mirror of
https://github.com/rust-lang/rust-clippy
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Auto merge of #8964 - tamaroning:read_zero_byte_vec, r=dswij
Warn about read into zero-length `Vec` Closes #8886 - \[x] Followed [lint naming conventions][lint_naming] - \[x] Added passing UI tests (including committed `.stderr` file) - \[x] `cargo test` passes locally - \[x] Executed `cargo dev update_lints` - \[x] Added lint documentation - \[x] Run `cargo dev fmt` changelog: none
This commit is contained in:
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commit
844c06a7c7
8 changed files with 299 additions and 0 deletions
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@ -3678,6 +3678,7 @@ Released 2018-09-13
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[`rc_buffer`]: https://rust-lang.github.io/rust-clippy/master/index.html#rc_buffer
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[`rc_clone_in_vec_init`]: https://rust-lang.github.io/rust-clippy/master/index.html#rc_clone_in_vec_init
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[`rc_mutex`]: https://rust-lang.github.io/rust-clippy/master/index.html#rc_mutex
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[`read_zero_byte_vec`]: https://rust-lang.github.io/rust-clippy/master/index.html#read_zero_byte_vec
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[`recursive_format_impl`]: https://rust-lang.github.io/rust-clippy/master/index.html#recursive_format_impl
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[`redundant_allocation`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_allocation
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[`redundant_clone`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone
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@ -271,6 +271,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
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LintId::of(ranges::RANGE_ZIP_WITH_LEN),
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LintId::of(ranges::REVERSED_EMPTY_RANGES),
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LintId::of(rc_clone_in_vec_init::RC_CLONE_IN_VEC_INIT),
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LintId::of(read_zero_byte_vec::READ_ZERO_BYTE_VEC),
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LintId::of(redundant_clone::REDUNDANT_CLONE),
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LintId::of(redundant_closure_call::REDUNDANT_CLOSURE_CALL),
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LintId::of(redundant_field_names::REDUNDANT_FIELD_NAMES),
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@ -55,6 +55,7 @@ store.register_group(true, "clippy::correctness", Some("clippy_correctness"), ve
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LintId::of(ptr::INVALID_NULL_PTR_USAGE),
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LintId::of(ptr::MUT_FROM_REF),
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LintId::of(ranges::REVERSED_EMPTY_RANGES),
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LintId::of(read_zero_byte_vec::READ_ZERO_BYTE_VEC),
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LintId::of(regex::INVALID_REGEX),
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LintId::of(self_assignment::SELF_ASSIGNMENT),
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LintId::of(serde_api::SERDE_API_MISUSE),
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@ -459,6 +459,7 @@ store.register_lints(&[
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ranges::RANGE_ZIP_WITH_LEN,
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ranges::REVERSED_EMPTY_RANGES,
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rc_clone_in_vec_init::RC_CLONE_IN_VEC_INIT,
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read_zero_byte_vec::READ_ZERO_BYTE_VEC,
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redundant_clone::REDUNDANT_CLONE,
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redundant_closure_call::REDUNDANT_CLOSURE_CALL,
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redundant_else::REDUNDANT_ELSE,
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@ -348,6 +348,7 @@ mod pub_use;
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mod question_mark;
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mod ranges;
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mod rc_clone_in_vec_init;
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mod read_zero_byte_vec;
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mod redundant_clone;
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mod redundant_closure_call;
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mod redundant_else;
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@ -908,6 +909,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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store.register_late_pass(|| Box::new(swap_ptr_to_ref::SwapPtrToRef));
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store.register_late_pass(|| Box::new(mismatching_type_param_order::TypeParamMismatch));
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store.register_late_pass(|| Box::new(as_underscore::AsUnderscore));
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store.register_late_pass(|| Box::new(read_zero_byte_vec::ReadZeroByteVec));
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// add lints here, do not remove this comment, it's used in `new_lint`
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}
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142
clippy_lints/src/read_zero_byte_vec.rs
Normal file
142
clippy_lints/src/read_zero_byte_vec.rs
Normal file
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@ -0,0 +1,142 @@
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use clippy_utils::{
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diagnostics::{span_lint, span_lint_and_sugg},
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higher::{get_vec_init_kind, VecInitKind},
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source::snippet,
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visitors::expr_visitor_no_bodies,
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};
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use hir::{intravisit::Visitor, ExprKind, Local, PatKind, PathSegment, QPath, StmtKind};
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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declare_clippy_lint! {
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/// ### What it does
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/// This lint catches reads into a zero-length `Vec`.
