422 lines
14 KiB
Rust
422 lines
14 KiB
Rust
//! This module implements some validity checks for attributes.
|
|
//! In particular it verifies that `#[inline]` and `#[repr]` attributes are
|
|
//! attached to items that actually support them and if there are
|
|
//! conflicts between multiple such attributes attached to the same
|
|
//! item.
|
|
|
|
use crate::hir;
|
|
use crate::hir::def_id::DefId;
|
|
use crate::hir::intravisit::{self, Visitor, NestedVisitorMap};
|
|
use crate::ty::TyCtxt;
|
|
use crate::ty::query::Providers;
|
|
|
|
use std::fmt::{self, Display};
|
|
use syntax::{attr, symbol::sym};
|
|
use syntax_pos::Span;
|
|
|
|
#[derive(Copy, Clone, PartialEq)]
|
|
pub(crate) enum Target {
|
|
ExternCrate,
|
|
Use,
|
|
Static,
|
|
Const,
|
|
Fn,
|
|
Closure,
|
|
Mod,
|
|
ForeignMod,
|
|
GlobalAsm,
|
|
TyAlias,
|
|
OpaqueTy,
|
|
Enum,
|
|
Struct,
|
|
Union,
|
|
Trait,
|
|
TraitAlias,
|
|
Impl,
|
|
Expression,
|
|
Statement,
|
|
}
|
|
|
|
impl Display for Target {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
write!(f, "{}", match *self {
|
|
Target::ExternCrate => "extern crate",
|
|
Target::Use => "use",
|
|
Target::Static => "static item",
|
|
Target::Const => "constant item",
|
|
Target::Fn => "function",
|
|
Target::Closure => "closure",
|
|
Target::Mod => "module",
|
|
Target::ForeignMod => "foreign module",
|
|
Target::GlobalAsm => "global asm",
|
|
Target::TyAlias => "type alias",
|
|
Target::OpaqueTy => "opaque type",
|
|
Target::Enum => "enum",
|
|
Target::Struct => "struct",
|
|
Target::Union => "union",
|
|
Target::Trait => "trait",
|
|
Target::TraitAlias => "trait alias",
|
|
Target::Impl => "item",
|
|
Target::Expression => "expression",
|
|
Target::Statement => "statement",
|
|
})
|
|
}
|
|
}
|
|
|
|
impl Target {
|
|
pub(crate) fn from_item(item: &hir::Item) -> Target {
|
|
match item.kind {
|
|
hir::ItemKind::ExternCrate(..) => Target::ExternCrate,
|
|
hir::ItemKind::Use(..) => Target::Use,
|
|
hir::ItemKind::Static(..) => Target::Static,
|
|
hir::ItemKind::Const(..) => Target::Const,
|
|
hir::ItemKind::Fn(..) => Target::Fn,
|
|
hir::ItemKind::Mod(..) => Target::Mod,
|
|
hir::ItemKind::ForeignMod(..) => Target::ForeignMod,
|
|
hir::ItemKind::GlobalAsm(..) => Target::GlobalAsm,
|
|
hir::ItemKind::TyAlias(..) => Target::TyAlias,
|
|
hir::ItemKind::OpaqueTy(..) => Target::OpaqueTy,
|
|
hir::ItemKind::Enum(..) => Target::Enum,
|
|
hir::ItemKind::Struct(..) => Target::Struct,
|
|
hir::ItemKind::Union(..) => Target::Union,
|
|
hir::ItemKind::Trait(..) => Target::Trait,
|
|
hir::ItemKind::TraitAlias(..) => Target::TraitAlias,
|
|
hir::ItemKind::Impl(..) => Target::Impl,
|
|
}
|
|
}
|
|
}
|
|
|
|
struct CheckAttrVisitor<'tcx> {
|
|
tcx: TyCtxt<'tcx>,
|
|
}
|
|
|
|
impl CheckAttrVisitor<'tcx> {
|
|
/// Checks any attribute.
