-use crate::utils::{has_drop, qpath_res, snippet_opt, span_lint, span_lint_and_sugg};
-use rustc::declare_lint_pass;
-use rustc::hir::def::{DefKind, Res};
-use rustc::hir::{BinOpKind, BlockCheckMode, Expr, ExprKind, Stmt, StmtKind, UnsafeSource};
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
+use clippy_utils::diagnostics::{span_lint_hir, span_lint_hir_and_then};
+use clippy_utils::source::snippet_opt;
+use clippy_utils::ty::has_drop;
use rustc_errors::Applicability;
-use rustc_session::declare_tool_lint;
+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;
declare_clippy_lint! {
- /// **What it does:** Checks for statements which have no effect.
+ /// ### What it does
+ /// Checks for statements which have no effect.
///
- /// **Why is this bad?** Similar to dead code, these statements are actually
+ /// ### 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:**
+ /// ### Example
/// ```rust
/// 0;
/// ```
}
declare_clippy_lint! {
- /// **What it does:** Checks for expression statements that can be reduced to a
+ /// ### 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.
+ /// ### Why is this bad?
+ /// Expressions by themselves often have no side-effects.
/// Having such expressions reduces readability.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// compute_array()[0];
/// ```
"outer expressions with no effect"
}
-fn has_no_effect(cx: &LateContext<'_, '_>, expr: &Expr<'_>) -> bool {
+fn has_no_effect(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
if expr.span.from_expansion() {
return false;
}
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::Array(ref v) | ExprKind::Tup(ref v) => v.iter().all(|val| has_no_effect(cx, val)),
- ExprKind::Repeat(ref inner, _)
- | ExprKind::Cast(ref inner, _)
- | ExprKind::Type(ref inner, _)
- | ExprKind::Unary(_, ref inner)
- | ExprKind::Field(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))
+ ExprKind::Path(..) => !has_drop(cx, cx.typeck_results().expr_ty(expr)),
+ ExprKind::Index(a, b) | ExprKind::Binary(_, a, b) => has_no_effect(cx, a) && has_no_effect(cx, b),
+ ExprKind::Array(v) | ExprKind::Tup(v) => v.iter().all(|val| has_no_effect(cx, val)),
+ ExprKind::Repeat(inner, _)
+ | ExprKind::Cast(inner, _)
+ | ExprKind::Type(inner, _)
+ | ExprKind::Unary(_, inner)
+ | ExprKind::Field(inner, _)
+ | ExprKind::AddrOf(_, _, inner)
+ | ExprKind::Box(inner) => has_no_effect(cx, inner),
+ ExprKind::Struct(_, fields, ref base) => {
+ !has_drop(cx, cx.typeck_results().expr_ty(expr))
+ && fields.iter().all(|field| has_no_effect(cx, field.expr))
&& base.as_ref().map_or(true, |base| has_no_effect(cx, base))
},
- ExprKind::Call(ref callee, ref args) => {
+ ExprKind::Call(callee, args) => {
if let ExprKind::Path(ref qpath) = callee.kind {
- let res = qpath_res(cx, qpath, callee.hir_id);
+ let res = cx.qpath_res(qpath, callee.hir_id);
match res {
- Res::Def(DefKind::Struct, ..) | Res::Def(DefKind::Variant, ..) | Res::Def(DefKind::Ctor(..), _) => {
- !has_drop(cx, cx.tables.expr_ty(expr)) && args.iter().all(|arg| has_no_effect(cx, arg))
+ Res::Def(DefKind::Struct | DefKind::Variant | DefKind::Ctor(..), ..) => {
+ !has_drop(cx, cx.typeck_results().expr_ty(expr))
+ && args.iter().all(|arg| has_no_effect(cx, arg))
},
_ => false,
}
