[3.10] bpo-44394: Ensure libexpat is linked against libm (GH-28617) (GH-28621)

* bpo-44394: Ensure libexpat is linked against libm (GH-28617)
(cherry picked from commit 6c1154b9de29e1c9cd3d05f5289543e5cff73895)

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

1 files changed, 3 insertions, 1 deletions

diff --git a/setup.py b/setup.py
index 3d250e7..a6fcc12 100644
--- a/setup.py
+++ b/setup.py
@@ -1765,7 +1765,9 @@ 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']