Auto merge of #12511 - humannum14916:assigning_clones_msrv, r=Alexendoo

`assigning_clones` should respect MSRV

Fixes: #12502

This PR fixes the `assigning_clones` lint suggesting to use `clone_from` or `clone_into` on incompatible MSRVs.

`assigning_clones` will suggest using either `clone_from` or `clone_into`, both of which were stabilized in 1.63. If the current MSRV is below 1.63, the lint should not trigger.

changelog: [`assigning_clones`]: don't lint when the MSRV is below 1.63.

8 files changed, 60 insertions, 11 deletions

diff --git a/book/src/lint_configuration.md b/book/src/lint_configuration.md
index a985346b3c0..a9234899746 100644
--- a/book/src/lint_configuration.md
+++ b/book/src/lint_configuration.md
@@ -602,6 +602,7 @@ The minimum rust version that the project supports. Defaults to the `rust-versio
 **Affected lints:**
 * [`almost_complete_range`](https://rust-lang.github.io/rust-clippy/master/index.html#almost_complete_range)
 * [`approx_constant`](https://rust-lang.github.io/rust-clippy/master/index.html#approx_constant)
+* [`assigning_clones`](https://rust-lang.github.io/rust-clippy/master/index.html#assigning_clones)
 * [`borrow_as_ptr`](https://rust-lang.github.io/rust-clippy/master/index.html#borrow_as_ptr)
 * [`cast_abs_to_unsigned`](https://rust-lang.github.io/rust-clippy/master/index.html#cast_abs_to_unsigned)
 * [`checked_conversions`](https://rust-lang.github.io/rust-clippy/master/index.html#checked_conversions)
diff --git a/clippy_config/src/conf.rs b/clippy_config/src/conf.rs
index 673b6328b39..3218fe7f456 100644
--- a/clippy_config/src/conf.rs
+++ b/clippy_config/src/conf.rs
@@ -262,7 +262,7 @@ define_Conf! {
     ///
     /// Suppress lints whenever the suggested change would cause breakage for other crates.
     (avoid_breaking_exported_api: bool = true),
-    /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, OPTION_MAP_UNWRAP_OR, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE, MAP_CLONE, BORROW_AS_PTR, MANUAL_BITS, ERR_EXPECT, CAST_ABS_TO_UNSIGNED, UNINLINED_FORMAT_ARGS, MANUAL_CLAMP, MANUAL_LET_ELSE, UNCHECKED_DURATION_SUBTRACTION, COLLAPSIBLE_STR_REPLACE, SEEK_FROM_CURRENT, SEEK_REWIND, UNNECESSARY_LAZY_EVALUATIONS, TRANSMUTE_PTR_TO_REF, ALMOST_COMPLETE_RANGE, NEEDLESS_BORROW, DERIVABLE_IMPLS, MANUAL_IS_ASCII_CHECK, MANUAL_REM_EUCLID, MANUAL_RETAIN, TYPE_REPETITION_IN_BOUNDS, TUPLE_ARRAY_CONVERSIONS, MANUAL_TRY_FOLD, MANUAL_HASH_ONE, ITER_KV_MAP, MANUAL_C_STR_LITERALS.
+    /// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, OPTION_MAP_UNWRAP_OR, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE, APPROX_CONSTANT, DEPRECATED_CFG_ATTR, INDEX_REFUTABLE_SLICE, MAP_CLONE, BORROW_AS_PTR, MANUAL_BITS, ERR_EXPECT, CAST_ABS_TO_UNSIGNED, UNINLINED_FORMAT_ARGS, MANUAL_CLAMP, MANUAL_LET_ELSE, UNCHECKED_DURATION_SUBTRACTION, COLLAPSIBLE_STR_REPLACE, SEEK_FROM_CURRENT, SEEK_REWIND, UNNECESSARY_LAZY_EVALUATIONS, TRANSMUTE_PTR_TO_REF, ALMOST_COMPLETE_RANGE, NEEDLESS_BORROW, DERIVABLE_IMPLS, MANUAL_IS_ASCII_CHECK, MANUAL_REM_EUCLID, MANUAL_RETAIN, TYPE_REPETITION_IN_BOUNDS, TUPLE_ARRAY_CONVERSIONS, MANUAL_TRY_FOLD, MANUAL_HASH_ONE, ITER_KV_MAP, MANUAL_C_STR_LITERALS, ASSIGNING_CLONES.
     ///
     /// The minimum rust version that the project supports. Defaults to the `rust-version` field in `Cargo.toml`
     #[default_text = ""]
diff --git a/clippy_config/src/msrvs.rs b/clippy_config/src/msrvs.rs
index a8a32f7ed20..bf4da5f14fe 100644
--- a/clippy_config/src/msrvs.rs
+++ b/clippy_config/src/msrvs.rs
@@ -23,6 +23,7 @@ msrv_aliases! {
     1,70,0 { OPTION_RESULT_IS_VARIANT_AND, BINARY_HEAP_RETAIN }
     1,68,0 { PATH_MAIN_SEPARATOR_STR }
     1,65,0 { LET_ELSE, POINTER_CAST_CONSTNESS }
+    1,63,0 { ASSIGNING_CLONES }
     1,62,0 { BOOL_THEN_SOME, DEFAULT_ENUM_ATTRIBUTE }
     1,59,0 { THREAD_LOCAL_INITIALIZER_CAN_BE_MADE_CONST }
     1,58,0 { FORMAT_ARGS_CAPTURE, PATTERN_TRAIT_CHAR_ARRAY }
diff --git a/clippy_lints/src/assigning_clones.rs b/clippy_lints/src/assigning_clones.rs
index b1c552c7a8d..ea5578572ea 100644
--- a/clippy_lints/src/assigning_clones.rs
+++ b/clippy_lints/src/assigning_clones.rs
@@ -1,3 +1,4 @@
+use clippy_config::msrvs::{self, Msrv};
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::macros::HirNode;
 use clippy_utils::sugg::Sugg;
@@ -6,7 +7,7 @@ use rustc_errors::Applicability;
 use rustc_hir::{self as hir, Expr, ExprKind, Node};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{self, Instance, Mutability};
-use rustc_session::declare_lint_pass;
+use rustc_session::impl_lint_pass;
 use rustc_span::def_id::DefId;
 use rustc_span::symbol::sym;
 use rustc_span::ExpnKind;
@@ -49,10 +50,26 @@ declare_clippy_lint! {
     perf,
     "assigning the result of cloning may be inefficient"
 }
-declare_lint_pass!(AssigningClones => [ASSIGNING_CLONES]);
+
+pub struct AssigningClones {
+    msrv: Msrv,
+}
+
+impl AssigningClones {
+    #[must_use]
+    pub fn new(msrv: Msrv) -> Self {
+        Self { msrv }
+    }
+}
+
+impl_lint_pass!(AssigningClones => [ASSIGNING_CLONES]);
 
