diff -r 67e50943a093 doc/tutorial/source/getting-started.rst
--- a/doc/tutorial/source/getting-started.rst	Thu Jun 21 18:28:31 2018 -0700
+++ b/doc/tutorial/source/getting-started.rst	Sun Jun 24 11:22:03 2018 -0700
@@ -592,7 +592,7 @@
 There is also an intermediate build profile, ``release``.  ``-d`` is a
 synonym for ``--build-profile``.
 
-The build profile controls the use of logging, assertions, and compiler optimization:
+The build profile controls the use of logging, assertions, warnings, and compiler optimization:
 
 +--------------------+---------------------------------+-----------------------------------------------------------------+
 | Feature            | Build Profile                                                                                     |
@@ -605,7 +605,8 @@
 +--------------------+---------------------------------+-------------------------------+---------------------------------+
 | Code Wrapper Macro | ``NS_BUILD_DEBUG(code)``        |  ``NS_BUILD_RELEASE(code)``   | ``NS_BUILD_OPTIMIZED(code)``    |
 +--------------------+---------------------------------+-------------------------------+---------------------------------+
-| Compiler Flags     | ``-O0 -ggdb -g3``               | ``-O3 -g0``                   | ``-O3 -g``                      |
+| Compiler Flags     | ``-O0 -ggdb -g3``               | ``-O2 -g``                    | ``-O3 -g0``                     |
+|                    | ``-Wall -Werror``               | ``-Wall``                     | ``-Wall``                       |
 |                    |                                 | ``-fomit-frame-pointer``      | ``-fstrict-overflow``           |
 |                    |                                 |                               | ``-march=native``               |
 +--------------------+---------------------------------+-------------------------------+---------------------------------+
@@ -624,6 +625,14 @@
   DoLongInvolvedComputation ();
   NS_BUILD_DEBUG (timer.Stop (); std::cout << "Done: " << timer << std::endl;)
 
+If you are using an older ns-3 release on a newer system, the -Werror option (treating
+all warnings as errors) may prevent a successful build.  This flag may be disabled
+by passing the --disable-werror flag to Waf configuration:
+
+::
+
+  $ ./waf configure -d debug --disable-werror ...
+
 By default Waf puts the build artifacts in the ``build`` directory.  
 You can specify a different output directory with the ``--out``
 option, e.g.
diff -r 67e50943a093 waf-tools/cflags.py
--- a/waf-tools/cflags.py	Thu Jun 21 18:28:31 2018 -0700
+++ b/waf-tools/cflags.py	Sun Jun 24 11:22:03 2018 -0700
@@ -18,7 +18,7 @@
 class GccTraits(CompilerTraits):
 	def __init__(self):
 		super(GccTraits, self).__init__()
-		# cumulative list of warnings per level
+		# cumulative list of warnings per level:  levels 1, 2, 3
 		self.warnings_flags = [['-Wall'], ['-Werror'], ['-Wextra']]
 
 	def get_warnings_flags(self, level):
@@ -159,6 +159,9 @@
 	opt.add_option('--check-profile',
 		       help=('print out current build profile'),
 		       default=False, dest='check_profile', action="store_true")
+	opt.add_option('--disable-werror',
+		       help=('disable -Werror flag (warnings treated as errors'),
+		       default=False, dest='disable_werror', action="store_true")
 def configure(conf):
 	cc = conf.env['COMPILER_CC'] or None
 	cxx = conf.env['COMPILER_CXX'] or None
@@ -181,7 +184,13 @@
 	optimizations = compiler.get_optimization_flags(opt_level)
 	debug, debug_defs = compiler.get_debug_flags(dbg_level)
 	warnings = compiler.get_warnings_flags(warn_level)
-	
+
+	if Options.options.disable_werror:
+		try:
+			warnings.remove ('-Werror')
+		except ValueError:
+			pass
+
 	if cc and not conf.env['CCFLAGS']:
 		conf.env.append_value('CCFLAGS', optimizations)
 		conf.env.append_value('CCFLAGS', debug)
diff -r 67e50943a093 wscript
--- a/wscript	Thu Jun 21 18:28:31 2018 -0700
+++ b/wscript	Sun Jun 24 11:22:03 2018 -0700
@@ -54,8 +54,8 @@
 cflags.profiles = {
     # profile name: [optimization_level, warnings_level, debug_level]
     'debug':     [0, 2, 3],
-    'optimized': [3, 2, 1],
-    'release':   [3, 2, 0],
+    'optimized': [3, 1, 0],
+    'release':   [2, 1, 1],
     }
 cflags.default_profile = 'debug'