libs: Add static compatiblity check for Rust

This patch adds a static compatiblity check
for most of structures from NuttX, which is used by Rust.

Currently, for most of them have a reserved field, which is for possible future use,
you can refer to https://github.com/no1wudi/libc/blob/39277b5357cb2aa7af1bd8344956ec292c35abed/src/unix/nuttx/mod.rs#L71
for more details.

I think we should define the initial version carefully, to avoid compatiblity problems in future as much as possible:
1. Struct reserved size is 2 pointer size, is it sufficient?
2. Which option should we preferred to use? Such as SYSTEM_TIME64 and FS_LARGEFILE?
3. Should we enable it by default to cover more cases in build CI? It can prevent introduce compatiblity issues.

Signed-off-by: Huang Qi <[email protected]>

Kconfig

@@ -2591,6 +2591,7 @@ source "libs/libc/Kconfig"
 source "libs/libm/Kconfig"
 source "libs/libxx/Kconfig"
 source "libs/libdsp/Kconfig"
+source "libs/librust/Kconfig"
 endmenu
 
 menu "Open Asymmetric Multi Processing"

libs/librust/CMakeLists.txt

@@ -0,0 +1,23 @@
+# ##############################################################################
+# libs/librust/CMakeLists.txt
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more contributor
+# license agreements.  See the NOTICE file distributed with this work for
+# additional information regarding copyright ownership.  The ASF licenses this
+# file to you under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License.  You may obtain a copy of
+# the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations under
+# the License.
+#
+# ##############################################################################
+
+if(CONFIG_LIBRUST)
+  nuttx_add_library(rust lib_rust.c)
+endif()

libs/librust/Kconfig

@@ -0,0 +1,15 @@
+#
+# For a description of the syntax of this configuration file,
+# see the file kconfig-language.txt in the NuttX tools repository.
+#
+
+config LIBRUST
+	bool "Rust Runtime Compatibility Checking"
+	default y
+	depends on SYSTEM_TIME64
+	depends on FS_LARGEFILE
+	depends on !SMALL_MEMORY
+	---help---
+		This option enables building and linking with Rust language support.
+		Currently, it only do static checking for the compatibility of structs
+		between Rust and C side.

libs/librust/Makefile

@@ -0,0 +1,65 @@
+############################################################################
+# libs/librust/Makefile
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.  The
+# ASF licenses this file to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance with the
+# License.  You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+############################################################################
+
+include $(TOPDIR)/Make.defs
+
+ifeq ($(CONFIG_LIBRUST),y)
+CSRCS += lib_rust.c
+endif
+
+AOBJS = $(ASRCS:.S=$(OBJEXT))
+COBJS = $(CSRCS:.c=$(OBJEXT))
+
+SRCS = $(ASRCS) $(CSRCS)
+OBJS = $(AOBJS) $(COBJS)
+
+BIN ?= librust$(LIBEXT)
+
+all: $(BIN)
+.PHONY:  depend clean distclean
+
+$(AOBJS): %$(OBJEXT): %.S
+	$(call ASSEMBLE, $<, $@)
+
+$(COBJS): %$(OBJEXT): %.c
+	$(call COMPILE, $<, $@)
+
+$(BIN): $(OBJS)
+	$(call ARCHIVE, $@, $(OBJS))
+
+makedepfile: $(CSRCS:.c=.ddc) $(ASRCS:.S=.dds)
+	$(call CATFILE, Make.dep, $^)
+	$(call DELFILE, $^)
+
+.depend: Makefile $(SRCS) $(TOPDIR)$(DELIM).config
+	$(Q) $(MAKE) makedepfile
+	$(Q) touch $@
+
+depend: .depend
+
+clean:
+	$(call DELFILE, $(BIN))
+	$(call CLEAN)
+
+distclean: clean
+	$(call DELFILE, Make.dep)
+	$(call DELFILE, .depend)
+
+-include Make.dep