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use dep_graph::DepNode;
use hir::map as hir_map;
use hir::def_id::{CRATE_DEF_INDEX};
use session::{config, Session};
use syntax::ast::NodeId;
use syntax::attr;
use syntax::entry::EntryPointType;
use syntax_pos::Span;
use hir::{Item, ItemFn, ImplItem, TraitItem};
use hir::itemlikevisit::ItemLikeVisitor;
struct EntryContext<'a, 'tcx: 'a> {
session: &'a Session,
map: &'a hir_map::Map<'tcx>,
main_fn: Option<(NodeId, Span)>,
attr_main_fn: Option<(NodeId, Span)>,
start_fn: Option<(NodeId, Span)>,
non_main_fns: Vec<(NodeId, Span)> ,
}
impl<'a, 'tcx> ItemLikeVisitor<'tcx> for EntryContext<'a, 'tcx> {
fn visit_item(&mut self, item: &'tcx Item) {
let def_id = self.map.local_def_id(item.id);
let def_key = self.map.def_key(def_id);
let at_root = def_key.parent == Some(CRATE_DEF_INDEX);
find_item(item, self, at_root);
}
fn visit_trait_item(&mut self, _trait_item: &'tcx TraitItem) {
}
fn visit_impl_item(&mut self, _impl_item: &'tcx ImplItem) {
}
}
pub fn find_entry_point(session: &Session, hir_map: &hir_map::Map) {
let _task = hir_map.dep_graph.in_task(DepNode::EntryPoint);
let any_exe = session.crate_types.borrow().iter().any(|ty| {
*ty == config::CrateTypeExecutable
});
if !any_exe {
return
}
if attr::contains_name(&hir_map.krate().attrs, "no_main") {
session.entry_type.set(Some(config::EntryNone));
return
}
let mut ctxt = EntryContext {
session: session,
map: hir_map,
main_fn: None,
attr_main_fn: None,
start_fn: None,
non_main_fns: Vec::new(),
};
hir_map.krate().visit_all_item_likes(&mut ctxt);
configure_main(&mut ctxt);
}
fn entry_point_type(item: &Item, at_root: bool) -> EntryPointType {
match item.node {
ItemFn(..) => {
if attr::contains_name(&item.attrs, "start") {
EntryPointType::Start
} else if attr::contains_name(&item.attrs, "main") {
EntryPointType::MainAttr
} else if item.name == "main" {
if at_root {
EntryPointType::MainNamed
} else {
EntryPointType::OtherMain
}
} else {
EntryPointType::None
}
}
_ => EntryPointType::None,
}
}
fn find_item(item: &Item, ctxt: &mut EntryContext, at_root: bool) {
match entry_point_type(item, at_root) {
EntryPointType::MainNamed => {
if ctxt.main_fn.is_none() {
ctxt.main_fn = Some((item.id, item.span));
} else {
span_err!(ctxt.session, item.span, E0136,
"multiple 'main' functions");
}
},
EntryPointType::OtherMain => {
ctxt.non_main_fns.push((item.id, item.span));
},
EntryPointType::MainAttr => {
if ctxt.attr_main_fn.is_none() {
ctxt.attr_main_fn = Some((item.id, item.span));
} else {
struct_span_err!(ctxt.session, item.span, E0137,
"multiple functions with a #[main] attribute")
.span_label(item.span, &format!("additional #[main] function"))
.span_label(ctxt.attr_main_fn.unwrap().1, &format!("first #[main] function"))
.emit();
}
},
EntryPointType::Start => {
if ctxt.start_fn.is_none() {
ctxt.start_fn = Some((item.id, item.span));
} else {
struct_span_err!(
ctxt.session, item.span, E0138,
"multiple 'start' functions")
.span_label(ctxt.start_fn.unwrap().1,
&format!("previous `start` function here"))
.span_label(item.span, &format!("multiple `start` functions"))
.emit();
}
},
EntryPointType::None => ()
}
}
fn configure_main(this: &mut EntryContext) {
if this.start_fn.is_some() {
*this.session.entry_fn.borrow_mut() = this.start_fn;
this.session.entry_type.set(Some(config::EntryStart));
} else if this.attr_main_fn.is_some() {
*this.session.entry_fn.borrow_mut() = this.attr_main_fn;
this.session.entry_type.set(Some(config::EntryMain));
} else if this.main_fn.is_some() {
*this.session.entry_fn.borrow_mut() = this.main_fn;
this.session.entry_type.set(Some(config::EntryMain));
} else {
let mut err = this.session.struct_err("main function not found");
if !this.non_main_fns.is_empty() {
err.note("the main function must be defined at the crate level \
but you have one or more functions named 'main' that are not \
defined at the crate level. Either move the definition or \
attach the `#[main]` attribute to override this behavior.");
for &(_, span) in &this.non_main_fns {
err.span_note(span, "here is a function named 'main'");
}
err.emit();
this.session.abort_if_errors();
} else {
err.emit();
}
}
}