bpo-35257: Avoid leaking LTO linker flags into distutils (GH-10900) (GH-11264)

vstinner · web-flow · commit 0198f52ea232 · 2018-12-20T16:03:01.000+01:00
When compiling 3rd party C extensions, the linker flags used by the compiler for the interpreter and the stdlib modules, will get leaked into distutils. In order to avoid that, the PY_CORE_LDFLAGS and PY_LDFLAGS_NODIST are introduced to keep those flags separated. (cherry picked from commit cf10a75)
diff --git a/Lib/_osx_support.py b/Lib/_osx_support.py
@@ -17,7 +17,7 @@
 _UNIVERSAL_CONFIG_VARS = ('CFLAGS', 'LDFLAGS', 'CPPFLAGS', 'BASECFLAGS',
                             'BLDSHARED', 'LDSHARED', 'CC', 'CXX',
                             'PY_CFLAGS', 'PY_LDFLAGS', 'PY_CPPFLAGS',
-                            'PY_CORE_CFLAGS')
+                            'PY_CORE_CFLAGS', 'PY_CORE_LDFLAGS')
 
 # configuration variables that may contain compiler calls
 _COMPILER_CONFIG_VARS = ('BLDSHARED', 'LDSHARED', 'CC', 'CXX')
diff --git a/Lib/test/pythoninfo.py b/Lib/test/pythoninfo.py
@@ -407,7 +407,10 @@ def collect_sysconfig(info_add):
         'OPT',
         'PY_CFLAGS',
         'PY_CFLAGS_NODIST',
+        'PY_CORE_LDFLAGS',
         'PY_LDFLAGS',
+        'PY_LDFLAGS_NODIST',
+        'PY_STDMODULE_CFLAGS',
         'Py_DEBUG',
         'Py_ENABLE_SHARED',
         'SHELL',
diff --git a/Lib/test/test__osx_support.py b/Lib/test/test__osx_support.py
@@ -24,7 +24,7 @@ def setUp(self):
         for cv in ('CFLAGS', 'LDFLAGS', 'CPPFLAGS',
                             'BASECFLAGS', 'BLDSHARED', 'LDSHARED', 'CC',
                             'CXX', 'PY_CFLAGS', 'PY_LDFLAGS', 'PY_CPPFLAGS',
-                            'PY_CORE_CFLAGS'):
+                            'PY_CORE_CFLAGS', 'PY_CORE_LDFLAGS'):
             if cv in self.env:
                 self.env.unset(cv)
 
diff --git a/Makefile.pre.in b/Makefile.pre.in
@@ -85,6 +85,10 @@ CONFIGURE_CFLAGS=	@CFLAGS@
 # Use it when a compiler flag should _not_ be part of the distutils CFLAGS
 # once Python is installed (Issue #21121).
 CONFIGURE_CFLAGS_NODIST=@CFLAGS_NODIST@
+# LDFLAGS_NODIST is used in the same manner as CFLAGS_NODIST.
+# Use it when a linker flag should _not_ be part of the distutils LDFLAGS
+# once Python is installed (bpo-35257)
+CONFIGURE_LDFLAGS_NODIST=@LDFLAGS_NODIST@
 CONFIGURE_CPPFLAGS=	@CPPFLAGS@
 CONFIGURE_LDFLAGS=	@LDFLAGS@
 # Avoid assigning CFLAGS, LDFLAGS, etc. so users can use them on the
@@ -97,6 +101,7 @@ PY_CFLAGS_NODIST=$(CONFIGURE_CFLAGS_NODIST) $(CFLAGS_NODIST)
 # environment variables
 PY_CPPFLAGS=	$(BASECPPFLAGS) -I. -I$(srcdir)/Include $(CONFIGURE_CPPFLAGS) $(CPPFLAGS)
 PY_LDFLAGS=	$(CONFIGURE_LDFLAGS) $(LDFLAGS)
+PY_LDFLAGS_NODIST=$(CONFIGURE_LDFLAGS_NODIST) $(LDFLAGS_NODIST)
 NO_AS_NEEDED=	@NO_AS_NEEDED@
 LDLAST=		@LDLAST@
 SGI_ABI=	@SGI_ABI@
@@ -109,6 +114,8 @@ CFLAGSFORSHARED=@CFLAGSFORSHARED@
 PY_STDMODULE_CFLAGS= $(PY_CFLAGS) $(PY_CFLAGS_NODIST) $(PY_CPPFLAGS) $(CFLAGSFORSHARED)
 PY_BUILTIN_MODULE_CFLAGS= $(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE_BUILTIN
 PY_CORE_CFLAGS=	$(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE
+# Linker flags used for building the interpreter object files
+PY_CORE_LDFLAGS=$(PY_LDFLAGS) $(PY_LDFLAGS_NODIST)
 # Strict or non-strict aliasing flags used to compile dtoa.c, see above
 CFLAGS_ALIASING=@CFLAGS_ALIASING@
 
