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Fixed compiler error in lint checker triggered by associated types

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When a function argument bound by `Pointer` is an associated type, we only
perform substitutions using the parameters from the callsite but don't attempt
to normalize since it may not succeed. A simplified version of the scenario that
triggered this error was added as a test case. Also fixed `Pointer::fmt` which
was being double-counted when called outside of macros and added a test case for
this.
This commit is contained in:
Ayrton 2020-10-06 17:55:46 -04:00
parent 432ebd57ef
commit d6fa7e15d6
3 changed files with 122 additions and 83 deletions
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118
compiler/rustc_mir/src/transform/function_references.rs
View file

@ -1,7 +1,11 @@
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_middle::ty::{
self,
subst::{GenericArgKind, Subst},
PredicateAtom, Ty, TyCtxt, TyS,
};
use rustc_session::lint::builtin::FUNCTION_ITEM_REFERENCES;
use rustc_span::{symbol::sym, Span};
use rustc_target::spec::abi::Abi;
@ -33,48 +37,50 @@ impl<'a, 'tcx> Visitor<'tcx> for FunctionItemRefChecker<'a, 'tcx> {
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);
let source_info = *self.body.source_info(location);
//this handles all function calls outside macros
if !source_info.span.from_expansion() {
let func_ty = func.ty(self.body, self.tcx);
if let ty::FnDef(def_id, substs_ref) = *func_ty.kind() {
//handle `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 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);
} else {
//handle any function call with `std::fmt::Pointer` as a bound trait
//this includes calls to `std::fmt::Pointer::fmt` outside of macros
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()) {
//get the argument types as they appear in the function signature
let arg_defs = self.tcx.fn_sig(def_id).skip_binder().inputs();
for (arg_num, arg_def) in arg_defs.iter().enumerate() {
//for all types reachable from the argument type in the fn sig
for generic_inner_ty in arg_def.walk() {
if let GenericArgKind::Type(inner_ty) =
generic_inner_ty.unpack()
{
//if the inner type matches the type bound by `Pointer`
if TyS::same_type(inner_ty, bound_ty) {
//do a substitution using the parameters from the callsite
let subst_ty = inner_ty.subst(self.tcx, substs_ref);
if let Some(fn_id) =
FunctionItemRefChecker::is_fn_ref(subst_ty)
{
let ident =
self.tcx.item_name(fn_id).to_ident_string();
let span = self.nth_arg_span(&args, arg_num);
self.emit_lint(ident, fn_id, source_info, span);
}
}
}
}
@ -87,19 +93,25 @@ impl<'a, 'tcx> Visitor<'tcx> for FunctionItemRefChecker<'a, 'tcx> {
}
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
//This handles `std::fmt::Pointer::fmt` when it's used in the formatting macros.
//It's handled as an operand instead of a Call terminator so it won't depend on
//whether the formatting macros call `fmt` directly, transmute it first or other
//internal fmt details.
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);
let source_info = *self.body.source_info(location);
if source_info.span.from_expansion() {
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) {
//the operand's ctxt wouldn't display the lint since it's inside a macro
//so we have to use the callsite's ctxt
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);
}
}
}
}