[PATCH] newlib: Enable building libstdc++ for newlib based toolchains

[Alejandro Enedino Hernandez Samaniego <alejandro@enedino.org>]

Some baremetal applications might require support from libstdc++.

On newlib based toolchains, libstdc++ can be built as a static
library that applications can then link against it.

Pass libsdtc++-(static)dev to LIBC_DEPENDENCIES allowing the
library to be present for cross compilation as well as on
sdk builds.

This also requires to modify the gcc-runtime recipe to
explictly build only libsdtc++ correctly.

Signed-off-by: Alejandro Enedino Hernandez Samaniego <alejandro@enedino.org>
---
 meta/conf/distro/include/tclibc-newlib.inc | 7 +++----
 meta/recipes-devtools/gcc/gcc-runtime.inc  | 6 ++++++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/meta/conf/distro/include/tclibc-newlib.inc b/meta/conf/distro/include/tclibc-newlib.inc
index 896c0b1..8338003 100644
--- a/meta/conf/distro/include/tclibc-newlib.inc
+++ b/meta/conf/distro/include/tclibc-newlib.inc
@@ -25,12 +25,11 @@ LIBC_DEPENDENCIES = "\
     libgloss-dbg \
     libgcc-dev \
     libgcc-dbg \
+    libstdc++-dev \
+    libstdc++-staticdev \
     "
 
-# compilerlibs defaults to gcc-runtime, but we get runtime from libgloss
-# we set ASSUME_PROVIDED because we cant set PREFERRED_PROVIDER
-# for compilerlibs since its overridden by tcmode-default
-ASSUME_PROVIDED += "virtual/${TARGET_PREFIX}compilerlibs virtual/crypt"
+ASSUME_PROVIDED += "virtual/crypt"
 
 # Its useful to be able to extend newlib, but we dont provide a native variant of libgloss
 NEWLIB_EXTENDED ?=  "libgloss libgcc"
diff --git a/meta/recipes-devtools/gcc/gcc-runtime.inc b/meta/recipes-devtools/gcc/gcc-runtime.inc
index d3f8ae8..f035fbd 100644
--- a/meta/recipes-devtools/gcc/gcc-runtime.inc
+++ b/meta/recipes-devtools/gcc/gcc-runtime.inc
@@ -17,6 +17,9 @@ EXTRA_OECONF_PATHS = "\
 EXTRA_OECONF_append_linuxstdbase = " --enable-clocale=gnu"
 EXTRA_OECONF_append = " --cache-file=${B}/config.cache"
 
+EXTRA_OECONF_remove_libc-newlib = "--enable-symvers=gnu"
+EXTRA_OECONF_append_libc-newlib = " --with-newlib"
+
 # Disable ifuncs for libatomic on arm conflicts -march/-mcpu
 EXTRA_OECONF_append_arm = " libat_cv_have_ifunc=no "
 
@@ -33,6 +36,9 @@ RUNTIMELIBITM_riscv64 = ""
 RUNTIMELIBSSP ?= ""
 RUNTIMELIBSSP_mingw32 ?= "libssp"
 
+# Only build libstdc++ for newlib
+RUNTIMETARGET_libc-newlib = "libstdc++-v3"
+
 RUNTIMETARGET = "${RUNTIMELIBSSP} libstdc++-v3 libgomp libatomic ${RUNTIMELIBITM} \
     ${@bb.utils.contains_any('FORTRAN', [',fortran',',f77'], 'libquadmath', '', d)} \
 "
-- 
2.7.4