This is an attempt to fix the problem described here:

https://sourceware.org/ml/newlib/2016/msg01139.html
https://gcc.gnu.org/ml/gcc/2016-12/msg00010.html

There is no change if libtool is used.

Some run-time support libraries provided by GCC (e.g. libgomp) use
configure checks to detect certain features, e.g. availability of
thread-local storage.  The configure script generates a test program and
tries to compile and link it.  It should use target libraries and
startfiles of the build tree if available and not random ones from the
installation prefix for this procedure.  The search directories
specified by -B are a bit special, see for_each_path() in gcc.c of the
GCC sources.  First a search is performed on all search paths with the
multilib directory appended (if desired), then a second search is
performed on demand with the base directory only.  For each multilib
there is a "newlib" subdirectory.  This directory is specified by a -B
option for the support libraries.  In order to find the newlib artifacts
(ctr0.o, libc.a, libg.a and libm.a) they must be located in a proper
multilib subdirectory withing the build directory.

Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>

newlib/Makefile.am

@@ -77,19 +77,25 @@ toollibdir = $(tooldir)/lib$(MULTISUBDIR)
 
 AR_FLAGS = rc
 
+noinst_DATA = stmp-targ-include
+
 if USE_LIBTOOL
 toollib_LTLIBRARIES = libm.la \
 	libc.la
 else
 toollib_LIBRARIES = libm.a \
 	libc.a
+if HAVE_MULTISUBDIR
+BUILD_MULTISUBDIR = $(builddir)$(MULTISUBDIR)
+if HAVE_CRT0
+noinst_DATA += $(BUILD_MULTISUBDIR)/$(CRT0)
+endif
+noinst_DATA += $(BUILD_MULTISUBDIR)/libc.a $(BUILD_MULTISUBDIR)/libm.a
+endif
 endif
 
-noinst_DATA = stmp-targ-include
-
 toollib_DATA = $(CRT0) $(CRT1)
 
-
 # The functions ldexp, frexp and modf are traditionally supplied in
 # both libc.a and libm.a.  We build them in libm.a and copy them over,
 # along with some required supporting routines.
@@ -171,23 +177,40 @@ libc/libc.a: ; @true
 
 libm.a: libm/libm.a
 	rm -f $@
-	ln libm/libm.a $@ >/dev/null 2>/dev/null || cp libm/libm.a $@
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
 
 libm/libm.a: ; @true
 
 endif # USE_LIBTOOL
 
+if HAVE_MULTISUBDIR
+$(BUILD_MULTISUBDIR):
+	$(MKDIR_P) $@
+
+$(BUILD_MULTISUBDIR)/crt0.o: $(CRT0_DIR)$(CRT0) $(BUILD_MULTISUBDIR)
+	rm -f $@
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
+
+$(BUILD_MULTISUBDIR)/libc.a: libc.a $(BUILD_MULTISUBDIR)
+	rm -f $@ $(BUILD_MULTISUBDIR)/libg.a
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
+	ln libg.a $(BUILD_MULTISUBDIR)/libg.a >/dev/null 2>/dev/null || \
+	cp libg.a $(BUILD_MULTISUBDIR)/libg.a
+
+$(BUILD_MULTISUBDIR)/libm.a: libm.a $(BUILD_MULTISUBDIR)
+	rm -f $@
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
+endif
+
 crt0.o: $(CRT0_DIR)$(CRT0)
 	rm -f $@
-	ln $(CRT0_DIR)$(CRT0) $@ >/dev/null 2>/dev/null \
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
-	 || cp $(CRT0_DIR)$(CRT0) $@
 
 $(CRT0_DIR)$(CRT0): ; @true
 
 crt1.o: $(CRT1_DIR)$(CRT1)
 	rm -f $@
-	ln $< $@ >/dev/null 2>/dev/null \
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
-	 || cp $< $@
 
 $(CRT1_DIR)$(CRT1): ; @true
 

newlib/Makefile.in

@@ -53,6 +53,8 @@ PRE_UNINSTALL = :
 POST_UNINSTALL = :
 build_triplet = @build@
 host_triplet = @host@
+@HAVE_CRT0_TRUE@@HAVE_MULTISUBDIR_TRUE@@USE_LIBTOOL_FALSE@am__append_1 = $(BUILD_MULTISUBDIR)/$(CRT0)
+@HAVE_MULTISUBDIR_TRUE@@USE_LIBTOOL_FALSE@am__append_2 = $(BUILD_MULTISUBDIR)/libc.a $(BUILD_MULTISUBDIR)/libm.a
 subdir = .
 DIST_COMMON = NEWS README ChangeLog $(srcdir)/Makefile.in \
 	$(srcdir)/Makefile.am $(top_srcdir)/configure \
@@ -380,13 +382,14 @@ SUBDIRS = libc libm \
 tooldir = $(exec_prefix)/$(host_alias)
 toollibdir = $(tooldir)/lib$(MULTISUBDIR)
 AR_FLAGS = rc
+noinst_DATA = stmp-targ-include $(am__append_1) $(am__append_2)
 @USE_LIBTOOL_TRUE@toollib_LTLIBRARIES = libm.la \
 @USE_LIBTOOL_TRUE@	libc.la
 
