-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-use middle::pat_util;
-use middle::ty;
-use middle::ty::adjustment;
-use util::nodemap::FnvHashMap;
+use rustc::hir::def::{Res, DefKind};
+use rustc::hir::def_id::DefId;
+use rustc::lint;
+use rustc::ty::{self, Ty};
+use rustc::ty::adjustment;
+use rustc_data_structures::fx::FxHashMap;
use lint::{LateContext, EarlyContext, LintContext, LintArray};
use lint::{LintPass, EarlyLintPass, LateLintPass};
-use std::collections::hash_map::Entry::{Occupied, Vacant};
-
use syntax::ast;
-use syntax::attr::{self, AttrMetaMethods};
-use syntax::codemap::Span;
-use syntax::feature_gate::{KNOWN_ATTRIBUTES, AttributeType};
-use syntax::ptr::P;
-
-use rustc_back::slice;
-use rustc_front::hir;
-use rustc_front::intravisit::FnKind;
-
-declare_lint! {
- pub UNUSED_MUT,
- Warn,
- "detect mut variables which don't need to be mutable"
-}
-
-#[derive(Copy, Clone)]
-pub struct UnusedMut;
-
-impl UnusedMut {
- fn check_unused_mut_pat(&self, cx: &LateContext, pats: &[P<hir::Pat>]) {
- // collect all mutable pattern and group their NodeIDs by their Identifier to
- // avoid false warnings in match arms with multiple patterns
-
- let mut mutables = FnvHashMap();
- for p in pats {
- pat_util::pat_bindings(&cx.tcx.def_map, p, |mode, id, _, path1| {
- let name = path1.node;
- if let hir::BindByValue(hir::MutMutable) = mode {
- if !name.as_str().starts_with("_") {
- match mutables.entry(name.0 as usize) {
- Vacant(entry) => { entry.insert(vec![id]); },
- Occupied(mut entry) => { entry.get_mut().push(id); },
- }
- }
- }
- });
- }
+use syntax::attr;
+use syntax::errors::Applicability;
+use syntax::feature_gate::{AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
+use syntax::print::pprust;
+use syntax::symbol::{kw, sym};
+use syntax::symbol::Symbol;
+use syntax::util::parser;
+use syntax_pos::{Span, BytePos};
- let used_mutables = cx.tcx.used_mut_nodes.borrow();
- for (_, v) in &mutables {
- if !v.iter().any(|e| used_mutables.contains(e)) {
- cx.span_lint(UNUSED_MUT, cx.tcx.map.span(v[0]),
- "variable does not need to be mutable");
- }
- }
- }
-}
+use rustc::hir;
-impl LintPass for UnusedMut {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_MUT)
- }
-}
-
-impl LateLintPass for UnusedMut {
- fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
- if let hir::ExprMatch(_, ref arms, _) = e.node {
- for a in arms {
- self.check_unused_mut_pat(cx, &a.pats)
- }
- }
- }
-
- fn check_stmt(&mut self, cx: &LateContext, s: &hir::Stmt) {
- if let hir::StmtDecl(ref d, _) = s.node {
- if let hir::DeclLocal(ref l) = d.node {
- self.check_unused_mut_pat(cx, slice::ref_slice(&l.pat));
- }
- }
- }
-
- fn check_fn(&mut self, cx: &LateContext,
- _: FnKind, decl: &hir::FnDecl,
- _: &hir::Block, _: Span, _: ast::NodeId) {
- for a in &decl.inputs {
- self.check_unused_mut_pat(cx, slice::ref_slice(&a.pat));
- }
- }
-}
+use log::debug;
declare_lint! {
pub UNUSED_MUST_USE,
Warn,
- "unused result of a type flagged as #[must_use]"
+ "unused result of a type flagged as `#[must_use]`",
+ report_in_external_macro: true
}
declare_lint! {
"unused result of an expression in a statement"
}
-#[derive(Copy, Clone)]
-pub struct UnusedResults;
-
-impl LintPass for UnusedResults {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_MUST_USE, UNUSED_RESULTS)
- }
-}
+declare_lint_pass!(UnusedResults => [UNUSED_MUST_USE, UNUSED_RESULTS]);
-impl LateLintPass for UnusedResults {
