rustc_hir_analysis/check/
entry.rsuse std::ops::Not;
use rustc_hir as hir;
use rustc_hir::Node;
use rustc_infer::infer::TyCtxtInferExt;
use rustc_middle::span_bug;
use rustc_middle::ty::{self, Ty, TyCtxt};
use rustc_session::config::EntryFnType;
use rustc_span::Span;
use rustc_span::def_id::{CRATE_DEF_ID, DefId, LocalDefId};
use rustc_span::symbol::sym;
use rustc_target::spec::abi::Abi;
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),
Some((def_id, EntryFnType::Start)) => check_start_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(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()
&& !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;
}
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();
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;
}
expected_return_type = norm_return_ty;
} else {
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,
Abi::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() {
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,
});
}
}
fn check_start_fn_ty(tcx: TyCtxt<'_>, start_def_id: DefId) {
let start_def_id = start_def_id.expect_local();
let start_id = tcx.local_def_id_to_hir_id(start_def_id);
let start_span = tcx.def_span(start_def_id);
let start_t = tcx.type_of(start_def_id).instantiate_identity();
match start_t.kind() {
ty::FnDef(..) => {
if let Node::Item(it) = tcx.hir_node(start_id) {
if let hir::ItemKind::Fn(sig, generics, _) = &it.kind {
let mut error = false;
if !generics.params.is_empty() {
tcx.dcx().emit_err(errors::StartFunctionParameters { span: generics.span });
error = true;
}
if generics.has_where_clause_predicates {
tcx.dcx().emit_err(errors::StartFunctionWhere {
span: generics.where_clause_span,
});
error = true;
}
if sig.header.asyncness.is_async() {
let span = tcx.def_span(it.owner_id);
tcx.dcx().emit_err(errors::StartAsync { span });
error = true;
}
let attrs = tcx.hir().attrs(start_id);
for attr in attrs {
if attr.has_name(sym::track_caller) {
tcx.dcx().emit_err(errors::StartTrackCaller {
span: attr.span,
start: start_span,
});
error = true;
}
if attr.has_name(sym::target_feature)
&& !tcx.sess.target.is_like_wasm
&& !tcx.sess.opts.actually_rustdoc
{
tcx.dcx().emit_err(errors::StartTargetFeature {
span: attr.span,
start: start_span,
});
error = true;
}
}
if error {
return;
}
}
}
let expected_sig = ty::Binder::dummy(tcx.mk_fn_sig(
[tcx.types.isize, Ty::new_imm_ptr(tcx, Ty::new_imm_ptr(tcx, tcx.types.u8))],
tcx.types.isize,
false,
hir::Safety::Safe,
Abi::Rust,
));
let _ = check_function_signature(
tcx,
ObligationCause::new(
start_span,
start_def_id,
ObligationCauseCode::StartFunctionType,
),
start_def_id.into(),
expected_sig,
);
}
_ => {
span_bug!(start_span, "start has a non-function type: found `{}`", start_t);
}
}
}