linkage_checker: resolve some variable install names on macOS

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

@@ -103,7 +103,7 @@ class Keg
 
   def each_linkage_for(file, linkage_type, &block)
     links = file.method(linkage_type)
-                .call
+                .call(resolve_variable_references: false)
                 .grep_v(/^@(loader_|executable_|r)path/)
     links.each(&block)
   end

Library/Homebrew/linkage_checker.rb

@@ -31,6 +31,7 @@ class LinkageChecker
     @unwanted_system_dylibs = []
     @version_conflict_deps = []
     @files_missing_rpaths = []
+    @executable_path_dylibs = []
 
     check_dylibs(rebuild_cache: rebuild_cache)
   end
@@ -39,13 +40,14 @@ class LinkageChecker
     display_items "System libraries", @system_dylibs
     display_items "Homebrew libraries", @brewed_dylibs
     display_items "Indirect dependencies with linkage", @indirect_deps
-    display_items "Variable-referenced libraries", @variable_dylibs
+    display_items "@rpath-referenced libraries", @variable_dylibs
     display_items "Missing libraries", @broken_dylibs
     display_items "Broken dependencies", @broken_deps
     display_items "Undeclared dependencies with linkage", @undeclared_deps
     display_items "Dependencies with no linkage", @unnecessary_deps
     display_items "Unwanted system libraries", @unwanted_system_dylibs
     display_items "Files with missing rpath", @files_missing_rpaths
+    display_items "@executable_path references in libraries", @executable_path_dylibs
   end
   alias generic_display_normal_output display_normal_output
   private :generic_display_normal_output
@@ -74,6 +76,7 @@ class LinkageChecker
 
     display_items "Undeclared dependencies with linkage", @undeclared_deps, puts_output: puts_output
     display_items "Files with missing rpath", @files_missing_rpaths, puts_output: puts_output
+    display_items "@executable_path references in libraries", @executable_path_dylibs, puts_output: puts_output
   end
   alias generic_display_test_output display_test_output
   private :generic_display_test_output
@@ -85,7 +88,7 @@ class LinkageChecker
     issues = [@broken_deps, unexpected_broken_dylibs]
     if test
       issues += [@unwanted_system_dylibs, @version_conflict_deps, unexpected_present_dylibs]
-      issues += [@undeclared_deps, @files_missing_rpaths] if strict
+      issues += [@undeclared_deps, @files_missing_rpaths, @executable_path_dylibs] if strict
     end
     issues.any?(&:present?)
   end
@@ -182,9 +185,12 @@ class LinkageChecker
 
         checked_dylibs << dylib
 
-        if dylib.start_with? "@"
+        if dylib.start_with? "@rpath"
           @variable_dylibs << dylib
           next
+        elsif dylib.start_with?("@executable_path") && !Pathname(file).binary_executable?
+          @executable_path_dylibs << dylib
+          next
         end
 
         begin

Library/Homebrew/os/mac/mach.rb

@@ -9,7 +9,7 @@ require "macho"
 module MachOShim
   extend Forwardable
 
-  delegate [:dylib_id, :rpaths] => :macho
+  delegate [:dylib_id] => :macho
 
   def macho
     @macho ||= MachO.open(to_s)
@@ -79,10 +79,32 @@ module MachOShim
     macho.write!
   end
 
-  def dynamically_linked_libraries(except: :none)
+  def dynamically_linked_libraries(except: :none, resolve_variable_references: true)
     lcs = macho.dylib_load_commands.reject { |lc| lc.type == except }
 
-    lcs.map(&:name).map(&:to_s).uniq
+    names = lcs.map(&:name).map(&:to_s).uniq
+
+    names.map! { |name| resolve_variable_name(name) } if resolve_variable_references
+
+    names
+  end
+
+  def rpaths(resolve_variable_references: true)
+    names = macho.rpaths.uniq
+
+    names.map! { |name| resolve_variable_name(name) } if resolve_variable_references
+
+    names
+  end
+
+  def resolve_variable_name(name)
+    if name.start_with? "@loader_path"
+      Pathname(name.sub("@loader_path", dirname)).cleanpath.to_s
+    elsif name.start_with?("@executable_path") && binary_executable?
+      Pathname(name.sub("@executable_path", dirname)).cleanpath.to_s
+    else
+      name
+    end
   end
 
   def archs