Move `force_coloring_in_ci` from `builder_helper` to `bootstrap`

It was only used in bootstrap. This move allows us to modify the function to work with `BootstrapCommand`, rather than `Command`.

src/bootstrap/src/core/build_steps/test.rs

@@ -2095,9 +2095,7 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
         let git_config = builder.config.git_config();
         cmd.arg("--git-repository").arg(git_config.git_repository);
         cmd.arg("--nightly-branch").arg(git_config.nightly_branch);
-
-        // FIXME: Move CiEnv back to bootstrap, it is only used here anyway
-        builder.ci_env.force_coloring_in_ci(cmd.as_command_mut());
+        cmd.force_coloring_in_ci(builder.ci_env);
 
         #[cfg(feature = "build-metrics")]
         builder.metrics.begin_test_suite(

src/bootstrap/src/core/builder.rs

@@ -2105,7 +2105,7 @@ impl<'a> Builder<'a> {
         // Try to use a sysroot-relative bindir, in case it was configured absolutely.
         cargo.env("RUSTC_INSTALL_BINDIR", self.config.bindir_relative());
 
-        self.ci_env.force_coloring_in_ci(cargo.as_command_mut());
+        cargo.force_coloring_in_ci(self.ci_env);
 
         // When we build Rust dylibs they're all intended for intermediate
         // usage, so make sure we pass the -Cprefer-dynamic flag instead of

src/bootstrap/src/utils/exec.rs

@@ -1,4 +1,5 @@
 use crate::Build;
+use build_helper::ci::CiEnv;
 use build_helper::drop_bomb::DropBomb;
 use std::ffi::OsStr;
 use std::fmt::{Debug, Formatter};
@@ -171,6 +172,18 @@ impl BootstrapCommand {
     pub fn get_created_location(&self) -> std::panic::Location<'static> {
         self.drop_bomb.get_created_location()
     }
+
+    /// If in a CI environment, forces the command to run with colors.
+    pub fn force_coloring_in_ci(&mut self, ci_env: CiEnv) {
+        if ci_env != CiEnv::None {
+            // Due to use of stamp/docker, the output stream of bootstrap is not
+            // a TTY in CI, so coloring is by-default turned off.
+            // The explicit `TERM=xterm` environment is needed for
+            // `--color always` to actually work. This env var was lost when
+            // compiling through the Makefile. Very strange.
+            self.env("TERM", "xterm").args(["--color", "always"]);
+        }
+    }
 }
 
 impl Debug for BootstrapCommand {

src/tools/build_helper/src/ci.rs

@@ -1,5 +1,3 @@
-use std::process::Command;
-
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum CiEnv {
     /// Not a CI environment.
@@ -21,18 +19,6 @@ impl CiEnv {
     pub fn is_ci() -> bool {
         Self::current() != CiEnv::None
     }
-
-    /// If in a CI environment, forces the command to run with colors.
-    pub fn force_coloring_in_ci(self, cmd: &mut Command) {
-        if self != CiEnv::None {
-            // Due to use of stamp/docker, the output stream of bootstrap is not
-            // a TTY in CI, so coloring is by-default turned off.
-            // The explicit `TERM=xterm` environment is needed for
-            // `--color always` to actually work. This env var was lost when
-            // compiling through the Makefile. Very strange.
-            cmd.env("TERM", "xterm").args(&["--color", "always"]);
-        }
-    }
 }
 
 pub mod gha {