run_make_support: move external deps to external_deps module

src/tools/run-make-support/src/env_checked.rs

@@ -1,5 +1,5 @@
-use std::ffi::OsString;
 use std::env;
+use std::ffi::OsString;
 
 #[track_caller]
 #[must_use]

src/tools/run-make-support/src/external_deps/htmldocck.rs

@@ -0,0 +1,14 @@
+use crate::command::Command;
+use crate::source_root;
+
+use super::python::python_command;
+
+/// `htmldocck` is a python script which is used for rustdoc test suites, it is assumed to be
+/// available at `$SOURCE_ROOT/src/etc/htmldocck.py`.
+#[track_caller]
+#[must_use]
+pub fn htmldocck() -> Command {
+    let mut python = python_command();
+    python.arg(source_root().join("src/etc/htmldocck.py"));
+    python
+}

src/tools/run-make-support/src/external_deps/mod.rs

@@ -0,0 +1,10 @@
+//! This module contains external tool dependencies that we assume are available in the environment,
+//! such as `cc` or `python`.
+
+pub mod cc;
+pub mod clang;
+pub mod htmldocck;
+pub mod llvm;
+pub mod python;
+pub mod rustc;
+pub mod rustdoc;

src/tools/run-make-support/src/external_deps/python.rs

@@ -0,0 +1,11 @@
+use crate::command::Command;
+use crate::env_checked::env_var;
+
+/// Obtain path of python as provided by the `PYTHON` environment variable. It is up to the caller
+/// to document and check if the python version is compatible with its intended usage.
+#[track_caller]
+#[must_use]
+pub fn python_command() -> Command {
+    let python_path = env_var("PYTHON");
+    Command::new(python_path)
+}

src/tools/run-make-support/src/lib.rs

@@ -3,17 +3,13 @@
 //! notably is built via cargo: this means that if your test wants some non-trivial utility, such
 //! as `object` or `wasmparser`, they can be re-exported and be made available through this library.
 
-pub mod cc;
-pub mod clang;
 mod command;
 pub mod diff;
 pub mod env_checked;
+pub mod external_deps;
 pub mod fs_wrapper;
-pub mod llvm;
 mod macros;
 pub mod run;
-pub mod rustc;
-pub mod rustdoc;
 pub mod targets;
 
 use std::fs;
@@ -27,17 +23,26 @@ pub use object;
 pub use regex;
 pub use wasmparser;
 
+// Re-exports of external dependencies.
+pub use external_deps::{cc, clang, htmldocck, llvm, python, rustc, rustdoc};
+
 pub use cc::{cc, extra_c_flags, extra_cxx_flags, Cc};
 pub use clang::{clang, Clang};
-pub use diff::{diff, Diff};
-pub use env_checked::{env_var, env_var_os};
+pub use htmldocck::htmldocck;
 pub use llvm::{
     llvm_ar, llvm_filecheck, llvm_objdump, llvm_profdata, llvm_readobj, LlvmAr, LlvmFilecheck,
     LlvmObjdump, LlvmProfdata, LlvmReadobj,
 };
-pub use run::{cmd, run, run_fail, run_with_args};
+pub use python::python_command;
 pub use rustc::{aux_build, bare_rustc, rustc, Rustc};
 pub use rustdoc::{bare_rustdoc, rustdoc, Rustdoc};
+
+pub use diff::{diff, Diff};
+
+pub use env_checked::{env_var, env_var_os};
+
+pub use run::{cmd, run, run_fail, run_with_args};
+
 pub use targets::{is_darwin, is_msvc, is_windows, target, uname};
 
 use command::{Command, CompletedProcess};
@@ -55,21 +60,6 @@ pub fn ar(inputs: &[impl AsRef<Path>], output_path: impl AsRef<Path>) {
     }
 }
 
-#[track_caller]
-#[must_use]
-pub fn python_command() -> Command {
-    let python_path = env_var("PYTHON");
-    Command::new(python_path)
-}
-
-#[track_caller]
-#[must_use]
-pub fn htmldocck() -> Command {
-    let mut python = python_command();
-    python.arg(source_root().join("src/etc/htmldocck.py"));
-    python
-}
-
 /// Returns the path for a local test file.
 pub fn path<P: AsRef<Path>>(p: P) -> PathBuf {
     cwd().join(p.as_ref())