false
}
},
- ExprKind::Block(ref block, _) => {
+ ExprKind::Block(block, _) => {
block.stmts.is_empty() && block.expr.as_ref().map_or(false, |expr| has_no_effect(cx, expr))
},
_ => false,
declare_lint_pass!(NoEffect => [NO_EFFECT, UNNECESSARY_OPERATION]);
-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 {
+impl<'tcx> LateLintPass<'tcx> for NoEffect {
+ fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) {
+ if let StmtKind::Semi(expr) = stmt.kind {
if has_no_effect(cx, expr) {
- span_lint(cx, NO_EFFECT, stmt.span, "statement with no effect");
+ span_lint_hir(cx, NO_EFFECT, expr.hir_id, stmt.span, "statement with no effect");
} else if let Some(reduced) = reduce_expression(cx, expr) {
let mut snippet = String::new();
for e in reduced {
return;
}
}
- span_lint_and_sugg(
+ span_lint_hir_and_then(
cx,
UNNECESSARY_OPERATION,
+ expr.hir_id,
stmt.span,
"statement can be reduced",
- "replace it with",
- snippet,
- Applicability::MachineApplicable,
+ |diag| {
+ diag.span_suggestion(stmt.span, "replace it with", snippet, Applicability::MachineApplicable);
+ },
);
}
}
}
}
-fn reduce_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr<'a>) -> Option<Vec<&'a Expr<'a>>> {
+fn reduce_expression<'a>(cx: &LateContext<'_>, expr: &'a Expr<'a>) -> Option<Vec<&'a Expr<'a>>> {
if expr.span.from_expansion() {
return None;
}
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::Index(a, b) => Some(vec![a, b]),
+ ExprKind::Binary(ref binop, a, b) if binop.node != BinOpKind::And && binop.node != BinOpKind::Or => {
+ Some(vec![a, b])
},
- ExprKind::Array(ref v) | ExprKind::Tup(ref v) => Some(v.iter().collect()),
- ExprKind::Repeat(ref inner, _)
- | ExprKind::Cast(ref inner, _)
- | ExprKind::Type(ref inner, _)
- | ExprKind::Unary(_, ref inner)
- | ExprKind::Field(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::Array(v) | ExprKind::Tup(v) => Some(v.iter().collect()),
+ ExprKind::Repeat(inner, _)
+ | ExprKind::Cast(inner, _)
+ | ExprKind::Type(inner, _)
+ | ExprKind::Unary(_, inner)
+ | ExprKind::Field(inner, _)
+ | ExprKind::AddrOf(_, _, inner)
+ | ExprKind::Box(inner) => reduce_expression(cx, inner).or_else(|| Some(vec![inner])),
+ ExprKind::Struct(_, fields, ref base) => {
+ if has_drop(cx, cx.typeck_results().expr_ty(expr)) {
None
} else {
Some(fields.iter().map(|f| &f.expr).chain(base).map(Deref::deref).collect())
}
},
- ExprKind::Call(ref callee, ref args) => {
+ ExprKind::Call(callee, args) => {
if let ExprKind::Path(ref qpath) = callee.kind {
- let res = qpath_res(cx, qpath, callee.hir_id);
+ let res = cx.qpath_res(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)) =>
+ Res::Def(DefKind::Struct | DefKind::Variant | DefKind::Ctor(..), ..)
+ if !has_drop(cx, cx.typeck_results().expr_ty(expr)) =>
{
Some(args.iter().collect())
},
None
}
},
- ExprKind::Block(ref block, _) => {
+ ExprKind::Block(block, _) => {
if block.stmts.is_empty() {
block.expr.as_ref().and_then(|e| {
match block.rules {
BlockCheckMode::UnsafeBlock(UnsafeSource::UserProvided) => None,
BlockCheckMode::DefaultBlock => Some(vec![&**e]),
// in case of compiler-inserted signaling blocks
- _ => reduce_expression(cx, e),
+ BlockCheckMode::UnsafeBlock(_) => reduce_expression(cx, e),
}
})
} else {
projects / rust.git / blobdiff