532 lines
20 KiB
Rust
532 lines
20 KiB
Rust
//! checks for attributes
|
|
|
|
use crate::reexport::Name;
|
|
use crate::utils::{
|
|
first_line_of_span, is_present_in_source, match_def_path, paths, snippet_opt, span_lint, span_lint_and_sugg,
|
|
span_lint_and_then, without_block_comments,
|
|
};
|
|
use if_chain::if_chain;
|
|
use rustc::lint::in_external_macro;
|
|
use rustc::ty;
|
|
use rustc_ast::ast::{AttrKind, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
|
|
use rustc_ast::util::lev_distance::find_best_match_for_name;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::{
|
|
Block, Expr, ExprKind, ImplItem, ImplItemKind, Item, ItemKind, StmtKind, TraitFn, TraitItem, TraitItemKind,
|
|
};
|
|
use rustc_lint::{CheckLintNameResult, EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
use rustc_span::source_map::Span;
|
|
use rustc_span::symbol::Symbol;
|
|
use semver::Version;
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for items annotated with `#[inline(always)]`,
|
|
/// unless the annotated function is empty or simply panics.
|
|
///
|
|
/// **Why is this bad?** While there are valid uses of this annotation (and once
|
|
/// you know when to use it, by all means `allow` this lint), it's a common
|
|
/// newbie-mistake to pepper one's code with it.
|
|
///
|
|
/// As a rule of thumb, before slapping `#[inline(always)]` on a function,
|
|
/// measure if that additional function call really affects your runtime profile
|
|
/// sufficiently to make up for the increase in compile time.
|
|
///
|
|
/// **Known problems:** False positives, big time. This lint is meant to be
|
|
/// deactivated by everyone doing serious performance work. This means having
|
|
/// done the measurement.
|
|
///
|
|
/// **Example:**
|
|
/// ```ignore
|
|
/// #[inline(always)]
|
|
/// fn not_quite_hot_code(..) { ... }
|
|
/// ```
|
|
pub INLINE_ALWAYS,
|
|
pedantic,
|
|
"use of `#[inline(always)]`"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `extern crate` and `use` items annotated with
|
|
/// lint attributes.
|
|
///
|
|
/// This lint whitelists `#[allow(unused_imports)]`, `#[allow(deprecated)]` and
|
|
/// `#[allow(unreachable_pub)]` on `use` items and `#[allow(unused_imports)]` on
|
|
/// `extern crate` items with a `#[macro_use]` attribute.
|
|
///
|
|
/// **Why is this bad?** Lint attributes have no effect on crate imports. Most
|
|
/// likely a `!` was forgotten.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```ignore
|
|
/// // Bad
|
|
/// #[deny(dead_code)]
|
|
/// extern crate foo;
|
|
/// #[forbid(dead_code)]
|
|
/// use foo::bar;
|
|
///
|
|
/// // Ok
|
|
/// #[allow(unused_imports)]
|
|
/// use foo::baz;
|
|
/// #[allow(unused_imports)]
|
|
/// #[macro_use]
|
|
/// extern crate baz;
|
|
/// ```
|
|
pub USELESS_ATTRIBUTE,
|
|
correctness,
|
|
"use of lint attributes on `extern crate` items"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `#[deprecated]` annotations with a `since`
|
|
/// field that is not a valid semantic version.
|
|
///
|
|
/// **Why is this bad?** For checking the version of the deprecation, it must be
|
|
/// a valid semver. Failing that, the contained information is useless.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// #[deprecated(since = "forever")]
|
|
/// fn something_else() { /* ... */ }
|
|
/// ```
|
|
pub DEPRECATED_SEMVER,
|
|
correctness,
|
|
"use of `#[deprecated(since = \"x\")]` where x is not semver"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for empty lines after outer attributes
|
|
///
|
|
/// **Why is this bad?**
|
|
/// Most likely the attribute was meant to be an inner attribute using a '!'.
|
|
/// If it was meant to be an outer attribute, then the following item
|
|
/// should not be separated by empty lines.
