style(lib): enforce clippy::unnested_or_patterns (#4256)

see #4071.

Lint doc: https://clippy.rust-lang.org/master/index.html#unnested_or_patterns

The rule rewrites patterns in disjunctive normal form (DNF) into
conjunctive normal form (CNF). Four patterns were flagged by this
rule, which were replaced with equivalent nested ones.

Author: trivikr

Cargo.toml

@@ -127,7 +127,6 @@ needless_pass_by_value = "allow"
 pattern_type_mismatch = "allow"
 redundant_else = "allow"
 struct_excessive_bools = "allow" # TODO: bogus lint?
-unnested_or_patterns = "allow"
 unused_async = "allow" # TODO: is it for API?
 unused_trait_names = "allow" # TODO: kinda annoying, but might be good to deny
 unwrap_in_result = "allow"

src/body/length.rs

@@ -68,7 +68,7 @@ impl DecodedLength {
     ))]
     pub(crate) fn sub_if(&mut self, amt: u64) {
         match self {
-            &mut DecodedLength::CHUNKED | &mut DecodedLength::CLOSE_DELIMITED => (),
+            &mut (DecodedLength::CHUNKED | DecodedLength::CLOSE_DELIMITED) => (),
             DecodedLength(known) => {
                 *known -= amt;
             }

src/error.rs

@@ -193,7 +193,7 @@ impl Error {
     pub fn is_parse_too_large(&self) -> bool {
         matches!(
             self.inner.kind,
-            Kind::Parse(Parse::TooLarge) | Kind::Parse(Parse::UriTooLong)
+            Kind::Parse(Parse::TooLarge | Parse::UriTooLong)
         )
     }
 

src/proto/h1/role.rs

@@ -493,10 +493,9 @@ impl Http1Transaction for Server {
     fn on_error(err: &crate::Error) -> Option<MessageHead<Self::Outgoing>> {
         use crate::error::Kind;
         let status = match *err.kind() {
-            Kind::Parse(Parse::Method)
-            | Kind::Parse(Parse::Header(_))
-            | Kind::Parse(Parse::Uri)
-            | Kind::Parse(Parse::Version) => StatusCode::BAD_REQUEST,
+            Kind::Parse(Parse::Method | Parse::Header(_) | Parse::Uri | Parse::Version) => {
+                StatusCode::BAD_REQUEST
+            }
             Kind::Parse(Parse::TooLarge) => StatusCode::REQUEST_HEADER_FIELDS_TOO_LARGE,
             Kind::Parse(Parse::UriTooLong) => StatusCode::URI_TOO_LONG,
             _ => return None,

src/proto/h2/upgrade.rs

@@ -179,7 +179,7 @@ impl Read for H2Upgraded {
                     }
                     Some(Err(e)) => {
                         return Poll::Ready(match e.reason() {
-                            Some(Reason::NO_ERROR) | Some(Reason::CANCEL) => Ok(()),
+                            Some(Reason::NO_ERROR | Reason::CANCEL) => Ok(()),
                             Some(Reason::STREAM_CLOSED) => {
                                 Err(std::io::Error::new(std::io::ErrorKind::BrokenPipe, e))
                             }