Add a CI builder for Windows building WASIp2

Should help fix a few issues that have cropped up on
WebAssembly/wasi-sdk#580

Author: alexcrichton

.github/workflows/main.yml

@@ -37,7 +37,10 @@ jobs:
             os: windows-2025
             clang_version: 20.1.8
             upload: windows-clang-20
-            args: -DBUILD_SHARED=OFF
+          - name: Build on WASIp2 Windows x86_64
+            os: windows-2025
+            clang_version: 20.1.8
+            args: -DTARGET_TRIPLE=wasm32-wasip2
 
           # Other versions of LLVM
           - name: Build with LLVM 11

CMakeLists.txt

@@ -218,7 +218,7 @@ endfunction()
 # the sysroot. The `*-shared` library is compiled with `-fPIC`.
 function(add_object_library name)
   add_library(${name}-shared OBJECT EXCLUDE_FROM_ALL ${ARGN})
-  set_target_properties(${name}-shared PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
+  set_pic(${name}-shared)
   target_compile_options(${name}-shared PRIVATE -fvisibility=default)
   add_dependencies(${name}-shared sysroot_inc)
   clang_format_target(${name}-shared)
@@ -243,6 +243,7 @@ endfunction()
 # and then ensures compile options are configured.
 function(add_internal_shared_library name)
   add_library(${name} SHARED EXCLUDE_FROM_ALL ${ARGN})
+  set_pic(${name})
   target_link_libraries(${name} PUBLIC musl-top-half-interface)
   add_dependencies(${name} sysroot-c builtins)
   target_compile_options(${name} PRIVATE -fvisibility=default)
@@ -278,6 +279,14 @@ function(sysroot_lib target file)
   endif()
 endfunction()
 
+function(set_pic target)
+  set_target_properties(${target} PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
+  # Windows needs an extra nudge to pass `-fPIC`
+  if (CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows")
+    target_compile_options(${target} PRIVATE -fPIC)
+  endif()
+endfunction()
+
 # =============================================================================
 # subdirectories
 #

cmake/ba-download.cmake

@@ -24,9 +24,11 @@ function(ba_download target repo version)
   endif()
 
   if (target STREQUAL wasmtime)
-    set(fmt xz)
+    set(fmt tar.xz)
+  elseif ((target STREQUAL wasm-component-ld) AND (os STREQUAL windows))
+    set(fmt zip)
   else()
-    set(fmt gz)
+    set(fmt tar.gz)
   endif()
 
   if (target STREQUAL wit-bindgen)
@@ -40,7 +42,7 @@ function(ba_download target repo version)
   ExternalProject_Add(
     ${target}
     EXCLUDE_FROM_ALL ON
-    URL "${repo}/releases/download/${tag}/${target}-${version}-${arch}-${os}.tar.${fmt}"
+    URL "${repo}/releases/download/${tag}/${target}-${version}-${arch}-${os}.${fmt}"
     CONFIGURE_COMMAND ""
     BUILD_COMMAND ""
     INSTALL_COMMAND ""

libc-bottom-half/CMakeLists.txt

@@ -198,7 +198,7 @@ foreach(file crt/crt1.c
   # create a custom target for each file
   add_library(${filename}.o OBJECT ${file})
   target_link_libraries(${filename}.o PUBLIC musl-top-half-interface)
-  set_target_properties(${filename}.o PROPERTIES POSITION_INDEPENDENT_CODE TRUE)
+  set_pic(${filename}.o)
   target_compile_options(${filename}.o PRIVATE -fvisibility=default)
 
   # add a custom command to compile the file