Fix defining the xxx_compiler variables in configure().

Due to recent changes, setting xxx_compiler in configure() had no effect.
This commit fixes the problem and changes the examples to show setting
the xxx_compiler variables at the top level of the wscript, so that
the default compilers are correctly reported in the help output.

waflib/Tools/compiler_c.py

@@ -15,11 +15,12 @@ Try to detect a C compiler from the list of supported compilers (gcc, msvc, etc)
 The compilers are associated to platforms in :py:attr:`waflib.Tools.compiler_c.c_compiler`. To register
 a new C compiler named *cfoo* (assuming the tool ``waflib/extras/cfoo.py`` exists), use::
 
+	from waflib.Tools.compiler_c import c_compiler
+	c_compiler['win32'] = ['cfoo', 'msvc', 'gcc']
+
 	def options(opt):
 		opt.load('compiler_c')
 	def configure(cnf):
-		from waflib.Tools.compiler_c import c_compiler
-		c_compiler['win32'] = ['cfoo', 'msvc', 'gcc']
 		cnf.load('compiler_c')
 	def build(bld):
 		bld.program(source='main.c', target='app')
@@ -54,11 +55,16 @@ Dict mapping the platform names to Waf tools finding specific C compilers::
 	c_compiler['linux'] = ['gcc', 'icc', 'suncc']
 """
 
+def default_compilers():
+	build_platform = Utils.unversioned_sys_platform()
+	possible_compiler_list = c_compiler.get(build_platform, c_compiler['default'])
+	return ' '.join(possible_compiler_list)
+
 def configure(conf):
 	"""
 	Try to find a suitable C compiler or raise a :py:class:`waflib.Errors.ConfigurationError`.
 	"""
-	try: test_for_compiler = conf.options.check_c_compiler
+	try: test_for_compiler = conf.options.check_c_compiler or default_compilers()
 	except AttributeError: conf.fatal("Add options(opt): opt.load('compiler_c')")
 
 	for compiler in re.split('[ ,]+', test_for_compiler):
@@ -85,15 +91,13 @@ def options(opt):
 
 		$ waf configure --check-c-compiler=gcc
 	"""
+	test_for_compiler = default_compilers()
 	opt.load_special_tools('c_*.py', ban=['c_dumbpreproc.py'])
-	global c_compiler
-	build_platform = Utils.unversioned_sys_platform()
-	possible_compiler_list = c_compiler.get(build_platform, c_compiler['default'])
-	test_for_compiler = ' '.join(possible_compiler_list)
 	cc_compiler_opts = opt.add_option_group('Configuration options')
-	cc_compiler_opts.add_option('--check-c-compiler', default=test_for_compiler,
+	cc_compiler_opts.add_option('--check-c-compiler', default=None,
 		help='list of C compilers to try [%s]' % test_for_compiler,
 		dest="check_c_compiler")
+
 	for x in test_for_compiler.split():
 		opt.load('%s' % x)
 

waflib/Tools/compiler_cxx.py

@@ -15,11 +15,12 @@ Try to detect a C++ compiler from the list of supported compilers (g++, msvc, et
 The compilers are associated to platforms in :py:attr:`waflib.Tools.compiler_cxx.cxx_compiler`. To register
 a new C++ compiler named *cfoo* (assuming the tool ``waflib/extras/cfoo.py`` exists), use::
 
+	from waflib.Tools.compiler_cxx import cxx_compiler
+	cxx_compiler['win32'] = ['cfoo', 'msvc', 'gcc']
+
 	def options(opt):
 		opt.load('compiler_cxx')
 	def configure(cnf):
-		from waflib.Tools.compiler_cxx import cxx_compiler
-		cxx_compiler['win32'] = ['cfoo', 'msvc', 'gcc']
 		cnf.load('compiler_cxx')
 	def build(bld):
 		bld.program(source='main.c', target='app')
@@ -55,12 +56,16 @@ Dict mapping the platform names to Waf tools finding specific C++ compilers::
 	cxx_compiler['linux'] = ['gxx', 'icpc', 'suncxx']
 """
 
+def default_compilers():
+	build_platform = Utils.unversioned_sys_platform()
+	possible_compiler_list = cxx_compiler.get(build_platform, cxx_compiler['default'])
+	return ' '.join(possible_compiler_list)
 
 def configure(conf):
 	"""
 	Try to find a suitable C++ compiler or raise a :py:class:`waflib.Errors.ConfigurationError`.
 	"""
-	try: test_for_compiler = conf.options.check_cxx_compiler
+	try: test_for_compiler = conf.options.check_cxx_compiler or default_compilers()
 	except AttributeError: conf.fatal("Add options(opt): opt.load('compiler_cxx')")
 
 	for compiler in re.split('[ ,]+', test_for_compiler):
@@ -87,13 +92,10 @@ def options(opt):
 
