[static] ELF platforms can build static binaries.

Static binaries can be built on other platforms, not just Linux; we use
the same check for ELF output to condition static binaries like for
static stdlib. However, since some ELF platforms don't need -ldl, pull
this out into a conditionally set variable.

As a side note: on OpenBSD, lld at HEAD does not work to link the test
binary, but the platform lld works fine, so XFAIL this temporarily.

Author: 3405691582

stdlib/public/runtime/CMakeLists.txt

@@ -96,9 +96,15 @@ else()
   endif()
 endif()
 
+# TODO: Put the logic for finding libdl in a module, similar to ICU.
+set(libdl)
+if(SWIFT_BUILD_STATIC_STDLIB AND "${sdk}" STREQUAL "LINUX")
+  set(libdl -ldl)
+endif()
+
 
 set(sdk "${SWIFT_HOST_VARIANT_SDK}")
-if(SWIFT_BUILD_STATIC_STDLIB AND "${sdk}" STREQUAL "LINUX")
+if(SWIFT_BUILD_STATIC_STDLIB AND ${SWIFT_SDK_${sdk}_OBJECT_FORMAT} STREQUAL ELF)
   list(REMOVE_ITEM swift_runtime_sources ImageInspectionELF.cpp)
   set(static_binary_lnk_file_list)
   string(TOLOWER "${sdk}" lowercase_sdk)
@@ -157,7 +163,7 @@ if(SWIFT_BUILD_STATIC_STDLIB AND "${sdk}" STREQUAL "LINUX")
 ${libicu_i18n_a}
 ${libicu_uc_a}
 ${libicu_data_a}
--ldl
+${libdl}
 -lstdc++
 -lm")
 
@@ -166,7 +172,7 @@ ${libicu_data_a}
                              DESTINATION "lib/swift_static/${lowercase_sdk}"
                              COMPONENT stdlib)
   add_custom_target(static_binary_magic ALL DEPENDS ${static_binary_lnk_file_list})
-  foreach(arch IN LISTS SWIFT_SDK_LINUX_ARCHITECTURES)
+  foreach(arch IN LISTS SWIFT_SDK_${sdk}_ARCHITECTURES)
     add_dependencies(static_binary_magic ${swift_image_inspection_${arch}_static})
   endforeach()
   add_dependencies(static_binary_magic ${swift_image_inspection_static_primary_arch})
@@ -286,7 +292,7 @@ foreach(sdk ${SWIFT_CONFIGURED_SDKS})
       string(TOLOWER "${sdk}" lowercase_sdk)
       set(linkfile ${lowercase_sdk}/static-stdlib-args.lnk)
       file(WRITE "${SWIFTSTATICLIB_DIR}/${linkfile}" "
--ldl
+${libdl}
 -lpthread
 -lswiftCore
 -lswiftImageInspectionShared

test/Driver/static-executable.swift

@@ -1,6 +1,7 @@
 // Create a self contained binary
 // REQUIRES: OS=linux-gnu
 // REQUIRES: static_stdlib
+// XFAIL: OS=openbsd
 print("hello world!")
 // RUN: %empty-directory(%t)
 // RUN: %target-swiftc_driver -static-executable -o %t/static-executable %s

test/Driver/static-stdlib-linux.swift test/Driver/static-stdlib.swifttest/Driver/static-stdlib-linux.swift renamed to test/Driver/static-stdlib.swift

@@ -1,5 +1,5 @@
 // Statically link a "hello world" program
-// REQUIRES: OS=linux-gnu
+// REQUIRES: OS=linux-gnu || OS=openbsd
 // REQUIRES: static_stdlib
 print("hello world!")
 // RUN: %empty-directory(%t)

unittests/runtime/CMakeLists.txt

@@ -29,7 +29,8 @@ if(("${SWIFT_HOST_VARIANT_SDK}" STREQUAL "${SWIFT_PRIMARY_VARIANT_SDK}") AND
   endif()
 
   set(swift_runtime_test_extra_libraries)
-  if(SWIFT_BUILD_STATIC_STDLIB AND "${SWIFT_HOST_VARIANT_SDK}" STREQUAL "LINUX")
+  if(SWIFT_BUILD_STATIC_STDLIB AND
+     ${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_OBJECT_FORMAT} STREQUAL ELF)
     list(APPEND swift_runtime_test_extra_libraries 
       $<TARGET_FILE:swiftImageInspectionShared-${SWIFT_SDK_${SWIFT_HOST_VARIANT_SDK}_LIB_SUBDIR}-${SWIFT_HOST_VARIANT_ARCH}>)
   endif()