--- a/layout/style/nsStyleContext.cpp
+++ b/layout/style/nsStyleContext.cpp
@@ -1210,22 +1210,22 @@ nsStyleContext::CalcStyleDifferenceInter
     // Both style contexts have a style-if-visited.
     bool change = false;
 
     // NB: Calling Peek on |this|, not |thisVis|, since callers may look
     // at a struct on |this| without looking at the same struct on
     // |thisVis| (including this function if we skip one of these checks
     // due to change being true already or due to the old style context
     // not having a style-if-visited), but not the other way around.
-#define STYLE_FIELD(name_) thisVisStruct->name_ != otherVisStruct->name_ ||
+#define STYLE_FIELD(name_) thisVisStruct->name_ != otherVisStruct->name_
 #define STYLE_STRUCT(name_, fields_)                                    \
     if (!change && PeekStyle##name_()) {                                \
       const nsStyle##name_* thisVisStruct = thisVis->Style##name_();    \
       const nsStyle##name_* otherVisStruct = otherVis->Style##name_();  \
-      if (MOZ_FOR_EACH(STYLE_FIELD, (), fields_) false) {               \
+      if (MOZ_FOR_EACH_SEPARATED(STYLE_FIELD, (||), (), fields_)) {     \
         change = true;                                                  \
       }                                                                 \
     }
 #include "nsCSSVisitedDependentPropList.h"
 #undef STYLE_STRUCT
 #undef STYLE_FIELD
 
     if (change) {

--- a/mfbt/MacroForEach.h
+++ b/mfbt/MacroForEach.h
@@ -29,130 +29,195 @@
  *   #define MACRO_B(k, x) (k + x) +
  *   int b = MOZ_FOR_EACH(MACRO_B, (5,), (1, 2)) 0;
  *   // Expands to: MACRO_B(5, 1) MACRO_B(5, 2) 0;
  *
  *   #define MACRO_C(k1, k2, x) (k1 + k2 + x) +
  *   int c = MOZ_FOR_EACH(MACRO_C, (5, 8,), (1, 2)) 0;
  *   // Expands to: MACRO_B(5, 8, 1) MACRO_B(5, 8, 2) 0;
  *
+ * MOZ_FOR_EACH_SEPARATED(aMacro, aSeparator, aFixedArgs, aArgs) is identical
+ * to MOZ_FOR_EACH except that it inserts |aSeparator| between each call to
+ * the macro. |aSeparator| must be wrapped by parens. For example:
+ *
+ *   #define MACRO_A(x) x
+ *   int a = MOZ_FOR_EACH_SEPARATED(MACRO_A, (+), (), (1, 2, 3));
+ *   // Expands to: MACRO_A(1) + MACRO_A(2) + MACRO_A(3);
+ *   // And further to: 1 + 2 + 3
+ *
+ *   #define MACRO_B(t, n) t n
+ *   void test(MOZ_FOR_EACH_SEPARATED(MACRO_B, (,), (int,), (a, b)));
+ *   // Expands to: void test(MACRO_B(int, a) , MACRO_B(int, b));
+ *   // And further to: void test(int a , int b);
+ *
  * If the |aFixedArgs| list is not empty, a trailing comma must be included.
  *
  * The |aArgs| list must be not be empty and may be up to 50 items long. Use
  * MOZ_STATIC_ASSERT_VALID_ARG_COUNT to ensure that violating this constraint
  * results in a compile-time error.
  */
 #define MOZ_FOR_EACH_EXPAND_HELPER(...) __VA_ARGS__
 #define MOZ_FOR_EACH_GLUE(a, b) a b
-#define MOZ_FOR_EACH(aMacro, aFixedArgs, aArgs) \
+#define MOZ_FOR_EACH_SEPARATED(aMacro, aSeparator, aFixedArgs, aArgs) \
   MOZ_FOR_EACH_GLUE( \
     MOZ_PASTE_PREFIX_AND_ARG_COUNT(MOZ_FOR_EACH_, \
                                    MOZ_FOR_EACH_EXPAND_HELPER aArgs), \
-    (aMacro, aFixedArgs, aArgs))
+    (aMacro, aSeparator, aFixedArgs, aArgs))
+#define MOZ_FOR_EACH(aMacro, aFixedArgs, aArgs) \
+  MOZ_FOR_EACH_SEPARATED(aMacro, (), aFixedArgs, aArgs)
 
 #define MOZ_FOR_EACH_HELPER_GLUE(a, b) a b
 #define MOZ_FOR_EACH_HELPER(aMacro, aFixedArgs, aArgs) \
   MOZ_FOR_EACH_HELPER_GLUE( \
     aMacro, \
     (MOZ_FOR_EACH_EXPAND_HELPER aFixedArgs MOZ_ARG_1 aArgs))
 
