apps/examples/elf: Add configuration optionst o support building the hello++4 example that depends upon having uClibc++ available. From Leo aloe3132.

examples/elf/Kconfig

@@ -16,7 +16,7 @@ config EXAMPLES_ELF_SYSCALL
 	default n
 	depends on LIB_SYSCALL && !BUILD_KERNEL
 	---help---
-		Link with the SYCALL library.  By default, all undefined symbols
+		Link with the SYSCALL library.  By default, all undefined symbols
 		must be provided via a symbol table.  But if this option is
 		selected, then each ELF test program will link with the SYSCALL
 		library and will interface with the OS system calls.  In this case,
@@ -54,4 +54,23 @@ config EXAMPLES_ELF_DEVPATH
 		Used for registering the RAM block driver that will hold the ROMFS file system
 		containing the ELF executables to be tested.  Default: "/dev/ram0"
 
+config EXAMPLES_ELF_CXXINITIALIZE
+	bool "C++ Initialization"
+	default y
+	depends on HAVE_CXX && HAVE_CXXINITIALIZE
+	---help---
+		By default, if CONFIG_HAVE_CXX and CONFIG_HAVE_CXXINITIALIZE are
+		defined, then this example will call the NuttX function to
+		initialize static C++ constructors.  This option may be disabled,
+		however, if that static initialization was performed elsewhere.
+
+config EXAMPLES_ELF_UCLIBCXX
+	bool "uClibc++ is installed"
+	default n
+	depends on UCLIBCXX
+	---help---
+		By default, uClibc++ is not installed and configured. If the
+		user installs and configures the C++ standard library, this
+		example will compile the demos using it.
+
 endif

examples/elf/elf_main.c

@@ -225,6 +225,12 @@ int elf_main(int argc, char *argv[])
   int ret;
   int i;
 
+  /* Call all C++ static constructors */
+
+#if defined(CONFIG_EXAMPLES_ELF_CXXINITIALIZE)
+  up_cxxinitialize();
+#endif
+
   /* Initialize the memory monitor */
 
   mm_initmonitor();

examples/elf/tests/helloxx/Makefile

@@ -67,8 +67,10 @@ BIN1 = hello++1
 BIN2 = hello++2
 ifeq ($(CONFIG_BINFMT_CONSTRUCTORS),y)
 BIN3 = hello++3
+ifeq ($(CONFIG_EXAMPLES_ELF_UCLIBCXX),y)
+BIN4 = hello++4
+endif
 endif
-#BIN4 = hello++4
 ALL_BIN = $(BIN1) $(BIN2) $(BIN3) $(BIN4)
 
 SRCS1 = $(BIN1).c
@@ -80,10 +82,12 @@ OBJS2 = $(SRCS2:.c=$(OBJEXT))
 ifeq ($(CONFIG_BINFMT_CONSTRUCTORS),y)
 SRCS3 = $(BIN3).c
 OBJS3 = $(SRCS3:.c=$(OBJEXT))
+ifeq ($(CONFIG_EXAMPLES_ELF_UCLIBCXX),y)
+SRCS4 = $(BIN4).c
+OBJS4 = $(SRCS4:.c=$(OBJEXT))
+endif
 endif
 
-#SRCS4 = $(BIN4).c
-#OBJS4 = $(SRCS4:.c=$(OBJEXT))
 
 SRCS = $(SRCS1) $(SRCS2) $(SRCS3) $(SRCS4)
 OBJS = $(OBJS1) $(OBJS2) $(OBJS3) $(OBJS4)
@@ -122,15 +126,17 @@ ifeq ($(CONFIG_BINFMT_CONSTRUCTORS),y)
 $(BIN3): $(OBJS3)
 	@echo "LD: $<"
 	$(Q) $(LD) $(LDELFFLAGS) $(LDLIBPATH) -o $@ $(ARCHCRT0OBJ) $^ $(LDLIBS)
-endif
 
 # BIN4 is similar to BIN3 except that it uses the streams code from libstdc++
 #
 # NOTE:  libstdc++ is not available for NuttX as of this writing
 #
-#$(BIN4): $(OBJS4)
+ifeq ($(CONFIG_EXAMPLES_ELF_UCLIBCXX),y)
-#	@echo "LD: $<"
+$(BIN4): $(OBJS4)
-#	$(Q) $(LD) $(LDELFFLAGS) $(LDLIBPATH) -o $@ $(ARCHCRT0OBJ) $^ $(LDLIBS)
+	@echo "LD: $<"
+	$(Q) $(LD) $(LDELFFLAGS) $(LDLIBPATH) -o $@ $(ARCHCRT0OBJ) $^ $(LDLIBS)
+endif
+endif
 
 clean:
 	$(call DELFILE, $(BIN1))
@@ -145,8 +151,10 @@ install: $(ALL_BIN)
 	$(Q) install $(BIN2) $(ROMFS_DIR)/$(BIN2)
 ifeq ($(CONFIG_BINFMT_CONSTRUCTORS),y)
 	$(Q) install $(BIN3) $(ROMFS_DIR)/$(BIN3)
+ifeq ($(CONFIG_EXAMPLES_ELF_UCLIBCXX),y)
+	$(Q) install $(BIN4) $(ROMFS_DIR)/$(BIN4)
+endif
 endif
-#	$(Q) install $(BIN4) $(ROMFS_DIR)/$(BIN4)