Link warning: seeing "19.0", expected "20" [-Wversion-check]

[CodingMarkus]

Version of emscripten/emsdk:

# emcc -v
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.66-git
clang version 19.0.0git
Target: wasm32-unknown-emscripten
Thread model: posix
InstalledDir: /opt/local/libexec/llvm-devel/bin

As you can see, my version of emcc uses clang version 19. But when I build binaries out of object files, I often get this warning:

emcc: warning: LLVM version for clang executable "/opt/local/libexec/llvm-devel/bin/clang" appears incorrect (seeing "19.0", expected "20") [-Wversion-check]

Where does "20" come from? I have no clang 20 installed on my system for sure. clang 20 doesn't even exist yet.

I have clang/llvm 19 and 16 installed, standalone, and the emcc version above (which comes with its own llvm 19 copy) and all code linked by emcc has been built with this emcc version (all *.o files were created by the same emcc that also performs the linking) and thus with clang 19.

[sbc100]

emscripten expects clang built from tip-to-tree, and llvm tip-of-tree currently reports version 20.

See #11362 for more on this issue.

The simplest way to get the correct version of llvm is to install via emsdk install latest.

[sbc100]

I'm guessing you were using an older version of emcc which expected version 19 and then at some point you updated to a newer version that included #22273 (from back in July where we updated the requirement from 19 to 20)