Fix `useless_vec` suggestion in `for _ in vec![..]`

5 files changed, 88 insertions, 51 deletions

diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 2f5932104c1..2dbdee977b0 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -699,7 +699,12 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     });
     let too_large_for_stack = conf.too_large_for_stack;
     store.register_late_pass(move |_| Box::new(escape::BoxedLocal { too_large_for_stack }));
-    store.register_late_pass(move |_| Box::new(vec::UselessVec { too_large_for_stack }));
+    store.register_late_pass(move |_| {
+        Box::new(vec::UselessVec {
+            too_large_for_stack,
+            msrv: msrv(),
+        })
+    });
     store.register_late_pass(|_| Box::new(panic_unimplemented::PanicUnimplemented));
     store.register_late_pass(|_| Box::new(strings::StringLitAsBytes));
     store.register_late_pass(|_| Box::new(derive::Derive));
diff --git a/clippy_lints/src/vec.rs b/clippy_lints/src/vec.rs
index 467805d90ff..25b6f40762d 100644
--- a/clippy_lints/src/vec.rs
+++ b/clippy_lints/src/vec.rs
@@ -2,6 +2,7 @@ use std::ops::ControlFlow;
 
 use clippy_utils::consts::{constant, Constant};
 use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::is_copy;
 use clippy_utils::visitors::for_each_local_use_after_expr;
@@ -18,9 +19,10 @@ use rustc_span::source_map::Span;
 use rustc_span::sym;
 
 #[expect(clippy::module_name_repetitions)]
-#[derive(Copy, Clone)]
+#[derive(Clone)]
 pub struct UselessVec {
     pub too_large_for_stack: u64,
+    pub msrv: Msrv,
 }
 
 declare_clippy_lint! {
@@ -122,14 +124,16 @@ impl<'tcx> LateLintPass<'tcx> for UselessVec {
         if_chain! {
             if let Some(higher::ForLoop { arg, .. }) = higher::ForLoop::hir(expr);
             if let Some(vec_args) = higher::VecArgs::hir(cx, arg);
-            if is_copy(cx, vec_type(cx.typeck_results().expr_ty_adjusted(arg)));
+            if self.msrv.meets(msrvs::ARRAY_INTO_ITERATOR);
             then {
                 // report the error around the `vec!` not inside `<std macros>:`
                 let span = arg.span.ctxt().outer_expn_data().call_site;
-                self.check_vec_macro(cx, &vec_args, Mutability::Not, span, SuggestSlice::Yes);
+                self.check_vec_macro(cx, &vec_args, Mutability::Not, span, SuggestSlice::No);
             }
         }
     }
+
+    extract_msrv_attr!(LateContext);
 }
 
 #[derive(Copy, Clone)]
@@ -142,7 +146,7 @@ enum SuggestSlice {
 
 impl UselessVec {
     fn check_vec_macro<'tcx>(
-        self,
+        &mut self,
         cx: &LateContext<'tcx>,
         vec_args: &higher::VecArgs<'tcx>,
         mutability: Mutability,
diff --git a/tests/ui/vec.fixed b/tests/ui/vec.fixed
index 1bdde69f6f4..55329ee843d 100644
--- a/tests/ui/vec.fixed
+++ b/tests/ui/vec.fixed
@@ -1,6 +1,6 @@
 //@run-rustfix
 #![warn(clippy::useless_vec)]
-#![allow(clippy::nonstandard_macro_braces, clippy::uninlined_format_args)]
+#![allow(clippy::nonstandard_macro_braces, clippy::uninlined_format_args, unused)]
 
 use std::rc::Rc;
 
@@ -8,9 +8,6 @@ struct StructWithVec {
     _x: Vec<i32>,
 }
 
-#[derive(Debug)]
-struct NonCopy;
-
 fn on_slice(_: &[u8]) {}
 
 fn on_mut_slice(_: &mut [u8]) {}
@@ -66,14 +63,6 @@ fn main() {
     on_mut_slice(&mut vec![2; line.length]);
     on_mut_slice(&mut vec![2; line.length()]);
 
-    for a in &[1, 2, 3] {
-        println!("{:?}", a);
-    }
-
-    for a in vec![NonCopy, NonCopy] {
-        println!("{:?}", a);
-    }
-
     on_vec(&vec![1; 201]); // Ok, size of `vec` higher than `too_large_for_stack`
     on_mut_vec(&mut vec![1; 201]); // Ok, size of `vec` higher than `too_large_for_stack`
 
@@ -91,7 +80,7 @@ fn main() {
 
     let _x: &[i32] = &[1, 2, 3];
 
-    for _ in &[1, 2, 3] {}
+    for _ in [1, 2, 3] {}
 
     // Don't lint
     let x = vec![1, 2, 3];
@@ -122,3 +111,25 @@ fn main() {
     // Too large
     let _x = vec![1; 201];
 }
+
+#[clippy::msrv = "1.53"]
+fn above() {
+    for a in [1, 2, 3] {
+        let _: usize = a;
+    }
+
+    for a in [String::new(), String::new()] {
+        let _: String = a;
+    }
+}
+
+#[clippy::msrv = "1.52"]
+fn below() {
+    for a in vec![1, 2, 3] {
+        let _: usize = a;
+    }
+
+    for a in vec![String::new(), String::new()] {
+        let _: String = a;
+    }
+}
diff --git a/tests/ui/vec.rs b/tests/ui/vec.rs
index 89c6a72f339..bab316fa620 100644
--- a/tests/ui/vec.rs
+++ b/tests/ui/vec.rs
@@ -1,6 +1,6 @@
 //@run-rustfix
 #![warn(clippy::useless_vec)]
-#![allow(clippy::nonstandard_macro_braces, clippy::uninlined_format_args)]
+#![allow(clippy::nonstandard_macro_braces, clippy::uninlined_format_args, unused)]
 
 use std::rc::Rc;
 
