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//! Lints in the Rust compiler.
//!
//! This contains lints which can feasibly be implemented as their own
//! AST visitor. Also see `rustc::lint::builtin`, which contains the
//! definitions of lints that are emitted directly inside the main
//! compiler.
//!
//! To add a new lint to rustc, declare it here using `declare_lint!()`.
//! Then add code to emit the new lint in the appropriate circumstances.
//! You can do that in an existing `LintPass` if it makes sense, or in a
//! new `LintPass`, or using `Session::add_lint` elsewhere in the
//! compiler. Only do the latter if the check can't be written cleanly as a
//! `LintPass` (also, note that such lints will need to be defined in
//! `rustc::lint::builtin`, not here).
//!
//! If you define a new `EarlyLintPass`, you will also need to add it to the
//! `add_early_builtin!` or `add_early_builtin_with_new!` invocation in
//! `lib.rs`. Use the former for unit-like structs and the latter for structs
//! with a `pub fn new()`.
//!
//! If you define a new `LateLintPass`, you will also need to add it to the
//! `late_lint_methods!` invocation in `lib.rs`.
use rustc::hir::def::{Res, DefKind};
use rustc::hir::def_id::{DefId, LOCAL_CRATE};
use rustc::ty::{self, Ty, TyCtxt};
use rustc::{lint, util};
use hir::Node;
use util::nodemap::HirIdSet;
use lint::{LateContext, LintContext, LintArray};
use lint::{LintPass, LateLintPass, EarlyLintPass, EarlyContext};
use rustc::util::nodemap::FxHashSet;
use syntax::tokenstream::{TokenTree, TokenStream};
use syntax::ast;
use syntax::ptr::P;
use syntax::ast::Expr;
use syntax::attr::{self, HasAttrs};
use syntax::source_map::Spanned;
use syntax::edition::Edition;
use syntax::feature_gate::{AttributeGate, AttributeTemplate, AttributeType};
use syntax::feature_gate::{Stability, deprecated_attributes};
use syntax_pos::{BytePos, Span, SyntaxContext};
use syntax::symbol::{Symbol, kw, sym};
use syntax::errors::{Applicability, DiagnosticBuilder};
use syntax::print::pprust::expr_to_string;
use syntax::visit::FnKind;
use rustc::hir::{self, GenericParamKind, PatKind};
use crate::nonstandard_style::{MethodLateContext, method_context};
use log::debug;
// hardwired lints from librustc
pub use lint::builtin::*;
declare_lint! {
WHILE_TRUE,
Warn,
"suggest using `loop { }` instead of `while true { }`"
}
declare_lint_pass!(WhileTrue => [WHILE_TRUE]);
/// Traverse through any amount of parenthesis and return the first non-parens expression.
fn pierce_parens(mut expr: &ast::Expr) -> &ast::Expr {
while let ast::ExprKind::Paren(sub) = &expr.node {
expr = sub;
}
expr
}
impl EarlyLintPass for WhileTrue {
fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
if let ast::ExprKind::While(cond, ..) = &e.node {
if let ast::ExprKind::Lit(ref lit) = pierce_parens(cond).node {
if let ast::LitKind::Bool(true) = lit.node {
if lit.span.ctxt() == SyntaxContext::empty() {
let msg = "denote infinite loops with `loop { ... }`";
let condition_span = cx.sess.source_map().def_span(e.span);
cx.struct_span_lint(WHILE_TRUE, condition_span, msg)
.span_suggestion_short(
condition_span,
"use `loop`",
"loop".to_owned(),
Applicability::MachineApplicable
)
.emit();
}
}
}
}
}
}
declare_lint! {
BOX_POINTERS,
Allow,
"use of owned (Box type) heap memory"
}
declare_lint_pass!(BoxPointers => [BOX_POINTERS]);
impl BoxPointers {
fn check_heap_type(&self, cx: &LateContext<'_, '_>, span: Span, ty: Ty<'_>) {
for leaf_ty in ty.walk() {
if leaf_ty.is_box() {
let m = format!("type uses owned (Box type) pointers: {}", ty);
cx.span_lint(BOX_POINTERS, span, &m);
}
}
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxPointers {
fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
match it.node {
hir::ItemKind::Fn(..) |
hir::ItemKind::Ty(..) |
hir::ItemKind::Enum(..) |
hir::ItemKind::Struct(..) |
hir::ItemKind::Union(..) => {
let def_id = cx.tcx.hir().local_def_id(it.hir_id);
self.check_heap_type(cx, it.span, cx.tcx.type_of(def_id))
}
_ => ()
}
// If it's a struct, we also have to check the fields' types
match it.node {
hir::ItemKind::Struct(ref struct_def, _) |
hir::ItemKind::Union(ref struct_def, _) => {
for struct_field in struct_def.fields() {
let def_id = cx.tcx.hir().local_def_id(struct_field.hir_id);
self.check_heap_type(cx, struct_field.span,
cx.tcx.type_of(def_id));
}
}
_ => (),
}
}
fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
let ty = cx.tables.node_type(e.hir_id);
self.check_heap_type(cx, e.span, ty);
}
}
declare_lint! {
NON_SHORTHAND_FIELD_PATTERNS,
Warn,
"using `Struct { x: x }` instead of `Struct { x }` in a pattern"
}
declare_lint_pass!(NonShorthandFieldPatterns => [NON_SHORTHAND_FIELD_PATTERNS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonShorthandFieldPatterns {
fn check_pat(&mut self, cx: &LateContext<'_, '_>, pat: &hir::Pat) {
if let PatKind::Struct(ref qpath, ref field_pats, _) = pat.node {
let variant = cx.tables.pat_ty(pat).ty_adt_def()
.expect("struct pattern type is not an ADT")
.variant_of_res(cx.tables.qpath_res(qpath, pat.hir_id));
for fieldpat in field_pats {
if fieldpat.node.is_shorthand {
continue;
}
if fieldpat.span.ctxt().outer_expn_info().is_some() {
// Don't lint if this is a macro expansion: macro authors
// shouldn't have to worry about this kind of style issue
// (Issue #49588)
continue;
}
if let PatKind::Binding(_, _, ident, None) = fieldpat.node.pat.node {
if cx.tcx.find_field_index(ident, &variant) ==
Some(cx.tcx.field_index(fieldpat.node.hir_id, cx.tables)) {
let mut err = cx.struct_span_lint(NON_SHORTHAND_FIELD_PATTERNS,
fieldpat.span,
&format!("the `{}:` in this pattern is redundant", ident));
let subspan = cx.tcx.sess.source_map().span_through_char(fieldpat.span,
':');
err.span_suggestion_short(
subspan,
"remove this",
ident.to_string(),
Applicability::MachineApplicable
);
err.emit();
}
}
}
}
}
}
declare_lint! {
UNSAFE_CODE,
Allow,
"usage of `unsafe` code"
}
declare_lint_pass!(UnsafeCode => [UNSAFE_CODE]);
impl UnsafeCode {
fn report_unsafe(&self, cx: &EarlyContext<'_>, span: Span, desc: &'static str) {
// This comes from a macro that has `#[allow_internal_unsafe]`.
