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
|
use std::ops::Not;
use rustc_abi::ExternAbi;
use rustc_hir as hir;
use rustc_hir::Node;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::span_bug;
use rustc_middle::ty::{self, TyCtxt, TypingMode};
use rustc_session::config::EntryFnType;
use rustc_span::def_id::{CRATE_DEF_ID, DefId, LocalDefId};
use rustc_span::{Span, sym};
use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode};
use super::check_function_signature;
use crate::errors;
pub(crate) fn check_for_entry_fn(tcx: TyCtxt<'_>) {
match tcx.entry_fn(()) {
Some((def_id, EntryFnType::Main { .. })) => check_main_fn_ty(tcx, def_id),
_ => {}
}
}
fn check_main_fn_ty(tcx: TyCtxt<'_>, main_def_id: DefId) {
let main_fnsig = tcx.fn_sig(main_def_id).instantiate_identity();
let main_span = tcx.def_span(main_def_id);
fn main_fn_diagnostics_def_id(tcx: TyCtxt<'_>, def_id: DefId, sp: Span) -> LocalDefId {
if let Some(local_def_id) = def_id.as_local() {
let hir_type = tcx.type_of(local_def_id).instantiate_identity();
if !matches!(hir_type.kind(), ty::FnDef(..)) {
span_bug!(sp, "main has a non-function type: found `{}`", hir_type);
}
local_def_id
} else {
CRATE_DEF_ID
}
}
fn main_fn_generics_params_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span> {
if !def_id.is_local() {
return None;
}
match tcx.hir_node_by_def_id(def_id.expect_local()) {
Node::Item(hir::Item { kind: hir::ItemKind::Fn { generics, .. }, .. }) => {
generics.params.is_empty().not().then_some(generics.span)
}
_ => {
span_bug!(tcx.def_span(def_id), "main has a non-function type");
}
}
}
fn main_fn_where_clauses_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span> {
if !def_id.is_local() {
return None;
}
match tcx.hir_node_by_def_id(def_id.expect_local()) {
Node::Item(hir::Item { kind: hir::ItemKind::Fn { generics, .. }, .. }) => {
Some(generics.where_clause_span)
}
_ => {
span_bug!(tcx.def_span(def_id), "main has a non-function type");
}
}
}
fn main_fn_asyncness_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span> {
if !def_id.is_local() {
return None;
}
Some(tcx.def_span(def_id))
}
fn main_fn_return_type_span(tcx: TyCtxt<'_>, def_id: DefId) -> Option<Span> {
if !def_id.is_local() {
return None;
}
match tcx.hir_node_by_def_id(def_id.expect_local()) {
Node::Item(hir::Item { kind: hir::ItemKind::Fn { sig: fn_sig, .. }, .. }) => {
Some(fn_sig.decl.output.span())
}
_ => {
span_bug!(tcx.def_span(def_id), "main has a non-function type");
}
}
}
let mut error = false;
let main_diagnostics_def_id = main_fn_diagnostics_def_id(tcx, main_def_id, main_span);
let main_asyncness = tcx.asyncness(main_def_id);
if main_asyncness.is_async() {
let asyncness_span = main_fn_asyncness_span(tcx, main_def_id);
tcx.dcx()
.emit_err(errors::MainFunctionAsync { span: main_span, asyncness: asyncness_span });
error = true;
}
for attr in tcx.get_attrs(main_def_id, sym::track_caller) {
tcx.dcx().emit_err(errors::TrackCallerOnMain { span: attr.span, annotated: main_span });
error = true;
}
if !tcx.codegen_fn_attrs(main_def_id).target_features.is_empty()
// Calling functions with `#[target_feature]` is not unsafe on WASM, see #84988
&& !tcx.sess.target.is_like_wasm
&& !tcx.sess.opts.actually_rustdoc
{
tcx.dcx().emit_err(errors::TargetFeatureOnMain { main: main_span });
error = true;
}
if error {
return;
}
// Main should have no WC, so empty param env is OK here.
let param_env = ty::ParamEnv::empty();
let expected_return_type;
if let Some(term_did) = tcx.lang_items().termination() {
let return_ty = main_fnsig.output();
let return_ty_span = main_fn_return_type_span(tcx, main_def_id).unwrap_or(main_span);
let Some(return_ty) = return_ty.no_bound_vars() else {
tcx.dcx().emit_err(errors::MainFunctionReturnTypeGeneric { span: return_ty_span });
return;
};
let infcx = tcx.infer_ctxt().build(TypingMode::non_body_analysis());
let cause = traits::ObligationCause::new(
return_ty_span,
main_diagnostics_def_id,
ObligationCauseCode::MainFunctionType,
);
let ocx = traits::ObligationCtxt::new_with_diagnostics(&infcx);
let norm_return_ty = ocx.normalize(&cause, param_env, return_ty);
ocx.register_bound(cause, param_env, norm_return_ty, term_did);
let errors = ocx.select_all_or_error();
if !errors.is_empty() {
infcx.err_ctxt().report_fulfillment_errors(errors);
error = true;
}
// now we can take the return type of the given main function
expected_return_type = norm_return_ty;
} else {
// standard () main return type
expected_return_type = tcx.types.unit;
}
if error {
return;
}
let expected_sig = ty::Binder::dummy(tcx.mk_fn_sig(
[],
expected_return_type,
false,
hir::Safety::Safe,
ExternAbi::Rust,
));
if check_function_signature(
tcx,
ObligationCause::new(
main_span,
main_diagnostics_def_id,
ObligationCauseCode::MainFunctionType,
),
main_def_id,
expected_sig,
)
.is_err()
{
return;
}
let main_fn_generics = tcx.generics_of(main_def_id);
let main_fn_predicates = tcx.predicates_of(main_def_id);
if main_fn_generics.count() != 0 || !main_fnsig.bound_vars().is_empty() {
let generics_param_span = main_fn_generics_params_span(tcx, main_def_id);
tcx.dcx().emit_err(errors::MainFunctionGenericParameters {
span: generics_param_span.unwrap_or(main_span),
label_span: generics_param_span,
});
} else if !main_fn_predicates.predicates.is_empty() {
// generics may bring in implicit predicates, so we skip this check if generics is present.
let generics_where_clauses_span = main_fn_where_clauses_span(tcx, main_def_id);
tcx.dcx().emit_err(errors::WhereClauseOnMain {
span: generics_where_clauses_span.unwrap_or(main_span),
generics_span: generics_where_clauses_span,
});
}
}
|