- fn check_stmt(&mut self, cx: &LateContext, s: &hir::Stmt) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedResults {
+ fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt) {
let expr = match s.node {
- hir::StmtSemi(ref expr, _) => &**expr,
- _ => return
+ hir::StmtKind::Semi(ref expr) => &**expr,
+ _ => return,
};
- if let hir::ExprRet(..) = expr.node {
+ if let hir::ExprKind::Ret(..) = expr.node {
return;
}
- let t = cx.tcx.expr_ty(&expr);
- let warned = match t.sty {
- ty::TyTuple(ref tys) if tys.is_empty() => return,
- ty::TyBool => return,
- ty::TyStruct(def, _) |
- ty::TyEnum(def, _) => {
- let attrs = cx.tcx.get_attrs(def.did);
- check_must_use(cx, &attrs[..], s.span)
- }
- _ => false,
+ let ty = cx.tables.expr_ty(&expr);
+ let type_permits_lack_of_use = check_must_use_ty(cx, ty, &expr, s.span, "", "", false);
+
+ let mut fn_warned = false;
+ let mut op_warned = false;
+ let maybe_def_id = match expr.node {
+ hir::ExprKind::Call(ref callee, _) => {
+ match callee.node {
+ hir::ExprKind::Path(ref qpath) => {
+ match cx.tables.qpath_res(qpath, callee.hir_id) {
+ Res::Def(DefKind::Fn, def_id)
+ | Res::Def(DefKind::Method, def_id) => Some(def_id),
+ // `Res::Local` if it was a closure, for which we
+ // do not currently support must-use linting
+ _ => None
+ }
+ },
+ _ => None
+ }
+ },
+ hir::ExprKind::MethodCall(..) => {
+ cx.tables.type_dependent_def_id(expr.hir_id)
+ },
+ _ => None
+ };
+ if let Some(def_id) = maybe_def_id {
+ fn_warned = check_must_use_def(cx, def_id, s.span, "return value of ", "");
+ } else if type_permits_lack_of_use {
+ // We don't warn about unused unit or uninhabited types.
+ // (See https://github.com/rust-lang/rust/issues/43806 for details.)
+ return;
+ }
+
+ let must_use_op = match expr.node {
+ // Hardcoding operators here seemed more expedient than the
+ // refactoring that would be needed to look up the `#[must_use]`
+ // attribute which does exist on the comparison trait methods
+ hir::ExprKind::Binary(bin_op, ..) => {
+ match bin_op.node {
+ hir::BinOpKind::Eq |
+ hir::BinOpKind::Lt |
+ hir::BinOpKind::Le |
+ hir::BinOpKind::Ne |
+ hir::BinOpKind::Ge |
+ hir::BinOpKind::Gt => {
+ Some("comparison")
+ },
+ hir::BinOpKind::Add |
+ hir::BinOpKind::Sub |
+ hir::BinOpKind::Div |
+ hir::BinOpKind::Mul |
+ hir::BinOpKind::Rem => {
+ Some("arithmetic operation")
+ },
+ hir::BinOpKind::And | hir::BinOpKind::Or => {
+ Some("logical operation")
+ },
+ hir::BinOpKind::BitXor |
+ hir::BinOpKind::BitAnd |
+ hir::BinOpKind::BitOr |
+ hir::BinOpKind::Shl |
+ hir::BinOpKind::Shr => {
+ Some("bitwise operation")
+ },
+ }
+ },
+ hir::ExprKind::Unary(..) => Some("unary operation"),
+ _ => None
};
- if !warned {
+
+ if let Some(must_use_op) = must_use_op {
+ cx.span_lint(UNUSED_MUST_USE, expr.span,
+ &format!("unused {} that must be used", must_use_op));
+ op_warned = true;
+ }
+
+ if !(type_permits_lack_of_use || fn_warned || op_warned) {
cx.span_lint(UNUSED_RESULTS, s.span, "unused result");
}
- fn check_must_use(cx: &LateContext, attrs: &[ast::Attribute], sp: Span) -> bool {
- for attr in attrs {
- if attr.check_name("must_use") {
- let mut msg = "unused result which must be used".to_string();
- // check for #[must_use="..."]
- match attr.value_str() {
- None => {}
- Some(s) => {
- msg.push_str(": ");
- msg.push_str(&s);
+ // Returns whether an error has been emitted (and thus another does not need to be later).