if span.allows_unsafe() {
return;
}
cx.span_lint(UNSAFE_CODE, span, desc);
}
}
impl EarlyLintPass for UnsafeCode {
fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
if attr.check_name(sym::allow_internal_unsafe) {
self.report_unsafe(cx, attr.span, "`allow_internal_unsafe` allows defining \
macros using unsafe without triggering \
the `unsafe_code` lint at their call site");
}
}
fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
if let ast::ExprKind::Block(ref blk, _) = e.node {
// Don't warn about generated blocks; that'll just pollute the output.
if blk.rules == ast::BlockCheckMode::Unsafe(ast::UserProvided) {
self.report_unsafe(cx, blk.span, "usage of an `unsafe` block");
}
}
}
fn check_item(&mut self, cx: &EarlyContext<'_>, it: &ast::Item) {
match it.node {
ast::ItemKind::Trait(_, ast::Unsafety::Unsafe, ..) => {
self.report_unsafe(cx, it.span, "declaration of an `unsafe` trait")
}
ast::ItemKind::Impl(ast::Unsafety::Unsafe, ..) => {
self.report_unsafe(cx, it.span, "implementation of an `unsafe` trait")
}
_ => return,
}
}
fn check_fn(&mut self,
cx: &EarlyContext<'_>,
fk: FnKind<'_>,
_: &ast::FnDecl,
span: Span,
_: ast::NodeId) {
match fk {
FnKind::ItemFn(_, ast::FnHeader { unsafety: ast::Unsafety::Unsafe, .. }, ..) => {
self.report_unsafe(cx, span, "declaration of an `unsafe` function")
}
FnKind::Method(_, sig, ..) => {
if sig.header.unsafety == ast::Unsafety::Unsafe {
self.report_unsafe(cx, span, "implementation of an `unsafe` method")
}
}
_ => (),
}
}
fn check_trait_item(&mut self, cx: &EarlyContext<'_>, item: &ast::TraitItem) {
if let ast::TraitItemKind::Method(ref sig, None) = item.node {
if sig.header.unsafety == ast::Unsafety::Unsafe {
self.report_unsafe(cx, item.span, "declaration of an `unsafe` method")
}
}
}
}
declare_lint! {
pub MISSING_DOCS,
Allow,
"detects missing documentation for public members",
report_in_external_macro: true
}
pub struct MissingDoc {
/// Stack of whether `#[doc(hidden)]` is set at each level which has lint attributes.
doc_hidden_stack: Vec<bool>,
/// Private traits or trait items that leaked through. Don't check their methods.
private_traits: FxHashSet<hir::HirId>,
}
impl_lint_pass!(MissingDoc => [MISSING_DOCS]);
fn has_doc(attr: &ast::Attribute) -> bool {
if !attr.check_name(sym::doc) {
return false;
}
if attr.is_value_str() {
return true;
}
if let Some(list) = attr.meta_item_list() {
for meta in list {
if meta.check_name(sym::include) || meta.check_name(sym::hidden) {
return true;
}
}
}
false
}
impl MissingDoc {
pub fn new() -> MissingDoc {
MissingDoc {
doc_hidden_stack: vec![false],
private_traits: FxHashSet::default(),
}
}
fn doc_hidden(&self) -> bool {
*self.doc_hidden_stack.last().expect("empty doc_hidden_stack")
}
fn check_missing_docs_attrs(&self,
cx: &LateContext<'_, '_>,
id: Option<hir::HirId>,
attrs: &[ast::Attribute],
sp: Span,
desc: &'static str) {
// If we're building a test harness, then warning about
// documentation is probably not really relevant right now.
if cx.sess().opts.test {
return;
}
// `#[doc(hidden)]` disables missing_docs check.
if self.doc_hidden() {
return;
}
// Only check publicly-visible items, using the result from the privacy pass.
// It's an option so the crate root can also use this function (it doesn't
// have a `NodeId`).
if let Some(id) = id {
if !cx.access_levels.is_exported(id) {
return;
}
}
let has_doc = attrs.iter().any(|a| has_doc(a));
if !has_doc {
cx.span_lint(MISSING_DOCS,
cx.tcx.sess.source_map().def_span(sp),
&format!("missing documentation for {}", desc));
}
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
fn enter_lint_attrs(&mut self, _: &LateContext<'_, '_>, attrs: &[ast::Attribute]) {
let doc_hidden = self.doc_hidden() ||
attrs.iter().any(|attr| {
attr.check_name(sym::doc) &&
match attr.meta_item_list() {
None => false,
Some(l) => attr::list_contains_name(&l, sym::hidden),
}
});
self.doc_hidden_stack.push(doc_hidden);
}
fn exit_lint_attrs(&mut self, _: &LateContext<'_, '_>, _attrs: &[ast::Attribute]) {
self.doc_hidden_stack.pop().expect("empty doc_hidden_stack");
}
fn check_crate(&mut self, cx: &LateContext<'_, '_>, krate: &hir::Crate) {
self.check_missing_docs_attrs(cx, None, &krate.attrs, krate.span, "crate");
for macro_def in &krate.exported_macros {
let has_doc = macro_def.attrs.iter().any(|a| has_doc(a));
if !has_doc {
cx.span_lint(MISSING_DOCS,
cx.tcx.sess.source_map().def_span(macro_def.span),
"missing documentation for macro");
}
}
}
fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
let desc = match it.node {
hir::ItemKind::Fn(..) => "a function",
hir::ItemKind::Mod(..) => "a module",
hir::ItemKind::Enum(..) => "an enum",
hir::ItemKind::Struct(..) => "a struct",
hir::ItemKind::Union(..) => "a union",
hir::ItemKind::Trait(.., ref trait_item_refs) => {
// Issue #11592: traits are always considered exported, even when private.
if let hir::VisibilityKind::Inherited = it.vis.node {
self.private_traits.insert(it.hir_id);
for trait_item_ref in trait_item_refs {
self.private_traits.insert(trait_item_ref.id.hir_id);
}
return;
}
"a trait"
}
hir::ItemKind::Ty(..) => "a type alias",
hir::ItemKind::Impl(.., Some(ref trait_ref), _, ref impl_item_refs) => {
// If the trait is private, add the impl items to `private_traits` so they don't get
// reported for missing docs.
