Remove powi, "square can be computed more efficiently"

powi(2) produces exactly the same native code as x * x

Author: mucinoab

clippy_lints/src/floating_point_arithmetic.rs

@@ -297,60 +297,6 @@ fn check_powf(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
     }
 }
 
-fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
-    if let Some((value, _)) = constant(cx, cx.typeck_results(), &args[1]) {
-        if value == Int(2) {
-            if let Some(parent) = get_parent_expr(cx, expr) {
-                if let Some(grandparent) = get_parent_expr(cx, parent) {
-                    if let ExprKind::MethodCall(PathSegment { ident: method_name, .. }, _, args, _) = grandparent.kind {
-                        if method_name.as_str() == "sqrt" && detect_hypot(cx, args).is_some() {
-                            return;
-                        }
-                    }
-                }
-
-                if let ExprKind::Binary(
-                    Spanned {
-                        node: BinOpKind::Add, ..
-                    },
-                    lhs,
-                    rhs,
-                ) = parent.kind
-                {
-                    let other_addend = if lhs.hir_id == expr.hir_id { rhs } else { lhs };
-
-                    span_lint_and_sugg(
-                        cx,
-                        SUBOPTIMAL_FLOPS,
-                        parent.span,
-                        "square can be computed more efficiently",
-                        "consider using",
-                        format!(
-                            "{}.mul_add({}, {})",
-                            Sugg::hir(cx, &args[0], ".."),
-                            Sugg::hir(cx, &args[0], ".."),
-                            Sugg::hir(cx, other_addend, ".."),
-                        ),
-                        Applicability::MachineApplicable,
-                    );
-
-                    return;
-                }
-            }
-
-            span_lint_and_sugg(
-                cx,
-                SUBOPTIMAL_FLOPS,
-                expr.span,
-                "square can be computed more efficiently",
-                "consider using",
-                format!("{} * {}", Sugg::hir(cx, &args[0], ".."), Sugg::hir(cx, &args[0], "..")),
-                Applicability::MachineApplicable,
-            );
-        }
-    }
-}
-
 fn detect_hypot(cx: &LateContext<'_>, args: &[Expr<'_>]) -> Option<String> {
     if let ExprKind::Binary(
         Spanned {
@@ -706,7 +652,6 @@ impl<'tcx> LateLintPass<'tcx> for FloatingPointArithmetic {
                     "ln" => check_ln1p(cx, expr, args),
                     "log" => check_log_base(cx, expr, args),
                     "powf" => check_powf(cx, expr, args),
-                    "powi" => check_powi(cx, expr, args),
                     "sqrt" => check_hypot(cx, expr, args),
                     _ => {},
                 }