--- firefox-111.0.1/build/moz.configure/rust.configure	2023-03-21 06:16:03.000000000 -0700
+++ firefox-111.0.1/build/moz.configure/rust.configure.new	2023-04-05 08:57:29.403219120 -0700
@@ -593,7 +593,7 @@
 
 # ==============================================================
 
-option(env="RUSTFLAGS", nargs=1, help="Rust compiler flags")
+option(env="RUSTFLAGS", nargs=1, help="Rust compiler flags", comma_split=False)
 set_config("RUSTFLAGS", depends("RUSTFLAGS")(lambda flags: flags))
 
 
--- firefox-111.0.1/python/mozbuild/mozbuild/configure/options.py	2023-03-21 06:16:09.000000000 -0700
+++ firefox-111.0.1/python/mozbuild/mozbuild/configure/options.py.new	2023-04-05 08:57:31.270193468 -0700
@@ -191,6 +191,10 @@
       to instantiate an option indirectly. Set this to a positive integer to
       force the script to look into a deeper stack frame when inferring the
       `category`.
+    - `comma_split` specifies whether the value string should be split on
+      commas. The default is True. Setting it False is necessary for things
+      like compiler flags which should be a single string that may contain
+      commas.
     """
 
     __slots__ = (
@@ -205,6 +209,7 @@
         "possible_origins",
         "category",
         "define_depth",
+        "comma_split",
     )
 
     def __init__(
@@ -218,6 +223,7 @@
         category=None,
         help=None,
         define_depth=0,
+        comma_split=True,
     ):
         if not name and not env:
             raise InvalidOptionError(
@@ -335,9 +341,10 @@
         self.choices = choices
         self.help = help
         self.category = category or _infer_option_category(define_depth)
+        self.comma_split = comma_split
 
     @staticmethod
-    def split_option(option):
+    def split_option(option, comma_split=True):
         """Split a flag or variable into a prefix, a name and values
 
         Variables come in the form NAME=values (no prefix).
@@ -350,7 +357,13 @@
 
         elements = option.split("=", 1)
         name = elements[0]
-        values = tuple(elements[1].split(",")) if len(elements) == 2 else ()
+        if len(elements) == 2:
+            if comma_split:
+                values = tuple(elements[1].split(","))
+            else:
+                values = (elements[1],)
+        else:
+            values = ()
         if name.startswith("--"):
             name = name[2:]
             if not name.islower():
@@ -426,7 +439,7 @@
                 % (option, origin, ", ".join(self.possible_origins))
             )
 
-        prefix, name, values = self.split_option(option)
+        prefix, name, values = self.split_option(option, self.comma_split)
         option = self._join_option(prefix, name)
 
         assert name in (self.name, self.env)