.push(target);
    }
    // Currently, trybuild always use debug build.
    trybuild_target.push("debug");
    if trybuild_target.is_dir() {
        let mut trybuild_targets = vec![];
        for metadata in trybuild_metadata(&cx.ws.metadata.target_directory)? {
            for package in metadata.packages {
                for target in package.targets {
                    trybuild_targets.push(target.name);
                }
            }
        }
        if !trybuild_targets.is_empty() {
            let re =
                Regex::new(&format!("^({})(-[0-9a-f]+)?$", trybuild_targets.join("|"))).unwrap();
            for entry in walk_target_dir(cx, &trybuild_target) {
                let path = make_relative(cx, entry.path());
                if let Some(file_stem) = fs::file_stem_recursive(path).unwrap().to_str() {
                    if re.is_match(file_stem) {
                        continue;
                    }
                }
                if is_executable::is_executable(path) {
                    files.push(path.to_owned().into_os_string());
                }
            }
        }
    }

    // This sort is necessary to make the result of `llvm-cov show` match between macos and linux.
    files.sort_unstable();

    Ok(files)
}

/// Collects metadata for packages generated by trybuild. If the trybuild test
/// directory is not found, it returns an empty vector.
fn trybuild_metadata(target_dir: &Utf8Path) -> Result<Vec<cargo_metadata::Metadata>> {
    let trybuild_dir = &target_dir.join("tests");
    if !trybuild_dir.is_dir() {
        return Ok(vec![]);
    }
    let mut metadata = vec![];
    for entry in fs::read_dir(trybuild_dir)?.filter_map(Result::ok) {
        let manifest_path = entry.path().join("Cargo.toml");
        if !manifest_path.is_file() {
            continue;
        }
        metadata.push(
            cargo_metadata::MetadataCommand::new().manifest_path(manifest_path).no_deps().exec()?,
        );
    }
    Ok(metadata)
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum Format {
    /// `llvm-cov report`
    None,
    /// `llvm-cov export -format=text`
    Json,
    /// `llvm-cov export -format=lcov`
    LCov,
    /// `llvm-cov show -format=text`
    Text,
    /// `llvm-cov show -format=html`
    Html,
}

impl Format {
    fn from_args(cx: &Context) -> Vec<Self> {
        if cx.cov.json {
            vec![Self::Json]
        } else if cx.cov.lcov {
            vec![Self::LCov]
        } else if cx.cov.text {
            vec![Self::Text]
        } else if cx.cov.html {
            vec![Self::Html]
        } else {
            vec![Self::None]
        }
    }

    const fn llvm_cov_args(self) -> &'static [&'static str] {
        match self {
            Self::None => &["report"],
            Self::Json => &["export", "-format=text"],
            Self::LCov => &["export", "-format=lcov"],
            Self::Text => &["show", "-format=text"],
            Self::Html => &["show", "-format=html"],
        }
    }

    fn use_color(self, cx: &Context) -> Option<&'static str> {
        if matches!(self, Self::Json | Self::LCov) {
            // `llvm-cov export` doesn't have `-use-color` flag.
            // https://llvm.org/docs/CommandGuide/llvm-cov.html#llvm-cov-export
            return None;
        }
        if self == Self::Text && cx.cov.output_dir.is_some() {
            return Some("-use-color=0");
        }
        match cx.build.color {
            Some(Coloring::Auto) | None => None,
            Some(Coloring::Always) => Some("-use-color=1"),
            Some(Coloring::Never) => Some("-use-color=0"),
        }
    }

    fn generate_report(
        self,
        cx: &Context,
        object_files: &[OsString],
        ignore_filename_regex: Option<&String>,
    ) -> Result<()> {
        let mut cmd = cx.process(&cx.llvm_cov);

