stm32: Support C++ code and user C modules written in C++.

Also build user C modules as part of the stm32 CI.
Signed-off-by: Damien George <damien@micropython.org>

.travis.yml

@@ -99,7 +99,7 @@ jobs:
         - make ${MAKEOPTS} -C ports/stm32 submodules
         - git submodule update --init lib/btstack
         - make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_F091RC
-        - make ${MAKEOPTS} -C ports/stm32 BOARD=PYBV11 MICROPY_PY_WIZNET5K=5200 MICROPY_PY_CC3K=1
+        - make ${MAKEOPTS} -C ports/stm32 BOARD=PYBV11 MICROPY_PY_WIZNET5K=5200 MICROPY_PY_CC3K=1 USER_C_MODULES=../../examples/usercmodule CFLAGS_EXTRA="-DMODULE_CEXAMPLE_ENABLED=1 -DMODULE_CPPEXAMPLE_ENABLED=1"
         - make ${MAKEOPTS} -C ports/stm32 BOARD=PYBD_SF2
         - make ${MAKEOPTS} -C ports/stm32 BOARD=PYBD_SF6 NANBOX=1 MICROPY_BLUETOOTH_NIMBLE=0 MICROPY_BLUETOOTH_BTSTACK=1
         - make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_H743ZI CFLAGS_EXTRA='-DMICROPY_PY_THREAD=1'

ports/stm32/Makefile

@@ -138,6 +138,13 @@ else
 COPT += -Os -DNDEBUG
 endif
 
+# Flags for optional C++ source code
+CXXFLAGS += $(filter-out -Wmissing-prototypes -Wold-style-definition -std=gnu99,$(CFLAGS))
+CXXFLAGS += $(CXXFLAGS_MOD)
+ifneq ($(SRC_CXX)$(SRC_MOD_CXX),)
+LDFLAGS += -L$(dir $(shell $(CXX) $(CXXFLAGS) -print-file-name=libstdc++.a))
+endif
+
 # Options for mpy-cross
 MPY_CROSS_FLAGS += -march=armv7m
 
@@ -330,6 +337,9 @@ SRC_C += \
 	adc.c \
 	$(wildcard $(BOARD_DIR)/*.c)
 
+SRC_CXX += \
+	$(SRC_MOD_CXX)
+
 SRC_O += \
 	$(STARTUP_FILE) \
 	$(SYSTEM_FILE)
@@ -511,6 +521,7 @@ OBJ += $(LIBM_O)
 OBJ += $(addprefix $(BUILD)/, $(EXTMOD_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(DRIVERS_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
+OBJ += $(addprefix $(BUILD)/, $(SRC_CXX:.cpp=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_O))
 OBJ += $(addprefix $(BUILD)/, $(SRC_HAL:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_USBDEV:.c=.o))
@@ -644,7 +655,7 @@ GEN_CDCINF_FILE = $(HEADER_BUILD)/pybcdc.inf
 GEN_CDCINF_HEADER = $(HEADER_BUILD)/pybcdc_inf.h
 
 # List of sources for qstr extraction
-SRC_QSTR += $(SRC_C) $(SRC_MOD) $(LIB_SRC_C) $(EXTMOD_SRC_C)
+SRC_QSTR += $(SRC_C) $(SRC_CXX) $(SRC_MOD) $(LIB_SRC_C) $(EXTMOD_SRC_C)
 # Append any auto-generated sources that are needed by sources listed in
 # SRC_QSTR
 SRC_QSTR_AUTO_DEPS += $(GEN_CDCINF_HEADER)

ports/stm32/boards/common_extratext_data_in_flash.ld

 /* This linker script fragment is intended to be included in SECTIONS. */
 
+/* For C++ exception handling */
+.ARM :
+{
+    __exidx_start = .;
+    *(.ARM.exidx*)
+    __exidx_end = .;
+} >FLASH
+
 /* Used by the start-up code to initialise data */
 _sidata = LOADADDR(.data);
 

ports/stm32/boards/common_extratext_data_in_flash_app.ld

 /* This linker script fragment is intended to be included in SECTIONS. */
 
+/* For C++ exception handling */
+.ARM :
+{
+    __exidx_start = .;
+    *(.ARM.exidx*)
+    __exidx_end = .;
+} >FLASH_APP
+
 /* Used by the start-up code to initialise data */
 _sidata = LOADADDR(.data);
 

ports/stm32/boards/common_extratext_data_in_flash_text.ld

 /* This linker script fragment is intended to be included in SECTIONS. */
 
+/* For C++ exception handling */
+.ARM :
+{
+    __exidx_start = .;
+    *(.ARM.exidx*)
+    __exidx_end = .;
+} >FLASH_TEXT
+
 /* Used by the start-up code to initialise data */
 _sidata = LOADADDR(.data);
 

ports/stm32/main.c

@@ -133,6 +133,10 @@ void nlr_jump_fail(void *val) {
     __fatal_error("");
 }
 
+void abort(void) {
+    __fatal_error("abort");
+}
+
 #ifndef NDEBUG
 void MP_WEAK __assert_func(const char *file, int line, const char *func, const char *expr) {
     (void)func;