-use rustc::lint::*;
use rustc::hir::*;
-use syntax::codemap::mk_sp;
-use utils::{differing_macro_contexts, snippet_opt, span_lint_and_then, SpanlessEq};
+use rustc::lint::*;
+use rustc::ty;
+use crate::utils::{differing_macro_contexts, match_type, paths, snippet, span_lint_and_then, walk_ptrs_ty, SpanlessEq};
+use crate::utils::sugg::Sugg;
-/// **What it does:** This lints manual swapping.
+/// **What it does:** Checks for manual swapping.
///
-/// **Why is this bad?** The `std::mem::swap` function exposes the intent better without
-/// deinitializing or copying either variable.
+/// **Why is this bad?** The `std::mem::swap` function exposes the intent better
+/// without deinitializing or copying either variable.
///
/// **Known problems:** None.
///
/// b = a;
/// a = t;
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub MANUAL_SWAP,
- Warn,
- "manual swap"
+ complexity,
+ "manual swap of two variables"
}
-/// **What it does:** This lints `foo = bar; bar = foo` sequences.
+/// **What it does:** Checks for `foo = bar; bar = foo` sequences.
///
/// **Why is this bad?** This looks like a failed attempt to swap.
///
/// a = b;
/// b = a;
/// ```
-declare_lint! {
+declare_clippy_lint! {
pub ALMOST_SWAPPED,
- Warn,
+ correctness,
"`foo = bar; bar = foo` sequence"
}
-#[derive(Copy,Clone)]
+#[derive(Copy, Clone)]
pub struct Swap;
impl LintPass for Swap {
}
}
-impl LateLintPass for Swap {
- fn check_block(&mut self, cx: &LateContext, block: &Block) {
+impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Swap {
+ fn check_block(&mut self, cx: &LateContext<'a, 'tcx>, block: &'tcx Block) {
check_manual_swap(cx, block);
check_suspicious_swap(cx, block);
}
/// Implementation of the `MANUAL_SWAP` lint.
fn check_manual_swap(cx: &LateContext, block: &Block) {
for w in block.stmts.windows(3) {
- if_let_chain!{[
+ if_chain! {
// let t = foo();
- let StmtDecl(ref tmp, _) = w[0].node,
- let DeclLocal(ref tmp) = tmp.node,
- let Some(ref tmp_init) = tmp.init,
- let PatKind::Binding(_, ref tmp_name, None) = tmp.pat.node,
+ if let StmtDecl(ref tmp, _) = w[0].node;
+ if let DeclLocal(ref tmp) = tmp.node;
+ if let Some(ref tmp_init) = tmp.init;
+ if let PatKind::Binding(_, _, ident, None) = tmp.pat.node;
// foo() = bar();
- let StmtSemi(ref first, _) = w[1].node,
- let ExprAssign(ref lhs1, ref rhs1) = first.node,
+ if let StmtSemi(ref first, _) = w[1].node;
+ if let ExprAssign(ref lhs1, ref rhs1) = first.node;
// bar() = t;
- let StmtSemi(ref second, _) = w[2].node,
- let ExprAssign(ref lhs2, ref rhs2) = second.node,
- let ExprPath(None, ref rhs2) = rhs2.node,
- rhs2.segments.len() == 1,
-
- tmp_name.node.as_str() == rhs2.segments[0].name.as_str(),
- SpanlessEq::new(cx).ignore_fn().eq_expr(tmp_init, lhs1),
- SpanlessEq::new(cx).ignore_fn().eq_expr(rhs1, lhs2)
- ], {
- let (what, lhs, rhs) = if let (Some(first), Some(second)) = (snippet_opt(cx, lhs1.span), snippet_opt(cx, rhs1.span)) {
- (format!(" `{}` and `{}`", first, second), first, second)
- } else {
- ("".to_owned(), "".to_owned(), "".to_owned())
- };
-
- let span = mk_sp(tmp.span.lo, second.span.hi);
-
- span_lint_and_then(cx,
- MANUAL_SWAP,
- span,
- &format!("this looks like you are swapping{} manually", what),
- |db| {
- if !what.is_empty() {
- db.span_suggestion(span, "try",
- format!("std::mem::swap(&mut {}, &mut {})", lhs, rhs));
- db.note("or maybe you should use `std::mem::replace`?");
- }
- });
- }}
+ if let StmtSemi(ref second, _) = w[2].node;
+ if let ExprAssign(ref lhs2, ref rhs2) = second.node;
+ if let ExprPath(QPath::Resolved(None, ref rhs2)) = rhs2.node;
+ if rhs2.segments.len() == 1;
+
+ if ident.as_str() == rhs2.segments[0].ident.as_str();
+ if SpanlessEq::new(cx).ignore_fn().eq_expr(tmp_init, lhs1);
+ if SpanlessEq::new(cx).ignore_fn().eq_expr(rhs1, lhs2);
+ then {
+ fn check_for_slice<'a>(
+ cx: &LateContext,
+ lhs1: &'a Expr,
+ lhs2: &'a Expr,
+ ) -> Option<(&'a Expr, &'a Expr, &'a Expr)> {
+ if let ExprIndex(ref lhs1, ref idx1) = lhs1.node {
+ if let ExprIndex(ref lhs2, ref idx2) = lhs2.node {
+ if SpanlessEq::new(cx).ignore_fn().eq_expr(lhs1, lhs2) {
+ let ty = walk_ptrs_ty(cx.tables.expr_ty(lhs1));
+
+ if matches!(ty.sty, ty::TySlice(_)) ||
+ matches!(ty.sty, ty::TyArray(_, _)) ||
+ match_type(cx, ty, &paths::VEC) ||
+ match_type(cx, ty, &paths::VEC_DEQUE) {
+ return Some((lhs1, idx1, idx2));
+ }
+ }
+ }
+ }
+
+ None
+ }
+
+ let (replace, what, sugg) = if let Some((slice, idx1, idx2)) = check_for_slice(cx, lhs1, lhs2) {
+ if let Some(slice) = Sugg::hir_opt(cx, slice) {
+ (false,
+ format!(" elements of `{}`", slice),
+ format!("{}.swap({}, {})",
+ slice.maybe_par(),
+ snippet(cx, idx1.span, ".."),
+ snippet(cx, idx2.span, "..")))
