Draft: Remove files after test finishes

Fixes #2

.gitlab/install-bindist.sh

@@ -2,7 +2,15 @@
 set -x
 set -eo pipefail
 
-runner_temp=$(mktemp -d)
+runner_temp=$(mktemp -d ghcup-ci.XXXXXXXX)
+
+# shellcheck disable=SC2064
+trap "rm -r '$runner_temp'" EXIT
+
+# Keep all other temp directories relative to the toplevel temp directory.
+nestedtemp () {
+    mktemp -p "$runner_temp" "$@"
+}
 
 if [ -z "$BINDIST_URL" ]; then
   cat build.env
@@ -10,7 +18,7 @@ if [ -z "$BINDIST_URL" ]; then
 fi
 
 # See GHC #24951 for a user with a misconfigured CDPATH variable
-cdpath_temp=$(mktemp -d)
+cdpath_temp=$(nestedtemp -d cdpath.XXXX)
 mkdir -p $cdpath_temp/lib
 mkdir -p $cdpath_temp/wrappers
 mkdir -p $cdpath_temp/doc
@@ -33,8 +41,8 @@ which ghcup | grep foobarbaz
 # Testing a manual installation
 if [ -n "$BINDIST_ONLY" ]; then
   install_dir="$runner_temp/ghc"
-  install_temp=$(mktemp -d)
-  download_temp=$(mktemp -d)
+  install_temp=$(nestedtemp -d)
+  download_temp=$(nestedtemp -d)
   pushd $download_temp
   if [ -n "$BINDIST_URL" ]; then
     wget "$BINDIST_URL"
@@ -103,8 +111,8 @@ fi
 [[ $(./main +RTS -s) -eq 2 ]]
 
 
-cabal install --lib --package-env=$(mktemp) clock
-cabal install --lib --package-env=$(mktemp) hashable
+cabal install --lib --package-env=$(nestedtemp clock.XXXX) clock
+cabal install --lib --package-env=$(nestedtemp hashable.XXXX) hashable
 
 
 case "$(uname)" in