Added type check and test case for string slice.

Author: Mason Ray Hanna III

clippy_lints/src/methods/path_join_correction.rs

@@ -1,28 +1,31 @@
-use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::{diagnostics::span_lint_and_sugg, 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::Span;
+use rustc_span::{symbol::sym::Path, Span};
 
 use super::PATH_JOIN_CORRECTION;
 
 pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>, join_arg: &'tcx Expr<'tcx>, span: Span) {
-    let applicability = Applicability::MachineApplicable;
-    if_chain!(
-      if let ExprKind::Lit(spanned) = &join_arg.kind;
-      if let LitKind::Str(symbol, _) = spanned.node;
-      if symbol.as_str().starts_with('/');
-      then {
-        span_lint_and_sugg(
-      cx,
-      PATH_JOIN_CORRECTION,
-      span.with_hi(expr.span.hi()),
-      r#"argument in join called on path contains a starting '/'"#,
-      "try removing first '/'",
-      "join(\"your/path/here\")".to_owned(),
-      applicability
+    let ty = cx.typeck_results().expr_ty(expr);
+    if is_type_diagnostic_item(cx, ty, Path) {
+        let applicability = Applicability::MachineApplicable;
+        if_chain!(
+         if let ExprKind::Lit(spanned) = &join_arg.kind;
+         if let LitKind::Str(symbol, _) = spanned.node;
+         if symbol.as_str().starts_with('/');
+          then {
+           span_lint_and_sugg(
+           cx,
+           PATH_JOIN_CORRECTION,
+           span.with_hi(expr.span.hi()),
+           r#"argument in join called on path contains a starting '/'"#,
+           "try removing first '/'",
+           "join(\"your/path/here\")".to_owned(),
+           applicability
+         );
+        }
         );
-      }
-    );
+    }
 }

tests/ui/path_join_correction.fixed

@@ -1,15 +1,22 @@
 // run-rustfix
 #![allow(unused)]
 #![warn(clippy::path_join_correction)]
+use std::path::Path;
+//use std::string::String;
 
 fn main() {
     // should be linted
-    let path = std::path::Path::new("/bin");
-    path.join("your/path/here");
+    let path = Path::new("/bin");
+    path.join("/sh");
     println!("{}", path.display());
 
+    // should not be linted
+    let path: &[&str] = &["/bin"];
+    path.join("/sh");
+    println!("{:?}", path);
+
     //should not be linted
-    let path = std::path::Path::new("/bin");
+    let path = Path::new("/bin");
     path.join("sh");
     println!("{}", path.display());
 }

tests/ui/path_join_correction.rs

@@ -1,15 +1,22 @@
 // run-rustfix
 #![allow(unused)]
 #![warn(clippy::path_join_correction)]
+use std::path::Path;
+//use std::string::String;
 
 fn main() {
     // should be linted
-    let path = std::path::Path::new("/bin");
+    let path = Path::new("/bin");
     path.join("/sh");
     println!("{}", path.display());
 
+    // should not be linted
+    let path: &[&str] = &["/bin"];
+    path.join("/sh");
+    println!("{:?}", path);
+
     //should not be linted
-    let path = std::path::Path::new("/bin");
+    let path = Path::new("/bin");
     path.join("sh");
     println!("{}", path.display());
 }