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Merge pull request #2413 from flip1995/assign_ops

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Improved suggestion on misrefactored_assign_op lint
This commit is contained in:
Oliver Schneider 2018-01-30 19:17:38 +01:00 • committed by GitHub
commit ee8d32850d
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3 changed files with 154 additions and 31 deletions
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83
clippy_lints/src/assign_ops.rs
View file

@ -1,4 +1,5 @@
use rustc::hir;
use rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
use rustc::lint::*;
use syntax::ast;
use utils::{get_trait_def_id, implements_trait, snippet_opt, span_lint_and_then, SpanlessEq};
@ -87,19 +88,29 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssignOps {
});
if let hir::ExprBinary(binop, ref l, ref r) = rhs.node {
if op.node == binop.node {
let lint = |assignee: &hir::Expr, rhs: &hir::Expr| {
let lint = |assignee: &hir::Expr, rhs_other: &hir::Expr| {
span_lint_and_then(
cx,
MISREFACTORED_ASSIGN_OP,
expr.span,
"variable appears on both sides of an assignment operation",
|db| if let (Some(snip_a), Some(snip_r)) =
(snippet_opt(cx, assignee.span), snippet_opt(cx, rhs.span))
(snippet_opt(cx, assignee.span), snippet_opt(cx, rhs_other.span))
{
let a = &sugg::Sugg::hir(cx, assignee, "..");
let r = &sugg::Sugg::hir(cx, rhs, "..");
let long = format!("{} = {}", snip_a, sugg::make_binop(higher::binop(op.node), a, r));
db.span_suggestion(
expr.span,
"replace it with",
format!("{} {}= {}", snip_a, op.node.as_str(), snip_r),
&format!("Did you mean {} = {} {} {} or {}? Consider replacing it with",
snip_a, snip_a, op.node.as_str(), snip_r,
long),
format!("{} {}= {}", snip_a, op.node.as_str(), snip_r)
);
db.span_suggestion(
expr.span,
"or",
long
);
},
);
@ -189,23 +200,34 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssignOps {
);
}
};
// a = a op b
if SpanlessEq::new(cx).ignore_fn().eq_expr(assignee, l) {
lint(assignee, r);
}
// a = b commutative_op a
if SpanlessEq::new(cx).ignore_fn().eq_expr(assignee, r) {
match op.node {
hir::BiAdd |
hir::BiMul |
hir::BiAnd |
hir::BiOr |
hir::BiBitXor |
hir::BiBitAnd |
hir::BiBitOr => {
lint(assignee, l);
},
_ => {},
let mut visitor = ExprVisitor {
assignee: assignee,
counter: 0,
cx: cx
};
walk_expr(&mut visitor, e);
if visitor.counter == 1 {
// a = a op b
if SpanlessEq::new(cx).ignore_fn().eq_expr(assignee, l) {
lint(assignee, r);
}
// a = b commutative_op a
if SpanlessEq::new(cx).ignore_fn().eq_expr(assignee, r) {
match op.node {
hir::BiAdd |
hir::BiMul |
hir::BiAnd |
hir::BiOr |
hir::BiBitXor |
hir::BiBitAnd |
hir::BiBitOr => {
lint(assignee, l);
},
_ => {},
}
}
}
}
@ -222,3 +244,22 @@ fn is_commutative(op: hir::BinOp_) -> bool {
BiSub | BiDiv | BiRem | BiShl | BiShr | BiLt | BiLe | BiGe | BiGt => false,
}
}
struct ExprVisitor<'a, 'tcx: 'a> {
assignee: &'a hir::Expr,
counter: u8,
cx: &'a LateContext<'a, 'tcx>,
}
impl<'a, 'tcx: 'a> Visitor<'tcx> for ExprVisitor<'a, 'tcx> {
fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
if SpanlessEq::new(self.cx).ignore_fn().eq_expr(self.assignee, &expr) {
self.counter += 1;
}
walk_expr(self, expr);
}
fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
NestedVisitorMap::None
}
}