refactor: eliminating indexing_slicing

deltachat-contact-tools/src/lib.rs

@@ -15,7 +15,7 @@
     clippy::explicit_into_iter_loop,
     clippy::cloned_instead_of_copied
 )]
-#![cfg_attr(not(test), warn(clippy::indexing_slicing))]
+#![cfg_attr(not(test), forbid(clippy::indexing_slicing))]
 #![allow(
     clippy::match_bool,
     clippy::mixed_read_write_in_expression,

deltachat-jsonrpc/src/lib.rs

@@ -1,4 +1,5 @@
 #![recursion_limit = "256"]
+#![cfg_attr(not(test), forbid(clippy::indexing_slicing))]
 pub mod api;
 pub use yerpc;
 

format-flowed/src/lib.rs

@@ -8,6 +8,7 @@
 //! is assumed to be set to "no".
 //!
 //! For received messages, DelSp parameter is honoured.
+#![cfg_attr(not(test), forbid(clippy::indexing_slicing))]
 
 /// Wraps line to 72 characters using format=flowed soft breaks.
 ///

src/authres.rs

@@ -260,7 +260,6 @@ fn parse_authservid_candidates_config(config: &Option<String>) -> BTreeSet<&str>
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
     use tokio::fs;
     use tokio::io::AsyncReadExt;
 

src/configure.rs

@@ -611,8 +611,6 @@ pub enum Error {
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
     use crate::config::Config;
     use crate::login_param::EnteredServerLoginParam;

src/configure/auto_mozilla.rs

@@ -272,8 +272,6 @@ pub(crate) async fn moz_autoconfigure(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
 
     #[test]

src/configure/auto_outlook.rs

@@ -215,8 +215,6 @@ pub(crate) async fn outlk_autodiscover(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
 
     #[test]

src/lib.rs

@@ -16,7 +16,7 @@
     clippy::explicit_into_iter_loop,
     clippy::cloned_instead_of_copied
 )]
-#![cfg_attr(not(test), warn(clippy::indexing_slicing))]
+#![cfg_attr(not(test), forbid(clippy::indexing_slicing))]
 #![allow(
     clippy::match_bool,
     clippy::mixed_read_write_in_expression,

src/location.rs

@@ -880,8 +880,6 @@ async fn maybe_send_locations(context: &Context) -> Result<Option<u64>> {
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
     use crate::config::Config;
     use crate::message::MessageState;

src/mimefactory.rs

@@ -2274,7 +2274,6 @@ mod tests {
         let msg = message.as_string();
 
         let header_end = msg.find("Hi").unwrap();
-        #[allow(clippy::indexing_slicing)]
         let headers = msg[0..header_end].trim();
 
         assert!(!headers.lines().any(|l| l.trim().is_empty()));

src/mimeparser.rs

@@ -665,11 +665,13 @@ impl MimeMessage {
     /// Delta Chat sends attachments, such as images, in two-part messages, with the first message
     /// containing a description. If such a message is detected, text from the first part can be
     /// moved to the second part, and the first part dropped.
-    #[allow(clippy::indexing_slicing)]
     fn squash_attachment_parts(&mut self) {
-        if let [textpart, filepart] = &self.parts[..] {
-            let need_drop = textpart.typ == Viewtype::Text
-                && match filepart.typ {
+        if self.parts.len() == 2
+            && self.parts.first().map(|textpart| textpart.typ) == Some(Viewtype::Text)
+            && self
+                .parts
+                .get(1)
+                .map_or(false, |filepart| match filepart.typ {
                     Viewtype::Image
                     | Viewtype::Gif
                     | Viewtype::Sticker
@@ -680,24 +682,24 @@ impl MimeMessage {
                     | Viewtype::File
                     | Viewtype::Webxdc => true,
                     Viewtype::Unknown | Viewtype::Text | Viewtype::VideochatInvitation => false,
-                };
-
-            if need_drop {
-                let mut filepart = self.parts.swap_remove(1);
-
-                // insert new one
-                filepart.msg.clone_from(&self.parts[0].msg);
-                if let Some(quote) = self.parts[0].param.get(Param::Quote) {
-                    filepart.param.set(Param::Quote, quote);
-                }
-
-                // forget the one we use now
-                self.parts[0].msg = "".to_string();
+                })
+        {
+            let mut parts = std::mem::take(&mut self.parts);
+            let Some(mut filepart) = parts.pop() else {
+                // Should never happen.
+                return;
+            };
+            let Some(textpart) = parts.pop() else {
+                // Should never happen.
+                return;
+            };
 
