| use rustc_ast::entry::EntryPointType; |
| use rustc_errors::error_code; |
| use rustc_hir::def::DefKind; |
| use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE}; |
| use rustc_hir::{ItemId, Node, CRATE_HIR_ID}; |
| use rustc_middle::ty::query::Providers; |
| use rustc_middle::ty::{DefIdTree, TyCtxt}; |
| use rustc_session::config::{sigpipe, CrateType, EntryFnType}; |
| use rustc_session::parse::feature_err; |
| use rustc_span::symbol::sym; |
| use rustc_span::{Span, Symbol}; |
| |
| use crate::errors::{ |
| AttrOnlyInFunctions, AttrOnlyOnMain, AttrOnlyOnRootMain, ExternMain, MultipleRustcMain, |
| MultipleStartFunctions, NoMainErr, UnixSigpipeValues, |
| }; |
| |
| struct EntryContext<'tcx> { |
| tcx: TyCtxt<'tcx>, |
| |
| /// The function that has attribute named `main`. |
| attr_main_fn: Option<(LocalDefId, Span)>, |
| |
| /// The function that has the attribute 'start' on it. |
| start_fn: Option<(LocalDefId, Span)>, |
| |
| /// The functions that one might think are `main` but aren't, e.g. |
| /// main functions not defined at the top level. For diagnostics. |
| non_main_fns: Vec<Span>, |
| } |
| |
| fn entry_fn(tcx: TyCtxt<'_>, (): ()) -> Option<(DefId, EntryFnType)> { |
| let any_exe = tcx.sess.crate_types().iter().any(|ty| *ty == CrateType::Executable); |
| if !any_exe { |
| // No need to find a main function. |
| return None; |
| } |
| |
| // If the user wants no main function at all, then stop here. |
| if tcx.sess.contains_name(&tcx.hir().attrs(CRATE_HIR_ID), sym::no_main) { |
| return None; |
| } |
| |
| let mut ctxt = |
| EntryContext { tcx, attr_main_fn: None, start_fn: None, non_main_fns: Vec::new() }; |
| |
| for id in tcx.hir().items() { |
| find_item(id, &mut ctxt); |
| } |
| |
| configure_main(tcx, &ctxt) |
| } |
| |
| // Beware, this is duplicated in `librustc_builtin_macros/test_harness.rs` |
| // (with `ast::Item`), so make sure to keep them in sync. |
| // A small optimization was added so that hir::Item is fetched only when needed. |
| // An equivalent optimization was not applied to the duplicated code in test_harness.rs. |
| fn entry_point_type(ctxt: &EntryContext<'_>, id: ItemId, at_root: bool) -> EntryPointType { |
| let attrs = ctxt.tcx.hir().attrs(id.hir_id()); |
| if ctxt.tcx.sess.contains_name(attrs, sym::start) { |
| EntryPointType::Start |
| } else if ctxt.tcx.sess.contains_name(attrs, sym::rustc_main) { |
| EntryPointType::RustcMainAttr |
| } else { |
| if let Some(name) = ctxt.tcx.opt_item_name(id.owner_id.to_def_id()) |
| && name == sym::main { |
| if at_root { |
| // This is a top-level function so can be `main`. |
| EntryPointType::MainNamed |
| } else { |
| EntryPointType::OtherMain |
| } |
| } else { |
| EntryPointType::None |
| } |
| } |
| } |
| |
| fn attr_span_by_symbol(ctxt: &EntryContext<'_>, id: ItemId, sym: Symbol) -> Option<Span> { |
| let attrs = ctxt.tcx.hir().attrs(id.hir_id()); |
| ctxt.tcx.sess.find_by_name(attrs, sym).map(|attr| attr.span) |
| } |
| |
| fn find_item(id: ItemId, ctxt: &mut EntryContext<'_>) { |
| let at_root = ctxt.tcx.opt_local_parent(id.owner_id.def_id) == Some(CRATE_DEF_ID); |
| |
| match entry_point_type(ctxt, id, at_root) { |
| EntryPointType::None => { |
| if let Some(span) = attr_span_by_symbol(ctxt, id, sym::unix_sigpipe) { |
| ctxt.tcx.sess.emit_err(AttrOnlyOnMain { span, attr: sym::unix_sigpipe }); |
| } |
| } |
| _ if !matches!(ctxt.tcx.def_kind(id.owner_id), DefKind::Fn) => { |
| for attr in [sym::start, sym::rustc_main] { |
| if let Some(span) = attr_span_by_symbol(ctxt, id, attr) { |
| ctxt.tcx.sess.emit_err(AttrOnlyInFunctions { span, attr }); |
| } |
| } |
| } |
| EntryPointType::MainNamed => (), |
| EntryPointType::OtherMain => { |
| if let Some(span) = attr_span_by_symbol(ctxt, id, sym::unix_sigpipe) { |
| ctxt.tcx.sess.emit_err(AttrOnlyOnRootMain { span, attr: sym::unix_sigpipe }); |
| } |
| ctxt.non_main_fns.push(ctxt.tcx.def_span(id.owner_id)); |
| } |
| EntryPointType::RustcMainAttr => { |
| if ctxt.attr_main_fn.is_none() { |
| ctxt.attr_main_fn = Some((id.owner_id.def_id, ctxt.tcx.def_span(id.owner_id))); |