let real_trait = trait_ref.path.res.def_id();
if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(real_trait) {
match cx.tcx.hir().find(hir_id) {
Some(Node::Item(item)) => {
if let hir::VisibilityKind::Inherited = item.vis.node {
for impl_item_ref in impl_item_refs {
self.private_traits.insert(impl_item_ref.id.hir_id);
}
}
}
_ => {}
}
}
return;
}
hir::ItemKind::Const(..) => "a constant",
hir::ItemKind::Static(..) => "a static",
_ => return,
};
self.check_missing_docs_attrs(cx, Some(it.hir_id), &it.attrs, it.span, desc);
}
fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, trait_item: &hir::TraitItem) {
if self.private_traits.contains(&trait_item.hir_id) {
return;
}
let desc = match trait_item.node {
hir::TraitItemKind::Const(..) => "an associated constant",
hir::TraitItemKind::Method(..) => "a trait method",
hir::TraitItemKind::Type(..) => "an associated type",
};
self.check_missing_docs_attrs(cx,
Some(trait_item.hir_id),
&trait_item.attrs,
trait_item.span,
desc);
}
fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
// If the method is an impl for a trait, don't doc.
if method_context(cx, impl_item.hir_id) == MethodLateContext::TraitImpl {
return;
}
let desc = match impl_item.node {
hir::ImplItemKind::Const(..) => "an associated constant",
hir::ImplItemKind::Method(..) => "a method",
hir::ImplItemKind::Type(_) => "an associated type",
hir::ImplItemKind::Existential(_) => "an associated existential type",
};
self.check_missing_docs_attrs(cx,
Some(impl_item.hir_id),
&impl_item.attrs,
impl_item.span,
desc);
}
fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, sf: &hir::StructField) {
if !sf.is_positional() {
self.check_missing_docs_attrs(cx,
Some(sf.hir_id),
&sf.attrs,
sf.span,
"a struct field")
}
}
fn check_variant(&mut self, cx: &LateContext<'_, '_>, v: &hir::Variant, _: &hir::Generics) {
self.check_missing_docs_attrs(cx,
Some(v.node.id),
&v.node.attrs,
v.span,
"a variant");
}
}
declare_lint! {
pub MISSING_COPY_IMPLEMENTATIONS,
Allow,
"detects potentially-forgotten implementations of `Copy`"
}
declare_lint_pass!(MissingCopyImplementations => [MISSING_COPY_IMPLEMENTATIONS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingCopyImplementations {
fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
if !cx.access_levels.is_reachable(item.hir_id) {
return;
}
let (def, ty) = match item.node {
hir::ItemKind::Struct(_, ref ast_generics) => {
if !ast_generics.params.is_empty() {
return;
}
let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
(def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
}
hir::ItemKind::Union(_, ref ast_generics) => {
if !ast_generics.params.is_empty() {
return;
}
let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
(def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
}
hir::ItemKind::Enum(_, ref ast_generics) => {
if !ast_generics.params.is_empty() {
return;
}
let def = cx.tcx.adt_def(cx.tcx.hir().local_def_id(item.hir_id));
(def, cx.tcx.mk_adt(def, cx.tcx.intern_substs(&[])))
}
_ => return,
};
if def.has_dtor(cx.tcx) {
return;
}
let param_env = ty::ParamEnv::empty();
if ty.is_copy_modulo_regions(cx.tcx, param_env, item.span) {
return;
}
if param_env.can_type_implement_copy(cx.tcx, ty).is_ok() {
cx.span_lint(MISSING_COPY_IMPLEMENTATIONS,
item.span,
"type could implement `Copy`; consider adding `impl \
Copy`")
}
}
}
declare_lint! {
MISSING_DEBUG_IMPLEMENTATIONS,
Allow,
"detects missing implementations of fmt::Debug"
}
#[derive(Default)]
pub struct MissingDebugImplementations {
impling_types: Option<HirIdSet>,
}
impl_lint_pass!(MissingDebugImplementations => [MISSING_DEBUG_IMPLEMENTATIONS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDebugImplementations {
fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
if !cx.access_levels.is_reachable(item.hir_id) {
return;
}
match item.node {
hir::ItemKind::Struct(..) |
hir::ItemKind::Union(..) |
hir::ItemKind::Enum(..) => {}
_ => return,
}
let debug = match cx.tcx.lang_items().debug_trait() {
Some(debug) => debug,
None => return,
};
if self.impling_types.is_none() {
let mut impls = HirIdSet::default();
cx.tcx.for_each_impl(debug, |d| {
if let Some(ty_def) = cx.tcx.type_of(d).ty_adt_def() {
if let Some(hir_id) = cx.tcx.hir().as_local_hir_id(ty_def.did) {
impls.insert(hir_id);
}
}
});
self.impling_types = Some(impls);
debug!("{:?}", self.impling_types);
}
if !self.impling_types.as_ref().unwrap().contains(&item.hir_id) {
cx.span_lint(MISSING_DEBUG_IMPLEMENTATIONS,
item.span,
"type does not implement `fmt::Debug`; consider adding #[derive(Debug)] \
or a manual implementation")
}
}
}
declare_lint! {
pub ANONYMOUS_PARAMETERS,
Allow,
"detects anonymous parameters"
}
declare_lint_pass!(
/// Checks for use of anonymous parameters (RFC 1685).
AnonymousParameters => [ANONYMOUS_PARAMETERS]
);
impl EarlyLintPass for AnonymousParameters {
fn check_trait_item(&mut self, cx: &EarlyContext<'_>, it: &ast::TraitItem) {
match it.node {
ast::TraitItemKind::Method(ref sig, _) => {
for arg in sig.decl.inputs.iter() {
match arg.pat.node {
ast::PatKind::Ident(_, ident, None) => {
if ident.name == kw::Invalid {
let ty_snip = cx
.sess
.source_map()
.span_to_snippet(arg.ty.span);
let (ty_snip, appl) = if let Ok(snip) = ty_snip {
(snip, Applicability::MachineApplicable)
} else {
("<type>".to_owned(), Applicability::HasPlaceholders)
};
cx.struct_span_lint(
ANONYMOUS_PARAMETERS,
arg.pat.span,
"anonymous parameters are deprecated and will be \
removed in the next edition."
).span_suggestion(
arg.pat.span,
"Try naming the parameter or explicitly \
ignoring it",
format!("_: {}", ty_snip),
appl
).emit();
}
}
_ => (),
}
}
},
_ => (),
}
}
}
/// Check for use of attributes which have been deprecated.
