c++ compile (g++) fails about fpc

[kagiannis]

Hello

extern "C" is used when fpc.c is compiled as c but then included by a c++ application

To make it work you should either compile fpc.c seperately as c application

gcc -Wall -O2 -DNDEBUG -c fpc.c -o fpc.o 

and then link it with c++

g++ -Wall -O2 -DNDEBUG cli.c fpc.o -o fpc

or if you want to compile both with g++ you should remove extern "C"

[kagiannis]

Also you should notice that fpc.c uses variable length arrays that they are not present in standard c++. They are included only in standard c (C99 and above). So it can be compiled as c++ only with compilers that support variable length arrays as extension like g++ and clang++.

[pulmark]

Thanks for the info. I made a static lib Makefile for fpc.c by using g++ and it works. Probably will use it instead of just using the #include "fpc.c" trick.

[pulmark]

Makefile for libfpc.a:

CC = g++
TARGET = libfpc.a
CFLAGS= -pipe -fPIC -O3 -g -Wall -c -march=native -mtune=native

INC = -I./
OBJ_DIR=./obj
OUT_DIR=./
SRC_DIR=./

#Lib for fpc.c
FILES = $(SRC_DIR)/fpc.c
$(TARGET): $(patsubst $(SRC_DIR)/%.c,$(OBJ_DIR)/%.o,$(FILES))
ar -rcs -o $(OUT_DIR)/$@ $^

#Compiling every *.c to *.o
$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c dirmake
$(CC) -c $(INC) $(CFLAGS) -o $@ $<

dirmake:
@mkdir -p $(OUT_DIR)
@mkdir -p $(OBJ_DIR)

clean:
rm -f $(OBJ_DIR)/*.o $(OUT_DIR)/$(TARGET)

rebuild: clean build