[Clippy] Swap unnecessary_owned_empty_strings to use diagnostic item instead of path

Author: GnomedDev

compiler/rustc_span/src/symbol.rs

@@ -1893,6 +1893,7 @@ symbols! {
         string_deref_patterns,
         string_from_utf8,
         string_insert_str,
+        string_new,
         string_push_str,
         stringify,
         struct_field_attributes,

library/alloc/src/string.rs

@@ -440,6 +440,7 @@ impl String {
     /// ```
     #[inline]
     #[rustc_const_stable(feature = "const_string_new", since = "1.39.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "string_new")]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     pub const fn new() -> String {

src/tools/clippy/clippy_lints/src/unnecessary_owned_empty_strings.rs

@@ -1,6 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::ty::is_type_lang_item;
-use clippy_utils::{match_def_path, paths};
 use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::{BorrowKind, Expr, ExprKind, LangItem, Mutability};
@@ -42,7 +41,7 @@ impl<'tcx> LateLintPass<'tcx> for UnnecessaryOwnedEmptyStrings {
             && let ty::Ref(_, inner_str, _) = cx.typeck_results().expr_ty_adjusted(expr).kind()
             && inner_str.is_str()
         {
-            if match_def_path(cx, fun_def_id, &paths::STRING_NEW) {
+            if cx.tcx.is_diagnostic_item(sym::string_new, fun_def_id) {
                 span_lint_and_sugg(
                     cx,
                     UNNECESSARY_OWNED_EMPTY_STRINGS,

src/tools/clippy/clippy_utils/src/paths.rs

@@ -51,7 +51,6 @@ pub const SERDE_DESERIALIZE: [&str; 3] = ["serde", "de", "Deserialize"];
 pub const SERDE_DE_VISITOR: [&str; 3] = ["serde", "de", "Visitor"];
 pub const STD_IO_SEEK_FROM_CURRENT: [&str; 4] = ["std", "io", "SeekFrom", "Current"];
 pub const STD_IO_SEEKFROM_START: [&str; 4] = ["std", "io", "SeekFrom", "Start"];
-pub const STRING_NEW: [&str; 4] = ["alloc", "string", "String", "new"];
 pub const SYMBOL: [&str; 3] = ["rustc_span", "symbol", "Symbol"];
 pub const SYMBOL_AS_STR: [&str; 4] = ["rustc_span", "symbol", "Symbol", "as_str"];
 pub const SYMBOL_INTERN: [&str; 4] = ["rustc_span", "symbol", "Symbol", "intern"];