Missing/broken ˋ__int128ˋ support

[MauriceKayser]

Environment

• OS and version: Windows 11
• VS Code: 1.104.1
• C/C++ extension: 1.27.7

Description

Display of __int128 values seems broken/not supported in cpptools (Windows) in comparison to lldb (Linux).

Reproduction

1. Create a new Rust binary project: cargo new crate_name
2. Modify src/main.rs:

   struct I64(i64);
   struct U64(u64);
   struct I128(i128);
   struct U128(u128);
   
   fn main() {
       let i64_1 = 123_i64;
       let i64_2 = I64(123);
       let i128_1 = 123_i128;
       let i128_2 = I128(123);
       let u128_1 = 123_u128;
       let u128_2 = U128(123);
       let u64_1 = 123_u64;
       let u64_2 = U64(123);
       println!();
   }
   

3. Set a breakpoint at println!() and debug the program by clicking on the "Debug" label next to fn main().

Expected result (output of lldb on Linux)

Variables
  Locals
    i64_1  = 123        (long)
    i64_2  = {__0:123}  (crate_name::I64)
      __0  = 123        (long)
    i128_1 = 123        (__int128)
    i128_2 = {__0:123}  (crate_name::I128)
      __0  = 123        (__int128)
    u128_1 = 123        (unsigned __int128)
    u128_2 = {__0:123}  (crate_name::U128)
      __0  = 123        (unsigned __int128)
    u64_1  = 123        (unsigned long)
    u64_2  = {__0:123}  (crate_name::U64)
      __0  = 123        (unsigned long)

Actual result (output of cpptools on Windows)

Variables
  Locals
    i64_1  = 123                                 (__int64)
    i64_2  = {__0=123 }                          (crate_name::I64)
      __0  = 123                                 (__int64)
    i128_1 = An unspecified error has occurred.  (i128_1)
    i128_2 = {__0=??? }                          (crate_name::I128)
      __0  = <Unable to read memory>             (__0)
    u64_1  = 123                                 (unsigned __int64)
    u64_2  = {__0=123 }                          (crate_name::U64)
      __0  = 123                                 (unsigned __int64)
    u128_1 = An unspecified error has occurred.  (u128_1)
    u128_2 = {__0=??? }                          (crate_name::U128)
      __0  = <Unable to read memory>             (__0)

Differences (normalized)

• Lines 9 & 12: An unspecified error has occurred. instead of 123.
• Lines 10 & 13: ??? instead of 123.
• Lines 11 & 14: <Unable to read memory> instead of 123.
• Lines 9, 11, 12, 14: (variable name) instead of (type name), e.g. (__0) instead of (__int128).
• Lines 4, 7, 10, 13: Trailing whitespace after the variable value: {__0:123 } instead of {__0:123}.

More information

IDA (disassembler) extracts the following structs from the PDB:

00000000 struct crate_name::I64 // sizeof=0x8
00000000 {
00000000     __int64 __0;
00000008 };

00000000 struct crate_name::U64 // sizeof=0x8
00000000 {
00000000     unsigned __int64 __0;
00000008 };

00000000 struct crate_name::I128 // sizeof=0x10
00000000 {
00000000     __int128 __0;
00000010 };

00000000 struct crate_name::U128 // sizeof=0x10
00000000 {
00000000     unsigned __int128 __0;
00000010 };