+ fn check_must_use_ty<'tcx>(
+ cx: &LateContext<'_, 'tcx>,
+ ty: Ty<'tcx>,
+ expr: &hir::Expr,
+ span: Span,
+ descr_pre: &str,
+ descr_post: &str,
+ plural: bool,
+ ) -> bool {
+ if ty.is_unit() || cx.tcx.is_ty_uninhabited_from(
+ cx.tcx.hir().get_module_parent(expr.hir_id), ty)
+ {
+ return true;
+ }
+
+ let plural_suffix = if plural { "s" } else { "" };
+
+ match ty.sty {
+ ty::Adt(..) if ty.is_box() => {
+ let boxed_ty = ty.boxed_ty();
+ let descr_pre = &format!("{}boxed ", descr_pre);
+ check_must_use_ty(cx, boxed_ty, expr, span, descr_pre, descr_post, plural)
+ }
+ ty::Adt(def, _) => {
+ check_must_use_def(cx, def.did, span, descr_pre, descr_post)
+ }
+ ty::Opaque(def, _) => {
+ let mut has_emitted = false;
+ for (predicate, _) in &cx.tcx.predicates_of(def).predicates {
+ if let ty::Predicate::Trait(ref poly_trait_predicate) = predicate {
+ let trait_ref = poly_trait_predicate.skip_binder().trait_ref;
+ let def_id = trait_ref.def_id;
+ let descr_pre = &format!(
+ "{}implementer{} of ",
+ descr_pre,
+ plural_suffix,
+ );
+ if check_must_use_def(cx, def_id, span, descr_pre, descr_post) {
+ has_emitted = true;
+ break;
+ }
}
}
- cx.span_lint(UNUSED_MUST_USE, sp, &msg);
- return true;
+ has_emitted
+ }
+ ty::Dynamic(binder, _) => {
+ let mut has_emitted = false;
+ for predicate in binder.skip_binder().iter() {
+ if let ty::ExistentialPredicate::Trait(ref trait_ref) = predicate {
+ let def_id = trait_ref.def_id;
+ let descr_post = &format!(
+ " trait object{}{}",
+ plural_suffix,
+ descr_post,
+ );
+ if check_must_use_def(cx, def_id, span, descr_pre, descr_post) {
+ has_emitted = true;
+ break;
+ }
+ }
+ }
+ has_emitted
}
+ ty::Tuple(ref tys) => {
+ let mut has_emitted = false;
+ let spans = if let hir::ExprKind::Tup(comps) = &expr.node {
+ debug_assert_eq!(comps.len(), tys.len());
+ comps.iter().map(|e| e.span).collect()
+ } else {
+ vec![]
+ };
+ for (i, ty) in tys.iter().map(|k| k.expect_ty()).enumerate() {
+ let descr_post = &format!(" in tuple element {}", i);
+ let span = *spans.get(i).unwrap_or(&span);
+ if check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, plural) {
+ has_emitted = true;
+ }
+ }
+ has_emitted
+ }
+ ty::Array(ty, len) => match len.try_eval_usize(cx.tcx, cx.param_env) {
+ // If the array is definitely non-empty, we can do `#[must_use]` checking.
+ Some(n) if n != 0 => {
+ let descr_pre = &format!(
+ "{}array{} of ",
+ descr_pre,
+ plural_suffix,
+ );
+ check_must_use_ty(cx, ty, expr, span, descr_pre, descr_post, true)
+ }
+ // Otherwise, we don't lint, to avoid false positives.
+ _ => false,
+ }
+ _ => false,
}
- false
}
- }
-}
-declare_lint! {
- pub UNUSED_UNSAFE,
- Warn,
- "unnecessary use of an `unsafe` block"
-}
-
-#[derive(Copy, Clone)]
-pub struct UnusedUnsafe;
-
-impl LintPass for UnusedUnsafe {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_UNSAFE)
- }
-}
-
-impl LateLintPass for UnusedUnsafe {
- fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
- if let hir::ExprBlock(ref blk) = e.node {
- // Don't warn about generated blocks, that'll just pollute the output.
