No matter what I tried, GDB just won't work on my Mac (Mojave). Common error but I've found no solutions

Question

it's my first post so I apologise in advance if I post anything wrong or incorrectly format.

My system: MacBook Pro running MacOS Mojave 10.14.1, Netbeans 8.2

I'm running a simple C++ program that prints hello world:

int main(int argc, char** argv) {

    cout << "Hello World" << endl;

    return 0;
}

So my issue is that I cannot run the debugger on my MacBook using Netbeans or Terminal commands. Every time I do, I get the following error:

not in executable format: file format not recognized

I originally had the problem where I had a missing debugger command. I followed the directions here and installed Homebrew, got gdb, and code-signed the gdb binary. After all that I started getting the error highlighted above.

I google this new problem, and I find this stack overflow post which suggests that I might be running a 32-bit gdb while building in 64-bit. However, based on the output when running gdb:

GNU gdb (GDB) 8.2
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin18.0.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.

For help, type "help".
Type "apropos word" to search for commands related to "word"...
BFD: /Users/Anon/Desktop/gdb_test/gdb_test: unknown load command 0x32
BFD: /Users/Anon/Desktop/gdb_test/gdb_test: unknown load command 0x32
"/Users/Anon/Desktop/gdb_test/gdb_test": not in executable format: file format not recognized

And the configuration of the GDB:

This GDB was configured as follows:
   configure --host=x86_64-apple-darwin18.0.0 --target=x86_64-apple-darwin18.0.0
         --with-auto-load-dir=:${prefix}/share/auto-load
         --with-auto-load-safe-path=:${prefix}/share/auto-load
         --with-expat
         --with-gdb-datadir=/usr/local/Cellar/gdb/8.2/share/gdb (relocatable)
         --with-jit-reader-dir=/usr/local/Cellar/gdb/8.2/lib/gdb (relocatable)
         --without-libunwind-ia64
         --without-lzma
         --without-babeltrace
         --without-intel-pt
         --disable-libmcheck
         --without-mpfr
         --with-python=/System/Library/Frameworks/Python.framework/Versions/2.7
         --without-guile
         --with-separate-debug-dir=/usr/local/Cellar/gdb/8.2/lib/debug (relocatable)

("Relocatable" means the directory can be moved with the GDB installation tree, and GDB will still find it.)

It seems that my GDB is indeed 64-bit so I'm guessing that's not the problem. I also found this post where the top answer suggests that gdb 8.2 is impossibly broken and I should just downgrade to 8.0.1. However, an edit says that an update by the GNU team has (supposedly) fixed the problem so I run:

brew update

and ensure that everything is up-to-date, but I still get the same error.

I'm at my wits end here, and I've put in WAY too much time into trying to resolve this issue. If it can't be fixed, can you suggest other hassle-free ways (massive emphasis on hassle-free) I can debug C/C++ programs on my Mac? Otherwise, I'll stick to my university's computer labs.

EDIT: here's how I compiled from the terminal

g++ -g main.cpp -o main

I'm compiling in Debug mode (64-bit) in Netbeans with C++14 standard using the g++ compiler.

I call gdb after compiling by writing to the terminal:

gdb main

or by simply using the GUI in Netbeans

Answer 1

The compilers on macOS are confusing. Apple supplies the LLVM compiler as part of Xcode, but it provides a stub at /usr/bin/g++ which leads people to believe they are using GCC, i.e. the GNU Compiler Collection. They then try to use gdb, i.e. the GNU Debugger with the LLVM-produced executables and find it doesn't work.

IMHO, you either need to use wholly Apple-supplied tools, or wholly GNU-supplied tools.

---

So, let's look at the first option - using Apple tools. In this case you compile with:

/usr/bin/g++ -g main.cpp -o main

and debug with:

/usr/bin/lldb ./main

and the debugger commands seem pretty similar to GDB.

---

The second option is using GCC and GDB which are normally best installed using homebrew. The installation commands are:

brew install gcc
brew install gdb

Then you will compile with something like:

/usr/local/bin/g++-8 -g main.cpp -o main

and debug with something like:

/usr/local/bin/gdb ./main

However, I cannot get this to work on macOS Mojave for the moment! I read here that GDB v8.1 doesn't work on macOS and you need to install v8.0.1 instead but cannot seem to do that with homebrew.