|
|
fn check_attributes(&self, item: &hir::Item, target: Target) {
|
|
let mut is_valid = true;
|
|
for attr in &item.attrs {
|
|
is_valid &= if attr.check_name(sym::inline) {
|
|
self.check_inline(attr, &item.span, target)
|
|
} else if attr.check_name(sym::non_exhaustive) {
|
|
self.check_non_exhaustive(attr, item, target)
|
|
} else if attr.check_name(sym::marker) {
|
|
self.check_marker(attr, item, target)
|
|
} else if attr.check_name(sym::target_feature) {
|
|
self.check_target_feature(attr, item, target)
|
|
} else if attr.check_name(sym::track_caller) {
|
|
self.check_track_caller(attr, &item, target)
|
|
} else {
|
|
true
|
|
};
|
|
}
|
|
|
|
if !is_valid {
|
|
return;
|
|
}
|
|
|
|
if target == Target::Fn {
|
|
self.tcx.codegen_fn_attrs(self.tcx.hir().local_def_id(item.hir_id));
|
|
}
|
|
|
|
self.check_repr(item, target);
|
|
self.check_used(item, target);
|
|
}
|
|
|
|
/// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
|
|
fn check_inline(&self, attr: &hir::Attribute, span: &Span, target: Target) -> bool {
|
|
if target != Target::Fn && target != Target::Closure {
|
|
struct_span_err!(self.tcx.sess,
|
|
attr.span,
|
|
E0518,
|
|
"attribute should be applied to function or closure")
|
|
.span_label(*span, "not a function or closure")
|
|
.emit();
|
|
false
|
|
} else {
|
|
true
|
|
}
|
|
}
|
|
|
|
/// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
|
|
fn check_track_caller(&self, attr: &hir::Attribute, item: &hir::Item, target: Target) -> bool {
|
|
if target != Target::Fn {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
attr.span,
|
|
E0739,
|
|
"attribute should be applied to function"
|
|
)
|
|
.span_label(item.span, "not a function")
|
|
.emit();
|
|
false
|
|
} else if attr::contains_name(&item.attrs, sym::naked) {
|
|
struct_span_err!(
|
|
self.tcx.sess,
|
|
attr.span,
|
|
E0736,
|
|
"cannot use `#[track_caller]` with `#[naked]`",
|
|
)
|
|
.emit();
|
|
false
|
|
} else {
|
|
true
|
|
}
|
|
}
|
|
|
|
/// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid.
|
|
fn check_non_exhaustive(
|
|
&self,
|
|
attr: &hir::Attribute,
|
|
item: &hir::Item,
|
|
target: Target,
|
|
) -> bool {
|
|
match target {
|
|
Target::Struct | Target::Enum => true,
|
|
_ => {
|
|
struct_span_err!(self.tcx.sess,
|
|
attr.span,
|
|
E0701,
|
|
"attribute can only be applied to a struct or enum")
|
|
.span_label(item.span, "not a struct or enum")
|
|
.emit();
|
|
false
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
|
|
fn check_marker(&self, attr: &hir::Attribute, item: &hir::Item, target: Target) -> bool {
|
|
match target {
|
|
Target::Trait => true,
|
|
_ => {
|
|
self.tcx.sess
|
|
.struct_span_err(attr.span, "attribute can only be applied to a trait")
|
|
.span_label(item.span, "not a trait")
|
|
.emit();
|
|
false
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
|
|
fn check_target_feature(
|
|
&self,
|
|
attr: &hir::Attribute,
|
|
item: &hir::Item,
|
|
target: Target,
|
|
) -> bool {
|
|
match target {
|
|
Target::Fn => true,
|
|
_ => {
|
|
self.tcx.sess
|
|
.struct_span_err(attr.span, "attribute should be applied to a function")
|
|
.span_label(item.span, "not a function")
|
|
.emit();
|
|
false
|
|
},
|
|
}
|
|
}
|
|
|
|
/// Checks if the `#[repr]` attributes on `item` are valid.
|
|
fn check_repr(&self, item: &hir::Item, target: Target) {
|
|
// Extract the names of all repr hints, e.g., [foo, bar, align] for:
|
|
// ```
|
|
// #[repr(foo)]
|
|
// #[repr(bar, align(8))]
|
|
// ```
|
|
let hints: Vec<_> = item.attrs
|
|
.iter()
|
|
.filter(|attr| attr.check_name(sym::repr))
|
|
.filter_map(|attr| attr.meta_item_list())
|
|
.flatten()
|
|
.collect();
|
|
|
|
let mut int_reprs = 0;
|
|
let mut is_c = false;
|
|
let mut is_simd = false;
|
|
let mut is_transparent = false;
|
|
|
|
for hint in &hints {
|
|
let (article, allowed_targets) = match hint.name_or_empty() {
|
|
name @ sym::C | name @ sym::align => {
|
|
is_c |= name == sym::C;
|
|
match target {
|
|
Target::Struct | Target::Union | Target::Enum => continue,
|
|
_ => ("a", "struct, enum, or union"),
|
|
}
|
|
}
|
|
sym::packed => {
|
|
if target != Target::Struct &&
|
|
target != Target::Union {
|
|
("a", "struct or union")
|
|
} else {
|
|
continue
|
|
}
|
|
}
|
|
sym::simd => {
|
|
is_simd = true;
|
|
if target != Target::Struct {
|
|
("a", "struct")
|
|
} else {
|
|
continue
|
|
}
|
|
}
|
|
sym::transparent => {
|
|
is_transparent = true;
|
|
match target {
|
|
Target::Struct | Target::Union | Target::Enum => continue,
|
|
_ => ("a", "struct, enum, or union"),
|
|
}
|
|
}
|
|
sym::i8 | sym::u8 | sym::i16 | sym::u16 |
|
|
sym::i32 | sym::u32 | sym::i64 | sym::u64 |
|
|
sym::isize | sym::usize => {
|
|
int_reprs += 1;
|
|
if target != Target::Enum {
|
|
("an", "enum")
|
|
} else {
|
|
continue
|
|
}
|
|
}
|
|
_ => continue,
|
|
};
|
|
self.emit_repr_error(
|
|
hint.span(),
|
|
item.span,
|
|
&format!("attribute should be applied to {}", allowed_targets),
|
|
&format!("not {} {}", article, allowed_targets),
|
|
)
|
|
}
|
|
|
|
// Just point at all repr hints if there are any incompatibilities.
