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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::ty::{is_type_diagnostic_item, is_type_lang_item};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, LangItem};
use rustc_lint::LateContext;
use rustc_span::symbol::sym;
use super::APPEND_INSTEAD_OF_EXTEND;
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, arg: &Expr<'_>) {
let ty = cx.typeck_results().expr_ty(recv).peel_refs();
if_chain! {
if is_type_diagnostic_item(cx, ty, sym::vec_type);
//check source object
if let ExprKind::MethodCall(src_method, _, [drain_vec, drain_arg], _) = &arg.kind;
if src_method.ident.as_str() == "drain";
if let src_ty = cx.typeck_results().expr_ty(drain_vec).peel_refs();
if is_type_diagnostic_item(cx, src_ty, sym::vec_type);
//check drain range
if let src_ty_range = cx.typeck_results().expr_ty(drain_arg).peel_refs();
if is_type_lang_item(cx, src_ty_range, LangItem::RangeFull);
then {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
APPEND_INSTEAD_OF_EXTEND,
expr.span,
"use of `extend` instead of `append` for adding the full range of a second vector",
"try this",
format!(
"{}.append(&mut {})",
snippet_with_applicability(cx, recv.span, "..", &mut applicability),
snippet_with_applicability(cx, drain_vec.span, "..", &mut applicability)
),
applicability,
);
}
}
}
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