Improved error message for set_len() on empty Vec
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Yechan Bae
parent
de0d2b1500
commit
2181387c3a
@ -1,5 +1,5 @@
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use clippy_utils::diagnostics::span_lint_and_then;
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use clippy_utils::higher::get_vec_init_kind;
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use clippy_utils::diagnostics::{span_lint, span_lint_and_then};
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use clippy_utils::higher::{get_vec_init_kind, VecInitKind};
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use clippy_utils::ty::{is_type_diagnostic_item, is_uninit_value_valid_for_ty};
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use clippy_utils::{is_lint_allowed, path_to_local_id, peel_hir_expr_while, SpanlessEq};
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use rustc_hir::{Block, Expr, ExprKind, HirId, PatKind, PathSegment, Stmt, StmtKind};
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@ -83,69 +83,108 @@ fn handle_uninit_vec_pair(
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if_chain! {
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if let Some(vec) = extract_init_or_reserve_target(cx, maybe_init_or_reserve);
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if let Some((set_len_self, call_span)) = extract_set_len_self(cx, maybe_set_len);
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if vec.eq_expr(cx, set_len_self);
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if vec.location.eq_expr(cx, set_len_self);
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if let ty::Ref(_, vec_ty, _) = cx.typeck_results().expr_ty_adjusted(set_len_self).kind();
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if let ty::Adt(_, substs) = vec_ty.kind();
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// Check T of Vec<T>
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if !is_uninit_value_valid_for_ty(cx, substs.type_at(0));
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// `#[allow(...)]` attribute can be set on enclosing unsafe block of `set_len()`
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if !is_lint_allowed(cx, UNINIT_VEC, maybe_set_len.hir_id);
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then {
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// FIXME: #7698, false positive of the internal lints
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#[allow(clippy::collapsible_span_lint_calls)]
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span_lint_and_then(
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cx,
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UNINIT_VEC,
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vec![call_span, maybe_init_or_reserve.span],
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"calling `set_len()` immediately after reserving a buffer creates uninitialized values",
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|diag| {
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diag.help("initialize the buffer or wrap the content in `MaybeUninit`");
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},
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);
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if vec.has_capacity() {
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// with_capacity / reserve -> set_len
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// Check T of Vec<T>
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if !is_uninit_value_valid_for_ty(cx, substs.type_at(0)) {
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// FIXME: #7698, false positive of the internal lints
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#[allow(clippy::collapsible_span_lint_calls)]
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span_lint_and_then(
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cx,
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UNINIT_VEC,
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vec![call_span, maybe_init_or_reserve.span],
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"calling `set_len()` immediately after reserving a buffer creates uninitialized values",
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|diag| {
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diag.help("initialize the buffer or wrap the content in `MaybeUninit`");
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},
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);
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}
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} else {
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// new / default -> set_len
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span_lint(
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cx,
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UNINIT_VEC,
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vec![call_span, maybe_init_or_reserve.span],
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"calling `set_len()` on empty `Vec` creates out-of-bound values",
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)
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}
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}
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}
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}
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#[derive(Clone, Copy, Debug)]
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enum LocalOrExpr<'tcx> {
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/// The target `Vec` that is initialized or reserved
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#[derive(Clone, Copy)]
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struct TargetVec<'tcx> {
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location: VecLocation<'tcx>,
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/// `None` if `reserve()`
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init_kind: Option<VecInitKind>,
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}
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impl TargetVec<'_> {
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pub fn has_capacity(self) -> bool {
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!matches!(self.init_kind, Some(VecInitKind::New | VecInitKind::Default))
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}
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}
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#[derive(Clone, Copy)]
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enum VecLocation<'tcx> {
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Local(HirId),
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Expr(&'tcx Expr<'tcx>),
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}
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impl<'tcx> LocalOrExpr<'tcx> {
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fn eq_expr(self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
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impl<'tcx> VecLocation<'tcx> {
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pub fn eq_expr(self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool {
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match self {
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LocalOrExpr::Local(hir_id) => path_to_local_id(expr, hir_id),
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LocalOrExpr::Expr(self_expr) => SpanlessEq::new(cx).eq_expr(self_expr, expr),
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VecLocation::Local(hir_id) => path_to_local_id(expr, hir_id),
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VecLocation::Expr(self_expr) => SpanlessEq::new(cx).eq_expr(self_expr, expr),
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}
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}
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}
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/// Finds the target location where the result of `Vec` initialization is stored
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/// or `self` expression for `Vec::reserve()`.
