Fallback to older bottle hashes when viable

Library/Homebrew/dev-cmd/generate-formula-api.rb

@@ -75,8 +75,7 @@ module Homebrew
               version = Version.new(formula.dig("versions", "stable"))
               pkg_version = PkgVersion.new(version, formula["revision"])
               rebuild = formula.dig("bottle", "stable", "rebuild") || 0
-              sha256 = formula.dig("bottle", "stable", "files", :all, "sha256")
+              sha256 = newest_bottle_sha256(formula, bottle_tag)
-              sha256 ||= formula.dig("bottle", "stable", "files", bottle_tag.to_sym, "sha256")
 
               [name, [pkg_version.to_s, rebuild, sha256]]
             end
@@ -88,6 +87,35 @@ module Homebrew
         end
       end
 
+      sig {
+        params(formula_json: T::Hash[String, T.untyped], bottle_tag: Utils::Bottles::Tag).returns(T.nilable(String))
+      }
+      def newest_bottle_sha256(formula_json, bottle_tag)
+        available_tags = formula_json.dig("bottle", "stable", "files")&.keys&.map(&:to_sym)
+        return unless available_tags
+
+        return formula_json.dig("bottle", "stable", "files", :all, "sha256") if available_tags.include? :all
+
+        if available_tags.include? bottle_tag.to_sym
+          return formula_json.dig("bottle", "stable", "files", bottle_tag.to_sym, "sha256")
+        end
+
+        return unless bottle_tag.macos?
+
+        # If the actual tag is not available, find the newest tag with matching arch that's older than the actual tag
+        newest_viable_macos_tag = available_tags.filter_map do |tag_sym|
+          tag = Utils::Bottles::Tag.from_symbol(tag_sym)
+          next unless tag.macos?
+          next if tag.arch != bottle_tag.arch
+          next if tag.to_macos_version > bottle_tag.to_macos_version
+
+          tag
+        end.max_by(&:to_macos_version)
+        return unless newest_viable_macos_tag
+
+        formula_json.dig("bottle", "stable", "files", newest_viable_macos_tag.to_sym, "sha256")
+      end
+
       private
 
       sig { params(title: String).returns(String) }

Library/Homebrew/test/dev-cmd/generate-formula-api_spec.rb

@@ -5,4 +5,58 @@ require "dev-cmd/generate-formula-api"
 
 RSpec.describe Homebrew::DevCmd::GenerateFormulaApi do
   it_behaves_like "parseable arguments"
+
+  describe "#newest_bottle_sha256" do
+    subject(:generate_formula_api) { described_class.new [] }
+
+    def make_json(bottles)
+      json = {
+        "bottle" => {
+          "stable" => {
+            "files" => {},
+          },
+        },
+      }
+      bottles.each do |tag, sha256|
+        json["bottle"]["stable"]["files"][tag] = { "sha256" => sha256 }
+      end
+      json
+    end
+
+    expected_sha256s = {
+      arm64_sequoia:  "abc123",
+      arm64_sonoma:   "abc123",
+      arm64_ventura:  "ghi789",
+      arm64_monterey: nil,
+      sequoia:        "jkl012",
+      sonoma:         "jkl012",
+      ventura:        "mno345",
+      monterey:       "mno345",
+      x86_64_linux:   "pqr678",
+      arm64_linux:    nil,
+    }.transform_keys do |tag|
+      Utils::Bottles::Tag.from_symbol(tag)
+    end
+
+    let(:all_json) { make_json all: "abc123" }
+    let(:standard_json) do
+      make_json arm64_sonoma:  "abc123",
+                arm64_ventura: "ghi789",
+                sonoma:        "jkl012",
+                big_sur:       "mno345",
+                x86_64_linux:  "pqr678"
+    end
+
+    it "returns the sha256 for the :all tag on all systems" do
+      expected_sha256s.each_key do |tag|
+        expect(generate_formula_api.newest_bottle_sha256(all_json, tag)).to eq("abc123")
+      end
+    end
+
+    expected_sha256s.each_key do |tag|
+      it "returns the corrent sha256 for #{tag}" do
+        expect(generate_formula_api.newest_bottle_sha256(standard_json, tag)).to eq(expected_sha256s[tag])
+      end
+    end
+  end
 end