-use crate::utils::{has_drop, in_macro, snippet_opt, span_lint, span_lint_and_sugg};
-use rustc::hir::def::Def;
-use rustc::hir::{BinOpKind, BlockCheckMode, Expr, ExprKind, Stmt, StmtKind, UnsafeSource};
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::{declare_tool_lint, lint_array};
+use crate::utils::{has_drop, qpath_res, snippet_opt, span_lint, span_lint_and_sugg};
use rustc_errors::Applicability;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::{BinOpKind, BlockCheckMode, Expr, ExprKind, Stmt, StmtKind, UnsafeSource};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
use std::ops::Deref;
-/// **What it does:** Checks for statements which have no effect.
-///
-/// **Why is this bad?** Similar to dead code, these statements are actually
-/// executed. However, as they have no effect, all they do is make the code less
-/// readable.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// 0;
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for statements which have no effect.
+ ///
+ /// **Why is this bad?** Similar to dead code, these statements are actually
+ /// executed. However, as they have no effect, all they do is make the code less
+ /// readable.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust
+ /// 0;
+ /// ```
pub NO_EFFECT,
complexity,
"statements with no effect"
}
-/// **What it does:** Checks for expression statements that can be reduced to a
-/// sub-expression.
-///
-/// **Why is this bad?** Expressions by themselves often have no side-effects.
-/// Having such expressions reduces readability.
-///
-/// **Known problems:** None.
-///
-/// **Example:**
-/// ```rust
-/// compute_array()[0];
-/// ```
declare_clippy_lint! {
+ /// **What it does:** Checks for expression statements that can be reduced to a
+ /// sub-expression.
+ ///
+ /// **Why is this bad?** Expressions by themselves often have no side-effects.
+ /// Having such expressions reduces readability.
+ ///
+ /// **Known problems:** None.
+ ///
+ /// **Example:**
+ /// ```rust,ignore
+ /// compute_array()[0];
+ /// ```
pub UNNECESSARY_OPERATION,
complexity,
"outer expressions with no effect"
}
-fn has_no_effect(cx: &LateContext<'_, '_>, expr: &Expr) -> bool {
- if in_macro(expr.span) {
+fn has_no_effect(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
+ if expr.span.from_expansion() {
return false;
}
- match expr.node {
- ExprKind::Lit(..) | ExprKind::Closure(.., _) => true,
+ match expr.kind {
+ ExprKind::Lit(..) | ExprKind::Closure(..) => true,
ExprKind::Path(..) => !has_drop(cx, cx.tables.expr_ty(expr)),
ExprKind::Index(ref a, ref b) | ExprKind::Binary(_, ref a, ref b) => {
has_no_effect(cx, a) && has_no_effect(cx, b)
| ExprKind::Type(ref inner, _)
| ExprKind::Unary(_, ref inner)
| ExprKind::Field(ref inner, _)
- | ExprKind::AddrOf(_, ref inner)
+ | ExprKind::AddrOf(_, _, ref inner)
| ExprKind::Box(ref inner) => has_no_effect(cx, inner),
ExprKind::Struct(_, ref fields, ref base) => {
!has_drop(cx, cx.tables.expr_ty(expr))
&& fields.iter().all(|field| has_no_effect(cx, &field.expr))
- && match *base {
- Some(ref base) => has_no_effect(cx, base),
- None => true,
- }
+ && base.as_ref().map_or(true, |base| has_no_effect(cx, base))
},
ExprKind::Call(ref callee, ref args) => {
- if let ExprKind::Path(ref qpath) = callee.node {
- let def = cx.tables.qpath_def(qpath, callee.hir_id);
- match def {
- Def::Struct(..) | Def::Variant(..) | Def::StructCtor(..) | Def::VariantCtor(..) => {
+ if let ExprKind::Path(ref qpath) = callee.kind {
+ let res = qpath_res(cx, qpath, callee.hir_id);
+ match res {
+ Res::Def(DefKind::Struct | DefKind::Variant | DefKind::Ctor(..), ..) => {
!has_drop(cx, cx.tables.expr_ty(expr)) && args.iter().all(|arg| has_no_effect(cx, arg))
},
_ => false,
}
},
ExprKind::Block(ref block, _) => {
- block.stmts.is_empty()
- && if let Some(ref expr) = block.expr {
- has_no_effect(cx, expr)
- } else {
- false
- }
+ block.stmts.is_empty() && block.expr.as_ref().map_or(false, |expr| has_no_effect(cx, expr))
},
_ => false,
}
}
-#[derive(Copy, Clone)]
-pub struct Pass;
-
-impl LintPass for Pass {
- fn get_lints(&self) -> LintArray {
- lint_array!(NO_EFFECT, UNNECESSARY_OPERATION)
- }
-
- fn name(&self) -> &'static str {
- "NoEffect"
- }
-}
+declare_lint_pass!(NoEffect => [NO_EFFECT, UNNECESSARY_OPERATION]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
- fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt) {
- if let StmtKind::Semi(ref expr) = stmt.node {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NoEffect {
+ fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt<'_>) {
+ if let StmtKind::Semi(ref expr) = stmt.kind {
if has_no_effect(cx, expr) {
span_lint(cx, NO_EFFECT, stmt.span, "statement with no effect");
} else if let Some(reduced) = reduce_expression(cx, expr) {
let mut snippet = String::new();
for e in reduced {
- if in_macro(e.span) {
+ if e.span.from_expansion() {
return;
}
if let Some(snip) = snippet_opt(cx, e.span) {
}
}
-fn reduce_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr) -> Option<Vec<&'a Expr>> {
- if in_macro(expr.span) {
+fn reduce_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr<'a>) -> Option<Vec<&'a Expr<'a>>> {
+ if expr.span.from_expansion() {
return None;
}
- match expr.node {
+ match expr.kind {
ExprKind::Index(ref a, ref b) => Some(vec![&**a, &**b]),
ExprKind::Binary(ref binop, ref a, ref b) if binop.node != BinOpKind::And && binop.node != BinOpKind::Or => {
Some(vec![&**a, &**b])
| ExprKind::Type(ref inner, _)
| ExprKind::Unary(_, ref inner)
| ExprKind::Field(ref inner, _)
- | ExprKind::AddrOf(_, ref inner)
+ | ExprKind::AddrOf(_, _, ref inner)
| ExprKind::Box(ref inner) => reduce_expression(cx, inner).or_else(|| Some(vec![inner])),
ExprKind::Struct(_, ref fields, ref base) => {
if has_drop(cx, cx.tables.expr_ty(expr)) {
}
},
ExprKind::Call(ref callee, ref args) => {
- if let ExprKind::Path(ref qpath) = callee.node {
- let def = cx.tables.qpath_def(qpath, callee.hir_id);
- match def {
- Def::Struct(..) | Def::Variant(..) | Def::StructCtor(..) | Def::VariantCtor(..)
+ if let ExprKind::Path(ref qpath) = callee.kind {
+ let res = qpath_res(cx, qpath, callee.hir_id);
+ match res {
+ Res::Def(DefKind::Struct, ..) | Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(..), _)
if !has_drop(cx, cx.tables.expr_ty(expr)) =>
{
Some(args.iter().collect())
projects / rust.git / blobdiff