[3.8] bpo-44394: Ensure libexpat is linked against libm (GH-28617) (GH-28620)

(cherry picked from commit 6c1154b9de29e1c9cd3d05f5289543e5cff73895)

Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>

diff --git a/setup.py b/setup.py
index 2d6b05682d2ba9d0bc87b5f67c2957488707437d..57be07a7e0f824471451ab9f02a9679c1552397a 100644 (file)
--- a/setup.py
+++ b/setup.py
@@ -1578,7 +1578,9 @@ class PyBuildExt(build_ext):
                 ('XML_POOR_ENTROPY', '1'),
             ]
             extra_compile_args = []
-            expat_lib = []
+            # bpo-44394: libexpat 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']