|
|
///
|
|
/// **Known problems:** Can cause false positives.
|
|
///
|
|
/// From the clippy side it's difficult to detect empty lines between an attributes and the
|
|
/// following item because empty lines and comments are not part of the AST. The parsing
|
|
/// currently works for basic cases but is not perfect.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// // Good (as inner attribute)
|
|
/// #![inline(always)]
|
|
///
|
|
/// fn this_is_fine() { }
|
|
///
|
|
/// // Bad
|
|
/// #[inline(always)]
|
|
///
|
|
/// fn not_quite_good_code() { }
|
|
///
|
|
/// // Good (as outer attribute)
|
|
/// #[inline(always)]
|
|
/// fn this_is_fine_too() { }
|
|
/// ```
|
|
pub EMPTY_LINE_AFTER_OUTER_ATTR,
|
|
nursery,
|
|
"empty line after outer attribute"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `allow`/`warn`/`deny`/`forbid` attributes with scoped clippy
|
|
/// lints and if those lints exist in clippy. If there is an uppercase letter in the lint name
|
|
/// (not the tool name) and a lowercase version of this lint exists, it will suggest to lowercase
|
|
/// the lint name.
|
|
///
|
|
/// **Why is this bad?** A lint attribute with a mistyped lint name won't have an effect.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// Bad:
|
|
/// ```rust
|
|
/// #![warn(if_not_els)]
|
|
/// #![deny(clippy::All)]
|
|
/// ```
|
|
///
|
|
/// Good:
|
|
/// ```rust
|
|
/// #![warn(if_not_else)]
|
|
/// #![deny(clippy::all)]
|
|
/// ```
|
|
pub UNKNOWN_CLIPPY_LINTS,
|
|
style,
|
|
"unknown_lints for scoped Clippy lints"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for `#[cfg_attr(rustfmt, rustfmt_skip)]` and suggests to replace it
|
|
/// with `#[rustfmt::skip]`.
|
|
///
|
|
/// **Why is this bad?** Since tool_attributes ([rust-lang/rust#44690](https://github.com/rust-lang/rust/issues/44690))
|
|
/// are stable now, they should be used instead of the old `cfg_attr(rustfmt)` attributes.
|
|
///
|
|
/// **Known problems:** This lint doesn't detect crate level inner attributes, because they get
|
|
/// processed before the PreExpansionPass lints get executed. See
|
|
/// [#3123](https://github.com/rust-lang/rust-clippy/pull/3123#issuecomment-422321765)
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// Bad:
|
|
/// ```rust
|
|
/// #[cfg_attr(rustfmt, rustfmt_skip)]
|
|
/// fn main() { }
|
|
/// ```
|
|
///
|
|
/// Good:
|
|
/// ```rust
|
|
/// #[rustfmt::skip]
|
|
/// fn main() { }
|
|
/// ```
|
|
pub DEPRECATED_CFG_ATTR,
|
|
complexity,
|
|
"usage of `cfg_attr(rustfmt)` instead of tool attributes"
|
|
}
|
|
|
|
declare_lint_pass!(Attributes => [
|
|
INLINE_ALWAYS,
|
|
DEPRECATED_SEMVER,
|
|
USELESS_ATTRIBUTE,
|
|
EMPTY_LINE_AFTER_OUTER_ATTR,
|
|
UNKNOWN_CLIPPY_LINTS,
|
|
]);
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Attributes {
|
|
fn check_attribute(&mut self, cx: &LateContext<'a, 'tcx>, attr: &'tcx Attribute) {
|
|
if let Some(items) = &attr.meta_item_list() {
|
|
if let Some(ident) = attr.ident() {
|
|
match &*ident.as_str() {
|
|
"allow" | "warn" | "deny" | "forbid" => {
