Do not export rlocation from test setup

The `rlocation` implementation lacks many of the features of the shell runfiles library, which should be dependend on explicitly instead.

When called, `rlocation` will now fail with an error message.

Closes #24256.

PiperOrigin-RevId: 695241586
Change-Id: I7059c329fd6ca518623d7be8ad3514082097c191

tools/test/test-setup.sh

@@ -125,8 +125,6 @@ function rlocation() {
   fi
 }
 
-export -f rlocation
-export -f is_absolute
 # If RUNFILES_MANIFEST_ONLY is set to 1 and the manifest file does exist,
 # then test programs should use manifest file to find runfiles.
 if [[ "${RUNFILES_MANIFEST_ONLY:-}" == "1" && -e "${RUNFILES_MANIFEST_FILE:-}" ]]; then
@@ -236,6 +234,15 @@ else
   TEST_PATH="$(rlocation $TEST_WORKSPACE/$EXE)"
 fi
 
+# Redefine rlocation to notify users of its removal - it used to be exported.
+# TODO: Remove this before Bazel 9.
+function rlocation() {
+  read LINE SUB FILE < <(caller 0);
+  >&2 echo "ERROR: rlocation is no longer implicitly provided by Bazel's test setup, but called from $SUB in line $LINE of $FILE. Please use https://github.com/bazelbuild/rules_shell/blob/main/shell/runfiles/runfiles.bash instead."
+  exit 1
+}
+export -f rlocation
+
 # TODO(jsharpe): Use --test_env=TEST_SHORT_EXEC_PATH=true to activate this code
 # path to workaround a bug with long executable paths when executing remote
 # tests on Windows.