 impl<'tcx> LateLintPass<'tcx> for AssigningClones {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, assign_expr: &'tcx hir::Expr<'_>) {
+        if !self.msrv.meets(msrvs::ASSIGNING_CLONES) {
+            return;
+        }
+
         // Do not fire the lint in macros
         let expn_data = assign_expr.span().ctxt().outer_expn_data();
         match expn_data.kind {
@@ -72,6 +89,8 @@ impl<'tcx> LateLintPass<'tcx> for AssigningClones {
             suggest(cx, assign_expr, lhs, &call);
         }
     }
+
+    extract_msrv_attr!(LateContext);
 }
 
 // Try to resolve the call to `Clone::clone` or `ToOwned::to_owned`.
diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs
index 9b22d7565e3..57fac351042 100644
--- a/clippy_lints/src/lib.rs
+++ b/clippy_lints/src/lib.rs
@@ -1122,7 +1122,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(move |_| Box::new(incompatible_msrv::IncompatibleMsrv::new(msrv())));
     store.register_late_pass(|_| Box::new(to_string_trait_impl::ToStringTraitImpl));
     store.register_early_pass(|| Box::new(multiple_bound_locations::MultipleBoundLocations));
-    store.register_late_pass(|_| Box::new(assigning_clones::AssigningClones));
+    store.register_late_pass(move |_| Box::new(assigning_clones::AssigningClones::new(msrv())));
     store.register_late_pass(|_| Box::new(zero_repeat_side_effects::ZeroRepeatSideEffects));
     store.register_late_pass(|_| Box::new(manual_unwrap_or_default::ManualUnwrapOrDefault));
     store.register_late_pass(|_| Box::new(integer_division_remainder_used::IntegerDivisionRemainderUsed));
diff --git a/tests/ui/assigning_clones.fixed b/tests/ui/assigning_clones.fixed
index c66e0c1f602..771c7f6f56a 100644
--- a/tests/ui/assigning_clones.fixed
+++ b/tests/ui/assigning_clones.fixed
@@ -128,6 +128,17 @@ fn ignore_generic_clone<T: Clone>(a: &mut T, b: &T) {
     *a = b.clone();
 }
 
