<idea-plugin>
    <extensions defaultExtensionNs="com.intellij">
        <experimentalFeature id="org.rust.cargo.build.tool.window" percentOfUsers="100">
            <description>Enable Cargo tasks to use Build Tool Window</description>
        </experimentalFeature>
        <experimentalFeature id="org.rust.lang.cfg.attributes" percentOfUsers="0">
            <description>Enable Rust cfg attributes support</description>
        </experimentalFeature>
    </extensions>
</idea-plugin>

<idea-plugin>
    <extensions defaultExtensionNs="com.intellij">
        <experimentalFeature id="org.rust.cargo.build.tool.window" percentOfUsers="100">
            <description>Enable Cargo tasks to use Build Tool Window</description>
        </experimentalFeature>
        <experimentalFeature id="org.rust.lang.cfg.attributes" percentOfUsers="100">
            <description>Enable Rust cfg attributes support</description>
        </experimentalFeature>
    </extensions>
</idea-plugin>

Enable cfg attributes support on nightly
Enable cfg attributes support on nightly
