From 1b5d546d5f8b6dd800e9fbda5037b37aac39753c Mon Sep 17 00:00:00 2001
From: Itamar Oren <itamarost@gmail.com>
Date: Tue, 20 Oct 2026 14:19:56 -0700
Subject: [PATCH] gh-144942: Link $(MODLIBS) into the macOS shared library and
 framework

The rules for the libpython dylib and for the macOS and iOS frameworks did
not pass $(MODLIBS), unlike the rule for libpython.so. When a module is
built in (for example via Modules/Setup.local), the libraries it needs,
such as the HACL* objects used by _blake2, were left out. The framework
link then fails with undefined symbols, while the dylib, which is linked
with -undefined dynamic_lookup, fails only when the missing symbol is
called at runtime.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 Makefile.pre.in                                             | 6 +++---
 .../Build/2026-10-20-20-00-00.gh-issue-144942.MdLibs.rst    | 3 +++
 2 files changed, 6 insertions(+), 3 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Build/2026-10-20-20-00-00.gh-issue-144942.MdLibs.rst

diff --git a/Makefile.pre.in b/Makefile.pre.in
index c49a16f1edc3be..1b5185a3a53f18 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1016,7 +1016,7 @@ libpython3.so:	libpython$(LDVERSION).so
 	$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^
 
 libpython$(LDVERSION).dylib: $(LIBRARY_OBJS)
-	 $(CC) -dynamiclib $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(SHLIBS) $(LIBC) $(LIBM); \
+	 $(CC) -dynamiclib $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(DTRACE_OBJS) $(MODLIBS) $(SHLIBS) $(LIBC) $(LIBM); \
 
 
 libpython$(VERSION).sl: $(LIBRARY_OBJS)
@@ -1050,7 +1050,7 @@ $(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK): \
 		-install_name $(PYTHONFRAMEWORKINSTALLNAMEPREFIX)/$(PYTHONFRAMEWORK) \
 		-compatibility_version $(VERSION) \
 		-current_version $(VERSION) \
-		-framework CoreFoundation $(LIBS);
+		-framework CoreFoundation $(MODLIBS) $(LIBS);
 	$(INSTALL) -d -m $(DIRMODE)  \
 		$(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/Resources/English.lproj
 	$(INSTALL_DATA) $(RESSRCDIR)/Info.plist \
@@ -1071,7 +1071,7 @@ $(PYTHONFRAMEWORKDIR)/$(PYTHONFRAMEWORK): \
 		-install_name $(PYTHONFRAMEWORKINSTALLNAMEPREFIX)/$(PYTHONFRAMEWORK) \
 		-compatibility_version $(VERSION) \
 		-current_version $(VERSION) \
-		-framework CoreFoundation $(LIBS);
+		-framework CoreFoundation $(MODLIBS) $(LIBS);
 	$(INSTALL_DATA) $(RESSRCDIR)/Info.plist $(PYTHONFRAMEWORKDIR)/Info.plist
 
 # This rule builds the Cygwin Python DLL and import library if configured
diff --git a/Misc/NEWS.d/next/Build/2026-10-20-20-00-00.gh-issue-144942.MdLibs.rst b/Misc/NEWS.d/next/Build/2026-10-20-20-00-00.gh-issue-144942.MdLibs.rst
new file mode 100644
index 00000000000000..94b25d67af2fe4
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2026-10-20-20-00-00.gh-issue-144942.MdLibs.rst
@@ -0,0 +1,3 @@
+Fix the macOS shared library and framework builds not linking the libraries
+required by built-in modules, such as the HACL* objects needed by ``_blake2``
+when it is built in via :file:`Modules/Setup.local`.