#[derive(Clone)]
pub struct DeprecatedAttr {
// This is not free to compute, so we want to keep it around, rather than
// compute it for every attribute.
depr_attrs: Vec<&'static (Symbol, AttributeType, AttributeTemplate, AttributeGate)>,
}
impl_lint_pass!(DeprecatedAttr => []);
impl DeprecatedAttr {
pub fn new() -> DeprecatedAttr {
DeprecatedAttr {
depr_attrs: deprecated_attributes(),
}
}
}
impl EarlyLintPass for DeprecatedAttr {
fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &ast::Attribute) {
for &&(n, _, _, ref g) in &self.depr_attrs {
if attr.ident().map(|ident| ident.name) == Some(n) {
if let &AttributeGate::Gated(Stability::Deprecated(link, suggestion),
ref name,
ref reason,
_) = g {
let msg = format!("use of deprecated attribute `{}`: {}. See {}",
name, reason, link);
let mut err = cx.struct_span_lint(DEPRECATED, attr.span, &msg);
err.span_suggestion_short(
attr.span,
suggestion.unwrap_or("remove this attribute"),
String::new(),
Applicability::MachineApplicable
);
err.emit();
}
return;
}
}
}
}
declare_lint! {
pub UNUSED_DOC_COMMENTS,
Warn,
"detects doc comments that aren't used by rustdoc"
}
declare_lint_pass!(UnusedDocComment => [UNUSED_DOC_COMMENTS]);
impl UnusedDocComment {
fn warn_if_doc(
&self,
cx: &EarlyContext<'_>,
node_span: Span,
node_kind: &str,
is_macro_expansion: bool,
attrs: &[ast::Attribute]
) {
let mut attrs = attrs.into_iter().peekable();
// Accumulate a single span for sugared doc comments.
let mut sugared_span: Option<Span> = None;
while let Some(attr) = attrs.next() {
if attr.is_sugared_doc {
sugared_span = Some(
sugared_span.map_or_else(
|| attr.span,
|span| span.with_hi(attr.span.hi()),
),
);
}
if attrs.peek().map(|next_attr| next_attr.is_sugared_doc).unwrap_or_default() {
continue;
}
let span = sugared_span.take().unwrap_or_else(|| attr.span);
if attr.check_name(sym::doc) {
let mut err = cx.struct_span_lint(UNUSED_DOC_COMMENTS, span, "unused doc comment");
err.span_label(
node_span,
format!("rustdoc does not generate documentation for {}", node_kind)
);
if is_macro_expansion {
err.help("to document an item produced by a macro, \
the macro must produce the documentation as part of its expansion");
}
err.emit();
}
}
}
}
impl EarlyLintPass for UnusedDocComment {
fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
if let ast::ItemKind::Mac(..) = item.node {
self.warn_if_doc(cx, item.span, "macro expansions", true, &item.attrs);
}
}
fn check_stmt(&mut self, cx: &EarlyContext<'_>, stmt: &ast::Stmt) {
let (kind, is_macro_expansion) = match stmt.node {
ast::StmtKind::Local(..) => ("statements", false),
ast::StmtKind::Item(..) => ("inner items", false),
ast::StmtKind::Mac(..) => ("macro expansions", true),
// expressions will be reported by `check_expr`.
ast::StmtKind::Semi(..) |
ast::StmtKind::Expr(..) => return,
};
self.warn_if_doc(cx, stmt.span, kind, is_macro_expansion, stmt.node.attrs());
}
fn check_arm(&mut self, cx: &EarlyContext<'_>, arm: &ast::Arm) {
let arm_span = arm.pats[0].span.with_hi(arm.body.span.hi());
self.warn_if_doc(cx, arm_span, "match arms", false, &arm.attrs);
}
fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &ast::Expr) {
self.warn_if_doc(cx, expr.span, "expressions", false, &expr.attrs);
}
}
declare_lint! {
PLUGIN_AS_LIBRARY,
Warn,
"compiler plugin used as ordinary library in non-plugin crate"
}
declare_lint_pass!(PluginAsLibrary => [PLUGIN_AS_LIBRARY]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PluginAsLibrary {
fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
if cx.tcx.plugin_registrar_fn(LOCAL_CRATE).is_some() {
// We're compiling a plugin; it's fine to link other plugins.
return;
}
match it.node {
hir::ItemKind::ExternCrate(..) => (),
_ => return,
};
let def_id = cx.tcx.hir().local_def_id(it.hir_id);
let prfn = match cx.tcx.extern_mod_stmt_cnum(def_id) {
Some(cnum) => cx.tcx.plugin_registrar_fn(cnum),
None => {
// Probably means we aren't linking the crate for some reason.
//
// Not sure if / when this could happen.
return;
}
};
if prfn.is_some() {
cx.span_lint(PLUGIN_AS_LIBRARY,
it.span,
"compiler plugin used as an ordinary library");
}
}
}
declare_lint! {
NO_MANGLE_CONST_ITEMS,
Deny,
"const items will not have their symbols exported"
}
declare_lint! {
NO_MANGLE_GENERIC_ITEMS,
Warn,
"generic items must be mangled"
}
declare_lint_pass!(InvalidNoMangleItems => [NO_MANGLE_CONST_ITEMS, NO_MANGLE_GENERIC_ITEMS]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidNoMangleItems {
fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
match it.node {
hir::ItemKind::Fn(.., ref generics, _) => {
if let Some(no_mangle_attr) = attr::find_by_name(&it.attrs, sym::no_mangle) {
for param in &generics.params {
match param.kind {
GenericParamKind::Lifetime { .. } => {}
GenericParamKind::Type { .. } |
GenericParamKind::Const { .. } => {
let mut err = cx.struct_span_lint(
NO_MANGLE_GENERIC_ITEMS,
it.span,
"functions generic over types or consts must be mangled",
);
err.span_suggestion_short(
no_mangle_attr.span,
"remove this attribute",
String::new(),
// Use of `#[no_mangle]` suggests FFI intent; correct
// fix may be to monomorphize source by hand
Applicability::MaybeIncorrect
);
err.emit();
break;
}
}
}
}
}
hir::ItemKind::Const(..) => {
if attr::contains_name(&it.attrs, sym::no_mangle) {
// Const items do not refer to a particular location in memory, and therefore
// don't have anything to attach a symbol to
let msg = "const items should never be #[no_mangle]";
let mut err = cx.struct_span_lint(NO_MANGLE_CONST_ITEMS, it.span, msg);
// account for "pub const" (#45562)
let start = cx.tcx.sess.source_map().span_to_snippet(it.span)
.map(|snippet| snippet.find("const").unwrap_or(0))
.unwrap_or(0) as u32;
// `const` is 5 chars
let const_span = it.span.with_hi(BytePos(it.span.lo().0 + start + 5));
err.span_suggestion(
const_span,
"try a static value",
"pub static".to_owned(),
Applicability::MachineApplicable
);
err.emit();
}
}
_ => {}
}
}
}
declare_lint! {
MUTABLE_TRANSMUTES,
Deny,
"mutating transmuted &mut T from &T may cause undefined behavior"
}
