Make curl an optional dependency when not building FoundationNetworking

When building for WASI, FoundationNetworking is not supported, so we
should not require curl to be present. This change makes curl an optional
dependency when FoundationNetworking is not being built.

CMakeLists.txt

@@ -63,6 +63,14 @@ if(BUILD_SHARED_LIBS)
     option(FOUNDATION_BUILD_TOOLS "build tools" ON)
 endif()
 
+set(FOUNDATION_BUILD_NETWORKING_default ON)
+if(CMAKE_SYSTEM_NAME STREQUAL WASI)
+    # Networking is not supported on WASI
+    set(FOUNDATION_BUILD_NETWORKING_default OFF)
+endif()
+option(FOUNDATION_BUILD_NETWORKING "build FoundationNetworking"
+    ${FOUNDATION_BUILD_NETWORKING_default})
+
 set(CMAKE_POSITION_INDEPENDENT_CODE YES)
 
 # Fetchable dependcies
@@ -121,7 +129,9 @@ if(NOT CMAKE_SYSTEM_NAME STREQUAL WASI)
     endif()
 endif()
 find_package(LibXml2 REQUIRED)
-find_package(CURL REQUIRED)
+if(FOUNDATION_BUILD_NETWORKING)
+    find_package(CURL REQUIRED)
+endif()
 
 # Common build flags (_CFURLSessionInterface, _CFXMLInterface, CoreFoundation)
 list(APPEND _Foundation_common_build_flags

Sources/CMakeLists.txt

@@ -14,12 +14,12 @@
 
 add_subdirectory(CoreFoundation)
 add_subdirectory(_CFXMLInterface)
-if(NOT CMAKE_SYSTEM_NAME STREQUAL "WASI")
+if(FOUNDATION_BUILD_NETWORKING)
     add_subdirectory(_CFURLSessionInterface)
 endif()
 add_subdirectory(Foundation)
 add_subdirectory(FoundationXML)
-if(NOT CMAKE_SYSTEM_NAME STREQUAL "WASI")
+if(FOUNDATION_BUILD_NETWORKING)
     add_subdirectory(FoundationNetworking)
 endif()
 if(FOUNDATION_BUILD_TOOLS)