gh-96269: static and shared ext need different deps (#96316)

Author: tiran

Makefile.pre.in

@@ -2572,7 +2572,9 @@ Python/thread.o: @THREADHEADERS@ $(srcdir)/Python/condvar.h
 ##########################################################################
 # Module dependencies and platform-specific files
 
-MODULE_DEPS=$(PYTHON_HEADERS) Modules/config.c $(EXPORTSYMS)
+# force rebuild when header file or module build flavor (static/shared) is changed
+MODULE_DEPS_STATIC=Modules/config.c
+MODULE_DEPS_SHARED=$(MODULE_DEPS_STATIC) $(EXPORTSYMS)
 
 MODULE_CMATH_DEPS=$(srcdir)/Modules/_math.h
 MODULE_MATH_DEPS=$(srcdir)/Modules/_math.h

Modules/makesetup

@@ -262,12 +262,15 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
 			esac
 			# custom flags first, PY_STDMODULE_CFLAGS may contain -I with system libmpdec
 			case $doconfig in
-			no)	cc="$cc $cpps \$(PY_STDMODULE_CFLAGS) \$(CCSHARED)";;
+			no)
+				cc="$cc $cpps \$(PY_STDMODULE_CFLAGS) \$(CCSHARED)"
+				rule="$obj: $src \$(MODULE_${mods_upper}_DEPS) \$(MODULE_DEPS_SHARED) \$(PYTHON_HEADERS); $cc -c $src -o $obj"
+				;;
 			*)
-				cc="$cc $cpps \$(PY_BUILTIN_MODULE_CFLAGS)";;
+				cc="$cc $cpps \$(PY_BUILTIN_MODULE_CFLAGS)"
+				rule="$obj: $src \$(MODULE_${mods_upper}_DEPS) \$(MODULE_DEPS_STATIC) \$(PYTHON_HEADERS); $cc -c $src -o $obj"
+				;;
 			esac
-			# force rebuild when header file or module build flavor (static/shared) is changed
-			rule="$obj: $src \$(MODULE_${mods_upper}_DEPS) \$(MODULE_DEPS); $cc -c $src -o $obj"
 			echo "$rule" >>$rulesf
 		done
 		case $doconfig in