1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
12 use front::map as ast_map;
13 use middle::def_id::{CRATE_DEF_INDEX};
14 use session::{config, Session};
15 use syntax::ast::NodeId;
17 use syntax::codemap::Span;
18 use syntax::entry::EntryPointType;
19 use rustc_front::hir::{Item, ItemFn};
20 use rustc_front::intravisit::Visitor;
22 struct EntryContext<'a, 'tcx: 'a> {
25 map: &'a ast_map::Map<'tcx>,
27 // The top-level function called 'main'
28 main_fn: Option<(NodeId, Span)>,
30 // The function that has attribute named 'main'
31 attr_main_fn: Option<(NodeId, Span)>,
33 // The function that has the attribute 'start' on it
34 start_fn: Option<(NodeId, Span)>,
36 // The functions that one might think are 'main' but aren't, e.g.
37 // main functions not defined at the top level. For diagnostics.
38 non_main_fns: Vec<(NodeId, Span)> ,
41 impl<'a, 'tcx> Visitor<'tcx> for EntryContext<'a, 'tcx> {
42 fn visit_item(&mut self, item: &'tcx Item) {
43 let def_id = self.map.local_def_id(item.id);
44 let def_key = self.map.def_key(def_id);
45 let at_root = def_key.parent == Some(CRATE_DEF_INDEX);
46 find_item(item, self, at_root);
50 pub fn find_entry_point(session: &Session, ast_map: &ast_map::Map) {
51 let any_exe = session.crate_types.borrow().iter().any(|ty| {
52 *ty == config::CrateTypeExecutable
55 // No need to find a main function
59 // If the user wants no main function at all, then stop here.
60 if attr::contains_name(&ast_map.krate().attrs, "no_main") {
61 session.entry_type.set(Some(config::EntryNone));
65 let mut ctxt = EntryContext {
71 non_main_fns: Vec::new(),
74 ast_map.krate().visit_all_items(&mut ctxt);
76 configure_main(&mut ctxt);
79 // Beware, this is duplicated in libsyntax/entry.rs, make sure to keep
81 fn entry_point_type(item: &Item, at_root: bool) -> EntryPointType {
84 if attr::contains_name(&item.attrs, "start") {
86 } else if attr::contains_name(&item.attrs, "main") {
87 EntryPointType::MainAttr
88 } else if item.name.as_str() == "main" {
90 // This is a top-level function so can be 'main'
91 EntryPointType::MainNamed
93 EntryPointType::OtherMain
99 _ => EntryPointType::None,
104 fn find_item(item: &Item, ctxt: &mut EntryContext, at_root: bool) {
105 match entry_point_type(item, at_root) {
106 EntryPointType::MainNamed => {
107 if ctxt.main_fn.is_none() {
108 ctxt.main_fn = Some((item.id, item.span));
110 span_err!(ctxt.session, item.span, E0136,
111 "multiple 'main' functions");
114 EntryPointType::OtherMain => {
115 ctxt.non_main_fns.push((item.id, item.span));
117 EntryPointType::MainAttr => {
118 if ctxt.attr_main_fn.is_none() {
119 ctxt.attr_main_fn = Some((item.id, item.span));
121 span_err!(ctxt.session, item.span, E0137,
122 "multiple functions with a #[main] attribute");
125 EntryPointType::Start => {
126 if ctxt.start_fn.is_none() {
127 ctxt.start_fn = Some((item.id, item.span));
129 span_err!(ctxt.session, item.span, E0138,
130 "multiple 'start' functions");
133 EntryPointType::None => ()
137 fn configure_main(this: &mut EntryContext) {
138 if this.start_fn.is_some() {
139 *this.session.entry_fn.borrow_mut() = this.start_fn;
140 this.session.entry_type.set(Some(config::EntryStart));
141 } else if this.attr_main_fn.is_some() {
142 *this.session.entry_fn.borrow_mut() = this.attr_main_fn;
143 this.session.entry_type.set(Some(config::EntryMain));
144 } else if this.main_fn.is_some() {
145 *this.session.entry_fn.borrow_mut() = this.main_fn;
146 this.session.entry_type.set(Some(config::EntryMain));
149 let mut err = this.session.struct_err("main function not found");
150 if !this.non_main_fns.is_empty() {
151 // There were some functions named 'main' though. Try to give the user a hint.
152 err.note("the main function must be defined at the crate level \
153 but you have one or more functions named 'main' that are not \
154 defined at the crate level. Either move the definition or \
155 attach the `#[main]` attribute to override this behavior.");
156 for &(_, span) in &this.non_main_fns {
157 err.span_note(span, "here is a function named 'main'");
160 this.session.abort_if_errors();