|
|
check_clippy_lint_names(cx, items);
|
|
},
|
|
_ => {},
|
|
}
|
|
if items.is_empty() || !attr.check_name(sym!(deprecated)) {
|
|
return;
|
|
}
|
|
for item in items {
|
|
if_chain! {
|
|
if let NestedMetaItem::MetaItem(mi) = &item;
|
|
if let MetaItemKind::NameValue(lit) = &mi.kind;
|
|
if mi.check_name(sym!(since));
|
|
then {
|
|
check_semver(cx, item.span(), lit);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item<'_>) {
|
|
if is_relevant_item(cx, item) {
|
|
check_attrs(cx, item.span, item.ident.name, &item.attrs)
|
|
}
|
|
match item.kind {
|
|
ItemKind::ExternCrate(..) | ItemKind::Use(..) => {
|
|
let skip_unused_imports = item.attrs.iter().any(|attr| attr.check_name(sym!(macro_use)));
|
|
|
|
for attr in item.attrs {
|
|
if in_external_macro(cx.sess(), attr.span) {
|
|
return;
|
|
}
|
|
if let Some(lint_list) = &attr.meta_item_list() {
|
|
if let Some(ident) = attr.ident() {
|
|
match &*ident.as_str() {
|
|
"allow" | "warn" | "deny" | "forbid" => {
|
|
// whitelist `unused_imports`, `deprecated` and `unreachable_pub` for `use` items
|
|
// and `unused_imports` for `extern crate` items with `macro_use`
|
|
for lint in lint_list {
|
|
match item.kind {
|
|
ItemKind::Use(..) => {
|
|
if is_word(lint, sym!(unused_imports))
|
|
|| is_word(lint, sym!(deprecated))
|
|
|| is_word(lint, sym!(unreachable_pub))
|
|
|| is_word(lint, sym!(unused))
|
|
{
|
|
return;
|
|
}
|
|
},
|
|
ItemKind::ExternCrate(..) => {
|
|
if is_word(lint, sym!(unused_imports)) && skip_unused_imports {
|
|
return;
|
|
}
|
|
if is_word(lint, sym!(unused_extern_crates)) {
|
|
return;
|
|
}
|
|
},
|
|
_ => {},
|
|
}
|
|
}
|
|
let line_span = first_line_of_span(cx, attr.span);
|
|
|
|
if let Some(mut sugg) = snippet_opt(cx, line_span) {
|
|
if sugg.contains("#[") {
|
|
span_lint_and_then(
|
|
cx,
|
|
USELESS_ATTRIBUTE,
|
|
line_span,
|
|
"useless lint attribute",
|
|
|db| {
|
|
sugg = sugg.replacen("#[", "#![", 1);
|
|
db.span_suggestion(
|
|
line_span,
|
|
"if you just forgot a `!`, use",
|
|
sugg,
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
},
|
|
);
|
|
}
|
|
}
|
|
},
|
|
_ => {},
|
|
}
|
|
}
|
|
}
|
|
}
|
|
},
|
|
_ => {},
|
|
}
|
|
}
|
|
|
|
fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem<'_>) {
|
|
if is_relevant_impl(cx, item) {
|
|
check_attrs(cx, item.span, item.ident.name, &item.attrs)
|
|
}
|
|
}
|
|
|
|
fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem<'_>) {
|
|
if is_relevant_trait(cx, item) {
|
|
check_attrs(cx, item.span, item.ident.name, &item.attrs)
|
|
}
|
|
}
|
|
}
|
|
|
|
#[allow(clippy::single_match_else)]
|
|
fn check_clippy_lint_names(cx: &LateContext<'_, '_>, items: &[NestedMetaItem]) {
|
|
let lint_store = cx.lints();
|
|
for lint in items {
|
|
if_chain! {
|
|
if let Some(meta_item) = lint.meta_item();
|
|
if meta_item.path.segments.len() > 1;
|
|
if let tool_name = meta_item.path.segments[0].ident;
|
|
if tool_name.as_str() == "clippy";
|
|
let name = meta_item.path.segments.last().unwrap().ident.name;
|
|
if let CheckLintNameResult::Tool(Err((None, _))) = lint_store.check_lint_name(
