rust/compiler/rustc_interface/src/interface.rs

use crate::util;

use rustc_ast::token;
use rustc_ast::{LitKind, MetaItemKind};
use rustc_codegen_ssa::traits::CodegenBackend;
use rustc_data_structures::defer;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stable_hasher::StableHasher;
use rustc_data_structures::sync::Lrc;
use rustc_errors::registry::Registry;
use rustc_errors::{DiagCtxt, ErrorGuaranteed};
use rustc_lint::LintStore;
use rustc_middle::ty;
use rustc_middle::util::Providers;
use rustc_parse::maybe_new_parser_from_source_str;
use rustc_query_impl::QueryCtxt;
use rustc_query_system::query::print_query_stack;
use rustc_session::config::{self, Cfg, CheckCfg, ExpectedValues, Input, OutFileName};
use rustc_session::filesearch::{self, sysroot_candidates};
use rustc_session::parse::ParseSess;
use rustc_session::{lint, CompilerIO, EarlyDiagCtxt, Session};
use rustc_span::source_map::FileLoader;
use rustc_span::symbol::sym;
use rustc_span::FileName;
use std::path::PathBuf;
use std::result;
use std::sync::Arc;

pub type Result<T> = result::Result<T, ErrorGuaranteed>;

/// Represents a compiler session. Note that every `Compiler` contains a
/// `Session`, but `Compiler` also contains some things that cannot be in
/// `Session`, due to `Session` being in a crate that has many fewer
/// dependencies than this crate.
///
/// Can be used to run `rustc_interface` queries.
/// Created by passing [`Config`] to [`run_compiler`].
pub struct Compiler {
    pub sess: Session,
    pub codegen_backend: Box<dyn CodegenBackend>,
    pub(crate) override_queries: Option<fn(&Session, &mut Providers)>,
}

/// Converts strings provided as `--cfg [cfgspec]` into a `Cfg`.
pub(crate) fn parse_cfg(dcx: &DiagCtxt, cfgs: Vec<String>) -> Cfg {
    cfgs.into_iter()
        .map(|s| {
            let psess = ParseSess::with_silent_emitter(
                vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
                format!("this error occurred on the command line: `--cfg={s}`"),
                true,
            );
            let filename = FileName::cfg_spec_source_code(&s);

            macro_rules! error {
                ($reason: expr) => {
                    #[allow(rustc::untranslatable_diagnostic)]
                    #[allow(rustc::diagnostic_outside_of_impl)]
                    dcx.fatal(format!(
                        concat!("invalid `--cfg` argument: `{}` (", $reason, ")"),
                        s
                    ));
                };
            }

            match maybe_new_parser_from_source_str(&psess, filename, s.to_string()) {
                Ok(mut parser) => match parser.parse_meta_item() {
                    Ok(meta_item) if parser.token == token::Eof => {
                        if meta_item.path.segments.len() != 1 {
                            error!("argument key must be an identifier");
                        }
                        match &meta_item.kind {
                            MetaItemKind::List(..) => {}
                            MetaItemKind::NameValue(lit) if !lit.kind.is_str() => {
                                error!("argument value must be a string");
                            }
                            MetaItemKind::NameValue(..) | MetaItemKind::Word => {
                                let ident = meta_item.ident().expect("multi-segment cfg key");
                                return (ident.name, meta_item.value_str());
                            }
                        }
                    }
                    Ok(..) => {}
                    Err(err) => err.cancel(),
                },
                Err(errs) => errs.into_iter().for_each(|err| err.cancel()),
            }

            // If the user tried to use a key="value" flag, but is missing the quotes, provide
            // a hint about how to resolve this.
            if s.contains('=') && !s.contains("=\"") && !s.ends_with('"') {
                error!(concat!(
                    r#"expected `key` or `key="value"`, ensure escaping is appropriate"#,
                    r#" for your shell, try 'key="value"' or key=\"value\""#
                ));
            } else {
                error!(r#"expected `key` or `key="value"`"#);
            }
        })
        .collect::<Cfg>()
}