@@ -148,7 +155,7 @@ CONFINCLUDEPY=	$(CONFINCLUDEDIR)/python$(LDVERSION)
 SHLIB_SUFFIX=	@SHLIB_SUFFIX@
 EXT_SUFFIX=	@EXT_SUFFIX@
 LDSHARED=	@LDSHARED@ $(PY_LDFLAGS)
-BLDSHARED=	@BLDSHARED@ $(PY_LDFLAGS)
+BLDSHARED=	@BLDSHARED@ $(PY_LDFLAGS_NODIST)
 LDCXXSHARED=	@LDCXXSHARED@
 DESTSHARED=	$(BINLIBDEST)/lib-dynload
 
@@ -497,7 +504,7 @@ profile-run-stamp:
 	touch $@
 
 build_all_generate_profile:
-	$(MAKE) @DEF_MAKE_RULE@ CFLAGS_NODIST="$(CFLAGS_NODIST) $(PGO_PROF_GEN_FLAG)" LDFLAGS="$(LDFLAGS) $(PGO_PROF_GEN_FLAG)" LIBS="$(LIBS)"
+	$(MAKE) @DEF_MAKE_RULE@ CFLAGS_NODIST="$(CFLAGS_NODIST) $(PGO_PROF_GEN_FLAG)" LDFLAGS_NODIST="$(LDFLAGS_NODIST) $(PGO_PROF_GEN_FLAG)" LIBS="$(LIBS)"
 
 run_profile_task:
 	@ # FIXME: can't run for a cross build
@@ -511,7 +518,7 @@ build_all_merge_profile:
 profile-opt: profile-run-stamp
 	@echo "Rebuilding with profile guided optimizations:"
 	-rm -f profile-clean-stamp
-	$(MAKE) @DEF_MAKE_RULE@ CFLAGS_NODIST="$(CFLAGS_NODIST) $(PGO_PROF_USE_FLAG)" LDFLAGS="$(LDFLAGS)"
+	$(MAKE) @DEF_MAKE_RULE@ CFLAGS_NODIST="$(CFLAGS_NODIST) $(PGO_PROF_USE_FLAG)" LDFLAGS_NODIST="$(LDFLAGS_NODIST)"
 
 # Compile and run with gcov
 .PHONY=coverage coverage-lcov coverage-report
@@ -568,7 +575,7 @@ clinic: check-clean-src $(srcdir)/Modules/_blake2/blake2s_impl.c
 
 # Build the interpreter
 $(BUILDPYTHON):	Programs/python.o $(LIBRARY) $(LDLIBRARY) $(PY3LIBRARY)
-	$(LINKCC) $(PY_LDFLAGS) $(LINKFORSHARED) -o $@ Programs/python.o $(BLDLIBRARY) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
+	$(LINKCC) $(PY_CORE_LDFLAGS) $(LINKFORSHARED) -o $@ Programs/python.o $(BLDLIBRARY) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
 
 platform: $(BUILDPYTHON) pybuilddir.txt
 	$(RUNSHARED) $(PYTHON_FOR_BUILD) -c 'import sys ; from sysconfig import get_platform ; print("%s-%d.%d" % (get_platform(), *sys.version_info[:2]))' >platform
@@ -633,7 +640,7 @@ libpython3.so:	libpython$(LDVERSION).so
 	$(BLDSHARED) $(NO_AS_NEEDED) -o $@ -Wl,-h$@ $^
 
 libpython$(LDVERSION).dylib: $(LIBRARY_OBJS)
-	 $(CC) -dynamiclib -Wl,-single_module $(PY_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(SHLIBS) $(LIBC) $(LIBM) $(LDLAST); \
+	 $(CC) -dynamiclib -Wl,-single_module $(PY_CORE_LDFLAGS) -undefined dynamic_lookup -Wl,-install_name,$(prefix)/lib/libpython$(LDVERSION).dylib -Wl,-compatibility_version,$(VERSION) -Wl,-current_version,$(VERSION) -o $@ $(LIBRARY_OBJS) $(SHLIBS) $(LIBC) $(LIBM) $(LDLAST); \
 
 
 libpython$(VERSION).sl: $(LIBRARY_OBJS)
@@ -658,7 +665,7 @@ $(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK): \
 		$(LIBRARY) \
 		$(RESSRCDIR)/Info.plist
 	$(INSTALL) -d -m $(DIRMODE) $(PYTHONFRAMEWORKDIR)/Versions/$(VERSION)
-	$(CC) -o $(LDLIBRARY) $(PY_LDFLAGS) -dynamiclib \
+	$(CC) -o $(LDLIBRARY) $(PY_CORE_LDFLAGS) -dynamiclib \
 		-all_load $(LIBRARY) -Wl,-single_module \
 		-install_name $(DESTDIR)$(PYTHONFRAMEWORKINSTALLDIR)/Versions/$(VERSION)/$(PYTHONFRAMEWORK) \
 		-compatibility_version $(VERSION) \
@@ -709,15 +716,15 @@ Modules/Setup: $(srcdir)/Modules/Setup.dist
 	fi
 
