gh-98707: configure --with-system-libmpdec and --with-system-expat no longer include vendored headers (#98711)

Author: hroncok

Makefile.pre.in

@@ -2588,13 +2588,13 @@ MODULE_DEPS=$(PYTHON_HEADERS) Modules/config.c $(EXPORTSYMS)
 
 MODULE_CMATH_DEPS=$(srcdir)/Modules/_math.h
 MODULE_MATH_DEPS=$(srcdir)/Modules/_math.h
-MODULE_PYEXPAT_DEPS=$(LIBEXPAT_HEADERS) @LIBEXPAT_INTERNAL@
+MODULE_PYEXPAT_DEPS=@LIBEXPAT_INTERNAL@
 MODULE_UNICODEDATA_DEPS=$(srcdir)/Modules/unicodedata_db.h $(srcdir)/Modules/unicodename_db.h
 MODULE__BLAKE2_DEPS=$(srcdir)/Modules/_blake2/impl/blake2-config.h $(srcdir)/Modules/_blake2/impl/blake2-impl.h $(srcdir)/Modules/_blake2/impl/blake2.h $(srcdir)/Modules/_blake2/impl/blake2b-load-sse2.h $(srcdir)/Modules/_blake2/impl/blake2b-load-sse41.h $(srcdir)/Modules/_blake2/impl/blake2b-ref.c $(srcdir)/Modules/_blake2/impl/blake2b-round.h $(srcdir)/Modules/_blake2/impl/blake2b.c $(srcdir)/Modules/_blake2/impl/blake2s-load-sse2.h $(srcdir)/Modules/_blake2/impl/blake2s-load-sse41.h $(srcdir)/Modules/_blake2/impl/blake2s-load-xop.h $(srcdir)/Modules/_blake2/impl/blake2s-ref.c $(srcdir)/Modules/_blake2/impl/blake2s-round.h $(srcdir)/Modules/_blake2/impl/blake2s.c $(srcdir)/Modules/_blake2/blake2module.h $(srcdir)/Modules/hashlib.h
 MODULE__CTYPES_DEPS=$(srcdir)/Modules/_ctypes/ctypes.h $(srcdir)/Modules/_ctypes/darwin/dlfcn.h
 MODULE__CTYPES_MALLOC_CLOSURE=@MODULE__CTYPES_MALLOC_CLOSURE@
-MODULE__DECIMAL_DEPS=$(srcdir)/Modules/_decimal/docstrings.h $(LIBMPDEC_HEADERS) @LIBMPDEC_INTERNAL@
-MODULE__ELEMENTTREE_DEPS=$(srcdir)/Modules/pyexpat.c $(LIBEXPAT_HEADERS) @LIBEXPAT_INTERNAL@
+MODULE__DECIMAL_DEPS=$(srcdir)/Modules/_decimal/docstrings.h @LIBMPDEC_INTERNAL@
+MODULE__ELEMENTTREE_DEPS=$(srcdir)/Modules/pyexpat.c @LIBEXPAT_INTERNAL@
 MODULE__HASHLIB_DEPS=$(srcdir)/Modules/hashlib.h
 MODULE__IO_DEPS=$(srcdir)/Modules/_io/_iomodule.h
 MODULE__MD5_DEPS=$(srcdir)/Modules/hashlib.h

Misc/NEWS.d/next/Build/2022-10-26-12-37-52.gh-issue-98707.eVXGEx.rst

@@ -0,0 +1,4 @@
+Don't use vendored ``libmpdec`` headers if :option:`--with-system-libmpdec`
+is passed to :program:`configure`.
+Don't use vendored ``libexpat`` headers if :option:`--with-system-expat`
+is passed to :program:`!configure`.

configure

@@ -3699,7 +3699,7 @@ AS_VAR_IF([with_system_expat], [yes], [
 ], [
   LIBEXPAT_CFLAGS="-I\$(srcdir)/Modules/expat"
   LIBEXPAT_LDFLAGS="-lm \$(LIBEXPAT_A)"
-  LIBEXPAT_INTERNAL="\$(LIBEXPAT_A)"
+  LIBEXPAT_INTERNAL="\$(LIBEXPAT_HEADERS) \$(LIBEXPAT_A)"
 ])
 
 AC_SUBST([LIBEXPAT_CFLAGS])
@@ -3808,7 +3808,7 @@ AS_VAR_IF([with_system_libmpdec], [yes], [
 ], [
   LIBMPDEC_CFLAGS="-I\$(srcdir)/Modules/_decimal/libmpdec"
   LIBMPDEC_LDFLAGS="-lm \$(LIBMPDEC_A)"
-  LIBMPDEC_INTERNAL="\$(LIBMPDEC_A)"
+  LIBMPDEC_INTERNAL="\$(LIBMPDEC_HEADERS) \$(LIBMPDEC_A)"
 
   dnl Disable forced inlining in debug builds, see GH-94847
   AS_VAR_IF([with_pydebug], [yes], [