declare_lint_pass!(MutableTransmutes => [MUTABLE_TRANSMUTES]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableTransmutes {
fn check_expr(&mut self, cx: &LateContext<'_, '_>, expr: &hir::Expr) {
use rustc_target::spec::abi::Abi::RustIntrinsic;
let msg = "mutating transmuted &mut T from &T may cause undefined behavior, \
consider instead using an UnsafeCell";
match get_transmute_from_to(cx, expr).map(|(ty1, ty2)| (&ty1.sty, &ty2.sty)) {
Some((&ty::Ref(_, _, from_mt), &ty::Ref(_, _, to_mt))) => {
if to_mt == hir::Mutability::MutMutable &&
from_mt == hir::Mutability::MutImmutable {
cx.span_lint(MUTABLE_TRANSMUTES, expr.span, msg);
}
}
_ => (),
}
fn get_transmute_from_to<'a, 'tcx>
(cx: &LateContext<'a, 'tcx>,
expr: &hir::Expr)
-> Option<(Ty<'tcx>, Ty<'tcx>)> {
let def = if let hir::ExprKind::Path(ref qpath) = expr.node {
cx.tables.qpath_res(qpath, expr.hir_id)
} else {
return None;
};
if let Res::Def(DefKind::Fn, did) = def {
if !def_id_is_transmute(cx, did) {
return None;
}
let sig = cx.tables.node_type(expr.hir_id).fn_sig(cx.tcx);
let from = sig.inputs().skip_binder()[0];
let to = *sig.output().skip_binder();
return Some((from, to));
}
None
}
fn def_id_is_transmute(cx: &LateContext<'_, '_>, def_id: DefId) -> bool {
cx.tcx.fn_sig(def_id).abi() == RustIntrinsic &&
cx.tcx.item_name(def_id) == sym::transmute
}
}
}
declare_lint! {
UNSTABLE_FEATURES,
Allow,
"enabling unstable features (deprecated. do not use)"
}
declare_lint_pass!(
/// Forbids using the `#[feature(...)]` attribute
UnstableFeatures => [UNSTABLE_FEATURES]
);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnstableFeatures {
fn check_attribute(&mut self, ctx: &LateContext<'_, '_>, attr: &ast::Attribute) {
if attr.check_name(sym::feature) {
if let Some(items) = attr.meta_item_list() {
for item in items {
ctx.span_lint(UNSTABLE_FEATURES, item.span(), "unstable feature");
}
}
}
}
}
declare_lint! {
UNIONS_WITH_DROP_FIELDS,
Warn,
"use of unions that contain fields with possibly non-trivial drop code"
}
declare_lint_pass!(
/// Lint for unions that contain fields with possibly non-trivial destructors.
UnionsWithDropFields => [UNIONS_WITH_DROP_FIELDS]
);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnionsWithDropFields {
fn check_item(&mut self, ctx: &LateContext<'_, '_>, item: &hir::Item) {
if let hir::ItemKind::Union(ref vdata, _) = item.node {
for field in vdata.fields() {
let field_ty = ctx.tcx.type_of(
ctx.tcx.hir().local_def_id(field.hir_id));
if field_ty.needs_drop(ctx.tcx, ctx.param_env) {
ctx.span_lint(UNIONS_WITH_DROP_FIELDS,
field.span,
"union contains a field with possibly non-trivial drop code, \
drop code of union fields is ignored when dropping the union");
return;
}
}
}
}
}
declare_lint! {
pub UNREACHABLE_PUB,
Allow,
"`pub` items not reachable from crate root"
}
declare_lint_pass!(
/// Lint for items marked `pub` that aren't reachable from other crates.
UnreachablePub => [UNREACHABLE_PUB]
);
impl UnreachablePub {
fn perform_lint(&self, cx: &LateContext<'_, '_>, what: &str, id: hir::HirId,
vis: &hir::Visibility, span: Span, exportable: bool) {
let mut applicability = Applicability::MachineApplicable;
match vis.node {
hir::VisibilityKind::Public if !cx.access_levels.is_reachable(id) => {
if span.ctxt().outer_expn_info().is_some() {
applicability = Applicability::MaybeIncorrect;
}
let def_span = cx.tcx.sess.source_map().def_span(span);
let mut err = cx.struct_span_lint(UNREACHABLE_PUB, def_span,
&format!("unreachable `pub` {}", what));
let replacement = if cx.tcx.features().crate_visibility_modifier {
"crate"
} else {
"pub(crate)"
}.to_owned();
err.span_suggestion(
vis.span,
"consider restricting its visibility",
replacement,
applicability,
);
if exportable {
err.help("or consider exporting it for use by other crates");
}
err.emit();
},
_ => {}
}
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnreachablePub {
fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
self.perform_lint(cx, "item", item.hir_id, &item.vis, item.span, true);
}
fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, foreign_item: &hir::ForeignItem) {
self.perform_lint(cx, "item", foreign_item.hir_id, &foreign_item.vis,
foreign_item.span, true);
}
fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField) {
self.perform_lint(cx, "field", field.hir_id, &field.vis, field.span, false);
}
fn check_impl_item(&mut self, cx: &LateContext<'_, '_>, impl_item: &hir::ImplItem) {
self.perform_lint(cx, "item", impl_item.hir_id, &impl_item.vis, impl_item.span, false);
}
}
declare_lint! {
TYPE_ALIAS_BOUNDS,
Warn,
"bounds in type aliases are not enforced"
}
declare_lint_pass!(
/// Lint for trait and lifetime bounds in type aliases being mostly ignored.
/// They are relevant when using associated types, but otherwise neither checked
/// at definition site nor enforced at use site.
TypeAliasBounds => [TYPE_ALIAS_BOUNDS]
);
impl TypeAliasBounds {
fn is_type_variable_assoc(qpath: &hir::QPath) -> bool {
match *qpath {
hir::QPath::TypeRelative(ref ty, _) => {
// If this is a type variable, we found a `T::Assoc`.
match ty.node {
hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
match path.res {
Res::Def(DefKind::TyParam, _) => true,
_ => false
}
}
_ => false
}
}
hir::QPath::Resolved(..) => false,
}
}
fn suggest_changing_assoc_types(ty: &hir::Ty, err: &mut DiagnosticBuilder<'_>) {
// Access to associates types should use `<T as Bound>::Assoc`, which does not need a
// bound. Let's see if this type does that.
// We use a HIR visitor to walk the type.
use rustc::hir::intravisit::{self, Visitor};
struct WalkAssocTypes<'a, 'db> {
err: &'a mut DiagnosticBuilder<'db>
}
impl<'a, 'db, 'v> Visitor<'v> for WalkAssocTypes<'a, 'db> {
fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'v>
{
intravisit::NestedVisitorMap::None
}
fn visit_qpath(&mut self, qpath: &'v hir::QPath, id: hir::HirId, span: Span) {
if TypeAliasBounds::is_type_variable_assoc(qpath) {
self.err.span_help(span,
"use fully disambiguated paths (i.e., `<T as Trait>::Assoc`) to refer to \
associated types in type aliases");
}
intravisit::walk_qpath(self, qpath, id, span)
}
}
// Let's go for a walk!