 Programs/_testembed: Programs/_testembed.o $(LIBRARY) $(LDLIBRARY) $(PY3LIBRARY)
-	$(LINKCC) $(PY_LDFLAGS) $(LINKFORSHARED) -o $@ Programs/_testembed.o $(BLDLIBRARY) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
+	$(LINKCC) $(PY_CORE_LDFLAGS) $(LINKFORSHARED) -o $@ Programs/_testembed.o $(BLDLIBRARY) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
 
 ############################################################################
 # Importlib
 
 Programs/_freeze_importlib.o: Programs/_freeze_importlib.c Makefile
 
 Programs/_freeze_importlib: Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN)
-	$(LINKCC) $(PY_LDFLAGS) -o $@ Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
+	$(LINKCC) $(PY_CORE_LDFLAGS) -o $@ Programs/_freeze_importlib.o $(LIBRARY_OBJS_OMIT_FROZEN) $(LIBS) $(MODLIBS) $(SYSLIBS) $(LDLAST)
 
 .PHONY: regen-importlib
 regen-importlib: Programs/_freeze_importlib
@@ -799,7 +806,7 @@ Python/sysmodule.o: $(srcdir)/Python/sysmodule.c Makefile
 $(IO_OBJS): $(IO_H)
 
 $(PGEN): $(PGENOBJS)
-		$(CC) $(OPT) $(PY_LDFLAGS) $(PGENOBJS) $(LIBS) -o $(PGEN)
+		$(CC) $(OPT) $(PY_CORE_LDFLAGS) $(PGENOBJS) $(LIBS) -o $(PGEN)
 
 .PHONY: regen-grammar
 regen-grammar: $(PGEN)
diff --git a/Misc/NEWS.d/next/Build/2018-12-05-22-28-40.bpo-35257.dmcd_s.rst b/Misc/NEWS.d/next/Build/2018-12-05-22-28-40.bpo-35257.dmcd_s.rst
@@ -0,0 +1,2 @@
+Avoid leaking the linker flags from Link Time Optimizations (LTO)
+into distutils when compiling C extensions.
diff --git a/configure b/configure
@@ -667,6 +667,7 @@ SHLIB_SUFFIX
 LIBTOOL_CRUFT
 OTHER_LIBTOOL_OPT
 UNIVERSAL_ARCH_FLAGS
+LDFLAGS_NODIST
 CFLAGS_NODIST
 BASECFLAGS
 CFLAGS_ALIASING
@@ -6671,7 +6672,7 @@ $as_echo "$as_me: llvm-ar found via xcrun: ${LLVM_AR}" >&6;}
   fi
 
   CFLAGS_NODIST="$CFLAGS_NODIST $LTOFLAGS"
-  LDFLAGS="$LDFLAGS $LTOFLAGS"
+  LDFLAGS_NODIST="$LDFLAGS_NODIST $LTOFLAGS"
 fi
 
 # Enable PGO flags.
@@ -6923,6 +6924,7 @@ fi
 
 
 
+
 # The -arch flags for universal builds on OSX
 UNIVERSAL_ARCH_FLAGS=
 
diff --git a/configure.ac b/configure.ac
@@ -1395,7 +1395,7 @@ if test "$Py_LTO" = 'true' ; then
   fi
 
   CFLAGS_NODIST="$CFLAGS_NODIST $LTOFLAGS"
-  LDFLAGS="$LDFLAGS $LTOFLAGS"
+  LDFLAGS_NODIST="$LDFLAGS_NODIST $LTOFLAGS"
 fi
 
 # Enable PGO flags.
@@ -1555,6 +1555,7 @@ fi
 
 AC_SUBST(BASECFLAGS)
 AC_SUBST(CFLAGS_NODIST)
+AC_SUBST(LDFLAGS_NODIST)
 
 # The -arch flags for universal builds on OSX
 UNIVERSAL_ARCH_FLAGS=
diff --git a/setup.py b/setup.py
@@ -18,11 +18,16 @@
 
 cross_compiling = "_PYTHON_HOST_PLATFORM" in os.environ
 
-# Add special CFLAGS reserved for building the interpreter and the stdlib
-# modules (Issue #21121).
-cflags = sysconfig.get_config_var('CFLAGS')
-py_cflags_nodist = sysconfig.get_config_var('PY_CFLAGS_NODIST')
-sysconfig.get_config_vars()['CFLAGS'] = cflags + ' ' + py_cflags_nodist
+# Set common compiler and linker flags derived from the Makefile,
+# reserved for building the interpreter and the stdlib modules.
+# See bpo-21121 and bpo-35257
+def set_compiler_flags(compiler_flags, compiler_py_flags_nodist):
+    flags = sysconfig.get_config_var(compiler_flags)
+    py_flags_nodist = sysconfig.get_config_var(compiler_py_flags_nodist)
+    sysconfig.get_config_vars()[compiler_flags] = flags + ' ' + py_flags_nodist
+
+set_compiler_flags('CFLAGS', 'PY_CFLAGS_NODIST')
+set_compiler_flags('LDFLAGS', 'PY_LDFLAGS_NODIST')
 
 class Dummy:
     """Hack for parallel build"""

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+Avoid leaking the linker flags from Link Time Optimizations (LTO)`
	`2`	`+into distutils when compiling C extensions.`