fix: tsconfig#extends must be a string

src/lib.rs

@@ -973,9 +973,9 @@ impl<Fs: FileSystem + Default> ResolverGeneric<Fs> {
         self.cache.tsconfig(path, |tsconfig| {
             let directory = self.cache.value(tsconfig.directory());
             tracing::trace!(tsconfig = ?tsconfig, "load_tsconfig");
+
             // Extend tsconfig
-            let mut extended_tsconfig_paths = vec![];
-            for tsconfig_extend_specifier in &tsconfig.extends {
+            if let Some(tsconfig_extend_specifier) = &tsconfig.extends {
                 let extended_tsconfig_path = match tsconfig_extend_specifier.as_bytes().first() {
                     None => {
                         return Err(ResolveError::Specifier(SpecifierError::Empty(
@@ -1004,13 +1004,12 @@ impl<Fs: FileSystem + Default> ResolverGeneric<Fs> {
                         })?
                         .to_path_buf(),
                 };
-                extended_tsconfig_paths.push(extended_tsconfig_path);
-            }
-            for extended_tsconfig_path in extended_tsconfig_paths {
+
                 let extended_tsconfig =
                     self.load_tsconfig(&extended_tsconfig_path, &TsconfigReferences::Disabled)?;
                 tsconfig.extend_tsconfig(&extended_tsconfig);
             }
+
             // Load project references
             match references {
                 TsconfigReferences::Disabled => {

src/tsconfig.rs

@@ -18,8 +18,10 @@ pub struct TsConfig {
     #[serde(skip)]
     path: PathBuf,
 
-    #[serde(default, deserialize_with = "deserialize_extends")]
-    pub extends: Vec<String>,
+    /// The value of extends must be a string containing a path to another configuration file to inherit from.
+    /// https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-1.html#configuration-inheritance
+    #[serde(default)]
+    pub extends: Option<String>,
 
     #[serde(default)]
     pub references: Vec<ProjectReference>,
@@ -50,22 +52,6 @@ pub struct CompilerOptions {
     paths_base: PathBuf,
 }
 
-fn deserialize_extends<'de, D>(deserializer: D) -> Result<Vec<String>, D::Error>
-where
-    D: serde::Deserializer<'de>,
-{
-    #[derive(serde::Deserialize)]
-    #[serde(untagged)]
-    enum StringOrArray {
-        String(String),
-        Array(Vec<String>),
-    }
-    Ok(match StringOrArray::deserialize(deserializer)? {
-        StringOrArray::String(s) => vec![s],
-        StringOrArray::Array(a) => a,
-    })
-}
-
 impl TsConfig {
     pub fn parse(path: &Path, json: &mut str) -> Result<Self, serde_json::Error> {
         _ = json_strip_comments::strip(json);