-                // swap new with old
-                self.parts.push(filepart); // push to the end
-                let _ = self.parts.swap_remove(0); // drops first element, replacing it with the last one in O(1)
+            filepart.msg.clone_from(&textpart.msg);
+            if let Some(quote) = textpart.param.get(Param::Quote) {
+                filepart.param.set(Param::Quote, quote);
             }
+
+            self.parts = vec![filepart];
         }
     }
 
@@ -1751,7 +1753,6 @@ impl MimeMessage {
     /// Some providers like GMX and Yahoo do not send standard NDNs (Non Delivery notifications).
     /// If you improve heuristics here you might also have to change prefetch_should_download() in imap/mod.rs.
     /// Also you should add a test in receive_imf.rs (there already are lots of test_parse_ndn_* tests).
-    #[allow(clippy::indexing_slicing)]
     async fn heuristically_parse_ndn(&mut self, context: &Context) {
         let maybe_ndn = if let Some(from) = self.get_header(HeaderDef::From_) {
             let from = from.to_ascii_lowercase();
@@ -1914,18 +1915,17 @@ pub(crate) struct DeliveryReport {
     pub failure: bool,
 }
 
-#[allow(clippy::indexing_slicing)]
 pub(crate) fn parse_message_ids(ids: &str) -> Vec<String> {
     // take care with mailparse::msgidparse() that is pretty untolerant eg. wrt missing `<` or `>`
     let mut msgids = Vec::new();
     for id in ids.split_whitespace() {
         let mut id = id.to_string();
-        if id.starts_with('<') {
-            id = id[1..].to_string();
-        }
-        if id.ends_with('>') {
-            id = id[..id.len() - 1].to_string();
-        }
+        if let Some(id_without_prefix) = id.strip_prefix('<') {
+            id = id_without_prefix.to_string();
+        };
+        if let Some(id_without_suffix) = id.strip_suffix('>') {
+            id = id_without_suffix.to_string();
+        };
         if !id.is_empty() {
             msgids.push(id);
         }
@@ -2362,8 +2362,6 @@ async fn ndn_maybe_add_info_msg(
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use mailparse::ParsedMail;
 
     use super::*;

src/provider.rs

@@ -288,8 +288,6 @@ pub fn get_provider_by_id(id: &str) -> Option<&'static Provider> {
 
 #[cfg(test)]
 mod tests {
-    #![allow(clippy::indexing_slicing)]
-
     use super::*;
     use crate::test_utils::TestContext;
 

src/qr.rs

@@ -367,9 +367,10 @@ pub fn format_backup(qr: &Qr) -> Result<String> {
 /// scheme: `OPENPGP4FPR:FINGERPRINT#a=ADDR&n=NAME&i=INVITENUMBER&s=AUTH`
 ///     or: `OPENPGP4FPR:FINGERPRINT#a=ADDR&g=GROUPNAME&x=GROUPID&i=INVITENUMBER&s=AUTH`
 ///     or: `OPENPGP4FPR:FINGERPRINT#a=ADDR`
-#[allow(clippy::indexing_slicing)]
 async fn decode_openpgp(context: &Context, qr: &str) -> Result<Qr> {
-    let payload = &qr[OPENPGP4FPR_SCHEME.len()..];
+    let payload = qr
+        .get(OPENPGP4FPR_SCHEME.len()..)
+        .context("Invalid OPENPGP4FPR scheme")?;
 
