build(docker): overwrite dockcross wasi CMake toolchain file with our flags

For emulated process clocks, signals, etc.

Author: thewtex

src/docker/itk-wasm-base/Dockerfile

@@ -9,6 +9,7 @@ LABEL org.opencontainers.image.source="https://github.com/InsightSoftwareConsort
 WORKDIR /
 
 COPY itk_wasm_env_vars.sh /
+COPY wasi-toolchain.cmake /opt/wasi-sdk/Toolchain.cmake
 
 # Note: on entry, emsdk will prepend to the path with its own node, so add to an earlier path
 ENV NODE_TAG=v22.9.0

src/docker/itk-wasm-base/wasi-toolchain.cmake

@@ -0,0 +1,15 @@
+set(WASI_SDK_PREFIX $ENV{WASI_SDK_PATH})
+include($ENV{WASI_SDK_PATH}/share/cmake/wasi-sdk.cmake)
+
+set(WASI 1)
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -flto -msimd128 -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL -D_WASI_EMULATED_PTHREAD")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -msimd128 -D_WASI_EMULATED_PROCESS_CLOCKS -D_WASI_EMULATED_SIGNAL -D_WASI_EMULATED_PTHREAD")
+set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -flto -lc-printscan-long-double -lwasi-emulated-process-clocks -lwasi-emulated-signal -lwasi-emulated-pthread")
+
+set(CMAKE_FIND_ROOT_PATH $ENV{CROSS_ROOT})
+set(CMAKE_SYSROOT $ENV{WASI_SYSROOT})
+
+set(CMAKE_C_COMPILER /usr/local/bin/clang-wasi-sysroot.sh)
+set(CMAKE_CXX_COMPILER /usr/local/bin/clang++-wasi-sysroot.sh)
+
+set(CMAKE_CROSSCOMPILING_EMULATOR /wasi-runtimes/wasmtime/bin/wasmtime-pwd.sh)