Revert "Rollup merge of rust-lang#111538 - chenyukang:yukang-fix-110067-version-issue, r=jyn514"

This reverts commit 9267843, reversing
changes made to e52fbff.

This breaks our ability to bump the src/version where we're bootstrapping with an older compiler
than usual (according to version number). It's not clear whether the intended use case has a clean
solution given this constraint, so reverting for now - we can reland with a fix of some kind implemented.

Author: Mark-Simulacrum

src/bootstrap/Cargo.lock

@@ -58,7 +58,6 @@ dependencies = [
  "once_cell",
  "opener",
  "pretty_assertions",
- "semver",
  "serde",
  "serde_derive",
  "serde_json",
@@ -646,12 +645,6 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
-[[package]]
-name = "semver"
-version = "1.0.17"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bebd363326d05ec3e2f532ab7660680f3b02130d780c299bca73469d521bc0ed"
-
 [[package]]
 name = "serde"
 version = "1.0.160"

src/bootstrap/Cargo.toml

@@ -57,7 +57,6 @@ walkdir = "2"
 sysinfo = { version = "0.26.0", optional = true }
 clap = { version = "4.2.4", default-features = false, features = ["std", "usage", "help", "derive", "error-context"] }
 clap_complete = "4.2.2"
-semver = "1.0.17"
 
 # Solaris doesn't support flock() and thus fd-lock is not option now
 [target.'cfg(not(target_os = "solaris"))'.dependencies]

src/bootstrap/config.rs

@@ -24,7 +24,6 @@ pub use crate::flags::Subcommand;
 use crate::flags::{Color, Flags, Warnings};
 use crate::util::{exe, output, t};
 use once_cell::sync::OnceCell;
-use semver::Version;
 use serde::{Deserialize, Deserializer};
 use serde_derive::Deserialize;
 
@@ -1118,7 +1117,6 @@ impl Config {
             config.download_beta_toolchain();
             config.out.join(config.build.triple).join("stage0/bin/rustc")
         });
-
         config.initial_cargo = build
             .cargo
             .map(|cargo| {
@@ -1780,42 +1778,6 @@ impl Config {
         self.rust_codegen_backends.get(0).cloned()
     }
 
-    pub fn check_build_rustc_version(&self) {
-        if self.dry_run() {
-            return;
-        }
-
-        // check rustc version is same or lower with 1 apart from the building one
-        let mut cmd = Command::new(&self.initial_rustc);
-        cmd.arg("--version");
-        let rustc_output = output(&mut cmd)
-            .lines()
-            .next()
-            .unwrap()
-            .split(' ')
-            .nth(1)
-            .unwrap()
-            .split('-')
-            .next()
-            .unwrap()
-            .to_owned();
-        let rustc_version = Version::parse(&rustc_output.trim()).unwrap();
-        let source_version =
-            Version::parse(&fs::read_to_string(self.src.join("src/version")).unwrap().trim())
-                .unwrap();
-        if !(source_version == rustc_version
-            || (source_version.major == rustc_version.major
-                && source_version.minor == rustc_version.minor + 1))
-        {
-            let prev_version = format!("{}.{}.x", source_version.major, source_version.minor - 1);
-            eprintln!(
-                "Unexpected rustc version: {}, we should use {}/{} to build source with {}",
-                rustc_version, prev_version, source_version, source_version
-            );
-            crate::detail_exit(1);
-        }
-    }
-
     /// Returns the commit to download, or `None` if we shouldn't download CI artifacts.
     fn download_ci_rustc_commit(&self, download_rustc: Option<StringOrBool>) -> Option<String> {
         // If `download-rustc` is not set, default to rebuilding.

src/bootstrap/lib.rs

@@ -414,7 +414,6 @@ impl Build {
                 bootstrap_out.display()
             )
         }
-        config.check_build_rustc_version();
 
         if rust_info.is_from_tarball() && config.description.is_none() {
             config.description = Some("built from a source tarball".to_owned());