 		$ waf configure --check-cxx-compiler=gxx
 	"""
+	test_for_compiler = default_compilers()
 	opt.load_special_tools('cxx_*.py')
-	global cxx_compiler
-	build_platform = Utils.unversioned_sys_platform()
-	possible_compiler_list = cxx_compiler.get(build_platform, cxx_compiler['default'])
-	test_for_compiler = ' '.join(possible_compiler_list)
 	cxx_compiler_opts = opt.add_option_group('Configuration options')
-	cxx_compiler_opts.add_option('--check-cxx-compiler', default=test_for_compiler,
+	cxx_compiler_opts.add_option('--check-cxx-compiler', default=None,
 		help='list of C++ compilers to try [%s]' % test_for_compiler,
 		dest="check_cxx_compiler")
 

waflib/Tools/compiler_d.py

@@ -33,11 +33,19 @@ Dict mapping the platform names to lists of names of D compilers to try, in orde
 	d_compiler['default'] = ['gdc', 'dmd', 'ldc2']
 """
 
+def default_compilers():
+	build_platform = Utils.unversioned_sys_platform()
+	possible_compiler_list = d_compiler.get(build_platform, d_compiler['default'])
+	return ' '.join(possible_compiler_list)
+
 def configure(conf):
 	"""
 	Try to find a suitable D compiler or raise a :py:class:`waflib.Errors.ConfigurationError`.
 	"""
-	for compiler in re.split('[ ,]+', conf.options.dcheck):
+	try: test_for_compiler = conf.options.check_d_compiler or default_compilers()
+	except AttributeError: conf.fatal("Add options(opt): opt.load('compiler_d')")
+
+	for compiler in re.split('[ ,]+', test_for_compiler):
 		conf.env.stash()
 		conf.start_msg('Checking for %r (D compiler)' % compiler)
 		try:
@@ -61,12 +69,11 @@ def options(opt):
 
 		$ waf configure --check-d-compiler=dmd
 	"""
-	build_platform = Utils.unversioned_sys_platform()
-	possible_compiler_list = d_compiler.get(build_platform, d_compiler['default'])
-	test_for_compiler = ' '.join(possible_compiler_list)
+	test_for_compiler = default_compilers()
 	d_compiler_opts = opt.add_option_group('Configuration options')
-	d_compiler_opts.add_option('--check-d-compiler', default=test_for_compiler, action='store',
-		help='list of D compilers to try [%s]' % test_for_compiler, dest='dcheck')
-	for d_compiler in ('gdc', 'dmd', 'ldc2'):
-		opt.load('%s' % d_compiler)
+	d_compiler_opts.add_option('--check-d-compiler', default=None,
+		help='list of D compilers to try [%s]' % test_for_compiler, dest='check_d_compiler')
+
+	for x in test_for_compiler.split():
+		opt.load('%s' % x)
 

waflib/Tools/compiler_fc.py

@@ -20,11 +20,16 @@ Dict mapping the platform names to lists of names of Fortran compilers to try, i
 	c_compiler['linux'] = ['gfortran', 'g95', 'ifort']
 """
 
+def default_compilers():
+	build_platform = Utils.unversioned_sys_platform()
+	possible_compiler_list = fc_compiler.get(build_platform, fc_compiler['default'])
+	return ' '.join(possible_compiler_list)
+
 def configure(conf):
 	"""
 	Try to find a suitable Fortran compiler or raise a :py:class:`waflib.Errors.ConfigurationError`.
 	"""
-	try: test_for_compiler = conf.options.check_fc
+	try: test_for_compiler = conf.options.check_fortran_compiler or default_compilers()
 	except AttributeError: conf.fatal("Add options(opt): opt.load('compiler_fc')")
 	for compiler in re.split('[ ,]+', test_for_compiler):
 		conf.env.stash()
@@ -50,16 +55,13 @@ def options(opt):
 
 		$ waf configure --check-fortran-compiler=ifort
 	"""
+	test_for_compiler = default_compilers()
 	opt.load_special_tools('fc_*.py')
-	build_platform = Utils.unversioned_sys_platform()
-	possible_compiler_list = fc_compiler.get(build_platform, fc_compiler['default'])
-	test_for_compiler = ' '.join(possible_compiler_list)
 	fortran_compiler_opts = opt.add_option_group('Configuration options')
-	fortran_compiler_opts.add_option('--check-fortran-compiler',
-			default=test_for_compiler,
+	fortran_compiler_opts.add_option('--check-fortran-compiler', default=None,
 			help='list of Fortran compiler to try [%s]' % test_for_compiler,
-		dest="check_fc")
+		dest="check_fortran_compiler")
 
-	for compiler in test_for_compiler.split():
-		opt.load('%s' % compiler)
+	for x in test_for_compiler.split():
+		opt.load('%s' % x)