add LDC2 (dlang) support

*Note:* ldmd2 is ldc2-wrapper, allow using dmd frontend flags.
      This support may be extended to gdc (gnu) if nuttx developers demand it
  or are interested in it.

arch/arm/src/common/Toolchain.defs

@@ -405,3 +405,7 @@ include $(TOPDIR)/tools/Zig.defs
 # Rust toolchain
 
 include $(TOPDIR)/tools/Rust.defs
+
+# LDC (LLVM D Compiler) toolchain
+
+include $(TOPDIR)/tools/D.defs

arch/risc-v/src/common/Toolchain.defs

@@ -399,3 +399,7 @@ include $(TOPDIR)/tools/Zig.defs
 # Rust toolchain
 
 include $(TOPDIR)/tools/Rust.defs
+
+# LDC (LLVM D Compiler) toolchain
+
+include $(TOPDIR)/tools/D.defs

boards/sim/sim/sim/scripts/Make.defs

@@ -192,6 +192,10 @@ include $(TOPDIR)/tools/Zig.defs
 
 include $(TOPDIR)/tools/Rust.defs
 
+# LDC (LLVM D Compiler) toolchain
+
+include $(TOPDIR)/tools/D.defs
+
 CFLAGS := $(ARCHOPTIMIZATION) $(ARCHCFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
 CXXFLAGS := $(ARCHOPTIMIZATION) $(ARCHCXXFLAGS) $(ARCHXXINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS) -pipe
 CPPFLAGS := $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS)

tools/Config.mk

@@ -362,6 +362,25 @@ define COMPILEZIG
 	$(ECHO_END)
 endef
 
+# COMPILED - Default macro to compile one D file
+# Example: $(call COMPILED, in-file, out-file)
+#
+# Depends on these settings defined in board-specific Make.defs file
+# installed at $(TOPDIR)/Make.defs:
+#
+#   DC - The command to invoke the D compiler
+#   DFLAGS - Options to pass to the D compiler
+#
+# '<filename>.d_DFLAGS += <options>' may also be used, as an example, to
+# change the options used with the single file <filename>.d. The same
+# applies mutatis mutandis.
+
+define COMPILED
+	$(ECHO_BEGIN)"DC: $1 "
+	$(Q) $(DC) -c $(DFLAGS) $($(strip $1)_DFLAGS) $1 -of $2
+	$(ECHO_END)
+endef
+
 # ASSEMBLE - Default macro to assemble one assembly language file
 # Example: $(call ASSEMBLE, in-file, out-file)
 #

tools/D.defs

@@ -0,0 +1,58 @@
+############################################################################
+# tools/D.defs
+#
+# 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.
+#
+############################################################################
+
+DC := ldmd2
+
+DFLAGS := -i
+
+ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
+  DFLAGS += -g
+endif
+
+ifeq ($(CONFIG_DEBUG_NOOPT),y)
+  DFLAGS += -O
+endif
+
+# Special handling for the SIM
+
+ifeq ($(CONFIG_ARCH_SIM),y)
+  ifeq ($(CONFIG_HOST_LINUX),y)
+    ifeq ($(LLVM_ARCHTYPE),x86)
+      # Only for x86 based host or x64 but m32 build
+      DFLAGS += -mtriple=i686-unknown-linux-$(LLVM_ABITYPE)
+    else
+      # For other archs, such as aarch64, arm etc
+      DFLAGS += -mtriple=$(LLVM_ARCHTYPE)-unknown-linux-$(LLVM_ABITYPE)
+      DFLAGS += -mcpu=$(LLVM_CPUTYPE)
+    endif
+  else ifeq ($(CONFIG_HOST_MACOS),y)
+    DFLAGS += -mtriple=$(LLVM_ARCHTYPE)-apple-$(LLVM_ABITYPE)
+  endif
+else ifeq ($(CONFIG_ARCH_RISCV),y)
+  # Traget triple is riscv[32|64][isa]-unknown-none-elf
+  DFLAGS += -mtriple=$(LLVM_ARCHTYPE)$(ARCHRVISAM)$(ARCHRVISAA)$(ARCHRVISAF)$(ARCHRVISAD)$(ARCHRVISAC)-unknown-none-elf
+  DFLAGS += -mattr=+m,+a,+f,+d,+c -mabi=ilp32d
+  DFLAGS += -mcpu=generic-rv32
+else
+  # For arm, but there are some other archs not support yet,
+  # such as xtensa, x86 bare metal, etc.
+  DFLAGS += -mtriple=$(LLVM_ARCHTYPE)-none-$(LLVM_ABITYPE)
+  DFLAGS += -mcpu=$(LLVM_CPUTYPE)
+endif

tools/mkexport.sh

@@ -250,6 +250,8 @@ echo "OBJCOPY          = ${OBJCOPY}" >>"${EXPORTDIR}/scripts/Make.defs"
 echo "OBJDUMP          = ${OBJDUMP}" >>"${EXPORTDIR}/scripts/Make.defs"
 echo "ZIG              = ${ZIG}" >>"${EXPORTDIR}/scripts/Make.defs"
 echo "ZIGFLAGS         = ${ZIGFLAGS}" >>"${EXPORTDIR}/scripts/Make.defs"
+echo "DC               = ${DC}" >>"${EXPORTDIR}/scripts/Make.defs"
+echo "DFLAGS           = ${DFLAGS}" >>"${EXPORTDIR}/scripts/Make.defs"
 echo "NXFLATLDFLAGS1   = ${NXFLATLDFLAGS1}" >>"${EXPORTDIR}/scripts/Make.defs"
 echo "NXFLATLDFLAGS2   = ${NXFLATLDFLAGS2}" >>"${EXPORTDIR}/scripts/Make.defs"
 echo "OBJEXT           = ${OBJEXT}" >>"${EXPORTDIR}/scripts/Make.defs"