| } else { |
| ctxt.tcx.sess.emit_err(MultipleRustcMain { |
| span: ctxt.tcx.def_span(id.owner_id.to_def_id()), |
| first: ctxt.attr_main_fn.unwrap().1, |
| additional: ctxt.tcx.def_span(id.owner_id.to_def_id()), |
| }); |
| } |
| } |
| EntryPointType::Start => { |
| if let Some(span) = attr_span_by_symbol(ctxt, id, sym::unix_sigpipe) { |
| ctxt.tcx.sess.emit_err(AttrOnlyOnMain { span, attr: sym::unix_sigpipe }); |
| } |
| if ctxt.start_fn.is_none() { |
| ctxt.start_fn = Some((id.owner_id.def_id, ctxt.tcx.def_span(id.owner_id))); |
| } else { |
| ctxt.tcx.sess.emit_err(MultipleStartFunctions { |
| span: ctxt.tcx.def_span(id.owner_id), |
| labeled: ctxt.tcx.def_span(id.owner_id.to_def_id()), |
| previous: ctxt.start_fn.unwrap().1, |
| }); |
| } |
| } |
| } |
| } |
| |
| fn configure_main(tcx: TyCtxt<'_>, visitor: &EntryContext<'_>) -> Option<(DefId, EntryFnType)> { |
| if let Some((def_id, _)) = visitor.start_fn { |
| Some((def_id.to_def_id(), EntryFnType::Start)) |
| } else if let Some((local_def_id, _)) = visitor.attr_main_fn { |
| let def_id = local_def_id.to_def_id(); |
| Some((def_id, EntryFnType::Main { sigpipe: sigpipe(tcx, def_id) })) |
| } else { |
| if let Some(main_def) = tcx.resolutions(()).main_def && let Some(def_id) = main_def.opt_fn_def_id() { |
| // non-local main imports are handled below |
| if let Some(def_id) = def_id.as_local() && matches!(tcx.hir().find_by_def_id(def_id), Some(Node::ForeignItem(_))) { |
| tcx.sess.emit_err(ExternMain { span: tcx.def_span(def_id) }); |
| return None; |
| } |
| |
| if main_def.is_import && !tcx.features().imported_main { |
| let span = main_def.span; |
| feature_err( |
| &tcx.sess.parse_sess, |
| sym::imported_main, |
| span, |
| "using an imported function as entry point `main` is experimental", |
| ) |
| .emit(); |
| } |
| return Some((def_id, EntryFnType::Main { sigpipe: sigpipe(tcx, def_id) })); |
| } |
| no_main_err(tcx, visitor); |
| None |
| } |
| } |
| |
| fn sigpipe(tcx: TyCtxt<'_>, def_id: DefId) -> u8 { |
| if let Some(attr) = tcx.get_attr(def_id, sym::unix_sigpipe) { |
| match (attr.value_str(), attr.meta_item_list()) { |
| (Some(sym::inherit), None) => sigpipe::INHERIT, |
| (Some(sym::sig_ign), None) => sigpipe::SIG_IGN, |
| (Some(sym::sig_dfl), None) => sigpipe::SIG_DFL, |
| (_, Some(_)) => { |
| // Keep going so that `fn emit_malformed_attribute()` can print |
| // an excellent error message |
| sigpipe::DEFAULT |
| } |
| _ => { |
| tcx.sess.emit_err(UnixSigpipeValues { span: attr.span }); |
| sigpipe::DEFAULT |
| } |
| } |
| } else { |
| sigpipe::DEFAULT |
| } |
| } |
| |
| fn no_main_err(tcx: TyCtxt<'_>, visitor: &EntryContext<'_>) { |
| let sp = tcx.def_span(CRATE_DEF_ID); |
| if *tcx.sess.parse_sess.reached_eof.borrow() { |
| // There's an unclosed brace that made the parser reach `Eof`, we shouldn't complain about |
| // the missing `fn main()` then as it might have been hidden inside an unclosed block. |
| tcx.sess.delay_span_bug(sp, "`main` not found, but expected unclosed brace error"); |
| return; |
| } |
| |
| // There is no main function. |
| let mut has_filename = true; |
| let filename = tcx.sess.local_crate_source_file.clone().unwrap_or_else(|| { |
| has_filename = false; |
| Default::default() |
| }); |
| let main_def_opt = tcx.resolutions(()).main_def; |
| let diagnostic_id = error_code!(E0601); |
| let add_teach_note = tcx.sess.teach(&diagnostic_id); |
| // The file may be empty, which leads to the diagnostic machinery not emitting this |
| // note. This is a relatively simple way to detect that case and emit a span-less |
| // note instead. |
| let file_empty = !tcx.sess.source_map().lookup_line(sp.hi()).is_ok(); |
| |
| tcx.sess.emit_err(NoMainErr { |
| sp, |
| crate_name: tcx.crate_name(LOCAL_CRATE), |
| has_filename, |
| filename, |
| file_empty, |
| non_main_fns: visitor.non_main_fns.clone(), |
| main_def_opt, |
| add_teach_note, |
| }); |
| } |
| |
| pub fn provide(providers: &mut Providers) { |
| *providers = Providers { entry_fn, ..*providers }; |
| } |
