Improve Compile Times with `serde_derive` (#1075)

This massively improves compile times by not forcing `serde` to depend
on `serde_derive`. This allows many crates to start compiling much
sooner, which ends up resulting in often quite massive compile time wins
for real world projects.

url/Cargo.toml

@@ -17,7 +17,8 @@ edition = "2018"
 rust-version = "1.63" # From libc
 
 [dev-dependencies]
-serde = { version = "1.0", features = ["derive"] }
+serde = "1.0"
+serde_derive = "1.0"
 serde_json = "1.0"
 bencher = "0.1"
 
@@ -28,7 +29,8 @@ wasm-bindgen-test = "0.3"
 form_urlencoded = { version = "1.2.2", path = "../form_urlencoded", default-features = false, features = ["alloc"] }
 idna = { version = "1.1.0", path = "../idna", default-features = false, features = ["alloc", "compiled_data"] }
 percent-encoding = { version = "2.3.2", path = "../percent_encoding", default-features = false, features = ["alloc"] }
-serde = { version = "1.0", optional = true, features = ["derive"], default-features = false }
+serde = { version = "1.0", optional = true, default-features = false }
+serde_derive = { version = "1.0", optional = true, default-features = false }
 
 [features]
 default = ["std"]
@@ -38,6 +40,8 @@ std = ["idna/std", "percent-encoding/std", "form_urlencoded/std", "serde?/std"]
 debugger_visualizer = []
 # Expose internal offsets of the URL.
 expose_internals = []
+# Enables serialization and deserialization via serde.
+serde = ["dep:serde", "dep:serde_derive"]
 
 [[test]]
 name = "url_wpt"

url/src/host.rs

@@ -16,7 +16,7 @@ use core::fmt::{self, Formatter};
 
 use percent_encoding::{percent_decode, utf8_percent_encode, CONTROLS};
 #[cfg(feature = "serde")]
-use serde::{Deserialize, Serialize};
+use serde_derive::{Deserialize, Serialize};
 
 use crate::parser::{ParseError, ParseResult};
 

url/tests/unit.rs

@@ -1370,7 +1370,7 @@ fn issue_974() {
 #[cfg(feature = "serde")]
 #[test]
 fn serde_error_message() {
-    use serde::Deserialize;
+    use serde_derive::Deserialize;
     #[derive(Debug, Deserialize)]
     #[allow(dead_code)]
     struct TypeWithUrl {

url/tests/wpt.rs

@@ -64,7 +64,7 @@ macro_rules! println {
     }
 }
 
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde_derive::Deserialize)]
 struct UrlTest {
     input: String,
     base: Option<String>,
@@ -72,7 +72,7 @@ struct UrlTest {
     result: UrlTestResult,
 }
 
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde_derive::Deserialize)]
 #[serde(untagged)]
 #[allow(clippy::large_enum_variant)]
 enum UrlTestResult {
@@ -80,7 +80,7 @@ enum UrlTestResult {
     Fail(UrlTestFail),
 }
 
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde_derive::Deserialize)]
 struct UrlTestOk {
     href: String,
     protocol: String,
@@ -94,19 +94,19 @@ struct UrlTestOk {
     hash: String,
 }
 
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde_derive::Deserialize)]
 struct UrlTestFail {
     failure: bool,
 }
 
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde_derive::Deserialize)]
 struct SetterTest {
     href: String,
     new_value: String,
     expected: SetterTestExpected,
 }
 
-#[derive(Debug, serde::Deserialize)]
+#[derive(Debug, serde_derive::Deserialize)]
 struct SetterTestExpected {
     href: Option<String>,
     protocol: Option<String>,