Merge pull request #14564 from compnerd/export

runtime: fix build of the runtime tests for Windows

Author: compnerd

unittests/runtime/CMakeLists.txt

@@ -47,6 +47,13 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
     $<TARGET_OBJECTS:swiftRuntime${SWIFT_PRIMARY_VARIANT_SUFFIX}>
     )
 
+  # The local stdlib implementation provides definitions of the swiftCore
+  # interfaes to avoid pulling in swiftCore itself.  Build the SwiftRuntimeTests
+  # with swiftCore_EXPORTS to permit exporting the stdlib interfaces.
+  target_compile_definitions(SwiftRuntimeTests
+                             PRIVATE
+                               swiftCore_EXPORTS)
+
   # FIXME: cross-compile for all variants.
   target_link_libraries(SwiftRuntimeTests
     swiftCore${SWIFT_PRIMARY_VARIANT_SUFFIX}