为何rustc自动降级？如何强制使用Rust 1.73.0新版本？

你卸载1.60.0后安装了1.73.0，但运行rustc时自动下载并切换回旧版本，可通过以下步骤强制使用1.73.0：

步骤1：查看当前工具链状态 #

先执行命令确认已安装的版本和默认配置：

rustup show

该命令会列出所有已安装的Rust工具链，以及当前全局默认使用的版本。

步骤2：设置全局默认工具链为1.73.0 #

执行以下任一命令，将全局默认工具链指定为目标版本：

# 直接指定1.73.0版本
rustup default 1.73.0
# 或者指定稳定版（后续稳定版更新会自动同步）
rustup default stable

步骤3：检查项目本地工具链配置 #

如果仅在特定项目中出现回退，检查项目根目录下是否存在rust-toolchain或rust-toolchain.toml文件——这类文件会强制项目使用指定版本。若文件内写了1.60.0，修改为stable或1.73.0即可。

步骤4：刷新环境变量 #

执行命令重新加载Cargo的环境变量，确保系统PATH指向正确的工具链路径：

source "$HOME/.cargo/env"

也可以直接重启当前终端窗口，效果一致。

步骤5：验证生效 #

运行以下命令确认当前使用的Rust版本：

rustc -V

正常情况下会输出rustc 1.73.0 (cc66ad468 2023-10-03)。

问题上下文日志 #

info: profile set to 'default'
info: default host triple is aarch64-apple-darwin
info: syncing channel updates for 'stable-aarch64-apple-darwin'
info: latest update on 2023-10-05, rust version 1.73.0 (cc66ad468 2023-10-03)
info: downloading component 'cargo'
info: downloading component 'clippy'
info: downloading component 'rust-docs'
info: downloading component 'rust-std'
info: downloading component 'rustc'
 54.4 MiB /  54.4 MiB (100 %)  27.7 MiB/s in  2s ETA:  0s
info: downloading component 'rustfmt'
info: installing component 'cargo'
info: installing component 'clippy'
info: installing component 'rust-docs'
 13.8 MiB /  13.8 MiB (100 %)   5.5 MiB/s in  1s ETA:  0s
info: installing component 'rust-std'
 24.5 MiB /  24.5 MiB (100 %)  21.1 MiB/s in  1s ETA:  0s
info: installing component 'rustc'
 54.4 MiB /  54.4 MiB (100 %)  23.3 MiB/s in  2s ETA:  0s
info: installing component 'rustfmt'
info: default toolchain set to 'stable-aarch64-apple-darwin'

  stable-aarch64-apple-darwin installed - rustc 1.73.0 (cc66ad468 2023-10-03)


Rust is installed now. Great!

To get started you may need to restart your current shell.
This would reload your PATH environment variable to include
Cargo's bin directory ($HOME/.cargo/bin).

To configure your current shell, run:
source "$HOME/.cargo/env"

(base) % rustc -V
info: syncing channel updates for '1.60.0-aarch64-apple-darwin'
info: latest update on 2022-04-07, rust version 1.60.0 (7737e0b5c 2022-04-04)
info: downloading component 'cargo'
info: downloading component 'clippy'
info: downloading component 'rust-docs'
info: downloading component 'rust-std'
info: downloading component 'rustc'
info: downloading component 'rustfmt'
info: installing component 'cargo'
info: installing component 'clippy'
info: installing component 'rust-docs'
info: installing component 'rust-std'
info: installing component 'rustc'
info: installing component 'rustfmt'
rustc 1.60.0 (7737e0b5c 2022-04-04)

内容的提问来源于stack exchange，提问作者Justin Zhang