- if blk.rules == hir::UnsafeBlock(hir::UserProvided) &&
- !cx.tcx.used_unsafe.borrow().contains(&blk.id) {
- cx.span_lint(UNUSED_UNSAFE, blk.span, "unnecessary `unsafe` block");
+ // Returns whether an error has been emitted (and thus another does not need to be later).
+ fn check_must_use_def(
+ cx: &LateContext<'_, '_>,
+ def_id: DefId,
+ span: Span,
+ descr_pre_path: &str,
+ descr_post_path: &str,
+ ) -> bool {
+ for attr in cx.tcx.get_attrs(def_id).iter() {
+ if attr.check_name(sym::must_use) {
+ let msg = format!("unused {}`{}`{} that must be used",
+ descr_pre_path, cx.tcx.def_path_str(def_id), descr_post_path);
+ let mut err = cx.struct_span_lint(UNUSED_MUST_USE, span, &msg);
+ // check for #[must_use = "..."]
+ if let Some(note) = attr.value_str() {
+ err.note(¬e.as_str());
+ }
+ err.emit();
+ return true;
+ }
}
+ false
}
}
}
"path statements with no effect"
}
-#[derive(Copy, Clone)]
-pub struct PathStatements;
-
-impl LintPass for PathStatements {
- fn get_lints(&self) -> LintArray {
- lint_array!(PATH_STATEMENTS)
- }
-}
+declare_lint_pass!(PathStatements => [PATH_STATEMENTS]);
-impl LateLintPass for PathStatements {
- fn check_stmt(&mut self, cx: &LateContext, s: &hir::Stmt) {
- if let hir::StmtSemi(ref expr, _) = s.node {
- if let hir::ExprPath(..) = expr.node {
- cx.span_lint(PATH_STATEMENTS, s.span,
- "path statement with no effect");
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PathStatements {
+ fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt) {
+ if let hir::StmtKind::Semi(ref expr) = s.node {
+ if let hir::ExprKind::Path(_) = expr.node {
+ cx.span_lint(PATH_STATEMENTS, s.span, "path statement with no effect");
}
}
}
}
#[derive(Copy, Clone)]
-pub struct UnusedAttributes;
+pub struct UnusedAttributes {
+ builtin_attributes: &'static FxHashMap<Symbol, &'static BuiltinAttribute>,
+}
-impl LintPass for UnusedAttributes {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_ATTRIBUTES)
+impl UnusedAttributes {
+ pub fn new() -> Self {
+ UnusedAttributes {
+ builtin_attributes: &*BUILTIN_ATTRIBUTE_MAP,
+ }
}
}
-impl LateLintPass for UnusedAttributes {
- fn check_attribute(&mut self, cx: &LateContext, attr: &ast::Attribute) {
- // Note that check_name() marks the attribute as used if it matches.
- for &(ref name, ty, _) in KNOWN_ATTRIBUTES {
+impl_lint_pass!(UnusedAttributes => [UNUSED_ATTRIBUTES]);
+
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAttributes {
+ fn check_attribute(&mut self, cx: &LateContext<'_, '_>, attr: &ast::Attribute) {
+ debug!("checking attribute: {:?}", attr);
+
+ let attr_info = attr.ident().and_then(|ident| self.builtin_attributes.get(&ident.name));
+
+ if let Some(&&(name, ty, ..)) = attr_info {
match ty {
- AttributeType::Whitelisted if attr.check_name(name) => {
- break;
- },
- _ => ()
+ AttributeType::Whitelisted => {
+ debug!("{:?} is Whitelisted", name);
+ return;
+ }
+ _ => (),
}
}
let plugin_attributes = cx.sess().plugin_attributes.borrow_mut();
- for &(ref name, ty) in plugin_attributes.iter() {
- if ty == AttributeType::Whitelisted && attr.check_name(&*name) {
+ for &(name, ty) in plugin_attributes.iter() {
+ if ty == AttributeType::Whitelisted && attr.check_name(name) {
+ debug!("{:?} (plugin attr) is whitelisted with ty {:?}", name, ty);
break;
}
}
+ let name = attr.name_or_empty();
if !attr::is_used(attr) {
+ debug!("emitting warning for: {:?}", attr);
cx.span_lint(UNUSED_ATTRIBUTES, attr.span, "unused attribute");
// Is it a builtin attribute that must be used at the crate level?
