Debugging Rust with gdb

Question

I'm aware of the debugging Rust questions here on StackOverflow and I also used gdb before with Go. However, I'm running into a problem where it seems gdb is unable to locate the debug symbols.

Consider this complex program in main.rs?

pub fn main () {
    println!("run");
}

I compile it with debug symbols

rustc -g main.rs

Then I run gdb

gdb main

This gives the first clue that something with the loading of debug symbols is not quite right.

Now when I'm in gdb and type

list

it leaves me with some C code which isn't what I expect.

What am I doing wrong? My gdb version is 7.7 and I'm on OS X 10.9.2 (13C64). My rustc version is rustc 0.11.0-pre (3035d8dfb13077e195eb056568183911c90c1b4b 2014-07-02 21:26:40 +0000)

It may also be helpful to see the output of `gdb --configuration``

$ gdb --configuration
This GDB was configured as follows:
   configure --host=x86_64-apple-darwin13.1.0 --target=x86_64-apple-darwin13.1.0
             --with-auto-load-dir=:${prefix}/share/auto-load
             --with-auto-load-safe-path=:${prefix}/share/auto-load
             --with-expat
             --with-gdb-datadir=/usr/local/share/gdb (relocatable)
             --with-jit-reader-dir=/usr/local/lib/gdb (relocatable)
             --without-libunwind-ia64
             --without-lzma
             --with-python=/System/Library/Frameworks/Python.framework/Versions/2.7
             --with-separate-debug-dir=/usr/local/lib/debug (relocatable)
             --with-zlib
             --without-babeltrace

Answer 1

Ok, I figured out what was wrong. I have to manually emit the main.o file. I thought the -g parameter would just cut it.

Now that I run

rustc -g main.rs --emit="obj,link"

I can run

gdb main

And everything works like a charme.

I created two aliases for my bash to make things simple:

alias rd='rustc -g --emit="obj,link"'

compile_and_run() {
     rustc -g --emit="obj,link" $1 && gdb ${1%.*}
}

alias rdr=compile_and_run

Now I can just call rdr main.rs and it will start debugging main.rs with gdb.

Answer 2

Same question, later Rust version (1.0.0-beta), totally different answer:

In GDB, when debugging a Rust executable, break main sets a breakpoint in some setup code that is part of the Rust standard library. This isn't what you want.

Instead type: break $YOUR_CRATE::main, substituting the name of your program for $YOUR_CRATE.