all: Use += rather than = everywhere for CFLAGS/LDFLAGS/LIBS.

This avoids a surprise where an = can cancel out an earlier +=. Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

Author: jimmo

docs/develop/porting.rst

@@ -98,8 +98,8 @@ We also need a Makefile at this point for the port:
  include $(TOP)/extmod/extmod.mk
 
  # Set CFLAGS and libraries.
- CFLAGS = -I. -I$(BUILD) -I$(TOP)
- LIBS = -lm
+ CFLAGS += -I. -I$(BUILD) -I$(TOP)
+ LIBS += -lm
 
  # Define the required source files.
  SRC_C = \

examples/embedding/Makefile

@@ -1,6 +1,6 @@
 MPTOP = ../..
-CFLAGS = -std=c99 -I. -I$(MPTOP) -DNO_QSTR
-LDFLAGS = -L./build
+CFLAGS += -std=c99 -I. -I$(MPTOP) -DNO_QSTR
+LDFLAGS += -L./build
 
 hello-embed: hello-embed.o -lmicropython
 

examples/embedding/Makefile.upylib

@@ -20,7 +20,7 @@ INC += -I$(BUILD)
 # compiler settings
 CWARN = -Wall -Werror
 CWARN += -Wpointer-arith -Wuninitialized
-CFLAGS = $(INC) $(CWARN) -std=gnu99 -DUNIX $(CFLAGS_MOD) $(COPT) $(CFLAGS_EXTRA)
+CFLAGS += $(INC) $(CWARN) -std=gnu99 -DUNIX $(CFLAGS_MOD) $(COPT) $(CFLAGS_EXTRA)
 
 # Some systems (eg MacOS) need -fno-common so that mp_state_ctx is placed in the BSS.
 CFLAGS += -fno-common
@@ -70,7 +70,7 @@ else
 # Use gcc syntax for map file
 LDFLAGS_ARCH = -Wl,-Map=$@.map,--cref
 endif
-LDFLAGS = $(LDFLAGS_MOD) $(LDFLAGS_ARCH) -lm $(LDFLAGS_EXTRA)
+LDFLAGS += $(LDFLAGS_MOD) $(LDFLAGS_ARCH) -lm $(LDFLAGS_EXTRA)
 
 ifeq ($(MICROPY_FORCE_32BIT),1)
 # Note: you may need to install i386 versions of dependency packages,

ports/cc3200/Makefile

@@ -20,15 +20,15 @@ include ../../py/mkenv.mk
 CROSS_COMPILE ?= arm-none-eabi-
 
 CFLAGS_CORTEX_M4 = -mthumb -mtune=cortex-m4 -march=armv7e-m -mabi=aapcs -mcpu=cortex-m4 -msoft-float -mfloat-abi=soft -fsingle-precision-constant -Wdouble-promotion
-CFLAGS = -Wall -Wpointer-arith -Werror -std=gnu99 -nostdlib $(CFLAGS_CORTEX_M4) -Os
+CFLAGS += -Wall -Wpointer-arith -Werror -std=gnu99 -nostdlib $(CFLAGS_CORTEX_M4) -Os
 CFLAGS += -g -ffunction-sections -fdata-sections -fno-common -fsigned-char -mno-unaligned-access
 CFLAGS += -Iboards/$(BOARD)
 CFLAGS += $(CFLAGS_MOD)
 
 # Workaround gcc 12.1 bug.
 CFLAGS += -Wno-array-bounds
 
-LDFLAGS = -Wl,-nostdlib -Wl,--gc-sections -Wl,-Map=$@.map
+LDFLAGS += -Wl,-nostdlib -Wl,--gc-sections -Wl,-Map=$@.map
 
 FLASH_SIZE_WIPY = 2M
 FLASH_SIZE_LAUNCHXL = 1M

ports/esp8266/Makefile

@@ -57,12 +57,12 @@ CFLAGS_XTENSA = -fsingle-precision-constant -Wdouble-promotion \
 -Wl,-EL -mlongcalls -mtext-section-literals -mforce-l32 \
 -DLWIP_OPEN_SRC
 
-CFLAGS = $(INC) -Wall -Wpointer-arith -Werror -std=gnu99 -nostdlib -DUART_OS=$(UART_OS) \
+CFLAGS += $(INC) -Wall -Wpointer-arith -Werror -std=gnu99 -nostdlib -DUART_OS=$(UART_OS) \
 $(CFLAGS_XTENSA) $(CFLAGS_MOD) $(COPT) $(CFLAGS_EXTRA) -I$(BOARD_DIR)
 
 LD_FILES ?= boards/esp8266_2m.ld
-LDFLAGS = -nostdlib -T $(LD_FILES) -Map=$(@:.elf=.map) --cref
-LIBS = -L$(ESP_SDK)/lib -lmain -ljson -llwip_open -lpp -lnet80211 -lwpa -lphy -lnet80211 $(LDFLAGS_MOD)
+LDFLAGS += -nostdlib -T $(LD_FILES) -Map=$(@:.elf=.map) --cref
+LIBS += -L$(ESP_SDK)/lib -lmain -ljson -llwip_open -lpp -lnet80211 -lwpa -lphy -lnet80211 $(LDFLAGS_MOD)
 
