BLD: suppress useless warnings

Author: Jeff Reback <[email protected]>

Closes #12589 from jreback/warnings and squashes the following commits:

0156618 [Jeff Reback] BLD: suppress useless warnings

Author: jreback

setup.py

@@ -375,6 +375,8 @@ def srcpath(name=None, suffix='.pyx', subdir='src'):
 def pxd(name):
     return os.path.abspath(pjoin('pandas', name + '.pxd'))
 
+# args to ignore warnings
+extra_compile_args=['-Wno-unused-function']
 
 lib_depends = lib_depends + ['pandas/src/numpy_helper.h',
                              'pandas/src/parse_helper.h']
@@ -440,7 +442,7 @@ def pxd(name):
                     sources=sources,
                     depends=data.get('depends', []),
                     include_dirs=include,
-                    extra_compile_args=['-w'])
+                    extra_compile_args=extra_compile_args)
 
     extensions.append(obj)
 
@@ -449,15 +451,15 @@ def pxd(name):
                        sources=[srcpath('sparse', suffix=suffix)],
                        include_dirs=[],
                        libraries=libraries,
-                       extra_compile_args=['-w'])
+                       extra_compile_args=extra_compile_args)
 
 extensions.extend([sparse_ext])
 
 testing_ext = Extension('pandas._testing',
                        sources=[srcpath('testing', suffix=suffix)],
                        include_dirs=[],
                        libraries=libraries,
-                       extra_compile_args=['-w'])
+                       extra_compile_args=extra_compile_args)
 
 extensions.extend([testing_ext])
 
@@ -478,7 +480,7 @@ def pxd(name):
                         language='c++',
                         include_dirs=['pandas/src/msgpack'] + common_include,
                         define_macros=macros,
-                        extra_compile_args=['-w'])
+                        extra_compile_args=extra_compile_args)
 unpacker_ext = Extension('pandas.msgpack._unpacker',
                         depends=['pandas/src/msgpack/unpack.h',
                                  'pandas/src/msgpack/unpack_define.h',
@@ -489,7 +491,7 @@ def pxd(name):
                         language='c++',
                         include_dirs=['pandas/src/msgpack'] + common_include,
                         define_macros=macros,
-                        extra_compile_args=['-w'])
+                        extra_compile_args=extra_compile_args)
 extensions.append(packer_ext)
 extensions.append(unpacker_ext)
 
@@ -513,7 +515,7 @@ def pxd(name):
                       include_dirs=['pandas/src/ujson/python',
                                     'pandas/src/ujson/lib',
                                     'pandas/src/datetime'] + common_include,
-                      extra_compile_args=['-D_GNU_SOURCE', '-w'])
+                      extra_compile_args=['-D_GNU_SOURCE'] + extra_compile_args)
 
 
 extensions.append(ujson_ext)