fix: forbid index slicing in parser

README.md

@@ -5,7 +5,7 @@
 [![build](https://img.shields.io/github/actions/workflow/status/hoodie/icalendar-rs/ci.yml?branch=main)](https://github.com/hoodie/icalendar-rs/actions?query=workflow%3A"Continuous+Integration")
 [![Crates.io](https://img.shields.io/crates/d/icalendar)](https://crates.io/crates/icalendar)
 [![contributors](https://img.shields.io/github/contributors/hoodie/icalendar-rs)](https://github.com/hoodie/icalendar-rs/graphs/contributors)
-![maintenance](https://img.shields.io/maintenance/yes/2023)
+![maintenance](https://img.shields.io/maintenance/yes/2025)
 
 [![version](https://img.shields.io/crates/v/icalendar)](https://crates.io/crates/icalendar/)
 [![documentation](https://img.shields.io/badge/docs-latest-blue.svg)](https://docs.rs/icalendar/)

src/lib.rs

@@ -66,6 +66,7 @@
     unused_import_braces,
     unused_qualifications,
     missing_debug_implementations,
+    clippy::indexing_slicing,
     clippy::dbg_macro,
     clippy::doc_markdown,
     clippy::redundant_closure_for_method_calls

src/parser/mod.rs

@@ -81,6 +81,11 @@ pub fn read_calendar(input: &str) -> Result<Calendar<'_>, String> {
         .map_err(|e: VerboseError<&str>| format!("error: {}", convert_error(input, e.clone())))
 }
 
+#[test]
+fn begin_crash() {
+    assert!(read_calendar("BEGIN:").is_ok());
+}
+
 /// Parse iCalendar file content into an array of [`Component`]s
 ///
 /// This version produces nice and readable errors with line numbers thanks the the awesomeness of [`nom`].

src/parser/utils.rs

@@ -16,7 +16,7 @@ use super::parsed_string::ParseString;
 pub fn property_key<'a, E: ParseError<&'a str> + ContextError<&'a str>>(
     input: &'a str,
 ) -> IResult<&'a str, &str, E> {
-    if &input[0..=2] == "END" || &input[0..=4] == "BEGIN" {
+    if input.get(0..=2) == Some("END") || input.get(0..=4) == Some("BEGIN") {
         IResult::Err(Err::Error(nom::error::make_error(
             input,
             nom::error::ErrorKind::Satisfy,

src/properties.rs

@@ -400,6 +400,7 @@ impl From<chrono::Duration> for Property {
 //}
 
 // Fold a content line as described in RFC 5545, Section 3.1
+#[allow(clippy::indexing_slicing)]
 pub(crate) fn fold_line(line: &str) -> String {
     let limit = 75;
     let len = line.len();