join_absolute_paths Address PR review

clippy_lints/src/methods/join_absolute_paths.rs

@@ -1,29 +1,51 @@
 use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::expr_or_init;
+use clippy_utils::source::snippet_opt;
 use clippy_utils::ty::is_type_diagnostic_item;
 use rustc_ast::ast::LitKind;
+use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::LateContext;
-use rustc_span::symbol::sym::Path;
+use rustc_span::symbol::sym;
+use rustc_span::Span;
 
 use super::JOIN_ABSOLUTE_PATHS;
 
-pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, join_arg: &'tcx Expr<'tcx>) {
-    let ty = cx.typeck_results().expr_ty(expr).peel_refs();
-    if is_type_diagnostic_item(cx, ty, Path)
-        && let ExprKind::Lit(spanned) = &join_arg.kind
+pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, recv: &'tcx Expr<'tcx>, join_arg: &'tcx Expr<'tcx>, expr_span: Span) {
+    let ty = cx.typeck_results().expr_ty(recv).peel_refs();
+    if (is_type_diagnostic_item(cx, ty, sym::Path) || is_type_diagnostic_item(cx, ty, sym::PathBuf))
+        && let ExprKind::Lit(spanned) = expr_or_init(cx, join_arg).kind
         && let LitKind::Str(symbol, _) = spanned.node
-        && (symbol.as_str().starts_with('/') || symbol.as_str().starts_with('\\'))
+        && let sym_str = symbol.as_str()
+        && (sym_str.starts_with('/') || sym_str.starts_with('\\'))
     {
         span_lint_and_then(
             cx,
             JOIN_ABSOLUTE_PATHS,
             join_arg.span,
             "argument to `Path::join` starts with a path separator",
             |diag| {
-                diag
-                      .note("joining a path starting with separator will replace the path instead")
-                      .help("if this is unintentional, try removing the starting separator")
-                      .help("if this is intentional, try creating a new Path instead");
+                let arg_str = snippet_opt(cx, spanned.span).unwrap_or_else(|| "..".to_string());
+
+                let no_separator = if sym_str.starts_with('/') {
+                    arg_str.replacen('/', "", 1)
+                } else {
+                    arg_str.replacen('\\', "", 1)
+                };
+
+                diag.note("joining a path starting with separator will replace the path instead")
+                .span_suggestion(
+                    spanned.span,
+                    "if this is unintentional, try removing the starting separator",
+                    no_separator,
+                    Applicability::Unspecified
+                )
+                .span_suggestion(
+                    expr_span,
+                    "if this is intentional, try creating a new Path instead",
+                    format!("PathBuf::from({arg_str})"),
+                    Applicability::Unspecified
+                );
             },
         );
     }

clippy_lints/src/methods/mod.rs

@@ -3566,11 +3566,14 @@ declare_clippy_lint! {
 
 declare_clippy_lint! {
     /// ### What it does
-    /// Checks for calls to `Path::join` that start with a path separator, like `\\` or `/`..
+    /// Checks for calls to `Path::join` that start with a path separator (`\\` or `/`).
     ///
     /// ### Why is this bad?
-    /// `.join()` arguments starting with a separator  (`/` or `\\`) can replace the entire path.
-    /// If this is intentional, prefer using `Path::new()` instead.
+    /// If the argument to `Path::join` starts with a separator, it will overwrite
+    /// the original path. If this is intentional, prefer using `Path::new` instead.
+    ///
+    /// Note the behavior is platform dependent. A leading `\\` will be accepted
+    /// on unix systems as part of the file name
     ///
     /// See [`Path::join()`](https://doc.rust-lang.org/std/path/struct.Path.html#method.join)
     ///
@@ -3598,7 +3601,7 @@ declare_clippy_lint! {
     #[clippy::version = "1.74.0"]
     pub JOIN_ABSOLUTE_PATHS,
     correctness,
-    "arg to .join called on a `Path` contains leading separator"
+    "calls to `Path::join` which will overwrite the original path"
 }
 
 pub struct Methods {
@@ -4102,7 +4105,7 @@ impl Methods {
                     if let Some(("collect", _, _, span, _)) = method_call(recv) {
                         unnecessary_join::check(cx, expr, recv, join_arg, span);
                     } else {
-                        join_absolute_paths::check(cx, recv, join_arg);
+                        join_absolute_paths::check(cx, recv, join_arg, expr.span);
                     }
                 },
                 ("last", []) => {

