Inaccurate debuginfo for pointer types in PDB

[artemmukhin]

Consider the following code compiled using x86_64-pc-windows-msvc toolchain:

fn func(
    my_string: String,
    my_string_ref: &String,
    my_string_ref_mut: &mut String,
    my_string_ptr_const: *const String,
    my_string_ptr_mut: *mut String,
) {
    zzz(); // break
}

References and raw pointers are practically indistinguishable during debugging:

In the raw PDB dump, we can see that my_string_ref, my_string_ref_mut, my_string_ptr_const, and my_string_ptr_mut share the same type:

PDB dump

2848 | S_LOCAL [size = 20] `my_string`
  type=0x115A (alloc::string::String&), flags = param
2868 | S_DEFRANGE_FRAMEPOINTER_REL [size = 20]
  offset = -40, range = [0001:5606,+56)
  gaps = 2
2888 | S_DEFRANGE_REGISTER [size = 16]
  register = RCX, may have no name = false, range start = 0001:5606, length = 21
  gaps = []
2904 | S_LOCAL [size = 24] `my_string_ref`
  type=0x1071 (alloc::string::String*), flags = param
2928 | S_DEFRANGE_FRAMEPOINTER_REL [size = 16]
  offset = -32, range = [0001:5622,+56)
  gaps = 2
2944 | S_LOCAL [size = 28] `my_string_ref_mut`
  type=0x1071 (alloc::string::String*), flags = param
2972 | S_DEFRANGE_FRAMEPOINTER_REL [size = 16]
  offset = -24, range = [0001:5622,+56)
  gaps = 2
2988 | S_LOCAL [size = 32] `my_string_ptr_const`
  type=0x1071 (alloc::string::String*), flags = param
3020 | S_DEFRANGE_FRAMEPOINTER_REL [size = 16]
  offset = -16, range = [0001:5622,+56)
  gaps = 2
3036 | S_LOCAL [size = 28] `my_string_ptr_mut`
  type=0x1071 (alloc::string::String*), flags = param
3064 | S_DEFRANGE_FRAMEPOINTER_REL [size = 16]
  offset = 48, range = [0001:5622,+56)
  gaps = 2

Meta

rustc --version --verbose:

rustc 1.68.0-nightly (3020239de 2023-01-09)
binary: rustc
commit-hash: 3020239de947ec52677e9b4e853a6a9fc073d1f9
commit-date: 2023-01-09
host: x86_64-pc-windows-msvc
release: 1.68.0-nightly
LLVM version: 15.0.6