fix: remove Option<T> from rust_std_features

Author: shrirambalaji

src/bootstrap/src/core/config/config.rs

@@ -287,7 +287,7 @@ pub struct Config {
     pub rust_profile_generate: Option<String>,
     pub rust_lto: RustcLto,
     pub rust_validate_mir_opts: Option<u32>,
-    pub rust_std_features: Option<BTreeSet<String>>,
+    pub rust_std_features: BTreeSet<String>,
     pub llvm_profile_use: Option<String>,
     pub llvm_profile_generate: bool,
     pub llvm_libunwind_default: Option<LlvmLibunwind>,
@@ -1142,7 +1142,7 @@ define_config! {
         download_rustc: Option<StringOrBool> = "download-rustc",
         lto: Option<String> = "lto",
         validate_mir_opts: Option<u32> = "validate-mir-opts",
-        std_features: Option<Vec<String>> = "std-features",
+        std_features: Option<BTreeSet<String>> = "std-features",
     }
 }
 
@@ -2096,10 +2096,8 @@ impl Config {
             );
         }
 
-        // std_features chosen during bootstrap
-        if let Some(std_features) = std_features {
-            config.rust_std_features = Some(BTreeSet::from_iter(std_features));
-        }
+        config.rust_std_features = std_features.unwrap_or_default();
+
         let default = debug == Some(true);
         config.rust_debug_assertions = debug_assertions.unwrap_or(default);
         config.rust_debug_assertions_std =

src/bootstrap/src/core/config/tests.rs

@@ -333,14 +333,14 @@ fn parse_rust_std_features() {
     let config = parse("rust.std-features = [\"panic-unwind\", \"backtrace\"]");
     let expected_features: BTreeSet<String> =
         ["panic-unwind", "backtrace"].into_iter().map(|s| s.to_string()).collect();
-    assert_eq!(config.rust_std_features, Some(expected_features));
+    assert_eq!(config.rust_std_features, expected_features);
 }
 
 #[test]
 fn parse_rust_std_features_empty() {
     let config = parse("rust.std-features = []");
     let expected_features: BTreeSet<String> = BTreeSet::new();
-    assert_eq!(config.rust_std_features, Some(expected_features));
+    assert_eq!(config.rust_std_features, expected_features);
 }
 
 #[test]

src/bootstrap/src/lib.rs

@@ -663,11 +663,8 @@ impl Build {
 
     /// Gets the space-separated set of activated features for the standard ibrary. This can be configured with the `std-features` key in config.toml.
     fn std_features(&self, target: TargetSelection) -> String {
-        let mut features: BTreeSet<&str> = if let Some(features) = &self.config.rust_std_features {
-            features.iter().map(|s| s.as_str()).collect()
-        } else {
-            BTreeSet::new()
-        };
+        let mut features: BTreeSet<&str> =
+            self.config.rust_std_features.iter().map(|s| s.as_str()).collect();
 
         features.insert("panic-unwind");