tests/ui/join_absolute_paths.rs

@@ -1,26 +1,30 @@
-#![allow(unused)]
+//@no-rustfix
+
+#![allow(clippy::needless_raw_string_hashes)]
 #![warn(clippy::join_absolute_paths)]
 
 use std::path::{Path, PathBuf};
 
 fn main() {
-    // should be linted
     let path = Path::new("/bin");
     path.join("/sh");
+    //~^ ERROR: argument to `Path::join` starts with a path separator
 
-    // should be linted
     let path = Path::new("C:\\Users");
     path.join("\\user");
+    //~^ ERROR: argument to `Path::join` starts with a path separator
+
+    let path = PathBuf::from("/bin");
+    path.join("/sh");
+    //~^ ERROR: argument to `Path::join` starts with a path separator
+
+    let path = PathBuf::from("/bin");
+    path.join(r#"/sh"#);
+    //~^ ERROR: argument to `Path::join` starts with a path separator
 
-    // should not be linted
     let path: &[&str] = &["/bin"];
     path.join("/sh");
 
-    // should not be linted
     let path = Path::new("/bin");
     path.join("sh");
-
-    // should be linted
-    let path = PathBuf::from("/bin");
-    path.join("/sh");
 }

tests/ui/join_absolute_paths.stderr

@@ -1,23 +1,67 @@
 error: argument to `Path::join` starts with a path separator
-  --> $DIR/join_absolute_paths.rs:9:15
+  --> $DIR/join_absolute_paths.rs:10:15
    |
 LL |     path.join("/sh");
    |               ^^^^^
    |
    = note: joining a path starting with separator will replace the path instead
-   = help: if this is unintentional, try removing the starting separator
-   = help: if this is intentional, try creating a new Path instead
    = note: `-D clippy::join-absolute-paths` implied by `-D warnings`
+help: if this is unintentional, try removing the starting separator
+   |
+LL |     path.join("sh");
+   |               ~~~~
+help: if this is intentional, try creating a new Path instead
+   |
+LL |     PathBuf::from("/sh");
+   |     ~~~~~~~~~~~~~~~~~~~~
 
 error: argument to `Path::join` starts with a path separator
-  --> $DIR/join_absolute_paths.rs:13:15
+  --> $DIR/join_absolute_paths.rs:14:15
    |
 LL |     path.join("\\user");
    |               ^^^^^^^^
    |
    = note: joining a path starting with separator will replace the path instead
-   = help: if this is unintentional, try removing the starting separator
-   = help: if this is intentional, try creating a new Path instead
+help: if this is unintentional, try removing the starting separator
+   |
+LL |     path.join("\user");
+   |               ~~~~~~~
+help: if this is intentional, try creating a new Path instead
+   |
+LL |     PathBuf::from("\\user");
+   |     ~~~~~~~~~~~~~~~~~~~~~~~
+
+error: argument to `Path::join` starts with a path separator
+  --> $DIR/join_absolute_paths.rs:18:15
+   |
+LL |     path.join("/sh");
+   |               ^^^^^
+   |
+   = note: joining a path starting with separator will replace the path instead
+help: if this is unintentional, try removing the starting separator
+   |
+LL |     path.join("sh");
+   |               ~~~~
+help: if this is intentional, try creating a new Path instead
+   |
+LL |     PathBuf::from("/sh");
+   |     ~~~~~~~~~~~~~~~~~~~~
+
+error: argument to `Path::join` starts with a path separator
+  --> $DIR/join_absolute_paths.rs:22:15
+   |
+LL |     path.join(r#"/sh"#);
+   |               ^^^^^^^^
+   |
+   = note: joining a path starting with separator will replace the path instead
+help: if this is unintentional, try removing the starting separator
+   |
+LL |     path.join(r#"sh"#);
+   |               ~~~~~~~
+help: if this is intentional, try creating a new Path instead
+   |
+LL |     PathBuf::from(r#"/sh"#);
+   |     ~~~~~~~~~~~~~~~~~~~~~~~
 
-error: aborting due to 2 previous errors
+error: aborting due to 4 previous errors