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/// Especially in the case of a call to `with_capacity`, this lint warns that read
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/// gets the number of bytes from the `Vec`'s length, not its capacity.
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///
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/// ### Why is this bad?
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/// Reading zero bytes is almost certainly not the intended behavior.
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///
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/// ### Known problems
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/// In theory, a very unusual read implementation could assign some semantic meaning
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/// to zero-byte reads. But it seems exceptionally unlikely that code intending to do
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/// a zero-byte read would allocate a `Vec` for it.
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///
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/// ### Example
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/// ```rust
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/// use std::io;
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/// fn foo<F: io::Read>(mut f: F) {
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/// let mut data = Vec::with_capacity(100);
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/// f.read(&mut data).unwrap();
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// use std::io;
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/// fn foo<F: io::Read>(mut f: F) {
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/// let mut data = Vec::with_capacity(100);
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/// data.resize(100, 0);
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/// f.read(&mut data).unwrap();
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/// }
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/// ```
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#[clippy::version = "1.63.0"]
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pub READ_ZERO_BYTE_VEC,
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correctness,
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"checks for reads into a zero-length `Vec`"
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}
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declare_lint_pass!(ReadZeroByteVec => [READ_ZERO_BYTE_VEC]);
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impl<'tcx> LateLintPass<'tcx> for ReadZeroByteVec {
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fn check_block(&mut self, cx: &LateContext<'tcx>, block: &hir::Block<'tcx>) {
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for (idx, stmt) in block.stmts.iter().enumerate() {
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if !stmt.span.from_expansion()
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// matches `let v = Vec::new();`
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&& let StmtKind::Local(local) = stmt.kind
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&& let Local { pat, init: Some(init), .. } = local
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&& let PatKind::Binding(_, _, ident, _) = pat.kind
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&& let Some(vec_init_kind) = get_vec_init_kind(cx, init)
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{
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// finds use of `_.read(&mut v)`
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let mut read_found = false;
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let mut visitor = expr_visitor_no_bodies(|expr| {
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if let ExprKind::MethodCall(path, [_self, arg], _) = expr.kind
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&& let PathSegment { ident: read_or_read_exact, .. } = *path
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&& matches!(read_or_read_exact.as_str(), "read" | "read_exact")
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&& let ExprKind::AddrOf(_, hir::Mutability::Mut, inner) = arg.kind
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&& let ExprKind::Path(QPath::Resolved(None, inner_path)) = inner.kind
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&& let [inner_seg] = inner_path.segments
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&& ident.name == inner_seg.ident.name
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{
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read_found = true;
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}
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!read_found
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});
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let next_stmt_span;
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if idx == block.stmts.len() - 1 {
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// case { .. stmt; expr }
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if let Some(e) = block.expr {
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visitor.visit_expr(e);
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next_stmt_span = e.span;
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} else {
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return;
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}
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} else {
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// case { .. stmt; stmt; .. }
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let next_stmt = &block.stmts[idx + 1];
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visitor.visit_stmt(next_stmt);
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next_stmt_span = next_stmt.span;
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}
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drop(visitor);
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if read_found && !next_stmt_span.from_expansion() {
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let applicability = Applicability::MaybeIncorrect;
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match vec_init_kind {
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VecInitKind::WithConstCapacity(len) => {
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span_lint_and_sugg(
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cx,
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READ_ZERO_BYTE_VEC,
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next_stmt_span,
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"reading zero byte data to `Vec`",
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"try",
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format!("{}.resize({}, 0); {}",
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ident.as_str(),
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len,
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snippet(cx, next_stmt_span, "..")
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),
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applicability,
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);
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}
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VecInitKind::WithExprCapacity(hir_id) => {
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let e = cx.tcx.hir().expect_expr(hir_id);
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span_lint_and_sugg(
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cx,
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READ_ZERO_BYTE_VEC,
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next_stmt_span,
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"reading zero byte data to `Vec`",
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"try",
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format!("{}.resize({}, 0); {}",
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ident.as_str(),
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snippet(cx, e.span, ".."),
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snippet(cx, next_stmt_span, "..")