/// Converts strings provided as `--check-cfg [specs]` into a `CheckCfg`.
pub(crate) fn parse_check_cfg(dcx: &DiagCtxt, specs: Vec<String>) -> CheckCfg {
    // If any --check-cfg is passed then exhaustive_values and exhaustive_names
    // are enabled by default.
    let exhaustive_names = !specs.is_empty();
    let exhaustive_values = !specs.is_empty();
    let mut check_cfg = CheckCfg { exhaustive_names, exhaustive_values, ..CheckCfg::default() };

    for s in specs {
        let psess = ParseSess::with_silent_emitter(
            vec![crate::DEFAULT_LOCALE_RESOURCE, rustc_parse::DEFAULT_LOCALE_RESOURCE],
            format!("this error occurred on the command line: `--check-cfg={s}`"),
            true,
        );
        let filename = FileName::cfg_spec_source_code(&s);

        macro_rules! error {
            ($reason:expr) => {
                #[allow(rustc::untranslatable_diagnostic)]
                #[allow(rustc::diagnostic_outside_of_impl)]
                dcx.fatal(format!(
                    concat!("invalid `--check-cfg` argument: `{}` (", $reason, ")"),
                    s
                ))
            };
        }

        let expected_error = || -> ! {
            error!("expected `cfg(name, values(\"value1\", \"value2\", ... \"valueN\"))`")
        };

        let mut parser = match maybe_new_parser_from_source_str(&psess, filename, s.to_string()) {
            Ok(parser) => parser,
            Err(errs) => {
                errs.into_iter().for_each(|err| err.cancel());
                expected_error();
            }
        };

        let meta_item = match parser.parse_meta_item() {
            Ok(meta_item) if parser.token == token::Eof => meta_item,
            Ok(..) => expected_error(),
            Err(err) => {
                err.cancel();
                expected_error();
            }
        };

        let Some(args) = meta_item.meta_item_list() else {
            expected_error();
        };

        if !meta_item.has_name(sym::cfg) {
            expected_error();
        }

        let mut names = Vec::new();
        let mut values: FxHashSet<_> = Default::default();

        let mut any_specified = false;
        let mut values_specified = false;
        let mut values_any_specified = false;

        for arg in args {
            if arg.is_word()
                && let Some(ident) = arg.ident()
            {
                if values_specified {
                    error!("`cfg()` names cannot be after values");
                }
                names.push(ident);
            } else if arg.has_name(sym::any)
                && let Some(args) = arg.meta_item_list()
            {
                if any_specified {
                    error!("`any()` cannot be specified multiple times");
                }
                any_specified = true;
                if !args.is_empty() {
                    error!("`any()` must be empty");
                }
            } else if arg.has_name(sym::values)
                && let Some(args) = arg.meta_item_list()
            {
                if names.is_empty() {
                    error!("`values()` cannot be specified before the names");
                } else if values_specified {
                    error!("`values()` cannot be specified multiple times");
                }
                values_specified = true;

                for arg in args {
                    if let Some(LitKind::Str(s, _)) = arg.lit().map(|lit| &lit.kind) {
                        values.insert(Some(*s));
                    } else if arg.has_name(sym::any)
                        && let Some(args) = arg.meta_item_list()
                    {
                        if values_any_specified {
                            error!("`any()` in `values()` cannot be specified multiple times");
                        }
                        values_any_specified = true;
                        if !args.is_empty() {
                            error!("`any()` must be empty");
                        }
                    } else if arg.has_name(sym::none)
                        && let Some(args) = arg.meta_item_list()
                    {
                        values.insert(None);
                        if !args.is_empty() {
                            error!("`none()` must be empty");
                        }
                    } else {
                        error!("`values()` arguments must be string literals, `none()` or `any()`");
                    }
                }
            } else {
                error!("`cfg()` arguments must be simple identifiers, `any()` or `values(...)`");
            }
        }

        if !values_specified && !any_specified {
            // `cfg(name)` is equivalent to `cfg(name, values(none()))` so add
            // an implicit `none()`
            values.insert(None);
        } else if !values.is_empty() && values_any_specified {
            error!(
                "`values()` arguments cannot specify string literals and `any()` at the same time"
            );
        }

        if any_specified {
            if names.is_empty() && values.is_empty() && !values_specified && !values_any_specified {
                check_cfg.exhaustive_names = false;
            } else {
                error!("`cfg(any())` can only be provided in isolation");
            }
        } else {
            for name in names {
                check_cfg
                    .expecteds
                    .entry(name.name)
                    .and_modify(|v| match v {
                        ExpectedValues::Some(v) if !values_any_specified => {
                            v.extend(values.clone())
                        }
                        ExpectedValues::Some(_) => *v = ExpectedValues::Any,
                        ExpectedValues::Any => {}
                    })
                    .or_insert_with(|| {
                        if values_any_specified {
                            ExpectedValues::Any
                        } else {
                            ExpectedValues::Some(values.clone())
                        }
                    });
            }
        }
    }

    check_cfg
}

/// The compiler configuration
pub struct Config {
    /// Command line options
    pub opts: config::Options,

