Merge pull request #20801 from Homebrew/copilot/fix-fab7d5fc-dabe-4a66-8fc4-ed32200d3d65

Add formula DSL support for omitting install name rewriting for `@rpath/*` install names

Author: MikeMcQuaid

Library/Homebrew/extend/os/mac/keg_relocate.rb

@@ -151,13 +151,23 @@ def dylib_id_for(file)
         # Swift dylib IDs should be /usr/lib/swift
         return file.dylib_id if file.dylib_id.start_with?("/usr/lib/swift/libswift")
 
+        # Preserve @rpath install names if the formula has specified preserve_rpath
+        return file.dylib_id if file.dylib_id.start_with?("@rpath") && formula_preserve_rpath?
+
         # The new dylib ID should have the same basename as the old dylib ID, not
         # the basename of the file itself.
         basename = File.basename(file.dylib_id)
         relative_dirname = file.dirname.relative_path_from(path)
         (opt_record/relative_dirname/basename).to_s
       end
 
+      sig { returns(T::Boolean) }
+      def formula_preserve_rpath?
+        ::Formula[name].preserve_rpath?
+      rescue FormulaUnavailableError
+        false
+      end
+
       sig { params(old_name: String, relocation: ::Keg::Relocation).returns(T.nilable(String)) }
       def relocated_name_for(old_name, relocation)
         old_prefix, new_prefix = relocation.replacement_pair_for(:prefix)

Library/Homebrew/formula.rb

@@ -347,6 +347,9 @@ def ensure_installed!(reason: "", latest: false, output_to_stderr: true, quiet:
     self
   end
 
+  sig { returns(T::Boolean) }
+  def preserve_rpath? = self.class.preserve_rpath?
+
   private
 
   # Allow full name logic to be re-used between names, aliases and installed aliases.
@@ -3406,6 +3409,7 @@ def inherited(child)
         @network_access_allowed = T.let(SUPPORTED_NETWORK_ACCESS_PHASES.to_h do |phase|
           [phase, DEFAULT_NETWORK_ACCESS_ALLOWED]
         end, T.nilable(T::Hash[Symbol, T::Boolean]))
+        @preserve_rpath = T.let(false, T.nilable(T::Boolean))
       end
     end
 
@@ -3416,6 +3420,7 @@ def freeze
       @conflicts.freeze
       @skip_clean_paths.freeze
       @link_overwrite_paths.freeze
+      @preserve_rpath&.freeze
       super
     end
 
@@ -4130,6 +4135,34 @@ def skip_clean(*paths)
       T.must(skip_clean_paths).merge(paths)
     end
 
+    # Preserve `@rpath` install names when fixing dynamic linkage on macOS.
+    #
+    # By default, Homebrew rewrites library install names (including those starting
+    # with `@rpath`) to use absolute paths. This can break tools like `macdeployqt`
+    # that expect `@rpath`-based install names to remain unchanged.
+    #
+    # Call this method to skip rewriting install names that start with `@rpath`.
+    #
+    # ### Example
+    #
+    # ```ruby
+    # preserve_rpath
+    # ```
+    #
+    # @api public
+    sig { params(value: T::Boolean).returns(T::Boolean) }
+    def preserve_rpath(value: true)
+      @preserve_rpath = value
+    end
+
+    # Check if `@rpath` install names should be preserved.
+    #
+    # @api internal
+    sig { returns(T::Boolean) }
+    def preserve_rpath?
+      @preserve_rpath == true
+    end
+
     # Software that will not be symlinked into the `brew --prefix` and will
     # only live in its Cellar. Other formulae can depend on it and Homebrew
     # will add the necessary includes, libraries and other paths while

Library/Homebrew/test/formula_spec.rb

@@ -2005,4 +2005,32 @@ def install
       end
     end
   end
+
+  describe "#preserve_rpath" do
+    it "defaults to false" do
+      f = formula do
+        url "foo-1.0"
+      end
+
+      expect(f.class.preserve_rpath?).to be(false)
+    end
+
+    it "can be enabled" do
+      f = formula do
+        url "foo-1.0"
+        preserve_rpath
+      end
+
+      expect(f.class.preserve_rpath?).to be(true)
+    end
+
+    it "can be explicitly disabled" do
+      f = formula do
+        url "foo-1.0"
+        preserve_rpath value: false
+      end
+
+      expect(f.class.preserve_rpath?).to be(false)
+    end
+  end
 end