Fix Windows CRLF Issue (#3455)

Cargo configs are injected as a literal string which, on Windows, can
end up with escaped CRLF line endings in `cargo-bazel.json` causing the
digests to be different on Linux/Windows. This PR parses the inner
string literal to prevent platform specific differences in the
`config.toml`. There might be a better way to do this, but adding a new
top level command to cargo-bazel to parse TOML into JSON felt wrong, and
adding a second binary seems even worse. I'm open to solving this
another way if ya'll have a better idea.

Author: timbess

crate_universe/src/config.rs

@@ -706,13 +706,34 @@ pub(crate) struct Config {
     pub(crate) rendering: RenderConfig,
 
     /// The contents of a Cargo configuration file
+    #[serde(default, deserialize_with = "deserialize_cargo_config")]
     pub(crate) cargo_config: Option<toml::Value>,
 
     /// A set of platform triples to use in generated select statements
     #[serde(default, skip_serializing_if = "BTreeSet::is_empty")]
     pub(crate) supported_platform_triples: BTreeSet<TargetTriple>,
 }
 
+// rules_rust/crate_universe/private/generate_utils.bzl:generate_config
+// injects the cargo_config as a literal JSON string, this causes line ending
+// instability in Unix vs Windows. Parsing it here fixes any cross platform differences.
+fn deserialize_cargo_config<'de, D>(deserializer: D) -> Result<Option<toml::Value>, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    let value: Option<serde_json::Value> = Option::deserialize(deserializer)?;
+    match value {
+        None | Some(serde_json::Value::Null) => Ok(None),
+        Some(serde_json::Value::String(s)) => s
+            .parse::<toml::Value>()
+            .map(Some)
+            .map_err(serde::de::Error::custom),
+        Some(other) => serde_json::from_value(other)
+            .map(Some)
+            .map_err(serde::de::Error::custom),
+    }
+}
+
 impl Config {
     pub(crate) fn try_from_path<T: AsRef<Path>>(path: T) -> Result<Self> {
         let data = fs::read_to_string(path)?;

crate_universe/src/lockfile.rs

@@ -376,4 +376,57 @@ mod test {
             digest,
         );
     }
+
+    #[test]
+    fn digest_stable_with_crlf_cargo_config() {
+        let context = Context::default();
+        let splicing_metadata = SplicingMetadata::default();
+
+        let json_config = |cargo_config: &str| {
+            serde_json::to_string(&serde_json::json!({
+                "generate_binaries": false,
+                "generate_build_scripts": false,
+                "cargo_config": cargo_config,
+                "rendering": {
+                    "repository_name": "test",
+                    "regen_command": "//test",
+                    "generate_cargo_toml_env_vars": true
+                }
+            }))
+            .unwrap()
+        };
+
+        let config_crlf: Config = serde_json::from_str(&json_config(
+            "[registries.my-registry]\r\nindex = \"sparse+https://example.com/\"",
+        ))
+        .unwrap();
+
+        let config_lf: Config = serde_json::from_str(&json_config(
+            "[registries.my-registry]\nindex = \"sparse+https://example.com/\"",
+        ))
+        .unwrap();
+
+        let digest_crlf = Digest::compute(
+            &context,
+            &config_crlf,
+            &splicing_metadata,
+            "0.1.0",
+            "cargo 1.57.0 (b2e52d7ca 2021-10-21)",
+            "rustc 1.57.0 (f1edd0429 2021-11-29)",
+        );
+
+        let digest_lf = Digest::compute(
+            &context,
+            &config_lf,
+            &splicing_metadata,
+            "0.1.0",
+            "cargo 1.57.0 (b2e52d7ca 2021-10-21)",
+            "rustc 1.57.0 (f1edd0429 2021-11-29)",
+        );
+
+        assert_eq!(
+            digest_crlf, digest_lf,
+            "Digests should be identical regardless of CRLF vs LF line endings in cargo_config"
+        );
+    }
 }