correct suggestion for map_with_unused_argument_over_ranges in a `n…

…o_std` environment

clippy_lints/src/methods/map_with_unused_argument_over_ranges.rs

@@ -3,7 +3,7 @@ use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::sugg::Sugg;
-use clippy_utils::{eager_or_lazy, higher, usage};
+use clippy_utils::{eager_or_lazy, higher, std_or_core, usage};
 use rustc_ast::LitKind;
 use rustc_ast::ast::RangeLimits;
 use rustc_data_structures::packed::Pu128;
@@ -75,6 +75,7 @@ pub(super) fn check(
         } = body_hir
         && !usage::BindingUsageFinder::are_params_used(cx, body_hir)
         && let Some(count) = extract_count_with_applicability(cx, range, &mut applicability)
+        && let Some(exec_context) = std_or_core(cx)
     {
         let method_to_use_name;
         let new_span;
@@ -105,7 +106,7 @@ pub(super) fn check(
         let mut parts = vec![
             (
                 receiver.span.to(method_call_span),
-                format!("std::iter::{method_to_use_name}"),
+                format!("{exec_context}::iter::{method_to_use_name}"),
             ),
             new_span,
         ];

tests/ui/map_with_unused_argument_over_ranges_nostd.fixed

@@ -0,0 +1,8 @@
+#![warn(clippy::map_with_unused_argument_over_ranges)]
+#![no_std]
+extern crate alloc;
+use alloc::vec::Vec;
+
+fn nostd(v: &mut [i32]) {
+    let _: Vec<_> = core::iter::repeat_n(3 + 1, 10).collect();
+}

tests/ui/map_with_unused_argument_over_ranges_nostd.rs

@@ -0,0 +1,8 @@
+#![warn(clippy::map_with_unused_argument_over_ranges)]
+#![no_std]
+extern crate alloc;
+use alloc::vec::Vec;
+
+fn nostd(v: &mut [i32]) {
+    let _: Vec<_> = (0..10).map(|_| 3 + 1).collect();
+}

tests/ui/map_with_unused_argument_over_ranges_nostd.stderr

@@ -0,0 +1,15 @@
+error: map of a closure that does not depend on its parameter over a range
+  --> tests/ui/map_with_unused_argument_over_ranges_nostd.rs:7:21
+   |
+LL |     let _: Vec<_> = (0..10).map(|_| 3 + 1).collect();
+   |                     ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: `-D clippy::map-with-unused-argument-over-ranges` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::map_with_unused_argument_over_ranges)]`
+help: remove the explicit range and use `repeat_n`
+   |
+LL |     let _: Vec<_> = core::iter::repeat_n(3 + 1, 10).collect();
+   |                     ~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~
+
+error: aborting due to 1 previous error
+