Use global mirror for CI toolchain e2e

Author: Sunrisepeak

.github/workflows/ci.yml

@@ -109,6 +109,12 @@ jobs:
           # above so they don't have to reinstall the sandbox.
           export MCPP_VENDORED_XLINGS="$XLINGS_BIN"
           test -x "$MCPP_VENDORED_XLINGS"
+          # GitHub-hosted runners are outside CN; keep CI toolchain downloads on
+          # the global mirror while mcpp's default remains CN for fresh local
+          # sandboxes. E2E tests with their own MCPP_HOME read this variable.
+          export MCPP_E2E_TOOLCHAIN_MIRROR=GLOBAL
+          "$MCPP" self config --mirror "$MCPP_E2E_TOOLCHAIN_MIRROR"
+          "$MCPP" self config
           # Pin the global default so test 28 (which exercises the
           # default-toolchain path) gets a deterministic GNU answer
           # instead of whatever auto-install picks on a fresh sandbox.

tests/e2e/26_toolchain_management.sh

@@ -36,6 +36,10 @@ out=$("$MCPP" build 2>&1) || rc=$?
 [[ "$out" == *"no toolchain configured"* ]] || { echo "FAIL: error not helpful: $out"; exit 1; }
 
 # 3) Install gcc 16.1.0
+if [[ -n "${MCPP_E2E_TOOLCHAIN_MIRROR:-}" ]]; then
+    "$MCPP" self config --mirror "$MCPP_E2E_TOOLCHAIN_MIRROR"
+    "$MCPP" self config
+fi
 rc=0
 "$MCPP" toolchain install gcc 16.1.0 > /tmp/_inst.log 2>&1 || rc=$?
 if [[ $rc -ne 0 ]]; then