        cmd.args(self.llvm_cov_args());
        cmd.args(self.use_color(cx));
        cmd.arg(format!("-instr-profile={}", cx.ws.profdata_file));
        cmd.args(object_files.iter().flat_map(|f| [OsStr::new("-object"), f]));
        if let Some(jobs) = cx.build.jobs {
            cmd.arg(format!("-num-threads={}", jobs));
        }
        if let Some(ignore_filename_regex) = ignore_filename_regex {
            cmd.arg("-ignore-filename-regex");
            cmd.arg(ignore_filename_regex);
        }

        match self {
            Self::Text | Self::Html => {
                cmd.args([
                    &format!("-show-instantiations={}", !cx.cov.hide_instantiations),
                    "-show-line-counts-or-regions",
                    "-show-expansions",
                    &format!("-Xdemangler={}", cx.current_exe.display()),
                    "-Xdemangler=llvm-cov",
                    "-Xdemangler=demangle",
                ]);
                if let Some(output_dir) = &cx.cov.output_dir {
                    if self == Self::Html {
                        cmd.arg(&format!("-output-dir={}", output_dir.join("html")));
                    } else {
                        cmd.arg(&format!("-output-dir={}", output_dir.join("text")));
                    }
                }
            }
            Self::Json | Self::LCov => {
                if cx.cov.summary_only {
                    cmd.arg("-summary-only");
                }
            }
            Self::None => {}
        }

        if let Some(flags) = &cx.cargo_llvm_cov_flags {
            cmd.args(flags.split(' ').filter(|s| !s.trim().is_empty()));
        }

        if let Some(output_path) = &cx.cov.output_path {
            if term::verbose() {
                status!("Running", "{}", cmd);
            }
            let out = cmd.read()?;
            fs::write(output_path, out)?;
            eprintln!();
            status!("Finished", "report saved to {}", output_path);
            return Ok(());
        }

        if term::verbose() {
            status!("Running", "{}", cmd);
        }
        cmd.run()?;
        if matches!(self, Self::Html | Self::Text) {
            if let Some(output_dir) = &cx.cov.output_dir {
                eprintln!();
                if self == Self::Html {
                    status!("Finished", "report saved to {}", output_dir.join("html"));
                } else {
                    status!("Finished", "report saved to {}", output_dir.join("text"));
                }
            }
        }
        Ok(())
    }

    /// Generates JSON to perform further analysis on it.
    fn get_json(
        self,
        cx: &Context,
        object_files: &[OsString],
        ignore_filename_regex: Option<&String>,
    ) -> Result<LlvmCovJsonExport> {
        if let Self::Json = self {
        } else {
            return Err(anyhow::anyhow!("requested JSON for non-JSON type"));
        }

        let mut cmd = cx.process(&cx.llvm_cov);
        cmd.args(self.llvm_cov_args());
        cmd.arg(format!("-instr-profile={}", cx.ws.profdata_file));
        cmd.args(object_files.iter().flat_map(|f| [OsStr::new("-object"), f]));
        if let Some(jobs) = cx.build.jobs {
            cmd.arg(format!("-num-threads={}", jobs));
        }
        if let Some(ignore_filename_regex) = ignore_filename_regex {
            cmd.arg("-ignore-filename-regex");
            cmd.arg(ignore_filename_regex);
        }
        if term::verbose() {
            status!("Running", "{}", cmd);
        }
        let cmd_out = cmd.read()?;
        let json = serde_json::from_str::<LlvmCovJsonExport>(&cmd_out)
            .context("failed to parse json from llvm-cov")?;
        Ok(json)
    }
}

fn ignore_filename_regex(cx: &Context) -> Option<String> {
    #[cfg(not(windows))]
    const SEPARATOR: &str = "/";
    #[cfg(windows)]
    const SEPARATOR: &str = "\\\\"; // On windows, we should escape the separator.

    fn default_ignore_filename_regex() -> String {
        // TODO: Should we use the actual target path instead of using `tests|examples|benches`?
        //       We may have a directory like tests/support, so maybe we need both?
        format!(r"(^|{0})(rustc{0}[0-9a-f]+|tests|examples|benches){0}", SEPARATOR)
    }

