CODEWITHSUNDEEP
c++makefilegdb
Devin B
Devin B

Reputation: 59

GDB not finding symbol table

I cannot determine the reason that gdb is either not finding the proper debugging symbols or they are not being generated by my makefile. I have added and removed various flags such as -g, -ggdb, and -O0 in as many combinations as I can think of. Any help would be appreciated!

Makefile:

FLAGS =-std=c++11 -ggdb -g -O0 -Wall -Werror
CC = g++
OBJS = main.o LSorter.o LNode.o

default: exec

exec: $(OBJS)
    $(CC) $(FLAGS) -o exec $(OBJS) 

main: main.cpp LSorter.h LNode.h
    $(CC) $(FLAGS) -c main.cpp -o main.o

LSorter: LSorter.cpp LSorter.h LNode.h
    $(CC) $(FLAGS) -c LSorter.cpp -o LSorter.o

LNode: LNode.cpp  LNode.h
    $(CC) $(FLAGS) -c LNode.cpp -o LNode.o

clean:
    rm exec $(OBJS)

Console Output:

gdb console output

Upvotes: 1

Views: 242

Answers (1)

Sam Varshavchik
Sam Varshavchik

Reputation: 118425

OBJS = main.o LSorter.o LNode.o

exec: $(OBJS)
    $(CC) $(FLAGS) -o exec $(OBJS)

This specifies that the exec target depends on main.o, LSorter.o, and LNode.o targets.

The make command then proceeds to search your Makefile for any rules to build main.o, Lsorter.o, and LNode.o.

Unfortunately, make fails miserably in this noble quest. Your Makefile fails to define any rules for targets named main.o, Lsorter.o, and LNode.o. make then defaults to using its implicit rules, that build .o files from .cpp files that it finds with the same name. The default built-in rules, that are built into make, know absolutely nothing about your FLAGS variables, and if you paid close attention to the commands that make was executing when compiling your cpp file you would've noticed that your cpp files were not compiled with your FLAGS, and therefore did not have any debugging data compiled in.

Your makefile does appear to have rules defined for targets main, LSorter and LNode, which use FLAGS to specify the -g option.

Unfortunately, those are not the targets that make was instructed to search for, as I explained.

This is an obvious oversight. Change your build rules to specify the correct dependency targets, then make clean and recompile.

Upvotes: 1

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