-#define MOZ_FOR_EACH_1(m, fa, a) \
+#define MOZ_FOR_EACH_1(m, s, fa, a) \
   MOZ_FOR_EACH_HELPER(m, fa, a)
-#define MOZ_FOR_EACH_2(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_1(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_3(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_2(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_4(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_3(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_5(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_4(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_6(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_5(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_7(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_6(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_8(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_7(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_9(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_8(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_10(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_9(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_11(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_10(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_12(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_11(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_13(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_12(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_14(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_13(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_15(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_14(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_16(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_15(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_17(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_16(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_18(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_17(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_19(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_18(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_20(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_19(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_21(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_20(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_22(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_21(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_23(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_22(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_24(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_23(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_25(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_24(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_26(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_25(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_27(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_26(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_28(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_27(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_29(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_28(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_30(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_29(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_31(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_30(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_32(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_31(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_33(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_32(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_34(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_33(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_35(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_34(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_36(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_35(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_37(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_36(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_38(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_37(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_39(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_38(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_40(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_39(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_41(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_40(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_42(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_41(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_43(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_42(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_44(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_43(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_45(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_44(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_46(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_45(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_47(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_46(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_48(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_47(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_49(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_48(m, fa, (MOZ_ARGS_AFTER_1 a))
-#define MOZ_FOR_EACH_50(m, fa, a) \
-  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_49(m, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_2(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_1(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_3(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_2(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_4(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_3(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_5(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_4(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_6(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_5(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_7(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_6(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_8(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_7(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_9(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_8(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_10(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_9(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_11(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_10(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_12(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_11(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_13(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_12(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_14(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_13(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_15(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_14(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_16(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_15(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_17(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_16(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_18(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_17(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_19(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_18(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_20(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_19(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_21(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_20(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_22(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_21(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_23(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_22(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_24(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_23(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_25(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_24(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_26(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_25(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_27(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_26(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_28(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_27(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_29(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_28(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_30(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_29(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_31(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_30(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_32(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_31(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_33(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_32(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_34(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_33(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_35(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_34(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_36(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_35(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_37(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_36(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_38(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_37(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_39(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_38(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_40(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_39(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_41(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_40(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_42(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_41(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_43(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_42(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_44(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_43(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_45(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_44(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_46(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_45(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_47(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_46(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_48(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_47(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_49(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_48(m, s, fa, (MOZ_ARGS_AFTER_1 a))
+#define MOZ_FOR_EACH_50(m, s, fa, a) \
+  MOZ_FOR_EACH_HELPER(m, fa, a) MOZ_FOR_EACH_EXPAND_HELPER s \
+  MOZ_FOR_EACH_49(m, s, fa, (MOZ_ARGS_AFTER_1 a))
 
 #endif /* mozilla_MacroForEach_h */

--- a/mfbt/tests/TestMacroForEach.cpp
+++ b/mfbt/tests/TestMacroForEach.cpp
@@ -2,33 +2,45 @@
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/Assertions.h"
 #include "mozilla/MacroForEach.h"
 
+#define HELPER_IDENTITY(x) x
 #define HELPER_IDENTITY_PLUS(x) x +
 static_assert(MOZ_FOR_EACH(HELPER_IDENTITY_PLUS, (), (10)) 0 == 10, "");
 static_assert(MOZ_FOR_EACH(HELPER_IDENTITY_PLUS, (), (1, 1, 1)) 0 == 3, "");
+static_assert(MOZ_FOR_EACH_SEPARATED(HELPER_IDENTITY, (+),
+                                     (), (10)) == 10, "");
+static_assert(MOZ_FOR_EACH_SEPARATED(HELPER_IDENTITY, (+),
+                                     (), (1, 1, 1)) == 3, "");
 
 #define HELPER_DEFINE_VAR(x) const int test1_##x = x;
 MOZ_FOR_EACH(HELPER_DEFINE_VAR, (), (10, 20))
 static_assert(test1_10 == 10 && test1_20 == 20, "");
 
 #define HELPER_DEFINE_VAR2(k, x) const int test2_##x = k + x;
 MOZ_FOR_EACH(HELPER_DEFINE_VAR2, (5,), (10, 20))
 static_assert(test2_10 == 15 && test2_20 == 25, "");
 
-#define HELPER_IDENTITY_COMMA(k1, k2, x) k1, k2, x,
+#define HELPER_DEFINE_PARAM(t, n) t n
+constexpr int
+test(MOZ_FOR_EACH_SEPARATED(HELPER_DEFINE_PARAM, (,), (int,), (a, b, c)))
+{
+  return a + b + c;
+}
+static_assert(test(1, 2, 3) == 6, "");
 
 int
 main()
 {
+#define HELPER_IDENTITY_COMMA(k1, k2, x) k1, k2, x,
   const int a[] = {
     MOZ_FOR_EACH(HELPER_IDENTITY_COMMA, (1, 2,), (10, 20, 30))
   };
   MOZ_RELEASE_ASSERT(a[0] == 1 && a[1] == 2 && a[2] == 10 &&
                      a[3] == 1 && a[4] == 2 && a[5] == 20 &&
                      a[6] == 1 && a[7] == 2 && a[8] == 30,
                      "MOZ_FOR_EACH args enumerated in incorrect order");
   return 0;