Enable setting target-api-features from config.toml

Move api-feature logic into its own function
and make it active in both the rustc and std
bootstrap config

Author: seritools

config.toml.example

@@ -546,6 +546,11 @@
 # probably don't want to use this.
 #qemu-rootfs = "..."
 
+# Comma separated list of target api features for the target. Currently, *all*
+# features have to be passed if this is specified. Inherited features are not
+# supported here yet.
+#target-api-feature = "...,..."
+
 # =============================================================================
 # Distribution options
 #

src/bootstrap/compile.rs

@@ -205,6 +205,43 @@ fn copy_self_contained_objects(
     target_deps
 }
 
+fn add_target_api_features_cargo(
+    builder: &Builder<'_>,
+    target: TargetSelection,
+    cargo: &mut Cargo,
+) {
+    if let Some(api_features) = builder.target_api_feature(target) {
+        for api_feature in api_features {
+            cargo.rustflag("--cfg");
+            cargo.rustflag(&format!("target_api_feature=\"{}\"", api_feature));
+        }
+    } else {
+        if target.contains("windows") {
+            // all `target_api_feature`s for the currently officially supported
+            // windows version for rust
+            const WINDOWS_VERSIONS: [&str; 12] = [
+                "3.10.511",  // NT 3.1
+                "3.10.528",  // NT 3.1 SP3
+                "3.50.807",  // NT 3.5
+                "3.51.1057", // NT 3.51
+                "4.0.1381",  // NT 4
+                "5.0.2195",  // 2000
+                "5.1.2600",  // XP
+                "5.2.3790",  // XP 64bit, Server 2003
+                "6.0.6000",  // Vista, Server 2008
+                "6.0.6001",  // Vista SP1, Server 2008 SP1
+                "6.0.6002",  // Vista SP2, Server 2008 SP2
+                "6.1.7600",  // 7, Server 2008 R2
+            ];
+
+            for v in &WINDOWS_VERSIONS {
+                cargo.rustflag("--cfg");
+                cargo.rustflag(&format!("target_api_feature=\"{}\"", v));
+            }
+        }
+    }
+}
+
 /// Configure cargo to compile the standard library, adding appropriate env vars
 /// and such.
 pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, cargo: &mut Cargo) {
@@ -296,6 +333,8 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
     if target.contains("riscv") {
         cargo.rustflag("-Cforce-unwind-tables=yes");
     }
+
+    add_target_api_features_cargo(builder, target, cargo);
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
@@ -604,28 +643,7 @@ pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetS
         }
     }
 
-    if target.contains("windows") {
-        // all `target_api_feature`s for the currently officially supported
-        // windows version for rust
-        const WINDOWS_VERSIONS: [&str; 12] = [
-            "3.10.511",  // NT 3.1
-            "3.10.528",  // NT 3.1 SP3
-            "3.50.807",  // NT 3.5
-            "3.51.1057", // NT 3.51
-            "4.0.1381",  // NT 4
-            "5.0.2195",  // 2000
-            "5.1.2600",  // XP
-            "5.2.3790",  // XP 64bit, Server 2003
-            "6.0.6000",  // Vista, Server 2008
-            "6.0.6001",  // Vista SP1, Server 2008 SP1
-            "6.0.6002",  // Vista SP2, Server 2008 SP2
-            "6.1.7600",  // 7, Server 2008 R2
-        ];
-
-        for v in &WINDOWS_VERSIONS {
-            cargo.rustflag(&format!("--cfg=target_api_feature=\"{}\"", v));
-        }
-    }
+    add_target_api_features_cargo(builder, target, cargo);
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]

src/bootstrap/config.rs

@@ -240,6 +240,7 @@ pub struct Target {
     pub wasi_root: Option<PathBuf>,
     pub qemu_rootfs: Option<PathBuf>,
     pub no_std: bool,
+    pub target_api_feature: Option<Vec<String>>,
 }
 
 impl Target {
@@ -432,6 +433,7 @@ struct TomlTarget {
     wasi_root: Option<String>,
     qemu_rootfs: Option<String>,
     no_std: Option<bool>,
+    target_api_feature: Option<String>,
 }
 
 impl Config {
@@ -703,6 +705,10 @@ impl Config {
                 target.musl_libdir = cfg.musl_libdir.clone().map(PathBuf::from);
                 target.wasi_root = cfg.wasi_root.clone().map(PathBuf::from);
                 target.qemu_rootfs = cfg.qemu_rootfs.clone().map(PathBuf::from);
+                target.target_api_feature = cfg
+                    .target_api_feature
+                    .as_ref()
+                    .map(|s| s.split(',').map(String::from).collect());
 
                 config.target_config.insert(TargetSelection::from_user(triple), target);
             }

src/bootstrap/lib.rs

@@ -921,6 +921,11 @@ impl Build {
         self.config.target_config.get(&target).and_then(|t| t.qemu_rootfs.as_ref()).map(|p| &**p)
     }
 
+    /// Returns the target api feature list if they are present
+    fn target_api_feature(&self, target: TargetSelection) -> Option<&Vec<String>> {
+        self.config.target_config.get(&target).and_then(|t| t.target_api_feature.as_ref())
+    }
+
     /// Path to the python interpreter to use
     fn python(&self) -> &Path {
         self.config.python.as_ref().unwrap()