ruby / ruby/rake

Rake executes file task when prerequisites have older timestamp

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Description

When a file task depends on some non-file task indirectly,
Rake executes the file task even if its immediate prerequisite files have older timestamp.

It looks like the behavior changed at 12.1.0.

Example
require "rake/clean"

CLEAN.include("config.yml", "component")

task "setup" do
  puts Rake::VERSION
  touch "config.yml" unless File.exist?("config.yml")
end

file "config.yml" => "setup"

file "component" => "config.yml" do |t|
  puts "[config.yml] #{File.mtime(t.prerequisites[0])}"
  puts "[component]  #{File.exist?(t.name) && File.mtime(t.name)}"
  sleep 1
  touch t.name
end

Based on the above Rakefile, clean up and create the "component" first.

$ rake clean && rake component

The next rake component results in different behavior as follows.
On 12.0.0:

$ rake component --trace
(in /path/to/Rakefile-directory)
** Invoke component (first_time, not_needed)
** Invoke config.yml (first_time)
** Invoke setup (first_time)
** Execute setup
12.0.0
** Execute config.yml

On 12.1.0:

$ rake component --trace
(in /path/to/Rakefile-directory)
** Invoke component (first_time)
** Invoke config.yml (first_time)
** Invoke setup (first_time)
** Execute setup
12.1.0
** Execute config.yml
** Execute component
[config.yml] 2018-01-01 15:13:19 +0900
[component]  2018-01-01 15:13:20 +0900
touch component

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the issue with the Rakefile example and compare the --trace output between the affected behavior and 12.0. Start by tracing how file-task prerequisites and timestamps are evaluated; done means rake component no longer executes the file task when its immediate prerequisite files are older.

Written by the indexing model from the issue text.

Assessment

Tech stack
ruby
Domain
build-system
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
38/100

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