|
|
// This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
|
|
let hint_spans = hints.iter().map(|hint| hint.span());
|
|
|
|
// Error on repr(transparent, <anything else>).
|
|
if is_transparent && hints.len() > 1 {
|
|
let hint_spans: Vec<_> = hint_spans.clone().collect();
|
|
span_err!(self.tcx.sess, hint_spans, E0692,
|
|
"transparent {} cannot have other repr hints", target);
|
|
}
|
|
// Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
|
|
if (int_reprs > 1)
|
|
|| (is_simd && is_c)
|
|
|| (int_reprs == 1 && is_c && is_c_like_enum(item)) {
|
|
let hint_spans: Vec<_> = hint_spans.collect();
|
|
span_warn!(self.tcx.sess, hint_spans, E0566,
|
|
"conflicting representation hints");
|
|
}
|
|
}
|
|
|
|
fn emit_repr_error(
|
|
&self,
|
|
hint_span: Span,
|
|
label_span: Span,
|
|
hint_message: &str,
|
|
label_message: &str,
|
|
) {
|
|
struct_span_err!(self.tcx.sess, hint_span, E0517, "{}", hint_message)
|
|
.span_label(label_span, label_message)
|
|
.emit();
|
|
}
|
|
|
|
fn check_stmt_attributes(&self, stmt: &hir::Stmt) {
|
|
// When checking statements ignore expressions, they will be checked later
|
|
if let hir::StmtKind::Local(ref l) = stmt.kind {
|
|
for attr in l.attrs.iter() {
|
|
if attr.check_name(sym::inline) {
|
|
self.check_inline(attr, &stmt.span, Target::Statement);
|
|
}
|
|
if attr.check_name(sym::repr) {
|
|
self.emit_repr_error(
|
|
attr.span,
|
|
stmt.span,
|
|
"attribute should not be applied to a statement",
|
|
"not a struct, enum, or union",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_expr_attributes(&self, expr: &hir::Expr) {
|
|
let target = match expr.kind {
|
|
hir::ExprKind::Closure(..) => Target::Closure,
|
|
_ => Target::Expression,
|
|
};
|
|
for attr in expr.attrs.iter() {
|
|
if attr.check_name(sym::inline) {
|
|
self.check_inline(attr, &expr.span, target);
|
|
}
|
|
if attr.check_name(sym::repr) {
|
|
self.emit_repr_error(
|
|
attr.span,
|
|
expr.span,
|
|
"attribute should not be applied to an expression",
|
|
"not defining a struct, enum, or union",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_used(&self, item: &hir::Item, target: Target) {
|
|
for attr in &item.attrs {
|
|
if attr.check_name(sym::used) && target != Target::Static {
|
|
self.tcx.sess
|
|
.span_err(attr.span, "attribute must be applied to a `static` variable");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Visitor<'tcx> for CheckAttrVisitor<'tcx> {
|
|
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
|
|
NestedVisitorMap::OnlyBodies(&self.tcx.hir())
|
|
}
|
|
|
|
fn visit_item(&mut self, item: &'tcx hir::Item) {
|
|
let target = Target::from_item(item);
|
|
self.check_attributes(item, target);
|
|
intravisit::walk_item(self, item)
|
|
}
|
|
|
|
|
|
fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt) {
|
|
self.check_stmt_attributes(stmt);
|
|
intravisit::walk_stmt(self, stmt)
|
|
}
|
|
|
|
fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
|
|
self.check_expr_attributes(expr);
|
|
intravisit::walk_expr(self, expr)
|
|
}
|
|
}
|
|
|
|
fn is_c_like_enum(item: &hir::Item) -> bool {
|
|
if let hir::ItemKind::Enum(ref def, _) = item.kind {
|
|
for variant in &def.variants {
|
|
match variant.data {
|
|
hir::VariantData::Unit(..) => { /* continue */ }
|
|
_ => { return false; }
|
|
}
|
|
}
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: DefId) {
|
|
tcx.hir().visit_item_likes_in_module(
|
|
module_def_id,
|
|
&mut CheckAttrVisitor { tcx }.as_deep_visitor()
|
|
);
|
|
}
|
|
|
|
pub(crate) fn provide(providers: &mut Providers<'_>) {
|
|
*providers = Providers {
|
|
check_mod_attrs,
|
|
..*providers
|
|
};
|
|
}
|