rust/clippy_lints/src/path_buf_push_overwrite.rs
2020-03-01 12:23:33 +09:00

72 lines
2.6 KiB
Rust

use crate::utils::{match_type, paths, span_lint_and_sugg, walk_ptrs_ty};
use if_chain::if_chain;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use std::path::{Component, Path};
declare_clippy_lint! {
/// **What it does:*** Checks for [push](https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.push)
/// calls on `PathBuf` that can cause overwrites.
///
/// **Why is this bad?** Calling `push` with a root path at the start can overwrite the
/// previous defined path.
///
/// **Known problems:** None.
///
/// **Example:**
/// ```rust
/// use std::path::PathBuf;
///
/// let mut x = PathBuf::from("/foo");
/// x.push("/bar");
/// assert_eq!(x, PathBuf::from("/bar"));
/// ```
/// Could be written:
///
/// ```rust
/// use std::path::PathBuf;
///
/// let mut x = PathBuf::from("/foo");
/// x.push("bar");
/// assert_eq!(x, PathBuf::from("/foo/bar"));
/// ```
pub PATH_BUF_PUSH_OVERWRITE,
nursery,
"calling `push` with file system root on `PathBuf` can overwrite it"
}
declare_lint_pass!(PathBufPushOverwrite => [PATH_BUF_PUSH_OVERWRITE]);
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PathBufPushOverwrite {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::MethodCall(ref path, _, ref args) = expr.kind;
if path.ident.name == sym!(push);
if args.len() == 2;
if match_type(cx, walk_ptrs_ty(cx.tables.expr_ty(&args[0])), &paths::PATH_BUF);
if let Some(get_index_arg) = args.get(1);
if let ExprKind::Lit(ref lit) = get_index_arg.kind;
if let LitKind::Str(ref path_lit, _) = lit.node;
if let pushed_path = Path::new(&*path_lit.as_str());
if let Some(pushed_path_lit) = pushed_path.to_str();
if pushed_path.has_root();
if let Some(root) = pushed_path.components().next();
if root == Component::RootDir;
then {
span_lint_and_sugg(
cx,
PATH_BUF_PUSH_OVERWRITE,
lit.span,
"Calling `push` with '/' or '\\' (file system root) will overwrite the previous path definition",
"try",
format!("\"{}\"", pushed_path_lit.trim_start_matches(|c| c == '/' || c == '\\')),
Applicability::MachineApplicable,
);
}
}
}
}