let mut visitor = WalkAssocTypes { err };
visitor.visit_ty(ty);
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeAliasBounds {
fn check_item(&mut self, cx: &LateContext<'_, '_>, item: &hir::Item) {
let (ty, type_alias_generics) = match item.node {
hir::ItemKind::Ty(ref ty, ref generics) => (&*ty, generics),
_ => return,
};
let mut suggested_changing_assoc_types = false;
// There must not be a where clause
if !type_alias_generics.where_clause.predicates.is_empty() {
let spans : Vec<_> = type_alias_generics.where_clause.predicates.iter()
.map(|pred| pred.span()).collect();
let mut err = cx.struct_span_lint(TYPE_ALIAS_BOUNDS, spans,
"where clauses are not enforced in type aliases");
err.help("the clause will not be checked when the type alias is used, \
and should be removed");
if !suggested_changing_assoc_types {
TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
suggested_changing_assoc_types = true;
}
err.emit();
}
// The parameters must not have bounds
for param in type_alias_generics.params.iter() {
let spans: Vec<_> = param.bounds.iter().map(|b| b.span()).collect();
if !spans.is_empty() {
let mut err = cx.struct_span_lint(
TYPE_ALIAS_BOUNDS,
spans,
"bounds on generic parameters are not enforced in type aliases",
);
err.help("the bound will not be checked when the type alias is used, \
and should be removed");
if !suggested_changing_assoc_types {
TypeAliasBounds::suggest_changing_assoc_types(ty, &mut err);
suggested_changing_assoc_types = true;
}
err.emit();
}
}
}
}
declare_lint_pass!(
/// Lint constants that are erroneous.
/// Without this lint, we might not get any diagnostic if the constant is
/// unused within this crate, even though downstream crates can't use it
/// without producing an error.
UnusedBrokenConst => []
);
fn check_const(cx: &LateContext<'_, '_>, body_id: hir::BodyId) {
let def_id = cx.tcx.hir().body_owner_def_id(body_id);
let param_env = if cx.tcx.is_static(def_id) {
// Use the same param_env as `codegen_static_initializer`, to reuse the cache.
ty::ParamEnv::reveal_all()
} else {
cx.tcx.param_env(def_id)
};
let cid = ::rustc::mir::interpret::GlobalId {
instance: ty::Instance::mono(cx.tcx, def_id),
promoted: None
};
// trigger the query once for all constants since that will already report the errors
// FIXME: Use ensure here
let _ = cx.tcx.const_eval(param_env.and(cid));
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedBrokenConst {
fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
match it.node {
hir::ItemKind::Const(_, body_id) => {
check_const(cx, body_id);
},
hir::ItemKind::Static(_, _, body_id) => {
check_const(cx, body_id);
},
_ => {},
}
}
}
declare_lint! {
TRIVIAL_BOUNDS,
Warn,
"these bounds don't depend on an type parameters"
}
declare_lint_pass!(
/// Lint for trait and lifetime bounds that don't depend on type parameters
/// which either do nothing, or stop the item from being used.
TrivialConstraints => [TRIVIAL_BOUNDS]
);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TrivialConstraints {
fn check_item(
&mut self,
cx: &LateContext<'a, 'tcx>,
item: &'tcx hir::Item,
) {
use rustc::ty::fold::TypeFoldable;
use rustc::ty::Predicate::*;
if cx.tcx.features().trivial_bounds {
let def_id = cx.tcx.hir().local_def_id(item.hir_id);
let predicates = cx.tcx.predicates_of(def_id);
for &(predicate, span) in &predicates.predicates {
let predicate_kind_name = match predicate {
Trait(..) => "Trait",
TypeOutlives(..) |
RegionOutlives(..) => "Lifetime",
// Ignore projections, as they can only be global
// if the trait bound is global
Projection(..) |
// Ignore bounds that a user can't type
WellFormed(..) |
ObjectSafe(..) |
ClosureKind(..) |
Subtype(..) |
ConstEvaluatable(..) => continue,
};
if predicate.is_global() {
cx.span_lint(
TRIVIAL_BOUNDS,
span,
&format!("{} bound {} does not depend on any type \
or lifetime parameters", predicate_kind_name, predicate),
);
}
}
}
}
}
declare_lint_pass!(
/// Does nothing as a lint pass, but registers some `Lint`s
/// which are used by other parts of the compiler.
SoftLints => [
WHILE_TRUE,
BOX_POINTERS,
NON_SHORTHAND_FIELD_PATTERNS,
UNSAFE_CODE,
MISSING_DOCS,
MISSING_COPY_IMPLEMENTATIONS,
MISSING_DEBUG_IMPLEMENTATIONS,
ANONYMOUS_PARAMETERS,
UNUSED_DOC_COMMENTS,
PLUGIN_AS_LIBRARY,
NO_MANGLE_CONST_ITEMS,
NO_MANGLE_GENERIC_ITEMS,
MUTABLE_TRANSMUTES,
UNSTABLE_FEATURES,
UNIONS_WITH_DROP_FIELDS,
UNREACHABLE_PUB,
TYPE_ALIAS_BOUNDS,
TRIVIAL_BOUNDS
]
);
declare_lint! {
pub ELLIPSIS_INCLUSIVE_RANGE_PATTERNS,
Warn,
"`...` range patterns are deprecated"
}
#[derive(Default)]
pub struct EllipsisInclusiveRangePatterns {
/// If `Some(_)`, suppress all subsequent pattern
/// warnings for better diagnostics.
node_id: Option<ast::NodeId>,
}
impl_lint_pass!(EllipsisInclusiveRangePatterns => [ELLIPSIS_INCLUSIVE_RANGE_PATTERNS]);
impl EarlyLintPass for EllipsisInclusiveRangePatterns {
fn check_pat(&mut self, cx: &EarlyContext<'_>, pat: &ast::Pat) {
if self.node_id.is_some() {
// Don't recursively warn about patterns inside range endpoints.
return
}
use self::ast::{PatKind, RangeEnd, RangeSyntax::DotDotDot};
/// If `pat` is a `...` pattern, return the start and end of the range, as well as the span
/// corresponding to the ellipsis.
