From 00bf7706bc2af3629293c6efca92e6226f8b4ff4 Mon Sep 17 00:00:00 2001
From: hi-rustin <rustin.liu@gmail.com>
Date: Fri, 25 Jun 2021 21:59:32 +0800
Subject: [PATCH] Include toolchain specification in error message

Signed-off-by: hi-rustin <rustin.liu@gmail.com>
---
 src/cargo/core/compiler/standard_lib.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/cargo/core/compiler/standard_lib.rs b/src/cargo/core/compiler/standard_lib.rs
index 0c554feb219..6b76a5681be 100644
--- a/src/cargo/core/compiler/standard_lib.rs
+++ b/src/cargo/core/compiler/standard_lib.rs
@@ -200,11 +200,19 @@ fn detect_sysroot_src_path(target_data: &RustcTargetData<'_>) -> CargoResult<Pat
         .join("rust");
     let lock = src_path.join("Cargo.lock");
     if !lock.exists() {
-        anyhow::bail!(
+        let msg = format!(
             "{:?} does not exist, unable to build with the standard \
              library, try:\n        rustup component add rust-src",
             lock
         );
+        match env::var("RUSTUP_TOOLCHAIN") {
+            Ok(rustup_toolchain) => {
+                anyhow::bail!("{} --toolchain {}", msg, rustup_toolchain);
+            }
+            Err(_) => {
+                anyhow::bail!(msg);
+            }
+        }
     }
     Ok(src_path)
 }