formula: update license specification

Library/.rubocop.yml

@@ -68,6 +68,10 @@ Style/HashTransformKeys:
 Style/HashTransformValues:
   Enabled: true
 
+# Allow for license expressions
+Style/HashAsLastArrayItem:
+  Enabled: false
+
 # Enabled now LineLength is lowish.
 Style/IfUnlessModifier:
   Enabled: true

Library/Homebrew/.rubocop.yml

@@ -61,6 +61,8 @@ Metrics/MethodLength:
 Metrics/ModuleLength:
   Enabled: true
   Max: 600
+  Exclude:
+    - 'test/**/*'
 Metrics/PerceivedComplexity:
   Enabled: true
   Max: 90
@@ -143,3 +145,9 @@ Style/GuardClause:
 # so many of these in formulae but none in here
 Style/StringConcatenation:
   Enabled: true
+
+# don't want this for formulae but re-enabled for Library/Homebrew
+Style/HashAsLastArrayItem:
+  Enabled: true
+  Exclude:
+    - 'test/utils/spdx_spec.rb'

Library/Homebrew/cmd/info.rb

@@ -8,6 +8,7 @@ require "formula"
 require "keg"
 require "tab"
 require "json"
+require "utils/spdx"
 
 module Homebrew
   module_function
@@ -211,13 +212,7 @@ module Homebrew
 
     puts "From: #{Formatter.url(github_info(f))}"
 
-    if f.license.present?
+    puts "License: #{SPDX.license_expression_to_string f.license}" if f.license.present?
-      licenses = f.license
-                  .map(&:to_s)
-                  .join(", ")
-                  .sub("public_domain", "Public Domain")
-      puts "License: #{licenses}"
-    end
 
     unless f.deps.empty?
       ohai "Dependencies"

Library/Homebrew/formula.rb

@@ -2219,18 +2219,20 @@ class Formula
     # @!attribute [w]
     # The SPDX ID of the open-source license that the formula uses.
     # Shows when running `brew info`.
-    # Multiple licenses means that the software is licensed under multiple licenses.
+    # Use `:any`, `:all` or `:with` to describe complex license expressions.
-    # Do not use multiple licenses if e.g. different parts are under different licenses.
+    # `:any` should be used when the user can choose which license to use.
+    # `:all` should be used when the user must use all licenses.
+    # `:with` should be used to specify a valid SPDX exception.
+    # Add `+` to an identifier to indicate that the formulae can be
+    # licensed under later versions of the same license.
+    # @see https://spdx.github.io/spdx-spec/appendix-IV-SPDX-license-expressions/ SPDX license expression guide
     # <pre>license "BSD-2-Clause"</pre>
-    # <pre>license ["MIT", "GPL-2.0"]</pre>
+    # <pre>license "EPL-1.0+"</pre>
+    # <pre>license any_of: ["MIT", "GPL-2.0-only"]</pre>
+    # <pre>license all_of: ["MIT", "GPL-2.0-only"]</pre>
+    # <pre>license "GPL-2.0-only" => { with: "LLVM-exception" }</pre>
     # <pre>license :public_domain</pre>
-    def license(args = nil)
+    attr_rw :license
-      if args.nil?
-        @licenses
-      else
-        @licenses = Array(args)
-      end
-    end
 
     # @!attribute [w] homepage
     # The homepage for the software. Used by users to get more information

Library/Homebrew/formula_installer.rb

@@ -19,6 +19,7 @@ require "messages"
 require "cask/cask_loader"
 require "cmd/install"
 require "find"
+require "utils/spdx"
 
 class FormulaInstaller
   include FormulaCellarChecks
@@ -1130,24 +1131,29 @@ class FormulaInstaller
                                             .to_s
                                             .sub("Public Domain", "public_domain")
                                             .split(" ")
+                                            .to_h do |license|
+      [license, SPDX.license_version_info(license)]
+    end
+
     return if forbidden_licenses.blank?
 
     compute_dependencies.each do |dep, _|
       next if @ignore_deps
 
       dep_f = dep.to_formula
-      next unless dep_f.license.all? { |license| forbidden_licenses.include?(license.to_s) }
+      next unless SPDX.licenses_forbid_installation? dep_f.license, forbidden_licenses
 
       raise CannotInstallFormulaError, <<~EOS
-        The installation of #{formula.name} has a dependency on #{dep.name} where all its licenses are forbidden: #{dep_f.license}.
+        The installation of #{formula.name} has a dependency on #{dep.name} where all its licenses are forbidden:
+          #{SPDX.license_expression_to_string dep_f.license}.
       EOS
     end
     return if @only_deps
 
-    return unless formula.license.all? { |license| forbidden_licenses.include?(license.to_s) }
+    return unless SPDX.licenses_forbid_installation? formula.license, forbidden_licenses
 
     raise CannotInstallFormulaError, <<~EOS
-      #{formula.name}'s licenses are all forbidden: #{formula.license}.
+      #{formula.name}'s licenses are all forbidden: #{SPDX.license_expression_to_string formula.license}.
     EOS
   end
 end