    #[derive(Default)]
    struct Out(String);

    impl Out {
        fn push(&mut self, s: impl AsRef<str>) {
            if !self.0.is_empty() {
                self.0.push('|');
            }
            self.0.push_str(s.as_ref());
        }

        fn push_abs_path(&mut self, path: impl AsRef<Path>) {
            #[cfg(not(windows))]
            let mut path = format!("^{}", path.as_ref().display());
            #[cfg(windows)]
            let mut path = format!(
                "^{}",
                path.as_ref().to_string_lossy().replace(std::path::MAIN_SEPARATOR, SEPARATOR),
            );
            let _ = write!(path, "($|{})", SEPARATOR);
            self.push(path);
        }
    }

    let mut out = Out::default();

    if let Some(ignore_filename) = &cx.cov.ignore_filename_regex {
        out.push(ignore_filename);
    }
    if !cx.cov.disable_default_ignore_filename_regex {
        out.push(default_ignore_filename_regex());
        out.push_abs_path(&cx.ws.target_dir);
        if cx.build.remap_path_prefix {
            for path in [home::home_dir(), home::cargo_home().ok(), home::rustup_home().ok()]
                .iter()
                .flatten()
            {
                out.push_abs_path(path);
            }
        } else {
            for path in [home::cargo_home().ok(), home::rustup_home().ok()].iter().flatten() {
                out.push_abs_path(path);
            }
        }
        for path in resolve_excluded_paths(cx) {
            out.push_abs_path(path);
        }
    }

    if out.0.is_empty() {
        None
    } else {
        Some(out.0)
    }
}

fn resolve_excluded_paths(cx: &Context) -> Vec<Utf8PathBuf> {
    let excluded: Vec<_> = cx
        .workspace_members
        .excluded
        .iter()
        .map(|id| cx.ws.metadata[id].manifest_path.parent().unwrap())
        .collect();
    let included = cx
        .workspace_members
        .included
        .iter()
        .map(|id| cx.ws.metadata[id].manifest_path.parent().unwrap());
    let mut excluded_path = vec![];
    let mut contains: HashMap<&Utf8Path, Vec<_>> = HashMap::new();
    for included in included {
        for &excluded in excluded.iter().filter(|e| included.starts_with(e)) {
            if let Some(v) = contains.get_mut(&excluded) {
                v.push(included);
            } else {
                contains.insert(excluded, vec![included]);
            }
        }
    }
    if contains.is_empty() {
        for &manifest_dir in &excluded {
            let package_path =
                manifest_dir.strip_prefix(&cx.ws.metadata.workspace_root).unwrap_or(manifest_dir);
            excluded_path.push(package_path.to_owned());
        }
        return excluded_path;
    }

    for &excluded in &excluded {
        let included = match contains.get(&excluded) {
            Some(included) => included,
            None => {
                let package_path =
                    excluded.strip_prefix(&cx.ws.metadata.workspace_root).unwrap_or(excluded);
                excluded_path.push(package_path.to_owned());
                continue;
            }
        };

        for _ in WalkDir::new(excluded).into_iter().filter_entry(|e| {
            let p = e.path();
            if !p.is_dir() {
                if p.extension().map_or(false, |e| e == "rs") {
                    let p = p.strip_prefix(&cx.ws.metadata.workspace_root).unwrap_or(p);
                    excluded_path.push(p.to_owned().try_into().unwrap());
                }
                return false;
            }

            let mut contains = false;
            for included in included {
                if included.starts_with(p) {
                    if p.starts_with(included) {
                        return false;
                    }
                    contains = true;
                }
            }
            if contains {
                // continue to walk
                return true;
            }
            let p = p.strip_prefix(&cx.ws.metadata.workspace_root).unwrap_or(p);
            excluded_path.push(p.to_owned().try_into().unwrap());
            false
        }) {}
    }
    excluded_path
}

/// Make the path relative if it's a descendent of the current working dir, otherwise just return
/// the original path
fn make_relative<'a>(cx: &Context, p: &'a Path) -> &'a Path {
    p.strip_prefix(&cx.current_dir).unwrap_or(p)
}