bpo-44394: Ensure libexpat is linked against libm (GH-28617)

diff --git a/setup.py b/setup.py
index 9e411cb35e00bd77011d4caed065c494b05e326d..9e71a223c0aabd0e617d2cace2d3c16343f61566 100644 (file)
--- a/setup.py
+++ b/setup.py
@@ -1767,7 +1767,9 @@ class PyBuildExt(build_ext):
                 ('XML_POOR_ENTROPY', '1'),
             ]
             extra_compile_args = []
-            expat_lib = []
+            # bpo-44394: libexpact uses isnan() of math.h and needs linkage
+            # against the libm
+            expat_lib = ['m']
             expat_sources = ['expat/xmlparse.c',
                              'expat/xmlrole.c',
                              'expat/xmltok.c']