fn matches_ellipsis_pat(pat: &ast::Pat) -> Option<(&P<Expr>, &P<Expr>, Span)> {
match &pat.node {
PatKind::Range(a, b, Spanned { span, node: RangeEnd::Included(DotDotDot), .. }) => {
Some((a, b, *span))
}
_ => None,
}
}
let (parenthesise, endpoints) = match &pat.node {
PatKind::Ref(subpat, _) => (true, matches_ellipsis_pat(&subpat)),
_ => (false, matches_ellipsis_pat(pat)),
};
if let Some((start, end, join)) = endpoints {
let msg = "`...` range patterns are deprecated";
let suggestion = "use `..=` for an inclusive range";
if parenthesise {
self.node_id = Some(pat.id);
let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, pat.span, msg);
err.span_suggestion(
pat.span,
suggestion,
format!("&({}..={})", expr_to_string(&start), expr_to_string(&end)),
Applicability::MachineApplicable,
);
err.emit();
} else {
let mut err = cx.struct_span_lint(ELLIPSIS_INCLUSIVE_RANGE_PATTERNS, join, msg);
err.span_suggestion_short(
join,
suggestion,
"..=".to_owned(),
Applicability::MachineApplicable,
);
err.emit();
};
}
}
fn check_pat_post(&mut self, _cx: &EarlyContext<'_>, pat: &ast::Pat) {
if let Some(node_id) = self.node_id {
if pat.id == node_id {
self.node_id = None
}
}
}
}
declare_lint! {
UNNAMEABLE_TEST_ITEMS,
Warn,
"detects an item that cannot be named being marked as #[test_case]",
report_in_external_macro: true
}
pub struct UnnameableTestItems {
boundary: hir::HirId, // HirId of the item under which things are not nameable
items_nameable: bool,
}
impl_lint_pass!(UnnameableTestItems => [UNNAMEABLE_TEST_ITEMS]);
impl UnnameableTestItems {
pub fn new() -> Self {
Self {
boundary: hir::DUMMY_HIR_ID,
items_nameable: true
}
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnameableTestItems {
fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
if self.items_nameable {
if let hir::ItemKind::Mod(..) = it.node {}
else {
self.items_nameable = false;
self.boundary = it.hir_id;
}
return;
}
if let Some(attr) = attr::find_by_name(&it.attrs, sym::rustc_test_marker) {
cx.struct_span_lint(
UNNAMEABLE_TEST_ITEMS,
attr.span,
"cannot test inner items",
).emit();
}
}
fn check_item_post(&mut self, _cx: &LateContext<'_, '_>, it: &hir::Item) {
if !self.items_nameable && self.boundary == it.hir_id {
self.items_nameable = true;
}
}
}
declare_lint! {
pub KEYWORD_IDENTS,
Allow,
"detects edition keywords being used as an identifier"
}
declare_lint_pass!(
/// Check for uses of edition keywords used as an identifier.
KeywordIdents => [KEYWORD_IDENTS]
);
struct UnderMacro(bool);
impl KeywordIdents {
fn check_tokens(&mut self, cx: &EarlyContext<'_>, tokens: TokenStream) {
for tt in tokens.into_trees() {
match tt {
// Only report non-raw idents.
TokenTree::Token(token) => if let Some((ident, false)) = token.ident() {
self.check_ident_token(cx, UnderMacro(true), ident);
}
TokenTree::Delimited(_, _, tts) => {
self.check_tokens(cx, tts)
},
}
}
}
fn check_ident_token(&mut self,
cx: &EarlyContext<'_>,
UnderMacro(under_macro): UnderMacro,
ident: ast::Ident)
{
let next_edition = match cx.sess.edition() {
Edition::Edition2015 => {
match ident.name {
kw::Async | kw::Await | kw::Try => Edition::Edition2018,
// rust-lang/rust#56327: Conservatively do not
// attempt to report occurrences of `dyn` within
// macro definitions or invocations, because `dyn`
// can legitimately occur as a contextual keyword
// in 2015 code denoting its 2018 meaning, and we
// do not want rustfix to inject bugs into working
// code by rewriting such occurrences.
//
// But if we see `dyn` outside of a macro, we know
// its precise role in the parsed AST and thus are
// assured this is truly an attempt to use it as
// an identifier.
kw::Dyn if !under_macro => Edition::Edition2018,
_ => return,
}
}
// There are no new keywords yet for the 2018 edition and beyond.
_ => return,
};
// Don't lint `r#foo`.
if cx.sess.parse_sess.raw_identifier_spans.borrow().contains(&ident.span) {
return;
}
let mut lint = cx.struct_span_lint(
KEYWORD_IDENTS,
ident.span,
&format!("`{}` is a keyword in the {} edition",
ident.as_str(),
next_edition),
);
lint.span_suggestion(
ident.span,
"you can use a raw identifier to stay compatible",
format!("r#{}", ident.as_str()),
Applicability::MachineApplicable,
);
lint.emit()
}
}
impl EarlyLintPass for KeywordIdents {
fn check_mac_def(&mut self, cx: &EarlyContext<'_>, mac_def: &ast::MacroDef, _id: ast::NodeId) {
self.check_tokens(cx, mac_def.stream());
}
fn check_mac(&mut self, cx: &EarlyContext<'_>, mac: &ast::Mac) {
self.check_tokens(cx, mac.node.tts.clone().into());
}
fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: ast::Ident) {
self.check_ident_token(cx, UnderMacro(false), ident);
}
}
declare_lint_pass!(ExplicitOutlivesRequirements => [EXPLICIT_OUTLIVES_REQUIREMENTS]);
impl ExplicitOutlivesRequirements {
fn lifetimes_outliving_lifetime<'tcx>(
inferred_outlives: &'tcx [ty::Predicate<'tcx>],
index: u32,
) -> Vec<ty::Region<'tcx>> {
inferred_outlives.iter().filter_map(|pred| {
match pred {
ty::Predicate::RegionOutlives(outlives) => {
let outlives = outlives.skip_binder();
match outlives.0 {
ty::ReEarlyBound(ebr) if ebr.index == index => {
Some(outlives.1)
}
_ => None,
}
}
_ => None
}
}).collect()
}
fn lifetimes_outliving_type<'tcx>(
inferred_outlives: &'tcx [ty::Predicate<'tcx>],
index: u32,
) -> Vec<ty::Region<'tcx>> {
inferred_outlives.iter().filter_map(|pred| {
match pred {
ty::Predicate::TypeOutlives(outlives) => {
let outlives = outlives.skip_binder();
if outlives.0.is_param(index) {
Some(outlives.1)
} else {
None
}
}
_ => None
}
}).collect()
}
fn collect_outlived_lifetimes<'tcx>(
&self,
param: &'tcx hir::GenericParam,
tcx: TyCtxt<'tcx>,
inferred_outlives: &'tcx [ty::Predicate<'tcx>],
ty_generics: &'tcx ty::Generics,
) -> Vec<ty::Region<'tcx>> {
let index = ty_generics.param_def_id_to_index[
&tcx.hir().local_def_id(param.hir_id)];
match param.kind {
hir::GenericParamKind::Lifetime { .. } => {
Self::lifetimes_outliving_lifetime(inferred_outlives, index)
}
hir::GenericParamKind::Type { .. } => {
Self::lifetimes_outliving_type(inferred_outlives, index)
}
hir::GenericParamKind::Const { .. } => Vec::new(),
}
}
fn collect_outlives_bound_spans<'tcx>(
&self,
tcx: TyCtxt<'tcx>,
bounds: &hir::GenericBounds,
inferred_outlives: &[ty::Region<'tcx>],
infer_static: bool,
) -> Vec<(usize, Span)> {
use rustc::middle::resolve_lifetime::Region;
bounds
.iter()
.enumerate()
.filter_map(|(i, bound)| {
if let hir::GenericBound::Outlives(lifetime) = bound {
let is_inferred = match tcx.named_region(lifetime.hir_id) {
Some(Region::Static) if infer_static => {
inferred_outlives.iter()
.any(|r| if let ty::ReStatic = r { true } else { false })
}
Some(Region::EarlyBound(index, ..)) => inferred_outlives
.iter()
.any(|r| {
if let ty::ReEarlyBound(ebr) = r {
ebr.index == index
} else {
false
}
}),
_ => false,
};
if is_inferred {
Some((i, bound.span()))
} else {
None
}
} else {
None
}
})
.collect()
}
fn consolidate_outlives_bound_spans(
&self,
lo: Span,
bounds: &hir::GenericBounds,
bound_spans: Vec<(usize, Span)>
) -> Vec<Span> {
if bounds.is_empty() {
return Vec::new();
}
if bound_spans.len() == bounds.len() {
let (_, last_bound_span) = bound_spans[bound_spans.len()-1];
// If all bounds are inferable, we want to delete the colon, so
// start from just after the parameter (span passed as argument)
vec![lo.to(last_bound_span)]
} else {
let mut merged = Vec::new();
let mut last_merged_i = None;
let mut from_start = true;
for (i, bound_span) in bound_spans {
match last_merged_i {
// If the first bound is inferable, our span should also eat the leading `+`.