@@ -8,9 +8,6 @@ struct StructWithVec {
     _x: Vec<i32>,
 }
 
-#[derive(Debug)]
-struct NonCopy;
-
 fn on_slice(_: &[u8]) {}
 
 fn on_mut_slice(_: &mut [u8]) {}
@@ -66,14 +63,6 @@ fn main() {
     on_mut_slice(&mut vec![2; line.length]);
     on_mut_slice(&mut vec![2; line.length()]);
 
-    for a in vec![1, 2, 3] {
-        println!("{:?}", a);
-    }
-
-    for a in vec![NonCopy, NonCopy] {
-        println!("{:?}", a);
-    }
-
     on_vec(&vec![1; 201]); // Ok, size of `vec` higher than `too_large_for_stack`
     on_mut_vec(&mut vec![1; 201]); // Ok, size of `vec` higher than `too_large_for_stack`
 
@@ -122,3 +111,25 @@ fn main() {
     // Too large
     let _x = vec![1; 201];
 }
+
+#[clippy::msrv = "1.53"]
+fn above() {
+    for a in vec![1, 2, 3] {
+        let _: usize = a;
+    }
+
+    for a in vec![String::new(), String::new()] {
+        let _: String = a;
+    }
+}
+
+#[clippy::msrv = "1.52"]
+fn below() {
+    for a in vec![1, 2, 3] {
+        let _: usize = a;
+    }
+
+    for a in vec![String::new(), String::new()] {
+        let _: String = a;
+    }
+}
diff --git a/tests/ui/vec.stderr b/tests/ui/vec.stderr
index f94a82d2171..f3a4bf925dd 100644
--- a/tests/ui/vec.stderr
+++ b/tests/ui/vec.stderr
@@ -1,5 +1,5 @@
 error: useless use of `vec!`
-  --> $DIR/vec.rs:34:14
+  --> $DIR/vec.rs:31:14
    |
 LL |     on_slice(&vec![]);
    |              ^^^^^^^ help: you can use a slice directly: `&[]`
@@ -7,82 +7,88 @@ LL |     on_slice(&vec![]);
    = note: `-D clippy::useless-vec` implied by `-D warnings`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:36:18
+  --> $DIR/vec.rs:33:18
    |
 LL |     on_mut_slice(&mut vec![]);
    |                  ^^^^^^^^^^^ help: you can use a slice directly: `&mut []`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:38:14
+  --> $DIR/vec.rs:35:14
    |
 LL |     on_slice(&vec![1, 2]);
    |              ^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:40:18
+  --> $DIR/vec.rs:37:18
    |
 LL |     on_mut_slice(&mut vec![1, 2]);
    |                  ^^^^^^^^^^^^^^^ help: you can use a slice directly: `&mut [1, 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:42:14
+  --> $DIR/vec.rs:39:14
    |
 LL |     on_slice(&vec![1, 2]);
    |              ^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:44:18
+  --> $DIR/vec.rs:41:18
    |
 LL |     on_mut_slice(&mut vec![1, 2]);
    |                  ^^^^^^^^^^^^^^^ help: you can use a slice directly: `&mut [1, 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:46:14
+  --> $DIR/vec.rs:43:14
    |
 LL |     on_slice(&vec!(1, 2));
    |              ^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:48:18
+  --> $DIR/vec.rs:45:18
    |
 LL |     on_mut_slice(&mut vec![1, 2]);
    |                  ^^^^^^^^^^^^^^^ help: you can use a slice directly: `&mut [1, 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:50:14
+  --> $DIR/vec.rs:47:14
    |
 LL |     on_slice(&vec![1; 2]);
    |              ^^^^^^^^^^^ help: you can use a slice directly: `&[1; 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:52:18
+  --> $DIR/vec.rs:49:18
    |
 LL |     on_mut_slice(&mut vec![1; 2]);
    |                  ^^^^^^^^^^^^^^^ help: you can use a slice directly: `&mut [1; 2]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:69:14
-   |
-LL |     for a in vec![1, 2, 3] {
-   |              ^^^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2, 3]`
-
-error: useless use of `vec!`
-  --> $DIR/vec.rs:86:17
+  --> $DIR/vec.rs:75:17
    |
 LL |     let mut x = vec![1, 2, 3];
    |                 ^^^^^^^^^^^^^ help: you can use an array directly: `[1, 2, 3]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:92:22
+  --> $DIR/vec.rs:81:22
    |
 LL |     let _x: &[i32] = &vec![1, 2, 3];
    |                      ^^^^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2, 3]`
 
 error: useless use of `vec!`
-  --> $DIR/vec.rs:94:14
+  --> $DIR/vec.rs:83:14
    |
 LL |     for _ in vec![1, 2, 3] {}
-   |              ^^^^^^^^^^^^^ help: you can use a slice directly: `&[1, 2, 3]`
+   |              ^^^^^^^^^^^^^ help: you can use an array directly: `[1, 2, 3]`
+
+error: useless use of `vec!`
+  --> $DIR/vec.rs:117:14
+   |
+LL |     for a in vec![1, 2, 3] {
+   |              ^^^^^^^^^^^^^ help: you can use an array directly: `[1, 2, 3]`
+
+error: useless use of `vec!`
+  --> $DIR/vec.rs:121:14
+   |
+LL |     for a in vec![String::new(), String::new()] {
+   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: you can use an array directly: `[String::new(), String::new()]`
 
-error: aborting due to 14 previous errors
+error: aborting due to 15 previous errors