     // macOS and iOS sometimes replace the # with %23 (uri encode it), we should be able to parse this wrong format too.
     // see issue https://github.com/deltachat/deltachat-core-rust/issues/1969 for more info
@@ -546,7 +547,7 @@ async fn decode_ideltachat(context: &Context, prefix: &str, qr: &str) -> Result<
 fn decode_account(qr: &str) -> Result<Qr> {
     let payload = qr
         .get(DCACCOUNT_SCHEME.len()..)
-        .context("invalid DCACCOUNT payload")?;
+        .context("Invalid DCACCOUNT payload")?;
     let url = url::Url::parse(payload).context("Invalid account URL")?;
     if url.scheme() == "http" || url.scheme() == "https" {
         Ok(Qr::Account {
@@ -564,7 +565,7 @@ fn decode_account(qr: &str) -> Result<Qr> {
 fn decode_webrtc_instance(_context: &Context, qr: &str) -> Result<Qr> {
     let payload = qr
         .get(DCWEBRTC_SCHEME.len()..)
-        .context("invalid DCWEBRTC payload")?;
+        .context("Invalid DCWEBRTC payload")?;
 
     let (_type, url) = Message::parse_webrtc_instance(payload);
     let url = url::Url::parse(&url).context("Invalid WebRTC instance")?;
@@ -637,7 +638,7 @@ fn decode_shadowsocks_proxy(qr: &str) -> Result<Qr> {
 fn decode_backup2(qr: &str) -> Result<Qr> {
     let payload = qr
         .strip_prefix(DCBACKUP2_SCHEME)
-        .ok_or_else(|| anyhow!("invalid DCBACKUP scheme"))?;
+        .ok_or_else(|| anyhow!("Invalid DCBACKUP2 scheme"))?;
     let (auth_token, node_addr) = payload
         .split_once('&')
         .context("Backup QR code has no separator")?;
@@ -668,9 +669,10 @@ struct CreateAccountErrorResponse {
 /// take a qr of the type DC_QR_ACCOUNT, parse it's parameters,
 /// download additional information from the contained url and set the parameters.
 /// on success, a configure::configure() should be able to log in to the account
-#[allow(clippy::indexing_slicing)]
 async fn set_account_from_qr(context: &Context, qr: &str) -> Result<()> {
-    let url_str = &qr[DCACCOUNT_SCHEME.len()..];
+    let url_str = qr
+        .get(DCACCOUNT_SCHEME.len()..)
+        .context("Invalid DCACCOUNT scheme")?;
 
     if !url_str.starts_with(HTTPS_SCHEME) {
         bail!("DCACCOUNT QR codes must use HTTPS scheme");
@@ -800,9 +802,10 @@ pub async fn set_config_from_qr(context: &Context, qr: &str) -> Result<()> {
 /// Extract address for the mailto scheme.
 ///
 /// Scheme: `mailto:addr...?subject=...&body=..`
-#[allow(clippy::indexing_slicing)]
 async fn decode_mailto(context: &Context, qr: &str) -> Result<Qr> {
-    let payload = &qr[MAILTO_SCHEME.len()..];
+    let payload = qr
+        .get(MAILTO_SCHEME.len()..)
+        .context("Invalid mailto: scheme")?;
 
     let (addr, query) = if let Some(query_index) = payload.find('?') {
         (&payload[..query_index], &payload[query_index + 1..])
@@ -855,9 +858,8 @@ async fn decode_mailto(context: &Context, qr: &str) -> Result<Qr> {
 /// Extract address for the smtp scheme.
 ///
 /// Scheme: `SMTP:addr...:subject...:body...`
-#[allow(clippy::indexing_slicing)]
 async fn decode_smtp(context: &Context, qr: &str) -> Result<Qr> {
-    let payload = &qr[SMTP_SCHEME.len()..];
+    let payload = qr.get(SMTP_SCHEME.len()..).context("Invalid SMTP scheme")?;
 