|
|
&name.as_str(),
|
|
Some(tool_name.name),
|
|
);
|
|
then {
|
|
span_lint_and_then(
|
|
cx,
|
|
UNKNOWN_CLIPPY_LINTS,
|
|
lint.span(),
|
|
&format!("unknown clippy lint: clippy::{}", name),
|
|
|db| {
|
|
let name_lower = name.as_str().to_lowercase();
|
|
let symbols = lint_store.get_lints().iter().map(
|
|
|l| Symbol::intern(&l.name_lower())
|
|
).collect::<Vec<_>>();
|
|
let sugg = find_best_match_for_name(
|
|
symbols.iter(),
|
|
&format!("clippy::{}", name_lower),
|
|
None,
|
|
);
|
|
if name.as_str().chars().any(char::is_uppercase)
|
|
&& lint_store.find_lints(&format!("clippy::{}", name_lower)).is_ok() {
|
|
db.span_suggestion(
|
|
lint.span(),
|
|
"lowercase the lint name",
|
|
format!("clippy::{}", name_lower),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else if let Some(sugg) = sugg {
|
|
db.span_suggestion(
|
|
lint.span(),
|
|
"did you mean",
|
|
sugg.to_string(),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
);
|
|
}
|
|
};
|
|
}
|
|
}
|
|
|
|
fn is_relevant_item(cx: &LateContext<'_, '_>, item: &Item<'_>) -> bool {
|
|
if let ItemKind::Fn(_, _, eid) = item.kind {
|
|
is_relevant_expr(cx, cx.tcx.body_tables(eid), &cx.tcx.hir().body(eid).value)
|
|
} else {
|
|
true
|
|
}
|
|
}
|
|
|
|
fn is_relevant_impl(cx: &LateContext<'_, '_>, item: &ImplItem<'_>) -> bool {
|
|
match item.kind {
|
|
ImplItemKind::Fn(_, eid) => is_relevant_expr(cx, cx.tcx.body_tables(eid), &cx.tcx.hir().body(eid).value),
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn is_relevant_trait(cx: &LateContext<'_, '_>, item: &TraitItem<'_>) -> bool {
|
|
match item.kind {
|
|
TraitItemKind::Fn(_, TraitFn::Required(_)) => true,
|
|
TraitItemKind::Fn(_, TraitFn::Provided(eid)) => {
|
|
is_relevant_expr(cx, cx.tcx.body_tables(eid), &cx.tcx.hir().body(eid).value)
|
|
},
|
|
_ => false,
|
|
}
|
|
}
|
|
|
|
fn is_relevant_block(cx: &LateContext<'_, '_>, tables: &ty::TypeckTables<'_>, block: &Block<'_>) -> bool {
|
|
if let Some(stmt) = block.stmts.first() {
|
|
match &stmt.kind {
|
|
StmtKind::Local(_) => true,
|
|
StmtKind::Expr(expr) | StmtKind::Semi(expr) => is_relevant_expr(cx, tables, expr),
|
|
_ => false,
|
|
}
|
|
} else {
|
|
block.expr.as_ref().map_or(false, |e| is_relevant_expr(cx, tables, e))
|
|
}
|
|
}
|
|
|
|
fn is_relevant_expr(cx: &LateContext<'_, '_>, tables: &ty::TypeckTables<'_>, expr: &Expr<'_>) -> bool {
|
|
match &expr.kind {
|
|
ExprKind::Block(block, _) => is_relevant_block(cx, tables, block),
|
|
ExprKind::Ret(Some(e)) => is_relevant_expr(cx, tables, e),
|
|
ExprKind::Ret(None) | ExprKind::Break(_, None) => false,
|
|
ExprKind::Call(path_expr, _) => {
|
|
if let ExprKind::Path(qpath) = &path_expr.kind {
|
|
if let Some(fun_id) = tables.qpath_res(qpath, path_expr.hir_id).opt_def_id() {
|
|
!match_def_path(cx, fun_id, &paths::BEGIN_PANIC)
|
|
} else {
|
|
true
|
|
}
|
|
} else {
|
|
true
|
|
}
|
|
},
|
|
_ => true,
|
|
}
|
|
}
|
|
|
|
fn check_attrs(cx: &LateContext<'_, '_>, span: Span, name: Name, attrs: &[Attribute]) {
|
|
if span.from_expansion() {
|
|
return;
