"undefined reference" error compiling a static library in C - c

Question

I have a file main.c, a header rippledp.h and a library rippledp.a. The problem is: when I execute the "make" command, I get this output:
g++ -O2 -DNDEBUG -static -o rippledp main.o rippledp.a -lm -pthread
main.o: In function `main':
main.c:(.text+0x24): undefined reference to `rippledp_read'
main.c:(.text+0x39): undefined reference to `rippledp'
main.c:(.text+0x43): undefined reference to `rippledp_write'
collect2: ld returned 1 exit status
make: ** [rippledp] Erro 1
Here is the Makefile:
#--------------------------------------------------#
# Ripple-DP (ISPD2015 contest version) #
# Copyright (c) 2015 #
# Department of Computer Science and Engineering #
# The Chinese Univeristy of Hong Kong #
# #
# Contact: #
# Wing-Kai Chow <wkchow#cse.cuhk.edu.hk> #
# Evangeline F.Y. Young <fyyoung#cse.cuhk.edu.hk> #
#--------------------------------------------------#
OPT= -O2 -DNDEBUG
#OPT= -O0 -ggdb
TYPE= -static
#WFLAG= -Wall -Winline
CC= g++ $(OPT) $(TYPE) $(WFLAG) $(DEBUG)
LIBS= -lm -pthread
SRCS = ${OBJS:%.o=%.c}
BFILE = rippledp
all: $(BFILE)
#$(BFILE): main.o rippledp.a libdef.a liblef.a
# $(CC) -o $(BFILE) main.o rippledp.a libdef.a liblef.a $(LIBS)
$(BFILE): main.o rippledp.a
$(CC) -o $(BFILE) main.o rippledp.a $(LIBS)
%.o : %.c %.h
$(CC) -c $*.c
clean:
rm -f *.o $(BFILE) core
Here is main.c:
#include "rippledp.h"
int main(int argc, char **argv){
/* read benchmark files: tech.lef, cells.lef, floorplan.def */
/* read global placement solution: placed.def */
rippledp_read((char*) "tech.lef", (char*) "cells.lef", (char*) "floorplan.def", (char*) "placed.def");
/* detailed placement with target utility and maximum displacement constraint */
rippledp(0.8, 200000);
/* write the detailed placement solution to output file */
rippledp_write((char*)"dplaced.def");
return 0;
}
And here is rippledp.h:
/*--------------------------------------------------*/
/* Ripple-DP (ISPD2014 contest version) */
/* Copyright (c) 2014 */
/* Department of Computer Science and Engineering */
/* The Chinese Univeristy of Hong Kong */
/* */
/* Contact: */
/* Wing-Kai Chow <wkchow#cse.cuhk.edu.hk> */
/* Evangeline F.Y. Young <fyyoung#cse.cuhk.edu.hk> */
/*--------------------------------------------------*/
#ifndef _RIPPLEDP_H_
#define _RIPPLEDP_H_
/*read benchmarks and placed global placement solution*/
void rippledp_read(char *tech_file, char *cell_file, char *floorplan_file, char *placed_file);
/*Perform displacement-constrained legalization and detailed placement*/
/* target_util = target utility */
/* max_disp = maximum displacement constraint */
void rippledp(double target_util, double max_disp);
/*write placement result in DEF format*/
void rippledp_write(char *output_file);
#endif
I also tried to compile and link manually. I first compiled using:
gcc -c main.c
Then, I tried all these alternatives for linking (I renamed rippledp.a to librippledp.a):
gcc -o out -L. -lrippledp main.o
gcc -o out -L. main.o -lrippledp
gcc -o out main.o -L. -lrippledp
gcc main.o -o out -L. -lrippledp
gcc -o out -lrippledp -L. main.o
gcc -lrippledp -o out -L. main.o
and the output was the same.
I dont have access to the library content.

Answer 1

Your library is compiled with C++ and thus contains C++ mangled names. But you compiled main.c as C, so it looked for unmangled names and thus couldn't find them. Rename main.c to main.cpp and compile it with g++ to fix this issue.