Missing CMAKE_ASM_NASM_COMPILER when compiling gRPC with MS visual studio - c++

Question

I am trying to build gRPC C++ (1.48.0) with Visual Studio 2022 on Windows 10. It's a CMake build (cmake 3.22.22011901-MSVC_2)
I was able to build everything else but am stuck at BoringSSL. The relevant CMakeList is trying to enable_language(ASM_NASM). Context below:
if(NOT OPENSSL_NO_ASM)
if(UNIX)
enable_language(ASM)
# Clang's integerated assembler does not support debug symbols.
if(NOT CMAKE_ASM_COMPILER_ID MATCHES "Clang")
set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -Wa,-g")
endif()
# CMake does not add -isysroot and -arch flags to assembly.
if(APPLE)
if(CMAKE_OSX_SYSROOT)
set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -isysroot \"${CMAKE_OSX_SYSROOT}\"")
endif()
foreach(arch ${CMAKE_OSX_ARCHITECTURES})
set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -arch ${arch}")
endforeach()
endif()
else()
set(CMAKE_ASM_NASM_FLAGS "${CMAKE_ASM_NASM_FLAGS} -gcv8")
enable_language(ASM_NASM)
endif()
endif()
It gives me CMake Error: "No CMAKE_ASM_NASM_COMPILER could be found."
I don't know enough about compilers / assemblers, and why boringSSL would need a specific one (which none of the other modules needed including gRPC).
What is the recommended way to fix this?

Answer 1

To answer at least some of my questions for my future self, and others who are at a similar point in the journey.
NASM is an assembly compiler (assembler). BoringSSL has some assembly language code, which is why it needs an assembly compiler (and gRPC or other modules don't). I'll let someone else opine on why NASM and not some other assembler.
To fix the issue, you have to download/install the relevant NASM executable from here. I found it easier to download the exe, place it in a folder, add that folder to the PATH and set another env variable ASM_NASM with the name of nasm.exe.
Once I did that, boringSSL and the whole gRPC compiled quite smoothly.