Do not duplicate flags from the OS environment - https://github.com/waf-project/waf/issues/1574

ChangeLog

@@ -4,6 +4,8 @@ NEW IN WAF 1.8.10
 * Fixed the hcode in why.py - https://github.com/waf-project/waf/issues/1561
 * Enabled execution from any folder: "waf configure --top=/arbitrary/folder --out=/tmp/build"
 * Enabled stateless out-of-tree builds by default: "waf configure --no-lock-in-top --no-lock-in-run"
+* Fixed the waf file generation on windows in Waf 1.8.9
+* Add OS flags such as LDFLAGS only once - https://github.com/waf-project/waf/issues/1574
 
 NEW IN WAF 1.8.9
 ----------------

waflib/Configure.py

@@ -352,7 +352,7 @@ def conf(f):
 	return f
 
 @conf
-def add_os_flags(self, var, dest=None):
+def add_os_flags(self, var, dest=None, dup=True):
 	"""
 	Import operating system environment values into ``conf.env`` dict::
 
@@ -363,10 +363,16 @@ def add_os_flags(self, var, dest=None):
 	:type var: string
 	:param dest: destination variable, by default the same as var
 	:type dest: string
+	:param dup: add the same set of flags again
+	:type dup: bool
 	"""
-	# do not use 'get' to make certain the variable is not defined
-	try: self.env.append_value(dest or var, shlex.split(self.environ[var]))
-	except KeyError: pass
+	try:
+		flags = shlex.split(self.environ[var])
+	except KeyError:
+		return
+	# TODO: in waf 1.9, make dup=False the default
+	if dup or ''.join(flags) not in ''.join(Utils.to_list(self.env[dest or var])):
+		self.env.append_value(dest or var, flags)
 
 @conf
 def cmd_to_list(self, cmd):

waflib/Tools/c_config.py

@@ -933,24 +933,24 @@ def cc_add_flags(conf):
 	"""
 	Add CFLAGS / CPPFLAGS from os.environ to conf.env
 	"""
-	conf.add_os_flags('CPPFLAGS', 'CFLAGS')
-	conf.add_os_flags('CFLAGS')
+	conf.add_os_flags('CPPFLAGS', dup=False)
+	conf.add_os_flags('CFLAGS', dup=False)
 
 @conf
 def cxx_add_flags(conf):
 	"""
 	Add CXXFLAGS / CPPFLAGS from os.environ to conf.env
 	"""
-	conf.add_os_flags('CPPFLAGS', 'CXXFLAGS')
-	conf.add_os_flags('CXXFLAGS')
+	conf.add_os_flags('CPPFLAGS', dup=False)
+	conf.add_os_flags('CXXFLAGS', dup=False)
 
 @conf
 def link_add_flags(conf):
 	"""
 	Add LINKFLAGS / LDFLAGS from os.environ to conf.env
 	"""
-	conf.add_os_flags('LINKFLAGS')
-	conf.add_os_flags('LDFLAGS')
+	conf.add_os_flags('LINKFLAGS', dup=False)
+	conf.add_os_flags('LDFLAGS', dup=False)
 
 @conf
 def cc_load_tools(conf):

waflib/Tools/fc_config.py

@@ -51,9 +51,9 @@ def fc_add_flags(conf):
 	"""
 	Add FCFLAGS / LDFLAGS / LINKFLAGS from os.environ to conf.env
 	"""
-	conf.add_os_flags('FCFLAGS')
-	conf.add_os_flags('LINKFLAGS')
-	conf.add_os_flags('LDFLAGS')
+	conf.add_os_flags('FCFLAGS', dup=False)
+	conf.add_os_flags('LINKFLAGS', dup=False)
+	conf.add_os_flags('LDFLAGS', dup=False)
 
 @conf
 def check_fortran(self, *k, **kw):