 @USE_LIBTOOL_FALSE@toollib_LIBRARIES = libm.a \
 @USE_LIBTOOL_FALSE@	libc.a
 
-noinst_DATA = stmp-targ-include
+@HAVE_MULTISUBDIR_TRUE@@USE_LIBTOOL_FALSE@BUILD_MULTISUBDIR = $(builddir)$(MULTISUBDIR)
 toollib_DATA = $(CRT0) $(CRT1)
 
 # The functions ldexp, frexp and modf are traditionally supplied in
@@ -930,21 +933,36 @@ uninstall-am: uninstall-toollibDATA uninstall-toollibLIBRARIES \
 
 @USE_LIBTOOL_FALSE@libm.a: libm/libm.a
 @USE_LIBTOOL_FALSE@	rm -f $@
-@USE_LIBTOOL_FALSE@	ln libm/libm.a $@ >/dev/null 2>/dev/null || cp libm/libm.a $@
+@USE_LIBTOOL_FALSE@	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
 
 @USE_LIBTOOL_FALSE@libm/libm.a: ; @true
 
+@HAVE_MULTISUBDIR_TRUE@$(BUILD_MULTISUBDIR):
+@HAVE_MULTISUBDIR_TRUE@	$(MKDIR_P) $@
+
+@HAVE_MULTISUBDIR_TRUE@$(BUILD_MULTISUBDIR)/crt0.o: $(CRT0_DIR)$(CRT0) $(BUILD_MULTISUBDIR)
+@HAVE_MULTISUBDIR_TRUE@	rm -f $@
+@HAVE_MULTISUBDIR_TRUE@	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
+
+@HAVE_MULTISUBDIR_TRUE@$(BUILD_MULTISUBDIR)/libc.a: libc.a $(BUILD_MULTISUBDIR)
+@HAVE_MULTISUBDIR_TRUE@	rm -f $@ $(BUILD_MULTISUBDIR)/libg.a
+@HAVE_MULTISUBDIR_TRUE@	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
+@HAVE_MULTISUBDIR_TRUE@	ln libg.a $(BUILD_MULTISUBDIR)/libg.a >/dev/null 2>/dev/null || \
+@HAVE_MULTISUBDIR_TRUE@	cp libg.a $(BUILD_MULTISUBDIR)/libg.a
+
+@HAVE_MULTISUBDIR_TRUE@$(BUILD_MULTISUBDIR)/libm.a: libm.a $(BUILD_MULTISUBDIR)
+@HAVE_MULTISUBDIR_TRUE@	rm -f $@
+@HAVE_MULTISUBDIR_TRUE@	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
+
 crt0.o: $(CRT0_DIR)$(CRT0)
 	rm -f $@
-	ln $(CRT0_DIR)$(CRT0) $@ >/dev/null 2>/dev/null \
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
-	 || cp $(CRT0_DIR)$(CRT0) $@
 
 $(CRT0_DIR)$(CRT0): ; @true
 
 crt1.o: $(CRT1_DIR)$(CRT1)
 	rm -f $@
-	ln $< $@ >/dev/null 2>/dev/null \
+	ln $< $@ >/dev/null 2>/dev/null || cp $< $@
-	 || cp $< $@
 
 $(CRT1_DIR)$(CRT1): ; @true
 

newlib/configure

@@ -632,7 +632,11 @@ CRT1_DIR
 CRT1
 CRT0_DIR
 CRT0
+HAVE_CRT0_FALSE
+HAVE_CRT0_TRUE
 EXTRA_DIRS
+HAVE_MULTISUBDIR_FALSE
+HAVE_MULTISUBDIR_TRUE
 HAVE_DOC_FALSE
 HAVE_DOC_TRUE
 subdirs
@@ -11776,7 +11780,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11779 "configure"
+#line 11783 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11882,7 +11886,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11885 "configure"
+#line 11889 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12157,13 +12161,13 @@ subdirs="$subdirs libm"
 
 
 if test -z "${with_multisubdir}"; then
+  have_multisubdir=no
   subdirs="$subdirs doc"
 
