macros: do not automatically pull rt-core (#2038)

tokio-macros/src/lib.rs

@@ -20,6 +20,7 @@ use proc_macro::TokenStream;
 use quote::quote;
 use std::num::NonZeroUsize;
 
+#[derive(Clone, Copy, PartialEq)]
 enum Runtime {
     Basic,
     Threaded,
@@ -145,21 +146,10 @@ fn parse_knobs(
         }
     }
 
-    let mut rt = quote! { tokio::runtime::Builder::new() };
-    match (runtime, is_test) {
-        (Some(Runtime::Threaded), _) => {
-            if rt_threaded {
-                rt = quote! { #rt.threaded_scheduler() }
-            }
-        }
-        (Some(Runtime::Basic), _) => rt = quote! { #rt.basic_scheduler() },
-        (None, true) => rt = quote! { #rt.basic_scheduler() },
-        (None, false) => {
-            if rt_threaded {
-                rt = quote! { #rt.threaded_scheduler() }
-            }
-        }
-    };
+    let mut rt = quote! { tokio::runtime::Builder::new().basic_scheduler() };
+    if rt_threaded && (runtime == Some(Runtime::Threaded) || (runtime.is_none() && !is_test)) {
+        rt = quote! { #rt.threaded_scheduler() };
+    }
     if let Some(v) = core_threads.map(|v| v.get()) {
         rt = quote! { #rt.core_threads(#v) };
     }

tokio/Cargo.toml

@@ -54,7 +54,7 @@ io-driver = ["mio", "lazy_static"]
 io-util = ["memchr"]
 # stdin, stdout, stderr
 io-std = ["rt-core"]
-macros = ["rt-core", "tokio-macros"]
+macros = ["tokio-macros"]
 net = ["dns", "tcp", "udp", "uds"]
 process = [
   "io-driver",

tokio/src/lib.rs

@@ -264,16 +264,18 @@ cfg_time! {
 mod util;
 
 cfg_macros! {
-    cfg_rt_threaded! {
-        #[cfg(not(test))] // Work around for rust-lang/rust#62127
-        pub use tokio_macros::main_threaded as main;
-        pub use tokio_macros::test_threaded as test;
-    }
+    doc_rt_core! {
+        cfg_rt_threaded! {
+            #[cfg(not(test))] // Work around for rust-lang/rust#62127
+            pub use tokio_macros::main_threaded as main;
+            pub use tokio_macros::test_threaded as test;
+        }
 
-    cfg_not_rt_threaded! {
-        #[cfg(not(test))] // Work around for rust-lang/rust#62127
-        pub use tokio_macros::main_basic as main;
-        pub use tokio_macros::test_basic as test;
+        cfg_not_rt_threaded! {
+            #[cfg(not(test))] // Work around for rust-lang/rust#62127
+            pub use tokio_macros::main_basic as main;
+            pub use tokio_macros::test_basic as test;
+        }
     }
 }