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bazel

How to use a filename based on a build setting

I have a build setting like:

string_flag(
    name = "version",
    build_setting_default = "0.1")

I want to use it to create a file, e.g.:

ctx.actions.run_shell(
    outputs = ["report-%s.csv" % (version)],
    inputs = ctx.files.inputs,
    command = "$(location //build:report-generator.sh) 2>&1"
)

However, I get the following error:

Error in run_shell: at index 0 of outputs, got element of type string, want File

Here is the docs for File: https://docs.bazel.build/versions/main/skylark/lib/File.html

created during the analysis phase

So my question is, how do you get the value of a build setting during the analysis phase?

Solution

  • As the error message says, the outputs argument to run_shell expects a list of File objects rather than strings. One generally obtains an appropriate output File object by declaring an output in the rule class definition or using the ctx.actions.declare_file method.