- let known_crate = KNOWN_ATTRIBUTES.iter().find(|&&(name, ty, _)| {
- attr.name() == name &&
- ty == AttributeType::CrateLevel
- }).is_some();
+ let known_crate = attr_info.map(|&&(_, ty, ..)| {
+ ty == AttributeType::CrateLevel
+ }).unwrap_or(false);
- // Has a plugin registered this attribute as one which must be used at
+ // Has a plugin registered this attribute as one that must be used at
// the crate level?
let plugin_crate = plugin_attributes.iter()
- .find(|&&(ref x, t)| {
- &*attr.name() == &*x &&
- AttributeType::CrateLevel == t
- }).is_some();
- if known_crate || plugin_crate {
- let msg = match attr.node.style {
- ast::AttrStyle::Outer => "crate-level attribute should be an inner \
- attribute: add an exclamation mark: #![foo]",
- ast::AttrStyle::Inner => "crate-level attribute should be in the \
- root module",
+ .find(|&&(x, t)| name == x && AttributeType::CrateLevel == t)
+ .is_some();
+ if known_crate || plugin_crate {
+ let msg = match attr.style {
+ ast::AttrStyle::Outer => {
+ "crate-level attribute should be an inner attribute: add an exclamation \
+ mark: `#![foo]`"
+ }
+ ast::AttrStyle::Inner => "crate-level attribute should be in the root module",
};
cx.span_lint(UNUSED_ATTRIBUTES, attr.span, msg);
}
+ } else {
+ debug!("Attr was used: {:?}", attr);
}
}
}
declare_lint! {
- UNUSED_PARENS,
+ pub(super) UNUSED_PARENS,
Warn,
"`if`, `match`, `while` and `return` do not need parentheses"
}
-#[derive(Copy, Clone)]
-pub struct UnusedParens;
+declare_lint_pass!(UnusedParens => [UNUSED_PARENS]);
impl UnusedParens {
- fn check_unused_parens_core(&self, cx: &EarlyContext, value: &ast::Expr, msg: &str,
- struct_lit_needs_parens: bool) {
- if let ast::ExprParen(ref inner) = value.node {
- let necessary = struct_lit_needs_parens && contains_exterior_struct_lit(&**inner);
- if !necessary {
- cx.span_lint(UNUSED_PARENS, value.span,
- &format!("unnecessary parentheses around {}", msg))
- }
+
+ fn is_expr_parens_necessary(inner: &ast::Expr, followed_by_block: bool) -> bool {
+ followed_by_block && match inner.node {
+ ast::ExprKind::Ret(_) | ast::ExprKind::Break(..) => true,
+ _ => parser::contains_exterior_struct_lit(&inner),
}
+ }
- /// Expressions that syntactically contain an "exterior" struct
- /// literal i.e. not surrounded by any parens or other
- /// delimiters, e.g. `X { y: 1 }`, `X { y: 1 }.method()`, `foo
- /// == X { y: 1 }` and `X { y: 1 } == foo` all do, but `(X {
- /// y: 1 }) == foo` does not.
- fn contains_exterior_struct_lit(value: &ast::Expr) -> bool {
- match value.node {
- ast::ExprStruct(..) => true,
-
- ast::ExprAssign(ref lhs, ref rhs) |
- ast::ExprAssignOp(_, ref lhs, ref rhs) |
- ast::ExprBinary(_, ref lhs, ref rhs) => {
- // X { y: 1 } + X { y: 2 }
- contains_exterior_struct_lit(&**lhs) ||
- contains_exterior_struct_lit(&**rhs)
- }
- ast::ExprUnary(_, ref x) |
- ast::ExprCast(ref x, _) |
- ast::ExprType(ref x, _) |
- ast::ExprField(ref x, _) |
- ast::ExprTupField(ref x, _) |
- ast::ExprIndex(ref x, _) => {
- // &X { y: 1 }, X { y: 1 }.y
- contains_exterior_struct_lit(&**x)
+ fn check_unused_parens_expr(&self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Expr,
+ msg: &str,
+ followed_by_block: bool,
+ left_pos: Option<BytePos>,
+ right_pos: Option<BytePos>) {
+ match value.node {
+ ast::ExprKind::Paren(ref inner) => {
+ if !Self::is_expr_parens_necessary(inner, followed_by_block) {
+ let expr_text = if let Ok(snippet) = cx.sess().source_map()
+ .span_to_snippet(value.span) {
+ snippet
+ } else {
+ pprust::expr_to_string(value)
+ };
+ let keep_space = (
+ left_pos.map(|s| s >= value.span.lo()).unwrap_or(false),
+ right_pos.map(|s| s <= value.span.hi()).unwrap_or(false),
+ );
+ Self::remove_outer_parens(cx, value.span, &expr_text, msg, keep_space);
}
+ }
+ ast::ExprKind::Let(_, ref expr) => {
+ // FIXME(#60336): Properly handle `let true = (false && true)`
+ // actually needing the parenthesis.