-  have_doc=yes
 else
-  have_doc=
+  have_multisubdir=yes
 fi
- if test x$have_doc = xyes; then
+ if test x$have_multisubdir = xno; then
   HAVE_DOC_TRUE=
   HAVE_DOC_FALSE='#'
 else
@@ -12172,6 +12176,28 @@ else
 fi
 
 
+# Some run-time support libraries provided by GCC (e.g. libgomp) use configure
+# checks to detect certain features, e.g. availability of thread-local storage.
+# The configure script generates a test program and tries to compile and link
+# it.  It should use target libraries and startfiles of the build tree if
+# available and not random ones from the installation prefix for this
+# procedure.  The search directories specified by -B are a bit special, see
+# for_each_path() in gcc.c of the GCC sources.  First a search is performed on
+# all search paths with the multilib directory appended (if desired), then a
+# second search is performed on demand with the base directory only.  For each
+# multilib there is a "newlib" subdirectory.  This directory is specified by a
+# -B option for the support libraries.  In order to find the newlib artifacts
+# (ctr0.o, libc.a, libg.a and libm.a) they must be located in a proper multilib
+# subdirectory withing the build directory.
+ if test x$have_multisubdir = xyes; then
+  HAVE_MULTISUBDIR_TRUE=
+  HAVE_MULTISUBDIR_FALSE='#'
+else
+  HAVE_MULTISUBDIR_TRUE='#'
+  HAVE_MULTISUBDIR_FALSE=
+fi
+
+
 EXTRA_DIRS=
 case $host in
   i[34567]86-pc-linux-*)
@@ -12188,6 +12214,14 @@ if test "x${have_crt0}" = "xyes"; then
   CRT0=crt0.o
   CRT0_DIR=libc/
 fi
+ if test x$have_crt0 = xyes; then
+  HAVE_CRT0_TRUE=
+  HAVE_CRT0_FALSE='#'
+else
+  HAVE_CRT0_TRUE='#'
+  HAVE_CRT0_FALSE=
+fi
+
 
 
 
@@ -12827,6 +12861,14 @@ if test -z "${HAVE_DOC_TRUE}" && test -z "${HAVE_DOC_FALSE}"; then
   as_fn_error $? "conditional \"HAVE_DOC\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${HAVE_MULTISUBDIR_TRUE}" && test -z "${HAVE_MULTISUBDIR_FALSE}"; then
+  as_fn_error $? "conditional \"HAVE_MULTISUBDIR\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
+if test -z "${HAVE_CRT0_TRUE}" && test -z "${HAVE_CRT0_FALSE}"; then
+  as_fn_error $? "conditional \"HAVE_CRT0\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${HAVE_LONG_DOUBLE_TRUE}" && test -z "${HAVE_LONG_DOUBLE_FALSE}"; then
   as_fn_error $? "conditional \"HAVE_LONG_DOUBLE\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5

newlib/configure.in

@@ -261,12 +261,27 @@ AC_CONFIG_SUBDIRS(libc)
 AC_CONFIG_SUBDIRS(libm)
 
 if test -z "${with_multisubdir}"; then
+  have_multisubdir=no
   AC_CONFIG_SUBDIRS(doc)
-  have_doc=yes
 else
-  have_doc=
+  have_multisubdir=yes
 fi
-AM_CONDITIONAL(HAVE_DOC, test x$have_doc = xyes)
+AM_CONDITIONAL(HAVE_DOC, test x$have_multisubdir = xno)
+
+# Some run-time support libraries provided by GCC (e.g. libgomp) use configure
+# checks to detect certain features, e.g. availability of thread-local storage.
+# The configure script generates a test program and tries to compile and link
+# it.  It should use target libraries and startfiles of the build tree if
+# available and not random ones from the installation prefix for this
+# procedure.  The search directories specified by -B are a bit special, see
+# for_each_path() in gcc.c of the GCC sources.  First a search is performed on
+# all search paths with the multilib directory appended (if desired), then a
+# second search is performed on demand with the base directory only.  For each
+# multilib there is a "newlib" subdirectory.  This directory is specified by a
+# -B option for the support libraries.  In order to find the newlib artifacts
+# (ctr0.o, libc.a, libg.a and libm.a) they must be located in a proper multilib
+# subdirectory withing the build directory.
+AM_CONDITIONAL(HAVE_MULTISUBDIR, test x$have_multisubdir = xyes)
 
 EXTRA_DIRS=
 case $host in
@@ -283,6 +298,7 @@ if test "x${have_crt0}" = "xyes"; then
   CRT0=crt0.o
   CRT0_DIR=libc/
 fi
+AM_CONDITIONAL(HAVE_CRT0, test x$have_crt0 = xyes)
 AC_SUBST(CRT0)
 AC_SUBST(CRT0_DIR)