|
|
}
|
|
|
|
for attr in attrs {
|
|
let attr_item = if let AttrKind::Normal(ref attr) = attr.kind {
|
|
attr
|
|
} else {
|
|
continue;
|
|
};
|
|
|
|
if attr.style == AttrStyle::Outer {
|
|
if attr_item.args.inner_tokens().is_empty() || !is_present_in_source(cx, attr.span) {
|
|
return;
|
|
}
|
|
|
|
let begin_of_attr_to_item = Span::new(attr.span.lo(), span.lo(), span.ctxt());
|
|
let end_of_attr_to_item = Span::new(attr.span.hi(), span.lo(), span.ctxt());
|
|
|
|
if let Some(snippet) = snippet_opt(cx, end_of_attr_to_item) {
|
|
let lines = snippet.split('\n').collect::<Vec<_>>();
|
|
let lines = without_block_comments(lines);
|
|
|
|
if lines.iter().filter(|l| l.trim().is_empty()).count() > 2 {
|
|
span_lint(
|
|
cx,
|
|
EMPTY_LINE_AFTER_OUTER_ATTR,
|
|
begin_of_attr_to_item,
|
|
"Found an empty line after an outer attribute. \
|
|
Perhaps you forgot to add a `!` to make it an inner attribute?",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
if let Some(values) = attr.meta_item_list() {
|
|
if values.len() != 1 || !attr.check_name(sym!(inline)) {
|
|
continue;
|
|
}
|
|
if is_word(&values[0], sym!(always)) {
|
|
span_lint(
|
|
cx,
|
|
INLINE_ALWAYS,
|
|
attr.span,
|
|
&format!(
|
|
"you have declared `#[inline(always)]` on `{}`. This is usually a bad idea",
|
|
name
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_semver(cx: &LateContext<'_, '_>, span: Span, lit: &Lit) {
|
|
if let LitKind::Str(is, _) = lit.kind {
|
|
if Version::parse(&is.as_str()).is_ok() {
|
|
return;
|
|
}
|
|
}
|
|
span_lint(
|
|
cx,
|
|
DEPRECATED_SEMVER,
|
|
span,
|
|
"the since field must contain a semver-compliant version",
|
|
);
|
|
}
|
|
|
|
fn is_word(nmi: &NestedMetaItem, expected: Symbol) -> bool {
|
|
if let NestedMetaItem::MetaItem(mi) = &nmi {
|
|
mi.is_word() && mi.check_name(expected)
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
declare_lint_pass!(DeprecatedCfgAttribute => [DEPRECATED_CFG_ATTR]);
|
|
|
|
impl EarlyLintPass for DeprecatedCfgAttribute {
|
|
fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &Attribute) {
|
|
if_chain! {
|
|
// check cfg_attr
|
|
if attr.check_name(sym!(cfg_attr));
|
|
if let Some(items) = attr.meta_item_list();
|
|
if items.len() == 2;
|
|
// check for `rustfmt`
|
|
if let Some(feature_item) = items[0].meta_item();
|
|
if feature_item.check_name(sym!(rustfmt));
|
|
// check for `rustfmt_skip` and `rustfmt::skip`
|
|
if let Some(skip_item) = &items[1].meta_item();
|
|
if skip_item.check_name(sym!(rustfmt_skip)) ||
|
|
skip_item.path.segments.last().expect("empty path in attribute").ident.name == sym!(skip);
|
|
// Only lint outer attributes, because custom inner attributes are unstable
|
|
// Tracking issue: https://github.com/rust-lang/rust/issues/54726
|
|
if let AttrStyle::Outer = attr.style;
|
|
then {
|
|
span_lint_and_sugg(
|
|
cx,
|
|
DEPRECATED_CFG_ATTR,
|
|
attr.span,
|
|
"`cfg_attr` is deprecated for rustfmt and got replaced by tool attributes",
|
|
"use",
|
|
"#[rustfmt::skip]".to_string(),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|