+ self.check_unused_parens_expr(
+ cx, expr,
+ "`let` head expression",
+ followed_by_block,
+ None, None
+ );
+ }
+ _ => {}
+ }
+ }
+
+ fn check_unused_parens_pat(&self,
+ cx: &EarlyContext<'_>,
+ value: &ast::Pat,
+ msg: &str) {
+ if let ast::PatKind::Paren(_) = value.node {
+ let pattern_text = if let Ok(snippet) = cx.sess().source_map()
+ .span_to_snippet(value.span) {
+ snippet
+ } else {
+ pprust::pat_to_string(value)
+ };
+ Self::remove_outer_parens(cx, value.span, &pattern_text, msg, (false, false));
+ }
+ }
- ast::ExprMethodCall(_, _, ref exprs) => {
- // X { y: 1 }.bar(...)
- contains_exterior_struct_lit(&*exprs[0])
+ fn remove_outer_parens(cx: &EarlyContext<'_>,
+ span: Span,
+ pattern: &str,
+ msg: &str,
+ keep_space: (bool, bool)) {
+ let span_msg = format!("unnecessary parentheses around {}", msg);
+ let mut err = cx.struct_span_lint(UNUSED_PARENS, span, &span_msg);
+ let mut ate_left_paren = false;
+ let mut ate_right_paren = false;
+ let parens_removed = pattern
+ .trim_matches(|c| {
+ match c {
+ '(' => {
+ if ate_left_paren {
+ false
+ } else {
+ ate_left_paren = true;
+ true
+ }
+ },
+ ')' => {
+ if ate_right_paren {
+ false
+ } else {
+ ate_right_paren = true;
+ true
+ }
+ },
+ _ => false,
}
+ });
- _ => false
+ let replace = {
+ let mut replace = if keep_space.0 {
+ let mut s = String::from(" ");
+ s.push_str(parens_removed);
+ s
+ } else {
+ String::from(parens_removed)
+ };
+
+ if keep_space.1 {
+ replace.push(' ');
}
- }
- }
-}
+ replace
+ };
-impl LintPass for UnusedParens {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_PARENS)
+ err.span_suggestion_short(
+ span,
+ "remove these parentheses",
+ replace,
+ Applicability::MachineApplicable,
+ );
+ err.emit();
}
}
impl EarlyLintPass for UnusedParens {
- fn check_expr(&mut self, cx: &EarlyContext, e: &ast::Expr) {
- let (value, msg, struct_lit_needs_parens) = match e.node {
- ast::ExprIf(ref cond, _, _) => (cond, "`if` condition", true),
- ast::ExprWhile(ref cond, _, _) => (cond, "`while` condition", true),
- ast::ExprIfLet(_, ref cond, _, _) => (cond, "`if let` head expression", true),
- ast::ExprWhileLet(_, ref cond, _, _) => (cond, "`while let` head expression", true),
- ast::ExprForLoop(_, ref cond, _, _) => (cond, "`for` head expression", true),
- ast::ExprMatch(ref head, _) => (head, "`match` head expression", true),
- ast::ExprRet(Some(ref value)) => (value, "`return` value", false),
- ast::ExprAssign(_, ref value) => (value, "assigned value", false),
- ast::ExprAssignOp(_, _, ref value) => (value, "assigned value", false),
- ast::ExprInPlace(_, ref value) => (value, "emplacement value", false),
- _ => return
- };
- self.check_unused_parens_core(cx, &**value, msg, struct_lit_needs_parens);
- }
+ fn check_expr(&mut self, cx: &EarlyContext<'_>, e: &ast::Expr) {
+ use syntax::ast::ExprKind::*;
