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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::ty::is_type_diagnostic_item;
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 rustc_span::symbol::sym;
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.
///
/// ### 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"));
/// ```
#[clippy::version = "1.36.0"]
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<'tcx> LateLintPass<'tcx> for PathBufPushOverwrite {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::MethodCall(path, args, _) = expr.kind;
if path.ident.name == sym!(push);
if args.len() == 2;
if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), sym::PathBuf);
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,
);
}
}
}
}
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