Remove build_helper

The majority of the code is only used by either rustbuild or
rustc_llvm's build script. Rust_build is compiled once for rustbuild and
once for every stage. This means that the majority of the code in this
crate is needlessly compiled multiple times. By moving only the code
actually used by the respective crates to rustbuild and rustc_llvm's
build script, this needless duplicate compilation is avoided.

1 files changed, 5 insertions, 7 deletions

diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index 4089a63f881..81b54c852cd 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -116,13 +116,14 @@ use std::os::unix::fs::symlink as symlink_file;
 #[cfg(windows)]
 use std::os::windows::fs::symlink_file;
 
-use build_helper::{mtime, output, run, run_suppressed, t, try_run, try_run_suppressed};
 use filetime::FileTime;
 
+use crate::build_helper::{mtime, output, run, run_suppressed, t, try_run, try_run_suppressed};
 use crate::builder::Kind;
 use crate::config::{LlvmLibunwind, TargetSelection};
 use crate::util::{exe, libdir, CiEnv};
 
+mod build_helper;
 mod builder;
 mod cache;
 mod cc_detect;
@@ -1301,13 +1302,10 @@ impl Build {
                 }
                 // Don't include optional deps if their features are not
                 // enabled. Ideally this would be computed from `cargo
-                // metadata --features …`, but that is somewhat slow. Just
-                // skip `build_helper` since there aren't any operations we
-                // want to perform on it. In the future, we may want to
-                // consider just filtering all build and dev dependencies in
-                // metadata::build.
+                // metadata --features …`, but that is somewhat slow. In
+                // the future, we may want to consider just filtering all
+                // build and dev dependencies in metadata::build.
                 if visited.insert(dep)
-                    && dep != "build_helper"
                     && (dep != "profiler_builtins"
                         || target
                             .map(|t| self.config.profiler_enabled(t))