Use is_no_std_crate for swap

Author: dswij

clippy_lints/src/swap.rs

@@ -2,7 +2,7 @@ use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::sugg::Sugg;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{any_parent_has_attr, can_mut_borrow_both, differing_macro_contexts, eq_expr_value};
+use clippy_utils::{can_mut_borrow_both, differing_macro_contexts, eq_expr_value, is_no_core_crate, is_no_std_crate};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::{BinOpKind, Block, Expr, ExprKind, PatKind, QPath, Stmt, StmtKind};
@@ -113,9 +113,9 @@ fn generate_swap_warning(cx: &LateContext<'_>, e1: &Expr<'_>, e2: &Expr<'_>, spa
 
     let first = Sugg::hir_with_applicability(cx, e1, "..", &mut applicability);
     let second = Sugg::hir_with_applicability(cx, e2, "..", &mut applicability);
-    let sugg = if !any_parent_has_attr(cx.tcx, e1.hir_id, sym::no_std) {
+    let sugg = if !is_no_std_crate(cx) {
         "std"
-    } else if any_parent_has_attr(cx.tcx, e1.hir_id, sym::no_core) {
+    } else if is_no_core_crate(cx) {
         ""
     } else {
         "core"
@@ -199,9 +199,9 @@ fn check_suspicious_swap(cx: &LateContext<'_>, block: &Block<'_>) {
                 };
 
                 let span = first.span.to(second.span);
-                let sugg = if !any_parent_has_attr(cx.tcx, block.hir_id, sym::no_std) {
+                let sugg = if !is_no_std_crate(cx) {
                     "std"
-                } else if any_parent_has_attr(cx.tcx, block.hir_id, sym::no_core) {
+                } else if is_no_core_crate(cx) {
                     ""
                 } else {
                     "core"

clippy_utils/src/lib.rs

@@ -1856,6 +1856,16 @@ pub fn is_no_std_crate(cx: &LateContext<'_>) -> bool {
     })
 }
 
+pub fn is_no_core_crate(cx: &LateContext<'_>) -> bool {
+    cx.tcx.hir().attrs(hir::CRATE_HIR_ID).iter().any(|attr| {
+        if let ast::AttrKind::Normal(ref attr, _) = attr.kind {
+            attr.path == sym::no_core
+        } else {
+            false
+        }
+    })
+}
+
 /// Check if parent of a hir node is a trait implementation block.
 /// For example, `f` in
 /// ```rust,ignore