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1bed0047ea Add AddressSanitizer support for clang-cl builds

Select the clang-cl-asan CMake preset (RelWithDebInfo, clang-cl,
ADDRESS_SANITIZER=ON) to instrument first-party code with AddressSanitizer.
The wiring lives in cmake/AddressSanitizer.cmake; SANITIZERS.md tells how to
add the clang-cl tools, build, and read the report.

Details:
- Add the clang-cl-asan preset so the asan build is one selection in Visual
  Studio, and a base for a CMakeUserPresets.json to inherit.
- Instrument first-party code only; the vendored libraries keep default flags.
- Use the release CRT and disable MSVC-STL container annotations, so
  instrumented and un-instrumented TUs stay compatible.
- Pass /bigobj to the TUs asan inflates past the COFF section cap.
- Link the asan runtime for clang-cl (lld-link does not infer it).
- Stub Bink into the exe: retail binkw32.dll cannot load in an asan process
  (its image base is the 32-bit shadow), so compile no-op exports instead.
- Route the asan report to gamedir/asan.report.<pid>, since every app is a
  WIN32 GUI app with no console to receive the default stderr report.
- Opt functions with 32-bit inline __asm out of instrumentation with
  cmake/asan-ignorelist.txt, one function at a time (asan reserves a register
  the asm needs). The rest of each translation unit stays instrumented.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2026-08-20 23:22:38 -03:00

1.8 KiB

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AddressSanitizer

AddressSanitizer (asan) finds memory errors at runtime: out-of-bounds accesses, use-after-free, and similar. It reports the exact faulting access.

Requirements

asan requires C++ Clang tools for Windows (MSVC's AddressSanitizer does not support -fsanitize-ignorelist).

It is NOT installed by default . You can install it via the Visual Studio Installer.

Build and run

Either use the included clang-cl-asan preset, or inherit from it in your own CMakeUserPresets.json

Debug from Visual Studio

asan needs clang_rt.asan_dynamic-i386.dll at run time. MSVC ships this DLL with the x86 tools, but Visual Studio does not add that folder to the debugger PATH. To start the exe with F5, add the tools folder to the debugger PATH:

Access the CMake Targets View in Solution Explorer
Right-click the exe target (for example JA2.exe) and select Add Debug Configuration. Visual Studio creates launch.vs.json in the .vs folder and adds a configuration with the correct projectTarget.
Add an env block to that configuration:

      "env": {
        "PATH": "C:\\Program Files\\Microsoft Visual Studio\\18\\Community\\VC\\Tools\\MSVC\\14.51.36231\\bin\\Hostx64\\x86;${env.PATH}"
      }

Set the first path to the bin\Hostx64\x86 folder of your MSVC tools. To find it, search your Visual Studio installation for clang_rt.asan_dynamic-i386.dll. Your edition (Community), MSVC version (14.51.36231), and host (Hostx64 or Hostx86) can differ.

Reading the report

Every app is a GUI app with no console, so asan writes the report to a file by default:

gamedir/asan.report.<pid>

When asan finds an error, the run stops and the report names the faulting access. Set the ASAN_OPTIONS environment variable to change asan behaviour.