1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
|
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().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 };
}
|