+ } else {
+ (false, "".to_owned(), "".to_owned())
+ }
+ } else if let (Some(first), Some(second)) = (Sugg::hir_opt(cx, lhs1), Sugg::hir_opt(cx, rhs1)) {
+ (true, format!(" `{}` and `{}`", first, second),
+ format!("std::mem::swap({}, {})", first.mut_addr(), second.mut_addr()))
+ } else {
+ (true, "".to_owned(), "".to_owned())
+ };
+
+ let span = w[0].span.to(second.span);
+
+ span_lint_and_then(cx,
+ MANUAL_SWAP,
+ span,
+ &format!("this looks like you are swapping{} manually", what),
+ |db| {
+ if !sugg.is_empty() {
+ db.span_suggestion(span, "try", sugg);
+
+ if replace {
+ db.note("or maybe you should use `std::mem::replace`?");
+ }
+ }
+ });
+ }
+ }
}
}
/// Implementation of the `ALMOST_SWAPPED` lint.
fn check_suspicious_swap(cx: &LateContext, block: &Block) {
for w in block.stmts.windows(2) {
- if_let_chain!{[
- let StmtSemi(ref first, _) = w[0].node,
- let StmtSemi(ref second, _) = w[1].node,
- !differing_macro_contexts(first.span, second.span),
- let ExprAssign(ref lhs0, ref rhs0) = first.node,
- let ExprAssign(ref lhs1, ref rhs1) = second.node,
- SpanlessEq::new(cx).ignore_fn().eq_expr(lhs0, rhs1),
- SpanlessEq::new(cx).ignore_fn().eq_expr(lhs1, rhs0)
- ], {
- let (what, lhs, rhs) = if let (Some(first), Some(second)) = (snippet_opt(cx, lhs0.span), snippet_opt(cx, rhs0.span)) {
- (format!(" `{}` and `{}`", first, second), first, second)
- } else {
- ("".to_owned(), "".to_owned(), "".to_owned())
- };
-
- let span = mk_sp(first.span.lo, second.span.hi);
-
- span_lint_and_then(cx,
- ALMOST_SWAPPED,
- span,
- &format!("this looks like you are trying to swap{}", what),
- |db| {
- if !what.is_empty() {
- db.span_suggestion(span, "try",
- format!("std::mem::swap(&mut {}, &mut {})", lhs, rhs));
- db.note("or maybe you should use `std::mem::replace`?");
- }
- });
- }}
+ if_chain! {
+ if let StmtSemi(ref first, _) = w[0].node;
+ if let StmtSemi(ref second, _) = w[1].node;
+ if !differing_macro_contexts(first.span, second.span);
+ if let ExprAssign(ref lhs0, ref rhs0) = first.node;
+ if let ExprAssign(ref lhs1, ref rhs1) = second.node;
+ if SpanlessEq::new(cx).ignore_fn().eq_expr(lhs0, rhs1);
+ if SpanlessEq::new(cx).ignore_fn().eq_expr(lhs1, rhs0);
+ then {
+ let lhs0 = Sugg::hir_opt(cx, lhs0);
+ let rhs0 = Sugg::hir_opt(cx, rhs0);
+ let (what, lhs, rhs) = if let (Some(first), Some(second)) = (lhs0, rhs0) {
+ (
+ format!(" `{}` and `{}`", first, second),
+ first.mut_addr().to_string(),
+ second.mut_addr().to_string(),
+ )
+ } else {
+ ("".to_owned(), "".to_owned(), "".to_owned())
+ };
+
+ let span = first.span.to(second.span);
+
+ span_lint_and_then(cx,
+ ALMOST_SWAPPED,
+ span,
+ &format!("this looks like you are trying to swap{}", what),
+ |db| {
+ if !what.is_empty() {
+ db.span_suggestion(span, "try",
+ format!("std::mem::swap({}, {})", lhs, rhs));
+ db.note("or maybe you should use `std::mem::replace`?");
+ }
+ });
+ }
+ }
}
}
projects / rust.git / blobdiff