+#[clippy::msrv = "1.62"]
+fn msrv_1_62(mut a: String, b: &str) {
+    // Should not be linted, as clone_into wasn't stabilized until 1.63
+    a = b.to_owned();
+}
+
+#[clippy::msrv = "1.63"]
+fn msrv_1_63(mut a: String, b: &str) {
+    b.clone_into(&mut a);
+}
+
 macro_rules! clone_inside {
     ($a:expr, $b: expr) => {
         $a = $b.clone();
diff --git a/tests/ui/assigning_clones.rs b/tests/ui/assigning_clones.rs
index b9f994d3e03..1320481322f 100644
--- a/tests/ui/assigning_clones.rs
+++ b/tests/ui/assigning_clones.rs
@@ -128,6 +128,17 @@ fn ignore_generic_clone<T: Clone>(a: &mut T, b: &T) {
     *a = b.clone();
 }
 
+#[clippy::msrv = "1.62"]
+fn msrv_1_62(mut a: String, b: &str) {
+    // Should not be linted, as clone_into wasn't stabilized until 1.63
+    a = b.to_owned();
+}
+
+#[clippy::msrv = "1.63"]
+fn msrv_1_63(mut a: String, b: &str) {
+    a = b.to_owned();
+}
+
 macro_rules! clone_inside {
     ($a:expr, $b: expr) => {
         $a = $b.clone();
diff --git a/tests/ui/assigning_clones.stderr b/tests/ui/assigning_clones.stderr
index b76323f3606..b8e20cee160 100644
--- a/tests/ui/assigning_clones.stderr
+++ b/tests/ui/assigning_clones.stderr
@@ -68,40 +68,46 @@ LL |         a = b.clone();
    |         ^^^^^^^^^^^^^ help: use `clone_from()`: `a.clone_from(&b)`
 
 error: assigning the result of `ToOwned::to_owned()` may be inefficient
-  --> tests/ui/assigning_clones.rs:145:5
+  --> tests/ui/assigning_clones.rs:139:5
+   |
+LL |     a = b.to_owned();
+   |     ^^^^^^^^^^^^^^^^ help: use `clone_into()`: `b.clone_into(&mut a)`
+
+error: assigning the result of `ToOwned::to_owned()` may be inefficient
+  --> tests/ui/assigning_clones.rs:156:5
    |
 LL |     *mut_string = ref_str.to_owned();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_into()`: `ref_str.clone_into(mut_string)`
 
 error: assigning the result of `ToOwned::to_owned()` may be inefficient
-  --> tests/ui/assigning_clones.rs:149:5
+  --> tests/ui/assigning_clones.rs:160:5
    |
 LL |     mut_string = ref_str.to_owned();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_into()`: `ref_str.clone_into(&mut mut_string)`
 
 error: assigning the result of `ToOwned::to_owned()` may be inefficient
-  --> tests/ui/assigning_clones.rs:170:5
+  --> tests/ui/assigning_clones.rs:181:5
    |
 LL |     **mut_box_string = ref_str.to_owned();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_into()`: `ref_str.clone_into(&mut (*mut_box_string))`
 
 error: assigning the result of `ToOwned::to_owned()` may be inefficient
-  --> tests/ui/assigning_clones.rs:174:5
+  --> tests/ui/assigning_clones.rs:185:5
    |
 LL |     **mut_box_string = ref_str.to_owned();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_into()`: `ref_str.clone_into(&mut (*mut_box_string))`
 
 error: assigning the result of `ToOwned::to_owned()` may be inefficient
-  --> tests/ui/assigning_clones.rs:178:5
+  --> tests/ui/assigning_clones.rs:189:5
    |
 LL |     *mut_thing = ToOwned::to_owned(ref_str);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_into()`: `ToOwned::clone_into(ref_str, mut_thing)`
 
 error: assigning the result of `ToOwned::to_owned()` may be inefficient
-  --> tests/ui/assigning_clones.rs:182:5
+  --> tests/ui/assigning_clones.rs:193:5
    |
 LL |     mut_thing = ToOwned::to_owned(ref_str);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use `clone_into()`: `ToOwned::clone_into(ref_str, &mut mut_thing)`
 
-error: aborting due to 17 previous errors
+error: aborting due to 18 previous errors