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Separate getting offsets and getting index expressions

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rail 2020-04-27 19:26:00 +12:00
parent 3d121d53af
commit 4f2617c059
1 changed files with 28 additions and 35 deletions
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63
clippy_lints/src/loops.rs
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@ -837,7 +837,7 @@ fn fetch_cloned_expr<'tcx>(expr: &'tcx Expr<'tcx>) -> &'tcx Expr<'tcx> {
}
}
fn get_fixed_offset_var<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &Expr<'_>, var: HirId) -> Option<FixedOffsetVar> {
fn get_offset<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, idx: &Expr<'_>, var: HirId) -> Option<Offset> {
fn extract_offset<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, e: &Expr<'_>, var: HirId) -> Option<String> {
match &e.kind {
ExprKind::Lit(l) => match l.node {
@ -849,38 +849,24 @@ fn get_fixed_offset_var<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &Expr<'_>, v
}
}
if let ExprKind::Index(seqexpr, idx) = expr.kind {
let ty = cx.tables.expr_ty(seqexpr);
if !is_slice_like(cx, ty) {
return None;
}
match idx.kind {
ExprKind::Binary(op, lhs, rhs) => match op.node {
BinOpKind::Add => {
let offset_opt = if same_var(cx, lhs, var) {
extract_offset(cx, rhs, var)
} else if same_var(cx, rhs, var) {
extract_offset(cx, lhs, var)
} else {
None
};
let offset = match idx.kind {
ExprKind::Binary(op, lhs, rhs) => match op.node {
BinOpKind::Add => {
let offset_opt = if same_var(cx, lhs, var) {
extract_offset(cx, rhs, var)
} else if same_var(cx, rhs, var) {
extract_offset(cx, lhs, var)
} else {
None
};
offset_opt.map(Offset::positive)
},
BinOpKind::Sub if same_var(cx, lhs, var) => extract_offset(cx, rhs, var).map(Offset::negative),
_ => None,
offset_opt.map(Offset::positive)
},
ExprKind::Path(..) if same_var(cx, idx, var) => Some(Offset::positive("0".into())),
BinOpKind::Sub if same_var(cx, lhs, var) => extract_offset(cx, rhs, var).map(Offset::negative),
_ => None,
};
offset.map(|o| FixedOffsetVar {
var_name: snippet_opt(cx, seqexpr.span).unwrap_or_else(|| "???".into()),
offset: o,
})
} else {
None
},
ExprKind::Path(..) if same_var(cx, idx, var) => Some(Offset::positive("0".into())),
_ => None,
}
}
@ -994,15 +980,22 @@ fn detect_manual_memcpy<'a, 'tcx>(
o.and_then(|(lhs, rhs)| {
let rhs = fetch_cloned_expr(rhs);
if_chain! {
if let Some(offset_left) = get_fixed_offset_var(cx, lhs, canonical_id);
if let Some(offset_right) = get_fixed_offset_var(cx, rhs, canonical_id);
if let ExprKind::Index(seqexpr_left, idx_left) = lhs.kind;
if let ExprKind::Index(seqexpr_right, idx_right) = rhs.kind;
if is_slice_like(cx, cx.tables.expr_ty(seqexpr_left))
&& is_slice_like(cx, cx.tables.expr_ty(seqexpr_right));
if let Some(offset_left) = get_offset(cx, &idx_left, canonical_id);
if let Some(offset_right) = get_offset(cx, &idx_right, canonical_id);
let var_name_left = snippet_opt(cx, seqexpr_left.span).unwrap_or_else(|| "???".into());
let var_name_right = snippet_opt(cx, seqexpr_right.span).unwrap_or_else(|| "???".into());
// Source and destination must be different
if offset_left.var_name != offset_right.var_name;
if var_name_left != var_name_right;
then {
Some((offset_left, offset_right))
Some((FixedOffsetVar { var_name: var_name_left, offset: offset_left },
FixedOffsetVar { var_name: var_name_right, offset: offset_right }))
} else {
return None
None
}
}
})