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),
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applicability,
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);
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}
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_ => {
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span_lint(
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cx,
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READ_ZERO_BYTE_VEC,
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next_stmt_span,
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"reading zero byte data to `Vec`",
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);
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}
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}
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}
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}
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}
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}
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}
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87
tests/ui/read_zero_byte_vec.rs
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87
tests/ui/read_zero_byte_vec.rs
Normal file
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@ -0,0 +1,87 @@
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#![warn(clippy::read_zero_byte_vec)]
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#![allow(clippy::unused_io_amount)]
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use std::fs::File;
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use std::io;
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use std::io::prelude::*;
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extern crate futures;
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use futures::io::{AsyncRead, AsyncReadExt};
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use tokio::io::{AsyncRead as TokioAsyncRead, AsyncReadExt as _, AsyncWrite as TokioAsyncWrite, AsyncWriteExt as _};
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fn test() -> io::Result<()> {
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let cap = 1000;
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let mut f = File::open("foo.txt").unwrap();
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// should lint
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let mut data = Vec::with_capacity(20);
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f.read_exact(&mut data).unwrap();
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// should lint
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let mut data2 = Vec::with_capacity(cap);
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f.read_exact(&mut data2)?;
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// should lint
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let mut data3 = Vec::new();
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f.read_exact(&mut data3)?;
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// should lint
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let mut data4 = vec![];
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let _ = f.read(&mut data4)?;
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// should lint
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let _ = {
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let mut data5 = Vec::new();
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f.read(&mut data5)
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};
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// should lint
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let _ = {
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let mut data6: Vec<u8> = Default::default();
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f.read(&mut data6)
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};
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// should not lint
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let mut buf = [0u8; 100];
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f.read(&mut buf)?;
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// should not lint
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let mut empty = vec![];
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let mut data7 = vec![];
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f.read(&mut empty);
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// should not lint
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f.read(&mut data7);
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// should not lint
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let mut data8 = Vec::new();
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data8.resize(100, 0);
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f.read_exact(&mut data8)?;
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// should not lint
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let mut data9 = vec![1, 2, 3];
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f.read_exact(&mut data9)?;
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Ok(())
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}
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async fn test_futures<R: AsyncRead + Unpin>(r: &mut R) {
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// should lint
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let mut data = Vec::new();
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r.read(&mut data).await.unwrap();
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// should lint
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let mut data2 = Vec::new();
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r.read_exact(&mut data2).await.unwrap();
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}
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async fn test_tokio<R: TokioAsyncRead + Unpin>(r: &mut R) {
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// should lint
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let mut data = Vec::new();
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r.read(&mut data).await.unwrap();
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// should lint
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let mut data2 = Vec::new();
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r.read_exact(&mut data2).await.unwrap();
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}
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fn main() {}
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64
tests/ui/read_zero_byte_vec.stderr
Normal file
64
tests/ui/read_zero_byte_vec.stderr
Normal file
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@ -0,0 +1,64 @@
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:17:5
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LL | f.read_exact(&mut data).unwrap();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `data.resize(20, 0); f.read_exact(&mut data).unwrap();`
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= note: `-D clippy::read-zero-byte-vec` implied by `-D warnings`
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:21:5
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LL | f.read_exact(&mut data2)?;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `data2.resize(cap, 0); f.read_exact(&mut data2)?;`
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:25:5
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LL | f.read_exact(&mut data3)?;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:29:5
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LL | let _ = f.read(&mut data4)?;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:34:9
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LL | f.read(&mut data5)
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| ^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:40:9
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LL | f.read(&mut data6)
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| ^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:70:5
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LL | r.read(&mut data).await.unwrap();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:74:5
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LL | r.read_exact(&mut data2).await.unwrap();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:80:5
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LL | r.read(&mut data).await.unwrap();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: reading zero byte data to `Vec`
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--> $DIR/read_zero_byte_vec.rs:84:5
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|
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LL | r.read_exact(&mut data2).await.unwrap();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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error: aborting due to 10 previous errors
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