     let addr = if let Some(query_index) = payload.find(':') {
         &payload[..query_index]
@@ -875,14 +877,13 @@ async fn decode_smtp(context: &Context, qr: &str) -> Result<Qr> {
 /// Scheme: `MATMSG:TO:addr...;SUB:subject...;BODY:body...;`
 ///
 /// There may or may not be linebreaks after the fields.
-#[allow(clippy::indexing_slicing)]
 async fn decode_matmsg(context: &Context, qr: &str) -> Result<Qr> {
     // Does not work when the text `TO:` is used in subject/body _and_ TO: is not the first field.
     // we ignore this case.
     let addr = if let Some(to_index) = qr.find("TO:") {
-        let addr = qr[to_index + 3..].trim();
+        let addr = qr.get(to_index + 3..).unwrap_or_default().trim();
         if let Some(semi_index) = addr.find(';') {
-            addr[..semi_index].trim()
+            addr.get(..semi_index).unwrap_or_default().trim()
         } else {
             addr
         }
@@ -903,7 +904,6 @@ static VCARD_EMAIL_RE: Lazy<regex::Regex> =
 /// Extract address for the vcard scheme.
 ///
 /// Scheme: `VCARD:BEGIN\nN:last name;first name;...;\nEMAIL;<type>:addr...;`
-#[allow(clippy::indexing_slicing)]
 async fn decode_vcard(context: &Context, qr: &str) -> Result<Qr> {
     let name = VCARD_NAME_RE
         .captures(qr)
@@ -915,8 +915,8 @@ async fn decode_vcard(context: &Context, qr: &str) -> Result<Qr> {
         })
         .unwrap_or_default();
 
-    let addr = if let Some(caps) = VCARD_EMAIL_RE.captures(qr) {
-        normalize_address(caps[2].trim())?
+    let addr = if let Some(cap) = VCARD_EMAIL_RE.captures(qr).and_then(|caps| caps.get(2)) {
+        normalize_address(cap.as_str().trim())?
     } else {
         bail!("Bad e-mail address");
     };

src/receive_imf.rs

@@ -2465,14 +2465,16 @@ async fn create_or_lookup_mailinglist(
     }
 }
 
-#[allow(clippy::indexing_slicing)]
 fn compute_mailinglist_name(
     list_id_header: &str,
     listid: &str,
     mime_parser: &MimeMessage,
 ) -> String {
-    let mut name = match LIST_ID_REGEX.captures(list_id_header) {
-        Some(cap) => cap[1].trim().to_string(),
+    let mut name = match LIST_ID_REGEX
+        .captures(list_id_header)
+        .and_then(|caps| caps.get(1))
+    {
+        Some(cap) => cap.as_str().trim().to_string(),
         None => "".to_string(),
     };
 
@@ -2519,8 +2521,11 @@ fn compute_mailinglist_name(
         // 51231231231231231231231232869f58.xing.com -> xing.com
         static PREFIX_32_CHARS_HEX: Lazy<Regex> =
             Lazy::new(|| Regex::new(r"([0-9a-fA-F]{32})\.(.{6,})").unwrap());
-        if let Some(cap) = PREFIX_32_CHARS_HEX.captures(listid) {
-            name = cap[2].to_string();
+        if let Some(cap) = PREFIX_32_CHARS_HEX
+            .captures(listid)
+            .and_then(|caps| caps.get(2))
+        {
+            name = cap.as_str().to_string();
         } else {
             name = listid.to_string();
         }

src/securejoin.rs

@@ -279,7 +279,6 @@ pub(crate) enum HandshakeMessage {
 ///
 /// When `handle_securejoin_handshake()` is called, the message is not yet filed in the
 /// database; this is done by `receive_imf()` later on as needed.
-#[allow(clippy::indexing_slicing)]
 pub(crate) async fn handle_securejoin_handshake(
     context: &Context,
     mime_message: &MimeMessage,