From 1094aa35d1688bec13f64fd9a04f3790a46246ae Mon Sep 17 00:00:00 2001
From: Owen Rafferty <owen@owenrafferty.com>
Date: Tue, 5 Jul 2022 15:57:58 -0500
Subject: [PATCH] rust: bootstrap with system compiler, et al if possible

---
 extra/rust/build | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/extra/rust/build b/extra/rust/build
index 301dabeb..b5f293be 100755
--- a/extra/rust/build
+++ b/extra/rust/build
@@ -6,17 +6,6 @@ patch -p1 < fix-curl.patch
 # change them to relative paths ($PWD/... ./...).
 export RUSTFLAGS="$RUSTFLAGS --remap-path-prefix=$PWD=."
 
-# This package mimics the download process of rust's 'x.py'
-# bootstrap library to allow for the removal of the internet
-# connection requirement per build.
-{
-    mkdir -p "${cache_dir:=build/cache/2022-05-19}"
-
-    for tarball in *.tar.xz\?no-extract; do
-        mv -f "$tarball" "$cache_dir/${tarball%%\?no-extract}"
-    done
-}
-
 # Set shared linking as the default.
 sed 's/\(crt_static_default = \)true/\1false/' \
     compiler/rustc_target/src/spec/linux_musl_base.rs > _
@@ -48,6 +37,31 @@ tools          = [ "cargo", "rustfmt" ]
 sanitizers     = false
 profiler       = false
 full-bootstrap = false
+EOF
+
+# If possible, use local rust to bootstrap.
+case $(rustc --version 2>/dev/null) in
+    *1.62*|*1.61*)
+        cat >> config.toml <<EOF
+cargo          = "/usr/bin/cargo"
+rustc          = "/usr/bin/rustc"
+rustfmt        = "/usr/bin/rustfmt"
+EOF
+    ;;
+
+    *)
+        # This mimics the download process of rust's 'x.py'
+        # bootstrap library to allow for the removal of the internet
+        # connection requirement per build.
+        mkdir -p "${cache_dir:=build/cache/2022-05-19}"
+
+        for tarball in *.tar.xz\?no-extract; do
+            mv -f "$tarball" "$cache_dir/${tarball%%\?no-extract}"
+        done
+    ;;
+esac
+
+cat >> config.toml <<EOF
 
 [install]
 prefix = "/usr"