+ let (value, msg, followed_by_block, left_pos, right_pos) = match e.node {
+ If(ref cond, ref block, ..) => {
+ let left = e.span.lo() + syntax_pos::BytePos(2);
+ let right = block.span.lo();
+ (cond, "`if` condition", true, Some(left), Some(right))
+ }
- fn check_stmt(&mut self, cx: &EarlyContext, s: &ast::Stmt) {
- let (value, msg) = match s.node {
- ast::StmtDecl(ref decl, _) => match decl.node {
- ast::DeclLocal(ref local) => match local.init {
- Some(ref value) => (value, "assigned value"),
- None => return
- },
- _ => return
+ While(ref cond, ref block, ..) => {
+ let left = e.span.lo() + syntax_pos::BytePos(5);
+ let right = block.span.lo();
+ (cond, "`while` condition", true, Some(left), Some(right))
},
- _ => return
+
+ ForLoop(_, ref cond, ref block, ..) => {
+ (cond, "`for` head expression", true, None, Some(block.span.lo()))
+ }
+
+ Match(ref head, _) => {
+ let left = e.span.lo() + syntax_pos::BytePos(5);
+ (head, "`match` head expression", true, Some(left), None)
+ }
+
+ Ret(Some(ref value)) => {
+ let left = e.span.lo() + syntax_pos::BytePos(3);
+ (value, "`return` value", false, Some(left), None)
+ }
+
+ Assign(_, ref value) => (value, "assigned value", false, None, None),
+ AssignOp(.., ref value) => (value, "assigned value", false, None, None),
+ // either function/method call, or something this lint doesn't care about
+ ref call_or_other => {
+ let (args_to_check, call_kind) = match *call_or_other {
+ Call(_, ref args) => (&args[..], "function"),
+ // first "argument" is self (which sometimes needs parens)
+ MethodCall(_, ref args) => (&args[1..], "method"),
+ // actual catch-all arm
+ _ => {
+ return;
+ }
+ };
+ // Don't lint if this is a nested macro expansion: otherwise, the lint could
+ // trigger in situations that macro authors shouldn't have to care about, e.g.,
+ // when a parenthesized token tree matched in one macro expansion is matched as
+ // an expression in another and used as a fn/method argument (Issue #47775)
+ if e.span.ctxt().outer_expn_info()
+ .map_or(false, |info| info.call_site.ctxt().outer_expn_info().is_some()) {
+ return;
+ }
+ let msg = format!("{} argument", call_kind);
+ for arg in args_to_check {
+ self.check_unused_parens_expr(cx, arg, &msg, false, None, None);
+ }
+ return;
+ }
};
- self.check_unused_parens_core(cx, &**value, msg, false);
+ self.check_unused_parens_expr(cx, &value, msg, followed_by_block, left_pos, right_pos);
+ }
+
+ fn check_pat(&mut self, cx: &EarlyContext<'_>, p: &ast::Pat) {
+ use ast::PatKind::{Paren, Range};
+ // The lint visitor will visit each subpattern of `p`. We do not want to lint any range
+ // pattern no matter where it occurs in the pattern. For something like `&(a..=b)`, there
+ // is a recursive `check_pat` on `a` and `b`, but we will assume that if there are
+ // unnecessary parens they serve a purpose of readability.
