Introduce python_major_minor_version DSL

Library/Homebrew/formula.rb

@@ -5248,6 +5248,17 @@ def link_overwrite(*paths)
       paths.flatten!
       T.must(link_overwrite_paths).merge(paths)
     end
+
+    # Returns the major.minor {Version} for the given Python executable,
+    # as a shorthand for `Language::Python.major_minor_version` in the formula DSL.
+    #
+    # @param python [String, Pathname] the Python executable (e.g. `"python3"`)
+    # @return [Version, nil] the major.minor version, or `nil` when the version cannot be determined
+    # @api public
+    sig { params(python: T.any(String, Pathname)).returns(T.nilable(Version)) }
+    def python_major_minor_version(python)
+      Language::Python.major_minor_version(python)
+    end
   end
 end
 

Library/Homebrew/test/formula_spec.rb

@@ -147,6 +147,15 @@
     end
   end
 
+  describe ".python_major_minor_version" do
+    it "delegates to Language::Python.major_minor_version" do
+      version = instance_double(Version, "version")
+      expect(Language::Python).to receive(:major_minor_version).with("python3").and_return(version)
+
+      expect(described_class.python_major_minor_version("python3")).to be(version)
+    end
+  end
+
   describe "#versioned_formulae" do
     let(:f) do
       formula "foo" do