Several gems need at least some value for total_allocated_objects

Author: chrisseaton

CHANGELOG.md

@@ -66,6 +66,7 @@ Compatibility:
 * Implemented the `Time.at` `in:` parameter.
 * Implemented `Kernel#raise` `cause` parameter.
 * Improved compatibility of `Signal.trap` and `Kernel#trap` (#2287, @chrisseaton).
+* Implemented `GC.stat(:total_allocated_objects)` as `0` (#2292, @chrisseaton).
 
 Performance:
 

spec/ruby/core/gc/stat_spec.rb

@@ -1,19 +1,16 @@
 require_relative '../../spec_helper'
 
 describe "GC.stat" do
-  it "supports access by key" do
-    keys = [:heap_free_slots, :total_allocated_objects, :count]
-    keys.each do |key|
-      GC.stat(key).should be_kind_of(Integer)
-    end
-  end
-
   it "returns hash of values" do
     stat = GC.stat
     stat.should be_kind_of(Hash)
     stat.keys.should include(:count)
   end
 
+  it "can return a single value" do
+    GC.stat(:count).should be_kind_of(Integer)
+  end
+
   it "increases count after GC is run" do
     count = GC.stat(:count)
     GC.start
@@ -25,4 +22,16 @@
     GC.start
     GC.stat(:major_gc_count).should > count
   end
+
+  it "provides some number for count" do
+    GC.stat(:count).should be_kind_of(Integer)
+  end
+
+  it "provides some number for heap_free_slots" do
+    GC.stat(:heap_free_slots).should be_kind_of(Integer)
+  end
+
+  it "provides some number for total_allocated_objects" do
+    GC.stat(:total_allocated_objects).should be_kind_of(Integer)
+  end
 end

src/main/ruby/truffleruby/core/gc.rb

@@ -76,10 +76,10 @@ def garbage_collect
   end
 
   def self.stat(option = nil)
-    time, count, minor_count, major_count, unknown_count, heap, memory_pool_names, memory_pool_info = Primitive.gc_stat()
+    time, count, minor_count, major_count, unknown_count, heap, memory_pool_names, memory_pool_info = Primitive.gc_stat
     used, committed, init, max = heap
 
-    # Initialize stat for statistics that come from memory pools, and populate it with some final stats
+    # Initialize stat for statistics that come from memory pools, and populate it with some final stats (ordering similar to MRI)
     stat = {
       count: count,
       time: time,
@@ -89,6 +89,7 @@ def self.stat(option = nil)
       heap_available_slots: committed,
       heap_live_slots: used,
       heap_free_slots: committed - used,
+      total_allocated_objects: 0,
       used: used,
       committed: committed,
       init: init,