--- old/make/common/Defs-windows.gmk	Fri Mar 30 09:12:49 2012
+++ new/make/common/Defs-windows.gmk	Fri Mar 30 09:12:49 2012
@@ -76,9 +76,36 @@
 EXTRA_LFLAGS += /LIBPATH:$(DXSDK_LIB_PATH)
 
 # Full Debug Symbols has been enabled on Windows since JDK1.4.1.
-# Default is enabled with debug info files ZIP'ed to save space.
+# The Full Debug Symbols (FDS) default for VARIANT == OPT builds is
+# enabled with debug info files ZIP'ed to save space. For VARIANT !=
+# OPT builds, FDS is always enabled, after all a debug build without
+# debug info isn't very useful. The ZIP_DEBUGINFO_FILES option only has
+# meaning when FDS is enabled.
+#
+# If you invoke a build with FULL_DEBUG_SYMBOLS=0, then FDS will be
+# disabled for a VARIANT == OPT build.
+#
+# Note: Use of a different variable name for the FDS override option
+# versus the FDS enabled check is intentional (FULL_DEBUG_SYMBOLS
+# versus ENABLE_FULL_DEBUG_SYMBOLS). For auto build systems that pass
+# in options via environment variables, use of distinct variables
+# prevents strange behaviours. For example, in a VARIANT != OPT build,
+# the FULL_DEBUG_SYMBOLS environment variable will be 0, but the
+# ENABLE_FULL_DEBUG_SYMBOLS make variable will be 1. If the same
+# variable name is used, then different values can be picked up by
+# different parts of the build. Just to be clear, we only need two
+# variable names because the incoming option value can be overridden
+# in some situations, e.g., a VARIANT != OPT build.
 
-ENABLE_FULL_DEBUG_SYMBOLS ?= 1
+ifeq ($(VARIANT), OPT)
+  FULL_DEBUG_SYMBOLS ?= 1
+  ENABLE_FULL_DEBUG_SYMBOLS = $(FULL_DEBUG_SYMBOLS)
+else
+  # debug variants always get Full Debug Symbols (if available)
+  ENABLE_FULL_DEBUG_SYMBOLS = 1
+endif
+_JUNK_ := $(shell \
+  echo >&2 "INFO: ENABLE_FULL_DEBUG_SYMBOLS=$(ENABLE_FULL_DEBUG_SYMBOLS)")
 
 ifeq ($(ENABLE_FULL_DEBUG_SYMBOLS),1)
   ZIP_DEBUGINFO_FILES ?= 1
@@ -85,6 +112,7 @@
 else
   ZIP_DEBUGINFO_FILES=0
 endif
+_JUNK_ := $(shell echo >&2 "INFO: ZIP_DEBUGINFO_FILES=$(ZIP_DEBUGINFO_FILES)")
 
 # C Compiler flag definitions
 
@@ -224,7 +252,9 @@
   # All builds get the same runtime setting
   CFLAGS_COMMON += $(MS_RUNTIME_OPTION) $(CFLAGS_$(COMPILER_VERSION))
 
-  LDEBUG = /debug
+  ifeq ($(ENABLE_FULL_DEBUG_SYMBOLS),1)
+    LDEBUG = /debug
+  endif
   
   ifeq ($(VTUNE_SUPPORT), true)
     OTHER_CFLAGS = -Z7 -Ox 
@@ -258,7 +288,9 @@
 #
 # Output options (use specific filenames to avoid parallel compile errors)
 #
-CFLAGS_COMMON += -Fd$(OBJDIR)/$(basename $(@F)).pdb -Fm$(OBJDIR)/$(basename $(@F)).map
+ifeq ($(ENABLE_FULL_DEBUG_SYMBOLS),1)
+  CFLAGS_COMMON += -Fd$(OBJDIR)/$(basename $(@F)).pdb -Fm$(OBJDIR)/$(basename $(@F)).map
+endif
 
 #
 # Use -wdNNNN to disable warning NNNN.