implement method calls

[tromey]

Make method calls work. There are two problems here:

• basic method calls. This probably requires implementing OP_FUNCALL in our evaluator
• calls via traits. I think we probably don't have the necessary debuginfo for this, so we'll need to at least file a bug against rustc

[tromey]

Simple method calls are done. Trait calls require some debuginfo fixes in rustc.

[m4b]

I can't seem to get simple method calls to work.

For a simple method call I would expect that strtab.get(10) would work in a gdb session, but it does not seem to. In my case, and I'm just guessing, but I believe the method is compiled as goblin::elf::strtab::{{impl}}::get (which is also problematic, since I cannot do info addr <method with squiggly braces> due to syntax errors 😕 )

Here is the struct+impl:

pub struct Strtab<'a> {
    bytes: &'a [u8],
}

// get_str is here

impl<'a> Strtab<'a> {
    pub fn get(&self, idx: usize) -> &'a str {
        get_str(idx, self.bytes)
    }

Here is the gdb transcript:

(gdb) whatis strtab
type = goblin::elf::strtab::Strtab
(gdb) ptype strtab
type = struct goblin::elf::strtab::Strtab {
  bytes: &[u8],
}
(gdb) p strtab
$8 = goblin::elf::strtab::Strtab {bytes: &[u8] {data_ptr: 0x5555557e8cc0 "@\016~UUU\000", length: 1498}}
(gdb) p goblin::elf::strtab::
Display all 200 possibilities? (y or n)
(gdb) p goblin::elf::strtab
strtab                                                      strtab::{{impl}}::get
strtab::{{impl}}                                            strtab::{{impl}}::index
strtab::{{impl}}::as_vec                                    strtab::Strtab
strtab::{{impl}}::as_vec::__STATIC_FMTSTR                   strtab::Strtab::as_vec::h30e94333d8995774
strtab::{{impl}}::fmt                                       strtab::Strtab::as_vec::__STATIC_FMTSTR::hf34e6606a77a043e
strtab::{{impl}}::fmt::__STATIC_FMTSTR                      strtab::Strtab::from_fd::h97f5e1513471d07e
strtab::{{impl}}::from_fd                                   strtab::Strtab::from_raw::h87949dc838301e59
strtab::{{impl}}::from_raw                                  strtab::Strtab::get::ha7566016f4176df0
(gdb) p goblin::elf::strtab{{
Display all 200 possibilities? (y or n)
(gdb) p goblin::elf::strtab::
Display all 200 possibilities? (y or n)
(gdb) p goblin::elf::strtab::{{
Display all 200 possibilities? (y or n)
(gdb) p goblin::elf::strtab::{{image..SharedObject$LT$$u27$static$GT$::drop.8862::hff056006e8f8f55f 
syntax error in expression, near `{{image..SharedObject$LT$$u27$static$GT$::drop.8862::hff056006e8f8f55f'.
(gdb) p goblin::elf::strtab::{{impl}}::get
syntax error in expression, near `{{impl}}::get'.
(gdb) info addr goblin::elf::strtab::{{impl}}::get
No symbol "goblin::elf::strtab::{{impl}}::get" in current context.
(gdb) info addr strtab::{{impl}}::get
No symbol "strtab::{{impl}}::get" in current context.
(gdb) info addr elf::strtab::{{impl}}::get
No symbol "elf::strtab::{{impl}}::get" in current context.
(gdb) info addr goblin::elf::strtab::{{impl}}::get
No symbol "goblin::elf::strtab::{{impl}}::get" in current context.
(gdb) info addr goblin::elf::strtab::
{{impl}}                                            {{impl}}::index
{{impl}}::as_vec                                    Strtab
{{impl}}::as_vec::__STATIC_FMTSTR                   Strtab::as_vec::h30e94333d8995774
{{impl}}::fmt                                       Strtab::as_vec::__STATIC_FMTSTR::hf34e6606a77a043e
{{impl}}::fmt::__STATIC_FMTSTR                      Strtab::from_fd::h97f5e1513471d07e
{{impl}}::from_fd                                   Strtab::from_raw::h87949dc838301e59
{{impl}}::from_raw                                  Strtab::get::ha7566016f4176df0
{{impl}}::get                                       
(gdb) info addr goblin::elf::strtab::Strtab
Strtab                                              Strtab::from_fd::h97f5e1513471d07e
Strtab::as_vec::h30e94333d8995774                   Strtab::from_raw::h87949dc838301e59
Strtab::as_vec::__STATIC_FMTSTR::hf34e6606a77a043e  Strtab::get::ha7566016f4176df0
(gdb) info addr goblin::elf::strtab::Strtab::
as_vec::h30e94333d8995774                   from_fd::h97f5e1513471d07e                  get::ha7566016f4176df0
as_vec::__STATIC_FMTSTR::hf34e6606a77a043e  from_raw::h87949dc838301e59   

Or perhaps I'm misunderstanding?

[tromey]

What version of rustc are you using?
There was a known bug with nightly in this area.
A fix for that landed but I haven't re-tested since then.

[m4b]

I'm on nightly rustc 1.10 in this case.