Remove sysroot-abi feature flag from proc-macro-test

crates/proc-macro-srv/Cargo.toml

@@ -37,7 +37,7 @@ expect-test = "1.4.0"
 proc-macro-test.path = "./proc-macro-test"
 
 [features]
-sysroot-abi = ["proc-macro-test/sysroot-abi"]
+sysroot-abi = []
 in-rust-tree = ["mbe/in-rust-tree", "sysroot-abi"]
 
 [lints]

crates/proc-macro-srv/proc-macro-test/Cargo.toml

@@ -14,6 +14,3 @@ cargo_metadata = "0.18.1"
 
 # local deps
 toolchain.workspace = true
-
-[features]
-sysroot-abi = []

crates/proc-macro-srv/proc-macro-test/build.rs

@@ -17,7 +17,6 @@ use cargo_metadata::Message;
 
 fn main() {
     println!("cargo:rerun-if-changed=imp");
-    println!("cargo:rerun-if-env-changed=PROC_MACRO_TEST_TOOLCHAIN");
 
     let out_dir = env::var_os("OUT_DIR").unwrap();
     let out_dir = Path::new(&out_dir);
@@ -53,15 +52,13 @@ fn main() {
 
     let target_dir = out_dir.join("target");
 
-    let mut cmd = if let Ok(toolchain) = std::env::var("PROC_MACRO_TEST_TOOLCHAIN") {
-        // leverage rustup to find user-specific toolchain
-        let mut cmd = Command::new("cargo");
-        cmd.arg(format!("+{toolchain}"));
-        cmd
-    } else {
-        Command::new(toolchain::cargo())
-    };
+    let is_nightly = String::from_utf8(
+        Command::new(toolchain::cargo()).arg("--version").output().unwrap().stdout,
+    )
+    .unwrap()
+    .contains("nightly");
 
+    let mut cmd = Command::new(toolchain::cargo());
     cmd.current_dir(&staging_dir)
         .args(["build", "-p", "proc-macro-test-impl", "--message-format", "json"])
         // Explicit override the target directory to avoid using the same one which the parent
@@ -70,8 +67,8 @@ fn main() {
         // instance to use the same target directory.
         .arg("--target-dir")
         .arg(&target_dir);
-    if cfg!(feature = "sysroot-abi") {
-        cmd.args(["--features", "sysroot-abi"]);
+    if is_nightly {
+        cmd.args(["--features", "nightly"]);
     }
 
     if let Ok(target) = std::env::var("TARGET") {

crates/proc-macro-srv/proc-macro-test/imp/Cargo.toml

@@ -14,6 +14,6 @@ proc-macro = true
 # and its own `Cargo.lock`
 
 [features]
-sysroot-abi = []
+nightly = []
 
 [workspace]

crates/proc-macro-srv/proc-macro-test/imp/src/lib.rs

@@ -1,10 +1,7 @@
 //! Exports a few trivial procedural macros for testing.
 
-#![allow(unexpected_cfgs)]
-#![cfg(feature = "sysroot-abi")]
-#![cfg(any(feature = "sysroot-abi", rust_analyzer))]
 #![warn(rust_2018_idioms, unused_lifetimes)]
-#![feature(proc_macro_span, proc_macro_def_site)]
+#![cfg_attr(feature = "nightly", feature(proc_macro_span, proc_macro_def_site))]
 
 use proc_macro::{Group, Ident, Literal, Punct, Span, TokenStream, TokenTree};
 
@@ -64,6 +61,7 @@ pub fn fn_like_span_join(args: TokenStream) -> TokenStream {
     )))
 }
 
+#[cfg(feature = "nightly")]
 #[proc_macro]
 pub fn fn_like_span_ops(args: TokenStream) -> TokenStream {
     let args = &mut args.into_iter();