None if i == 0 => {
merged.push(bound_span.to(bounds[1].span().shrink_to_lo()));
last_merged_i = Some(0);
},
// If consecutive bounds are inferable, merge their spans
Some(h) if i == h+1 => {
if let Some(tail) = merged.last_mut() {
// Also eat the trailing `+` if the first
// more-than-one bound is inferable
let to_span = if from_start && i < bounds.len() {
bounds[i+1].span().shrink_to_lo()
} else {
bound_span
};
*tail = tail.to(to_span);
last_merged_i = Some(i);
} else {
bug!("another bound-span visited earlier");
}
},
_ => {
// When we find a non-inferable bound, subsequent inferable bounds
// won't be consecutive from the start (and we'll eat the leading
// `+` rather than the trailing one)
from_start = false;
merged.push(bounds[i-1].span().shrink_to_hi().to(bound_span));
last_merged_i = Some(i);
}
}
}
merged
}
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ExplicitOutlivesRequirements {
fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
use rustc::middle::resolve_lifetime::Region;
let infer_static = cx.tcx.features().infer_static_outlives_requirements;
let def_id = cx.tcx.hir().local_def_id(item.hir_id);
if let hir::ItemKind::Struct(_, ref hir_generics)
| hir::ItemKind::Enum(_, ref hir_generics)
| hir::ItemKind::Union(_, ref hir_generics) = item.node
{
let inferred_outlives = cx.tcx.inferred_outlives_of(def_id);
if inferred_outlives.is_empty() {
return;
}
let ty_generics = cx.tcx.generics_of(def_id);
let mut bound_count = 0;
let mut lint_spans = Vec::new();
for param in &hir_generics.params {
let has_lifetime_bounds = param.bounds.iter().any(|bound| {
if let hir::GenericBound::Outlives(_) = bound {
true
} else {
false
}
});
if !has_lifetime_bounds {
continue;
}
let relevant_lifetimes = self.collect_outlived_lifetimes(
param,
cx.tcx,
inferred_outlives,
ty_generics,
);
if relevant_lifetimes.is_empty() {
continue;
}
let bound_spans = self.collect_outlives_bound_spans(
cx.tcx, &param.bounds, &relevant_lifetimes, infer_static,
);
bound_count += bound_spans.len();
lint_spans.extend(
self.consolidate_outlives_bound_spans(
param.span.shrink_to_hi(), &param.bounds, bound_spans
)
);
}
let mut where_lint_spans = Vec::new();
let mut dropped_predicate_count = 0;
let num_predicates = hir_generics.where_clause.predicates.len();
for (i, where_predicate) in hir_generics.where_clause.predicates.iter().enumerate() {
let (relevant_lifetimes, bounds, span) = match where_predicate {
hir::WherePredicate::RegionPredicate(predicate) => {
if let Some(Region::EarlyBound(index, ..))
= cx.tcx.named_region(predicate.lifetime.hir_id)
{
(
Self::lifetimes_outliving_lifetime(inferred_outlives, index),
&predicate.bounds,
predicate.span,
)
} else {
continue;
}
}
hir::WherePredicate::BoundPredicate(predicate) => {
// FIXME we can also infer bounds on associated types,
// and should check for them here.
match predicate.bounded_ty.node {
hir::TyKind::Path(hir::QPath::Resolved(
None,
ref path,
)) => {
if let Res::Def(DefKind::TyParam, def_id) = path.res {
let index = ty_generics.param_def_id_to_index[&def_id];
(
Self::lifetimes_outliving_type(inferred_outlives, index),
&predicate.bounds,
predicate.span,
)
} else {
continue;
}
},
_ => { continue; }
}
}
_ => continue,
};
if relevant_lifetimes.is_empty() {
continue;
}
let bound_spans = self.collect_outlives_bound_spans(
cx.tcx, bounds, &relevant_lifetimes, infer_static,
);
bound_count += bound_spans.len();
let drop_predicate = bound_spans.len() == bounds.len();
if drop_predicate {
dropped_predicate_count += 1;
}
// If all the bounds on a predicate were inferable and there are
// further predicates, we want to eat the trailing comma.
if drop_predicate && i + 1 < num_predicates {
let next_predicate_span = hir_generics.where_clause.predicates[i + 1].span();
where_lint_spans.push(
span.to(next_predicate_span.shrink_to_lo())
);
} else {
where_lint_spans.extend(
self.consolidate_outlives_bound_spans(
span.shrink_to_lo(),
bounds,
bound_spans
)
);
}
}
// If all predicates are inferable, drop the entire clause
// (including the `where`)
if num_predicates > 0 && dropped_predicate_count == num_predicates {
let where_span = hir_generics.where_clause.span()
.expect("span of (nonempty) where clause should exist");
// Extend the where clause back to the closing `>` of the
// generics, except for tuple struct, which have the `where`
// after the fields of the struct.
let full_where_span = if let hir::ItemKind::Struct(hir::VariantData::Tuple(..), _)
= item.node
{
where_span
} else {
hir_generics.span.shrink_to_hi().to(where_span)
};
lint_spans.push(
full_where_span
);
} else {
lint_spans.extend(where_lint_spans);
}
if !lint_spans.is_empty() {
let mut err = cx.struct_span_lint(
EXPLICIT_OUTLIVES_REQUIREMENTS,
lint_spans.clone(),
"outlives requirements can be inferred"
);
err.multipart_suggestion(
if bound_count == 1 {
"remove this bound"
} else {
"remove these bounds"
},
lint_spans.into_iter().map(|span| (span, "".to_owned())).collect::<Vec<_>>(),
Applicability::MachineApplicable
);
err.emit();
}
}
}
}
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