refactor(linter): replace MIME guessing with extension check

Cargo.toml

@@ -169,7 +169,6 @@ markdown = "1.0.0-alpha.21"
 memchr = "2.7.4"
 miette = { package = "oxc-miette", version = "1.0.2", features = ["fancy-no-syscall"] }
 mimalloc = "0.1.43"
-mime_guess = "2.0.5"
 nonmax = "0.5.5"
 num-bigint = "0.4.6"
 num-traits = "0.2.19"

apps/oxlint/src/lint.rs

@@ -856,4 +856,10 @@ mod test {
             vec![String::from("src/target"), String::from("!src/dist"), String::from("!!src/dist")]
         );
     }
+
+    #[test]
+    fn test_non_json_config() {
+        let args = &["-c", "test.js"];
+        Tester::new().with_cwd("fixtures/eslintrc_env".into()).test_and_snapshot(args);
+    }
 }

apps/oxlint/src/snapshots/fixtures__eslintrc_env_-c test.js@oxlint.snap

@@ -0,0 +1,15 @@
+---
+source: apps/oxlint/src/tester.rs
+---
+########## 
+arguments: -c test.js
+working directory: fixtures/eslintrc_env
+----------
+Failed to parse configuration file.
+
+  × Failed to parse eslint config "<cwd>/fixtures/eslintrc_env/test.js".
+  │ Only JSON configuration files are supported
+
+----------
+CLI result: InvalidOptionConfig
+----------

crates/oxc_linter/Cargo.toml

@@ -48,7 +48,6 @@ json-strip-comments = { workspace = true }
 language-tags = { workspace = true }
 lazy_static = { workspace = true }
 memchr = { workspace = true }
-mime_guess = { workspace = true }
 nonmax = { workspace = true }
 phf = { workspace = true, features = ["macros"] }
 rayon = { workspace = true }

crates/oxc_linter/src/config/oxlintrc.rs

@@ -1,4 +1,7 @@
-use std::path::{Path, PathBuf};
+use std::{
+    ffi::OsStr,
+    path::{Path, PathBuf},
+};
 
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
@@ -109,14 +112,14 @@ impl Oxlintrc {
         })?;
 
         let json = serde_json::from_str::<serde_json::Value>(&string).map_err(|err| {
-            let guess = mime_guess::from_path(path);
-            let err = match guess.first() {
+            let ext = path.extension().and_then(OsStr::to_str);
+            let err = match ext {
                 // syntax error
-                Some(mime) if mime.subtype() == "json" => err.to_string(),
-                Some(_) => "Only json configuration is supported".to_string(),
+                Some(ext) if is_json_ext(ext) => err.to_string(),
+                Some(_) => "Only JSON configuration files are supported".to_string(),
                 None => {
                     format!(
-                        "{err}, if the configuration is not a json file, please use json instead."
+                        "{err}, if the configuration is not a JSON file, please use JSON instead."
                     )
                 }
             };
@@ -133,6 +136,10 @@ impl Oxlintrc {
     }
 }
 
+fn is_json_ext(ext: &str) -> bool {
+    ext == "json" || ext == "jsonc"
+}
+
 #[cfg(test)]
 mod test {
     use serde_json::json;