Given this BUILD file for Bazel below, how can I get the absolute path to the top level of the compiler_files file group? I have tried using $(location //X:Y) and its variants, but I just get back a massive list of files with their paths relative to the sandbox. What is the idiomatic way to update the PATH environment variable in a genrule with a path to a tool provided in the tools attribute?

package(default_visibility = ['//visibility:public'])

filegroup(
    name = "script",
    srcs = ["src/inspect.sh"],
)

genrule(
    name = "inspect",
    srcs = [":script"],
    cmd = """
# Instead of /tmp below I need to refer to the path of one of the tools
# export PATH=/tmp:$$PATH
source $(location :script)
cp output.txt $(RULEDIR)/
""",
    tools = [
        "@emsdk//emscripten_toolchain:compiler_files"
    ],
    outs = ["generated.txt"]
)