Issue #13756: Fix building extensions modules on Cygwin

Patch by Roumen Petrov, based on original patch by Jason Tishler.

Lib/distutils/command/build_ext.py

@@ -715,13 +715,6 @@ class build_ext(Command):
                 return ext.libraries + [pythonlib]
             else:
                 return ext.libraries
-        elif sys.platform[:6] == "cygwin":
-            template = "python%d.%d"
-            pythonlib = (template %
-                   (sys.hexversion >> 24, (sys.hexversion >> 16) & 0xff))
-            # don't extend ext.libraries, it may be shared with other
-            # extensions, it is a reference to the original list
-            return ext.libraries + [pythonlib]
         elif sys.platform[:6] == "atheos":
             from distutils import sysconfig
 

Makefile.pre.in

@@ -674,7 +674,7 @@ $(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK): \
 
 # This rule builds the Cygwin Python DLL and import library if configured
 # for a shared core library; otherwise, this rule is a noop.
-$(DLLLIBRARY) libpython$(VERSION).dll.a: $(LIBRARY_OBJS)
+$(DLLLIBRARY) libpython$(LDVERSION).dll.a: $(LIBRARY_OBJS)
 	if test -n "$(DLLLIBRARY)"; then \
 		$(LDSHARED) -Wl,--out-implib=$@ -o $(DLLLIBRARY) $^ \
 			$(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST); \

Misc/NEWS

@@ -173,6 +173,9 @@ Windows
 Build
 -----
 
+- Issue #13756: Fix building extensions modules on Cygwin.  Patch by Roumen
+  Petrov, based on original patch by Jason Tishler.
+
 - Issue #21085: Add configure check for siginfo_t.si_band, which Cygwin does
   not provide.  Patch by Masayuki Yamamoto with review and rebase by Erik Bray.
 

Modules/makesetup

@@ -91,7 +91,7 @@ CYGWIN*) if test $libdir = .
 	 else
 	 	ExtraLibDir='$(LIBPL)'
 	 fi
-	 ExtraLibs="-L$ExtraLibDir -lpython\$(VERSION)";;
+	 ExtraLibs="-L$ExtraLibDir -lpython\$(LDVERSION)";;
 esac
 
 # Main loop