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fn extract_init_or_reserve_target<'tcx>(cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'tcx>) -> Option<LocalOrExpr<'tcx>> {
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fn extract_init_or_reserve_target<'tcx>(cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'tcx>) -> Option<TargetVec<'tcx>> {
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match stmt.kind {
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StmtKind::Local(local) => {
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if_chain! {
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if let Some(init_expr) = local.init;
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if let PatKind::Binding(_, hir_id, _, None) = local.pat.kind;
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if get_vec_init_kind(cx, init_expr).is_some();
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if let Some(init_kind) = get_vec_init_kind(cx, init_expr);
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then {
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Some(LocalOrExpr::Local(hir_id))
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} else {
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None
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return Some(TargetVec {
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location: VecLocation::Local(hir_id),
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init_kind: Some(init_kind),
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})
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}
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}
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},
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StmtKind::Expr(expr) | StmtKind::Semi(expr) => match expr.kind {
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ExprKind::Assign(lhs, rhs, _span) if get_vec_init_kind(cx, rhs).is_some() => Some(LocalOrExpr::Expr(lhs)),
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ExprKind::MethodCall(path, _, [self_expr, _], _) if is_reserve(cx, path, self_expr) => {
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Some(LocalOrExpr::Expr(self_expr))
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ExprKind::Assign(lhs, rhs, _span) => {
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if let Some(init_kind) = get_vec_init_kind(cx, rhs) {
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return Some(TargetVec {
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location: VecLocation::Expr(lhs),
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init_kind: Some(init_kind),
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});
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}
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},
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_ => None,
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ExprKind::MethodCall(path, _, [self_expr, _], _) if is_reserve(cx, path, self_expr) => {
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return Some(TargetVec {
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location: VecLocation::Expr(self_expr),
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init_kind: None,
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});
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},
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_ => (),
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},
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StmtKind::Item(_) => None,
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StmtKind::Item(_) => (),
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}
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None
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}
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fn is_reserve(cx: &LateContext<'_>, path: &PathSegment<'_>, self_expr: &Expr<'_>) -> bool {
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@ -21,7 +21,7 @@ LL | vec.set_len(200);
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= help: initialize the buffer or wrap the content in `MaybeUninit`
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error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
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error: calling `set_len()` on empty `Vec` creates out-of-bound values
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--> $DIR/uninit_vec.rs:24:5
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LL | let mut vec: Vec<u8> = Vec::new();
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@ -29,10 +29,8 @@ LL | let mut vec: Vec<u8> = Vec::new();
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LL | unsafe {
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LL | vec.set_len(200);
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| ^^^^^^^^^^^^^^^^
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= help: initialize the buffer or wrap the content in `MaybeUninit`
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error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
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error: calling `set_len()` on empty `Vec` creates out-of-bound values
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--> $DIR/uninit_vec.rs:30:5
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LL | let mut vec: Vec<u8> = Default::default();
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@ -40,10 +38,8 @@ LL | let mut vec: Vec<u8> = Default::default();
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LL | unsafe {
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LL | vec.set_len(200);
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| ^^^^^^^^^^^^^^^^
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= help: initialize the buffer or wrap the content in `MaybeUninit`
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error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
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error: calling `set_len()` on empty `Vec` creates out-of-bound values
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--> $DIR/uninit_vec.rs:35:5
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LL | let mut vec: Vec<u8> = Vec::default();
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@ -51,8 +47,6 @@ LL | let mut vec: Vec<u8> = Vec::default();
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LL | unsafe {
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LL | vec.set_len(200);
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| ^^^^^^^^^^^^^^^^
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= help: initialize the buffer or wrap the content in `MaybeUninit`
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error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
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--> $DIR/uninit_vec.rs:49:5
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