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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_context;
use clippy_utils::visitors::is_const_evaluatable;
use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use super::STR_SPLIT_AT_NEWLINE;
pub(super) fn check<'a>(cx: &LateContext<'a>, expr: &'_ Expr<'_>, split_recv: &'a Expr<'_>, split_arg: &'_ Expr<'_>) {
// We're looking for `A.trim().split(B)`, where the adjusted type of `A` is `&str` (e.g. an
// expression returning `String`), and `B` is a `Pattern` that hard-codes a newline (either `"\n"`
// or `"\r\n"`). There are a lot of ways to specify a pattern, and this lint only checks the most
// basic ones: a `'\n'`, `"\n"`, and `"\r\n"`.
if let ExprKind::MethodCall(trim_method_name, trim_recv, [], _) = split_recv.kind
&& trim_method_name.ident.as_str() == "trim"
&& cx.typeck_results().expr_ty_adjusted(trim_recv).peel_refs().is_str()
&& !is_const_evaluatable(cx, trim_recv)
&& let ExprKind::Lit(split_lit) = split_arg.kind
&& (matches!(split_lit.node, LitKind::Char('\n'))
|| matches!(split_lit.node, LitKind::Str(sym, _) if (sym.as_str() == "\n" || sym.as_str() == "\r\n")))
{
let mut app = Applicability::MaybeIncorrect;
span_lint_and_sugg(
cx,
STR_SPLIT_AT_NEWLINE,
expr.span,
"using `str.trim().split()` with hard-coded newlines",
"use `str.lines()` instead",
format!(
"{}.lines()",
snippet_with_context(cx, trim_recv.span, expr.span.ctxt(), "..", &mut app).0
),
app,
);
}
}
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