deprecate assign_ops lint

clippy_lints/src/assign_ops.rs

@@ -7,25 +7,6 @@ use rustc::{declare_lint, lint_array};
 use if_chain::if_chain;
 use syntax::ast;
 
-/// **What it does:** Checks for compound assignment operations (`+=` and
-/// similar).
-///
-/// **Why is this bad?** Projects with many developers from languages without
-/// those operations may find them unreadable and not worth their weight.
-///
-/// **Known problems:** Types implementing `OpAssign` don't necessarily
-/// implement `Op`.
-///
-/// **Example:**
-/// ```rust
-/// a += 1;
-/// ```
-declare_clippy_lint! {
-    pub ASSIGN_OPS,
-    restriction,
-    "any compound assignment operation"
-}
-
 /// **What it does:** Checks for `a = a op b` or `a = b commutative_op a`
 /// patterns.
 ///
@@ -73,7 +54,7 @@ pub struct AssignOps;
 
 impl LintPass for AssignOps {
     fn get_lints(&self) -> LintArray {
-        lint_array!(ASSIGN_OPS, ASSIGN_OP_PATTERN, MISREFACTORED_ASSIGN_OP)
+        lint_array!(ASSIGN_OP_PATTERN, MISREFACTORED_ASSIGN_OP)
     }
 }
 
@@ -81,16 +62,6 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AssignOps {
     fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr) {
         match expr.node {
             hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
-                span_lint_and_then(cx, ASSIGN_OPS, expr.span, "assign operation detected", |db| {
-                    let lhs = &sugg::Sugg::hir(cx, lhs, "..");
-                    let rhs = &sugg::Sugg::hir(cx, rhs, "..");
-
-                    db.span_suggestion(
-                        expr.span,
-                        "replace it with",
-                        format!("{} = {}", lhs, sugg::make_binop(higher::binop(op.node), lhs, rhs)),
-                    );
-                });
                 if let hir::ExprKind::Binary(binop, ref l, ref r) = rhs.node {
                     if op.node == binop.node {
                         let lint = |assignee: &hir::Expr, rhs_other: &hir::Expr| {

clippy_lints/src/deprecated_lints.rs

@@ -82,3 +82,13 @@ declare_deprecated_lint! {
     pub MISALIGNED_TRANSMUTE,
     "this lint has been split into cast_ptr_alignment and transmute_ptr_to_ptr"
 }
+
+/// **What it does:** Nothing. This lint has been deprecated.
+///
+/// **Deprecation reason:** This lint is too subjective, not having a good reason for being in clippy.
+/// Additionally, compound assignment operators may be overloaded separately from their non-assigning
+/// counterparts, so this lint may suggest a change in behavior or the code may not compile.
+declare_deprecated_lint! {
+    pub ASSIGN_OPS,
+    "using compound assignment operators (e.g. `+=`) is harmless"
+}

clippy_lints/src/lib.rs

@@ -261,6 +261,10 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>) {
         "misaligned_transmute",
         "this lint has been split into cast_ptr_alignment and transmute_ptr_to_ptr",
     );
+    store.register_removed(
+        "assign_ops",
+        "using compound assignment operators (e.g. `+=`) is harmless",
+    );
     // end deprecated lints, do not remove this comment, it’s used in `update_lints`
 
     reg.register_late_lint_pass(box serde_api::Serde);
@@ -406,7 +410,6 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry<'_>) {
     reg.register_lint_group("clippy_restriction", vec![
         arithmetic::FLOAT_ARITHMETIC,
         arithmetic::INTEGER_ARITHMETIC,
-        assign_ops::ASSIGN_OPS,
         else_if_without_else::ELSE_IF_WITHOUT_ELSE,
         indexing_slicing::INDEXING_SLICING,
         inherent_impl::MULTIPLE_INHERENT_IMPL,