undefined method `empty?' for nil:NilClass at target_validator.rb:118 when changing swift_versions in pre_install step

[acecilia]

• I've read and understood the CONTRIBUTING guidelines and have done my best effort to follow.

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What did you do?

Got the following Podfile:

use_frameworks!
platform :ios, '11.0'

pod 'InputMask', '4.2.0'

pre_install do |installer|
  installer.analysis_result.specifications.each do |s|
    s.root.swift_versions << '4.2' if s.root.swift_versions.empty?
  end
end

What did you expect to happen?

pod install does not crash

What happened instead?

pod install crashed with:

NoMethodError - undefined method `empty?' for nil:NilClass
/Users/user/Desktop/vendor/bundle/ruby/2.6.0/bundler/gems/Cocoapods-2b774aa58f1e/lib/cocoapods/installer/xcode/target_validator.rb:118:in `block in verify_swift_pods_swift_version'

CocoaPods Environment

Tested with cocoapods versions:

• 1.8.4: not crashing
• 1.9.1: crashing
• latest on master at the time of writing: crashing

Catalina 10.15.4, Xcode 11.3.1.

Project that demonstrates the issue

Just run pod install in the Podfile I shown above.

Looks similar issue than the one explained in #9688

[dnkoutso]

Its because the Podfile has no target declaration. Not super related I dont think to #9688.