C / C++

Debugger: GDB 14+ (--interpreter=dap) or lldb-dap Status: Stable Transport: stdin/stdout (not TCP)

Prerequisites

GDB (Linux)

# Ubuntu/Debian
sudo apt install gdb
gdb --version   # must be 14+

# Fedora/RHEL
sudo dnf install gdb

lldb-dap (macOS)

# Via Xcode Command Line Tools
xcode-select --install

# Or via Homebrew
brew install llvm
lldb-dap --version

GDB 14 added native DAP support via --interpreter=dap. Earlier versions are not supported.

Quick Start

The adapter compiles source files automatically with debug symbols if you provide a .c or .cpp file:

# Compile and debug a C program
krometrail launch "gcc -g -o app app.c && ./app" --break app.c:42

# Or let the adapter compile:
krometrail launch "app.c" --break app.c:42

# C++ with g++
krometrail launch "g++ -g -o app app.cpp && ./app" --break app.cpp:42

# Debug an existing binary
krometrail launch "./app" --break app.c:42 --language cpp

Conditional Breakpoints

C/C++ expressions:

krometrail break "order.c:147 when discount < 0"
krometrail break "loop.c:25 when i == 99"
krometrail break "api.c:30 when strcmp(method, \"POST\") == 0"

Inspecting C/C++ Values

Structs and unions are shown with their fields:

Locals:
  order    = {id=482, total=149.97, tier=2}
  discount = -149.97
  items    = 0x... -> [{price=49.99, qty=3}, ...]

Pointers show the address and the dereferenced value. Use debug_evaluate with GDB expressions for deeper inspection:

krometrail eval "order->tier"
krometrail eval "*(double*)(&raw_value)"
krometrail eval "((Order*)ptr)->id"

stdin/stdout Transport

Unlike other adapters, C/C++ uses stdin/stdout transport (GDB's DAP mode communicates via pipes, not TCP). This is handled transparently — no configuration needed.

Tips

• Always compile with -g (debug info) and without -O2/-O3 (optimization breaks debug info)
• For CMake projects: cmake -DCMAKE_BUILD_TYPE=Debug .. then debug the built binary
• Thread debugging works — debug_threads lists pthreads created by pthread_create
• Valgrind and AddressSanitizer can be combined: krometrail launch "valgrind --vgdb=yes ./app" for memory debugging

GDB vs lldb-dap

krometrail doctor checks for both. GDB is the default on Linux; lldb-dap is preferred on macOS. Override with --language if needed:

krometrail launch "./app" --language cpp