92 lines
3.4 KiB
Rust
92 lines
3.4 KiB
Rust
use crate::utils::{is_try, match_qpath, match_trait_method, paths, span_lint};
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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:** Checks for unused written/read amount.
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///
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/// **Why is this bad?** `io::Write::write(_vectored)` and
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/// `io::Read::read(_vectored)` are not guaranteed to
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/// process the entire buffer. They return how many bytes were processed, which
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/// might be smaller
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/// than a given buffer's length. If you don't need to deal with
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/// partial-write/read, use
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/// `write_all`/`read_exact` instead.
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///
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/// **Known problems:** Detects only common patterns.
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///
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/// **Example:**
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/// ```rust,ignore
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/// use std::io;
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/// fn foo<W: io::Write>(w: &mut W) -> io::Result<()> {
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/// // must be `w.write_all(b"foo")?;`
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/// w.write(b"foo")?;
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/// Ok(())
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/// }
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/// ```
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pub UNUSED_IO_AMOUNT,
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correctness,
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"unused written/read amount"
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}
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declare_lint_pass!(UnusedIoAmount => [UNUSED_IO_AMOUNT]);
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnusedIoAmount {
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fn check_stmt(&mut self, cx: &LateContext<'_, '_>, s: &hir::Stmt<'_>) {
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let expr = match s.kind {
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hir::StmtKind::Semi(ref expr) | hir::StmtKind::Expr(ref expr) => &**expr,
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_ => return,
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};
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match expr.kind {
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hir::ExprKind::Match(ref res, _, _) if is_try(expr).is_some() => {
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if let hir::ExprKind::Call(ref func, ref args) = res.kind {
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if let hir::ExprKind::Path(ref path) = func.kind {
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if match_qpath(path, &paths::TRY_INTO_RESULT) && args.len() == 1 {
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check_method_call(cx, &args[0], expr);
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}
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}
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} else {
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check_method_call(cx, res, expr);
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}
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},
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hir::ExprKind::MethodCall(ref path, _, ref args, _) => match &*path.ident.as_str() {
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"expect" | "unwrap" | "unwrap_or" | "unwrap_or_else" => {
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check_method_call(cx, &args[0], expr);
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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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fn check_method_call(cx: &LateContext<'_, '_>, call: &hir::Expr<'_>, expr: &hir::Expr<'_>) {
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if let hir::ExprKind::MethodCall(ref path, _, _, _) = call.kind {
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let symbol = &*path.ident.as_str();
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let read_trait = match_trait_method(cx, call, &paths::IO_READ);
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let write_trait = match_trait_method(cx, call, &paths::IO_WRITE);
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match (read_trait, write_trait, symbol) {
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(true, _, "read") => span_lint(
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cx,
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UNUSED_IO_AMOUNT,
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expr.span,
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"read amount is not handled. Use `Read::read_exact` instead",
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),
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(true, _, "read_vectored") => span_lint(cx, UNUSED_IO_AMOUNT, expr.span, "read amount is not handled"),
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(_, true, "write") => span_lint(
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cx,
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UNUSED_IO_AMOUNT,
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expr.span,
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"written amount is not handled. Use `Write::write_all` instead",
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),
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(_, true, "write_vectored") => span_lint(cx, UNUSED_IO_AMOUNT, expr.span, "written amount is not handled"),
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_ => (),
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}
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}
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}
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