    /// Unparsed cfg! configuration in addition to the default ones.
    pub crate_cfg: Vec<String>,
    pub crate_check_cfg: Vec<String>,

    pub input: Input,
    pub output_dir: Option<PathBuf>,
    pub output_file: Option<OutFileName>,
    pub ice_file: Option<PathBuf>,
    pub file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
    pub locale_resources: &'static [&'static str],

    pub lint_caps: FxHashMap<lint::LintId, lint::Level>,

    /// This is a callback from the driver that is called when [`ParseSess`] is created.
    pub psess_created: Option<Box<dyn FnOnce(&mut ParseSess) + Send>>,

    /// This is a callback to hash otherwise untracked state used by the caller, if the
    /// hash changes between runs the incremental cache will be cleared.
    ///
    /// e.g. used by Clippy to hash its config file
    pub hash_untracked_state: Option<Box<dyn FnOnce(&Session, &mut StableHasher) + Send>>,

    /// This is a callback from the driver that is called when we're registering lints;
    /// it is called during lint loading when we have the LintStore in a non-shared state.
    ///
    /// Note that if you find a Some here you probably want to call that function in the new
    /// function being registered.
    pub register_lints: Option<Box<dyn Fn(&Session, &mut LintStore) + Send + Sync>>,

    /// This is a callback from the driver that is called just after we have populated
    /// the list of queries.
    pub override_queries: Option<fn(&Session, &mut Providers)>,

    /// This is a callback from the driver that is called to create a codegen backend.
    pub make_codegen_backend:
        Option<Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>>,

    /// Registry of diagnostics codes.
    pub registry: Registry,

    /// The inner atomic value is set to true when a feature marked as `internal` is
    /// enabled. Makes it so that "please report a bug" is hidden, as ICEs with
    /// internal features are wontfix, and they are usually the cause of the ICEs.
    /// None signifies that this is not tracked.
    pub using_internal_features: Arc<std::sync::atomic::AtomicBool>,

    /// All commandline args used to invoke the compiler, with @file args fully expanded.
    /// This will only be used within debug info, e.g. in the pdb file on windows
    /// This is mainly useful for other tools that reads that debuginfo to figure out
    /// how to call the compiler with the same arguments.
    pub expanded_args: Vec<String>,
}

// JUSTIFICATION: before session exists, only config
#[allow(rustc::bad_opt_access)]
#[allow(rustc::untranslatable_diagnostic)] // FIXME: make this translatable
pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Send) -> R {
    trace!("run_compiler");

    // Set parallel mode before thread pool creation, which will create `Lock`s.
    rustc_data_structures::sync::set_dyn_thread_safe_mode(config.opts.unstable_opts.threads > 1);

    // Check jobserver before run_in_thread_pool_with_globals, which call jobserver::acquire_thread
    let early_dcx = EarlyDiagCtxt::new(config.opts.error_format);
    early_dcx.initialize_checked_jobserver();

    util::run_in_thread_pool_with_globals(
        config.opts.edition,
        config.opts.unstable_opts.threads,
        || {
            crate::callbacks::setup_callbacks();

            let early_dcx = EarlyDiagCtxt::new(config.opts.error_format);

            let sysroot = filesearch::materialize_sysroot(config.opts.maybe_sysroot.clone());

            let target = config::build_target_config(&early_dcx, &config.opts, &sysroot);

            let codegen_backend = match config.make_codegen_backend {
                None => util::get_codegen_backend(
                    &early_dcx,
                    &sysroot,
                    config.opts.unstable_opts.codegen_backend.as_deref(),
                    &target,
                ),
                Some(make_codegen_backend) => {
                    // N.B. `make_codegen_backend` takes precedence over
                    // `target.default_codegen_backend`, which is ignored in this case.
                    make_codegen_backend(&config.opts)
                }
            };

            let temps_dir = config.opts.unstable_opts.temps_dir.as_deref().map(PathBuf::from);

            let bundle = match rustc_errors::fluent_bundle(
                config.opts.maybe_sysroot.clone(),
                sysroot_candidates().to_vec(),
                config.opts.unstable_opts.translate_lang.clone(),
                config.opts.unstable_opts.translate_additional_ftl.as_deref(),
                config.opts.unstable_opts.translate_directionality_markers,
            ) {
                Ok(bundle) => bundle,
                Err(e) => {
                    early_dcx.early_fatal(format!("failed to load fluent bundle: {e}"));
                }
            };

