Use hashbrown over std hash tables

`hashbrown` is no-std compatible!

Cargo.lock

@@ -11,12 +11,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "allocator-api2"
-version = "0.2.21"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
-
 [[package]]
 name = "anyhow"
 version = "1.0.102"
@@ -286,6 +280,12 @@ version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d9c4f5dac5e15c24eb999c26181a6ca40b39fe946cbe4c263c7209467bc83af2"
 
+[[package]]
+name = "foldhash"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"
+
 [[package]]
 name = "foreign-types"
 version = "0.3.2"
@@ -441,7 +441,7 @@ version = "0.15.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
 dependencies = [
- "foldhash",
+ "foldhash 0.1.5",
 ]
 
 [[package]]
@@ -450,7 +450,7 @@ version = "0.17.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a"
 dependencies = [
- "allocator-api2",
+ "foldhash 0.2.0",
 ]
 
 [[package]]

Cargo.toml

@@ -49,7 +49,7 @@ arc-swap       = { version = "1.7.0", optional = true }
 bytes          = { version = "1.2", optional = true, default-features = false }
 chrono         = { version = "0.4.35", optional = true, default-features = false } # 0.4.35 deprecates Duration::seconds()
 futures-util   = { version = "0.3", optional = true }
-hashbrown      = { version = "0.17.0", optional = true, default-features = false, features = ["allocator-api2", "inline-more"] } # 0.14.2 introduces explicit hashing
+hashbrown      = { version = "0.17.0", optional = true, default-features = false, features = ["default-hasher", "inline-more"] }
 heapless       = { version = "0.9.2", optional = true }
 libc           = { version = "0.2.153", default-features = false, optional = true } # 0.2.79 is the first version that has IP_PMTUDISC_OMIT
 log            = { version = "0.4.22", optional = true }
@@ -73,7 +73,7 @@ tracing-subscriber = { version = "0.3.18", optional = true, features = ["env-fil
 default     = ["std", "rand"]
 
 # Support for libraries
-alloc       = ["jiff/alloc", "octseq/alloc", "serde?/alloc"]
+alloc       = ["dep:hashbrown", "jiff/alloc", "octseq/alloc", "serde?/alloc"]
 bumpalo     = ["dep:bumpalo", "std"]
 bytes       = ["dep:bytes", "octseq/bytes"]
 chrono      = ["dep:chrono"]
@@ -81,7 +81,7 @@ heapless    = ["dep:heapless", "octseq/heapless"]
 rand        = ["dep:rand"]
 serde       = ["dep:serde", "octseq/serde"]
 smallvec    = ["dep:smallvec", "octseq/smallvec"]
-std         = ["alloc", "dep:hashbrown", "bumpalo?/std", "bytes?/std", "octseq/std", "jiff/std", "serde?/std"]
+std         = ["alloc", "bumpalo?/std", "bytes?/std", "octseq/std", "jiff/std", "serde?/std"]
 tracing     = ["dep:log", "dep:tracing"]
 
 # Cryptographic backends

src/rdata/svcb/value.rs

@@ -1,7 +1,7 @@
 #[cfg(feature = "alloc")]
 use alloc::collections::BTreeSet;
-#[cfg(feature = "std")]
-use std::collections::HashSet;
+#[cfg(feature = "alloc")]
+use hashbrown::HashSet;
 
 use super::{
     ComposeSvcParamValue, LongSvcParam, ParseSvcParamValue, PushError,
@@ -140,7 +140,7 @@ macro_rules! values_enum {
             }
         }
 
-        #[cfg(feature = "std")]
+        #[cfg(feature = "alloc")]
         impl<SrcOcts, Octs> ScanSvcParamValue<SrcOcts, Octs>
         for AllValues<Octs>
         where
@@ -2012,7 +2012,7 @@ impl<Octs: AsRef<[u8]>> TlsSupportedGroups<Octs> {
     }
 }
 
-#[cfg(feature = "std")]
+#[cfg(feature = "alloc")]
 impl<SrcOcts, Octs> ScanSvcParamValue<SrcOcts, Octs>
     for TlsSupportedGroups<Octs>
 where