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|
use rustc_hir::def_id::DefId;
use rustc_middle::mir::visit::Visitor;
use rustc_middle::mir::*;
use rustc_middle::ty::{self, subst::GenericArgKind, PredicateAtom, Ty, TyCtxt, TyS};
use rustc_session::lint::builtin::FUNCTION_ITEM_REFERENCES;
use rustc_span::{symbol::sym, Span};
use rustc_target::spec::abi::Abi;
use crate::transform::MirPass;
pub struct FunctionItemReferences;
impl<'tcx> MirPass<'tcx> for FunctionItemReferences {
fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
let mut checker = FunctionItemRefChecker { tcx, body };
checker.visit_body(&body);
}
}
struct FunctionItemRefChecker<'a, 'tcx> {
tcx: TyCtxt<'tcx>,
body: &'a Body<'tcx>,
}
impl<'a, 'tcx> Visitor<'tcx> for FunctionItemRefChecker<'a, 'tcx> {
fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
if let TerminatorKind::Call {
func,
args,
destination: _,
cleanup: _,
from_hir_call: _,
fn_span: _,
} = &terminator.kind
{
let func_ty = func.ty(self.body, self.tcx);
if let ty::FnDef(def_id, substs_ref) = *func_ty.kind() {
//check arguments for `std::mem::transmute`
if self.tcx.is_diagnostic_item(sym::transmute, def_id) {
let arg_ty = args[0].ty(self.body, self.tcx);
for generic_inner_ty in arg_ty.walk() {
if let GenericArgKind::Type(inner_ty) = generic_inner_ty.unpack() {
if let Some(fn_id) = FunctionItemRefChecker::is_fn_ref(inner_ty) {
let ident = self.tcx.item_name(fn_id).to_ident_string();
let source_info = *self.body.source_info(location);
let span = self.nth_arg_span(&args, 0);
self.emit_lint(ident, fn_id, source_info, span);
}
}
}
} else {
//check arguments for any function with `std::fmt::Pointer` as a bound trait
let param_env = self.tcx.param_env(def_id);
let bounds = param_env.caller_bounds();
for bound in bounds {
if let Some(bound_ty) = self.is_pointer_trait(&bound.skip_binders()) {
let arg_defs = self.tcx.fn_sig(def_id).skip_binder().inputs();
for (arg_num, arg_def) in arg_defs.iter().enumerate() {
for generic_inner_ty in arg_def.walk() {
if let GenericArgKind::Type(inner_ty) =
generic_inner_ty.unpack()
{
//if any type reachable from the argument types in the fn sig matches the type bound by `Pointer`
if TyS::same_type(inner_ty, bound_ty) {
//check if this type is a function reference in the function call
let norm_ty =
self.tcx.subst_and_normalize_erasing_regions(
substs_ref, param_env, &inner_ty,
);
if let Some(fn_id) =
FunctionItemRefChecker::is_fn_ref(norm_ty)
{
let ident =
self.tcx.item_name(fn_id).to_ident_string();
let source_info = *self.body.source_info(location);
let span = self.nth_arg_span(&args, arg_num);
self.emit_lint(ident, fn_id, source_info, span);
}
}
}
}
}
}
}
}
}
}
self.super_terminator(terminator, location);
}
//check for `std::fmt::Pointer::<T>::fmt` where T is a function reference
//this is used in formatting macros, but doesn't rely on the specific expansion
fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location) {
let op_ty = operand.ty(self.body, self.tcx);
if let ty::FnDef(def_id, substs_ref) = *op_ty.kind() {
if self.tcx.is_diagnostic_item(sym::pointer_trait_fmt, def_id) {
let param_ty = substs_ref.type_at(0);
if let Some(fn_id) = FunctionItemRefChecker::is_fn_ref(param_ty) {
let source_info = *self.body.source_info(location);
let callsite_ctxt = source_info.span.source_callsite().ctxt();
let span = source_info.span.with_ctxt(callsite_ctxt);
let ident = self.tcx.item_name(fn_id).to_ident_string();
self.emit_lint(ident, fn_id, source_info, span);
}
}
}
self.super_operand(operand, location);
}
}
impl<'a, 'tcx> FunctionItemRefChecker<'a, 'tcx> {
//return the bound parameter type if the trait is `std::fmt::Pointer`
fn is_pointer_trait(&self, bound: &PredicateAtom<'tcx>) -> Option<Ty<'tcx>> {
if let ty::PredicateAtom::Trait(predicate, _) = bound {
if self.tcx.is_diagnostic_item(sym::pointer_trait, predicate.def_id()) {
Some(predicate.trait_ref.self_ty())
} else {
None
}
} else {
None
}
}
fn is_fn_ref(ty: Ty<'tcx>) -> Option<DefId> {
let referent_ty = match ty.kind() {
ty::Ref(_, referent_ty, _) => Some(referent_ty),
ty::RawPtr(ty_and_mut) => Some(&ty_and_mut.ty),
_ => None,
};
referent_ty
.map(
|ref_ty| {
if let ty::FnDef(def_id, _) = *ref_ty.kind() { Some(def_id) } else { None }
},
)
.unwrap_or(None)
}
fn nth_arg_span(&self, args: &Vec<Operand<'tcx>>, n: usize) -> Span {
match &args[n] {
Operand::Copy(place) | Operand::Move(place) => {
self.body.local_decls[place.local].source_info.span
}
Operand::Constant(constant) => constant.span,
}
}
fn emit_lint(&self, ident: String, fn_id: DefId, source_info: SourceInfo, span: Span) {
let lint_root = self.body.source_scopes[source_info.scope]
.local_data
.as_ref()
.assert_crate_local()
.lint_root;
let fn_sig = self.tcx.fn_sig(fn_id);
let unsafety = fn_sig.unsafety().prefix_str();
let abi = match fn_sig.abi() {
Abi::Rust => String::from(""),
other_abi => {
let mut s = String::from("extern \"");
s.push_str(other_abi.name());
s.push_str("\" ");
s
}
};
let num_args = fn_sig.inputs().map_bound(|inputs| inputs.len()).skip_binder();
let variadic = if fn_sig.c_variadic() { ", ..." } else { "" };
let ret = if fn_sig.output().skip_binder().is_unit() { "" } else { " -> _" };
self.tcx.struct_span_lint_hir(FUNCTION_ITEM_REFERENCES, lint_root, span, |lint| {
lint.build(&format!(
"cast `{}` with `as {}{}fn({}{}){}` to use it as a pointer",
ident,
unsafety,
abi,
vec!["_"; num_args].join(", "),
variadic,
ret,
))
.emit();
});
}
}
|