            let mut locale_resources = Vec::from(config.locale_resources);
            locale_resources.push(codegen_backend.locale_resource());

            let mut sess = rustc_session::build_session(
                early_dcx,
                config.opts,
                CompilerIO {
                    input: config.input,
                    output_dir: config.output_dir,
                    output_file: config.output_file,
                    temps_dir,
                },
                bundle,
                config.registry.clone(),
                locale_resources,
                config.lint_caps,
                config.file_loader,
                target,
                sysroot,
                util::rustc_version_str().unwrap_or("unknown"),
                config.ice_file,
                config.using_internal_features,
                config.expanded_args,
            );

            codegen_backend.init(&sess);

            let cfg = parse_cfg(&sess.dcx(), config.crate_cfg);
            let mut cfg = config::build_configuration(&sess, cfg);
            util::add_configuration(&mut cfg, &mut sess, &*codegen_backend);
            sess.psess.config = cfg;

            let mut check_cfg = parse_check_cfg(&sess.dcx(), config.crate_check_cfg);
            check_cfg.fill_well_known(&sess.target);
            sess.psess.check_config = check_cfg;

            if let Some(psess_created) = config.psess_created {
                psess_created(&mut sess.psess);
            }

            if let Some(hash_untracked_state) = config.hash_untracked_state {
                let mut hasher = StableHasher::new();
                hash_untracked_state(&sess, &mut hasher);
                sess.opts.untracked_state_hash = hasher.finish()
            }

            // Even though the session holds the lint store, we can't build the
            // lint store until after the session exists. And we wait until now
            // so that `register_lints` sees the fully initialized session.
            let mut lint_store = rustc_lint::new_lint_store(sess.enable_internal_lints());
            if let Some(register_lints) = config.register_lints.as_deref() {
                register_lints(&sess, &mut lint_store);
                sess.registered_lints = true;
            }
            sess.lint_store = Some(Lrc::new(lint_store));

            let compiler =
                Compiler { sess, codegen_backend, override_queries: config.override_queries };

            rustc_span::set_source_map(compiler.sess.psess.clone_source_map(), move || {
                // There are two paths out of `f`.
                // - Normal exit.
                // - Panic, e.g. triggered by `abort_if_errors`.
                //
                // We must run `finish_diagnostics` in both cases.
                let res = {
                    // If `f` panics, `finish_diagnostics` will run during
                    // unwinding because of the `defer`.
                    let mut guar = None;
                    let sess_abort_guard = defer(|| {
                        guar = compiler.sess.finish_diagnostics(&config.registry);
                    });

                    let res = f(&compiler);

                    // If `f` doesn't panic, `finish_diagnostics` will run
                    // normally when `sess_abort_guard` is dropped.
                    drop(sess_abort_guard);

                    // If `finish_diagnostics` emits errors (e.g. stashed
                    // errors) we can't return an error directly, because the
                    // return type of this function is `R`, not `Result<R, E>`.
                    // But we need to communicate the errors' existence to the
                    // caller, otherwise the caller might mistakenly think that
                    // no errors occurred and return a zero exit code. So we
                    // abort (panic) instead, similar to if `f` had panicked.
                    if guar.is_some() {
                        compiler.sess.dcx().abort_if_errors();
                    }

                    res
                };

                let prof = compiler.sess.prof.clone();
                prof.generic_activity("drop_compiler").run(move || drop(compiler));

                res
            })
        },
    )
}

pub fn try_print_query_stack(
    dcx: &DiagCtxt,
    num_frames: Option<usize>,
    file: Option<std::fs::File>,
) {
    eprintln!("query stack during panic:");

    // Be careful relying on global state here: this code is called from
    // a panic hook, which means that the global `DiagCtxt` may be in a weird
    // state if it was responsible for triggering the panic.
    let i = ty::tls::with_context_opt(|icx| {
        if let Some(icx) = icx {
            ty::print::with_no_queries!(print_query_stack(
                QueryCtxt::new(icx.tcx),
                icx.query,
                dcx,
                num_frames,
                file,
            ))
        } else {
            0
        }
    });

    if num_frames == None || num_frames >= Some(i) {
        eprintln!("end of query stack");
    } else {
        eprintln!("we're just showing a limited slice of the query stack");
    }
}