 LIBGCC_FILE_NAME = $(shell $(CC) $(CFLAGS) -print-libgcc-file-name)
 LIBS += -L$(dir $(LIBGCC_FILE_NAME)) -lgcc

ports/mimxrt/Makefile

@@ -393,7 +393,7 @@ CFLAGS += $(CFLAGS_MOD) $(CFLAGS_EXTRA)
 # Linker Flags
 # =============================================================================
 
-LDFLAGS = \
+LDFLAGS += \
 --cref \
 --gc-sections \
 --print-memory-usage \

ports/minimal/Makefile

@@ -23,12 +23,12 @@ ifeq ($(CROSS), 1)
 DFU = $(TOP)/tools/dfu.py
 PYDFU = $(TOP)/tools/pydfu.py
 CFLAGS_CORTEX_M4 = -mthumb -mtune=cortex-m4 -mcpu=cortex-m4 -msoft-float -fsingle-precision-constant -Wdouble-promotion -Wfloat-conversion
-CFLAGS = $(INC) -Wall -Werror -std=c99 -nostdlib $(CFLAGS_CORTEX_M4) $(COPT)
-LDFLAGS = -nostdlib -T stm32f405.ld -Map=$@.map --cref --gc-sections
+CFLAGS += $(INC) -Wall -Werror -std=c99 -nostdlib $(CFLAGS_CORTEX_M4) $(COPT)
+LDFLAGS += -nostdlib -T stm32f405.ld -Map=$@.map --cref --gc-sections
 else
 LD = gcc
-CFLAGS = $(INC) -Wall -Werror -Wdouble-promotion -Wfloat-conversion -std=c99 $(COPT)
-LDFLAGS = -Wl,-Map=$@.map,--cref -Wl,--gc-sections
+CFLAGS += $(INC) -Wall -Werror -Wdouble-promotion -Wfloat-conversion -std=c99 $(COPT)
+LDFLAGS += -Wl,-Map=$@.map,--cref -Wl,--gc-sections
 endif
 
 CSUPEROPT = -Os # save some code space

ports/nrf/Makefile

@@ -129,7 +129,7 @@ CFLAGS += -fno-strict-aliasing
 CFLAGS += -Iboards/$(BOARD)
 CFLAGS += -DNRF5_HAL_H='<$(MCU_VARIANT)_hal.h>'
 
-LDFLAGS = $(CFLAGS)
+LDFLAGS += $(CFLAGS)
 LDFLAGS += -Xlinker -Map=$(@:.elf=.map)
 LDFLAGS += -mthumb -mabi=aapcs $(addprefix -T,$(LD_FILES)) -L boards/
 

ports/pic16bit/Makefile

@@ -21,7 +21,7 @@ INC += -I$(XC16)/include
 INC += -I$(XC16)/support/$(PARTFAMILY)/h
 
 CFLAGS_PIC16BIT = -mcpu=$(PART) -mlarge-code
-CFLAGS = $(INC) -Wall -Werror -std=gnu99 -nostdlib $(CFLAGS_PIC16BIT) $(COPT)
+CFLAGS += $(INC) -Wall -Werror -std=gnu99 -nostdlib $(CFLAGS_PIC16BIT) $(COPT)
 
 #Debugging/Optimization
 ifeq ($(DEBUG), 1)
@@ -30,8 +30,8 @@ else
 CFLAGS += -O1 -DNDEBUG
 endif
 
-LDFLAGS = --heap=0 -nostdlib -T $(XC16)/support/$(PARTFAMILY)/gld/p$(PART).gld -Map=$@.map --cref -p$(PART)
-LIBS = -L$(XC16)/lib -L$(XC16)/lib/$(PARTFAMILY) -lc -lm -lpic30
+LDFLAGS += --heap=0 -nostdlib -T $(XC16)/support/$(PARTFAMILY)/gld/p$(PART).gld -Map=$@.map --cref -p$(PART)
+LIBS += -L$(XC16)/lib -L$(XC16)/lib/$(PARTFAMILY) -lc -lm -lpic30
 
 SRC_C = \
 main.c \

ports/powerpc/Makefile

@@ -21,14 +21,14 @@ INC += -I.
 INC += -I$(TOP)
 INC += -I$(BUILD)
 
-CFLAGS = $(INC) -g -Wall -Wdouble-promotion -Wfloat-conversion -std=c99 $(COPT)
+CFLAGS += $(INC) -g -Wall -Wdouble-promotion -Wfloat-conversion -std=c99 $(COPT)
 CFLAGS += -mno-string -mno-multiple -mno-vsx -mno-altivec -nostdlib
 CFLAGS += -mlittle-endian -mstrict-align -msoft-float
 CFLAGS += -Os
 CFLAGS += -fdata-sections -ffunction-sections -fno-stack-protector -ffreestanding
 CFLAGS += -U_FORTIFY_SOURCE
 
-LDFLAGS = -N -T powerpc.lds -nostdlib
+LDFLAGS += -N -T powerpc.lds -nostdlib
 
 LIBS =