+ if let Paren(ref pat) = p.node {
+ match pat.node {
+ Range(..) => {}
+ _ => self.check_unused_parens_pat(cx, &p, "pattern")
+ }
+ }
+ }
+
+ fn check_stmt(&mut self, cx: &EarlyContext<'_>, s: &ast::Stmt) {
+ if let ast::StmtKind::Local(ref local) = s.node {
+ if let Some(ref value) = local.init {
+ self.check_unused_parens_expr(cx, &value, "assigned value", false, None, None);
+ }
+ }
}
}
"unnecessary braces around an imported item"
}
-#[derive(Copy, Clone)]
-pub struct UnusedImportBraces;
+declare_lint_pass!(UnusedImportBraces => [UNUSED_IMPORT_BRACES]);
-impl LintPass for UnusedImportBraces {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_IMPORT_BRACES)
- }
-}
+impl UnusedImportBraces {
+ fn check_use_tree(&self, cx: &EarlyContext<'_>, use_tree: &ast::UseTree, item: &ast::Item) {
+ if let ast::UseTreeKind::Nested(ref items) = use_tree.kind {
+ // Recursively check nested UseTrees
+ for &(ref tree, _) in items {
+ self.check_use_tree(cx, tree, item);
+ }
-impl LateLintPass for UnusedImportBraces {
- fn check_item(&mut self, cx: &LateContext, item: &hir::Item) {
- if let hir::ItemUse(ref view_path) = item.node {
- if let hir::ViewPathList(_, ref items) = view_path.node {
- if items.len() == 1 {
- if let hir::PathListIdent {ref name, ..} = items[0].node {
- let m = format!("braces around {} is unnecessary",
- name);
- cx.span_lint(UNUSED_IMPORT_BRACES, item.span,
- &m[..]);
+ // Trigger the lint only if there is one nested item
+ if items.len() != 1 {
+ return;
+ }
+
+ // Trigger the lint if the nested item is a non-self single item
+ let node_ident;
+ match items[0].0.kind {
+ ast::UseTreeKind::Simple(rename, ..) => {
+ let orig_ident = items[0].0.prefix.segments.last().unwrap().ident;
+ if orig_ident.name == kw::SelfLower {
+ return;
}
+ node_ident = rename.unwrap_or(orig_ident);
+ }
+ ast::UseTreeKind::Glob => {
+ node_ident = ast::Ident::from_str("*");
+ }
+ ast::UseTreeKind::Nested(_) => {
+ return;
}
}
+
+ let msg = format!("braces around {} is unnecessary", node_ident.name);
+ cx.span_lint(UNUSED_IMPORT_BRACES, item.span, &msg);
+ }
+ }
+}
+
+impl EarlyLintPass for UnusedImportBraces {
+ fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
+ if let ast::ItemKind::Use(ref use_tree) = item.node {
+ self.check_use_tree(cx, use_tree, item);
}
}
}
declare_lint! {
- UNUSED_ALLOCATION,
+ pub(super) UNUSED_ALLOCATION,
Warn,
"detects unnecessary allocations that can be eliminated"
}
-#[derive(Copy, Clone)]
-pub struct UnusedAllocation;
-
-impl LintPass for UnusedAllocation {
- fn get_lints(&self) -> LintArray {
- lint_array!(UNUSED_ALLOCATION)
- }
-}
+declare_lint_pass!(UnusedAllocation => [UNUSED_ALLOCATION]);
-impl LateLintPass for UnusedAllocation {
- fn check_expr(&mut self, cx: &LateContext, e: &hir::Expr) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedAllocation {
+ fn check_expr(&mut self, cx: &LateContext<'_, '_>, e: &hir::Expr) {
match e.node {
- hir::ExprBox(_) => {}
- _ => return
+ hir::ExprKind::Box(_) => {}
+ _ => return,
}
- if let Some(adjustment) = cx.tcx.tables.borrow().adjustments.get(&e.id) {
- if let adjustment::AdjustDerefRef(adjustment::AutoDerefRef {
- ref autoref, ..
- }) = *adjustment {
- match autoref {
- &Some(adjustment::AutoPtr(_, hir::MutImmutable)) => {
- cx.span_lint(UNUSED_ALLOCATION, e.span,
- "unnecessary allocation, use & instead");
- }
- &Some(adjustment::AutoPtr(_, hir::MutMutable)) => {
- cx.span_lint(UNUSED_ALLOCATION, e.span,
- "unnecessary allocation, use &mut instead");
- }
- _ => ()
- }
+ for adj in cx.tables.expr_adjustments(e) {
+ if let adjustment::Adjust::Borrow(adjustment::AutoBorrow::Ref(_, m)) = adj.kind {
+ let msg = match m {
+ adjustment::AutoBorrowMutability::Immutable =>
+ "unnecessary allocation, use `&` instead",
+ adjustment::AutoBorrowMutability::Mutable { .. }=>
+ "unnecessary allocation, use `&mut` instead"
+ };
+ cx.span_lint(UNUSED_ALLOCATION, e.span, msg);
}
}
}
projects / rustc.git / blobdiff