96 lines
3.0 KiB
Rust
96 lines
3.0 KiB
Rust
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use crate::methods::method_call;
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::peel_blocks;
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use rustc_ast::LitKind;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_middle::ty;
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use rustc_session::declare_lint_pass;
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use rustc_span::{sym, BytePos, Span};
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declare_clippy_lint! {
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/// ### What it does
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/// Checks if both `.write(true)` and `.append(true)` methods are called
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/// on a same `OpenOptions`.
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///
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/// ### Why is this bad?
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/// `.append(true)` already enables `write(true)`, making this one
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/// superflous.
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///
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/// ### Example
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/// ```no_run
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/// # use std::fs::OpenOptions;
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/// let _ = OpenOptions::new()
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/// .write(true)
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/// .append(true)
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/// .create(true)
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/// .open("file.json");
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/// ```
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/// Use instead:
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/// ```no_run
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/// # use std::fs::OpenOptions;
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/// let _ = OpenOptions::new()
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/// .append(true)
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/// .create(true)
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/// .open("file.json");
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/// ```
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#[clippy::version = "1.76.0"]
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pub INEFFECTIVE_OPEN_OPTIONS,
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suspicious,
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"usage of both `write(true)` and `append(true)` on same `OpenOptions`"
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}
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declare_lint_pass!(IneffectiveOpenOptions => [INEFFECTIVE_OPEN_OPTIONS]);
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fn index_if_arg_is_boolean(args: &[Expr<'_>], call_span: Span) -> Option<Span> {
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if let [arg] = args
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&& let ExprKind::Lit(lit) = peel_blocks(arg).kind
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&& lit.node == LitKind::Bool(true)
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{
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// The `.` is not included in the span so we cheat a little bit to include it as well.
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Some(call_span.with_lo(call_span.lo() - BytePos(1)))
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} else {
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None
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}
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}
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impl<'tcx> LateLintPass<'tcx> for IneffectiveOpenOptions {
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fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
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let Some(("open", mut receiver, [_arg], _, _)) = method_call(expr) else {
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return;
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};
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let receiver_ty = cx.typeck_results().expr_ty(receiver);
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match receiver_ty.peel_refs().kind() {
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ty::Adt(adt, _) if cx.tcx.is_diagnostic_item(sym::FsOpenOptions, adt.did()) => {},
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_ => return,
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}
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let mut append = None;
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let mut write = None;
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while let Some((name, recv, args, _, span)) = method_call(receiver) {
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if name == "append" {
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append = index_if_arg_is_boolean(args, span);
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} else if name == "write" {
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write = index_if_arg_is_boolean(args, span);
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}
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receiver = recv;
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}
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if let Some(write_span) = write
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&& append.is_some()
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{
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span_lint_and_sugg(
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cx,
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INEFFECTIVE_OPEN_OPTIONS,
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write_span,
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"unnecessary use of `.write(true)` because there is `.append(true)`",
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"remove `.write(true)`",
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String::new(),
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Applicability::MachineApplicable,
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);
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}
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}
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}
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