no_std support for the url crate

.github/workflows/main.yml

@@ -33,6 +33,13 @@ jobs:
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{ matrix.rust }}
+      # Add toolchain for no_std tests
+      - run: rustup toolchain install nightly
+      - name: Build `aarch64-unknown-none` with `no_std`
+        if: |
+          matrix.os == 'ubuntu-latest' &&
+          matrix.rust == 'nightly'
+        run: rustup target add aarch64-unknown-none && rustup component add rust-src --toolchain nightly-x86_64-unknown-linux-gnu && cargo +nightly build -Zbuild-std=core,alloc --target aarch64-unknown-none -v --release --no-default-features --features=alloc,unstable
       - run: cargo build --all-targets
         # Run tests
       - name: Run tests
@@ -48,7 +55,7 @@ jobs:
           matrix.rust == 'nightly'
         run: cargo test --test debugger_visualizer --features "url/serde,url/debugger_visualizer" -- --test-threads=1
       - name: Test `no_std` support
-        run: cargo test --no-default-features --features=alloc
+        run: cargo test --no-default-features --features=alloc,no_std_net
 
   WASM:
     runs-on: ubuntu-latest

data-url/Cargo.toml

@@ -17,7 +17,7 @@ alloc = []
 
 [dev-dependencies]
 tester = "0.9"
-serde = {version = "1.0", features = ["derive"]}
+serde = { version = "1.0", default-features = false, features = ["alloc", "derive"] }
 serde_json = "1.0"
 
 [lib]

idna/Cargo.toml

@@ -17,6 +17,8 @@ doctest = false
 default = ["std"]
 std = ["alloc", "unicode-bidi/std", "unicode-normalization/std"]
 alloc = []
+# Enable nightly features
+unstable = []
 
 [[test]]
 name = "tests"
@@ -29,7 +31,7 @@ name = "unit"
 assert_matches = "1.3"
 bencher = "0.1"
 tester = "0.9"
-serde_json = "1.0"
+serde_json = { version = "1.0" }
 
 [dependencies]
 unicode-bidi = { version = "0.3.10", default-features = false, features = ["hardcoded-data"] }

idna/src/lib.rs

@@ -32,7 +32,7 @@
 //! > that minimizes the impact of this transition for client software,
 //! > allowing client software to access domains that are valid under either system.
 #![no_std]
-
+#[cfg_attr(feature = "unstable", feature("error_in_core"))]
 // For forwards compatibility
 #[cfg(feature = "std")]
 extern crate std;

idna/src/uts46.rs

@@ -453,7 +453,7 @@ impl Idna {
             return Errors::default();
         }
         let mut errors = processing(domain, self.config, &mut self.normalized, out);
-        self.output = std::mem::replace(out, String::with_capacity(out.len()));
+        self.output = core::mem::replace(out, String::with_capacity(out.len()));
         let mut first = true;
         for label in self.output.split('.') {
             if !first {
@@ -713,6 +713,9 @@ impl From<Errors> for Result<(), Errors> {
 #[cfg(feature = "std")]
 impl std::error::Error for Errors {}
 
+#[cfg(feature = "nightly")]
+impl core::error::Error for Errors {}
+
 impl fmt::Display for Errors {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt::Debug::fmt(self, f)

idna/tests/punycode.rs

@@ -8,8 +8,7 @@
 
 use crate::test::TestFn;
 use idna::punycode::{decode, encode_str};
-use serde_json::map::Map;
-use serde_json::Value;
+use serde_json::{map::Map, Value};
 use std::str::FromStr;
 
 fn one_test(decoded: &str, encoded: &str) {

url/Cargo.toml

@@ -28,18 +28,25 @@ debugger_test = "0.1"
 debugger_test_parser = "0.1"
 
 [dependencies]
-form_urlencoded = { version = "1.2.0", path = "../form_urlencoded" }
-idna = { version = "0.4.0", path = "../idna" }
-percent-encoding = { version = "2.3.0", path = "../percent_encoding" }
+form_urlencoded = { version = "1.2.0", path = "../form_urlencoded", default-features = false, features = ["alloc"] }
+idna = { version = "0.4.0", path = "../idna", default-features = false, features = ["alloc"] }
+percent-encoding = { version = "2.3.0", path = "../percent_encoding", default-features = false, features = ["alloc"] }
 serde = {version = "1.0", optional = true, features = ["derive"]}
+no-std-net = { version = "0.6.0", default-features = false, optional = true }
 
 [features]
-default = []
+default = ["std"]
+std = ["idna/std", "percent-encoding/std", "form_urlencoded/std", "alloc"]
+alloc = []
 # UNSTABLE FEATURES (requires Rust nightly)
 # Enable to use the #[debugger_visualizer] attribute.
 debugger_visualizer = []
 # Expose internal offsets of the URL.
 expose_internals = []
+# For no_std: Allow the use of no_std_net instead of nightly
+no_std_net = ["no-std-net"]
+# For no_std: Use errors_in_core and net_in_core
+unstable = ["idna/unstable"]
 
 [[bench]]
 name = "parse_url"

url/src/host.rs

@@ -6,9 +6,16 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use std::cmp;
-use std::fmt::{self, Formatter};
-use std::net::{Ipv4Addr, Ipv6Addr};
+use crate::net::{Ipv4Addr, Ipv6Addr};
+use alloc::{
+    borrow::ToOwned,
+    string::{String, ToString},
+    vec::Vec,
+};
+use core::{
+    cmp,
+    fmt::{self, Formatter},
+};
 
 use percent_encoding::{percent_decode, utf8_percent_encode, CONTROLS};
 #[cfg(feature = "serde")]