Disable stable ABI on freestanding stdlib (#39674)

Author: kubamracek

stdlib/cmake/modules/AddSwiftStdlib.cmake

@@ -1726,10 +1726,7 @@ function(add_swift_target_library name)
   endif()
 
   # Turn off implicit import of _Concurrency when building libraries
-  if(SWIFT_ENABLE_EXPERIMENTAL_CONCURRENCY)
-    list(APPEND SWIFTLIB_SWIFT_COMPILE_FLAGS 
-                      "-Xfrontend;-disable-implicit-concurrency-module-import")
-  endif()
+  list(APPEND SWIFTLIB_SWIFT_COMPILE_FLAGS "-Xfrontend;-disable-implicit-concurrency-module-import")
 
   # Turn off implicit import of _Distributed when building libraries
   if(SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED)

stdlib/cmake/modules/SwiftSource.cmake

@@ -894,6 +894,10 @@ function(_compile_swift_files
         COMMENT "Generating ${module_file}")
 
     if(SWIFTFILE_STATIC)
+      set(command_copy_interface_file)
+      if(interface_file)
+        set(command_copy_interface_file COMMAND "${CMAKE_COMMAND}" "-E" "copy" ${interface_file} ${interface_file_static})
+      endif()
       add_custom_command_target(
         module_dependency_target_static
         COMMAND
@@ -903,8 +907,7 @@ function(_compile_swift_files
           "${CMAKE_COMMAND}" "-E" "copy" ${module_file} ${module_file_static}
         COMMAND
           "${CMAKE_COMMAND}" "-E" "copy" ${module_doc_file} ${module_doc_file_static}
-        COMMAND
-          "${CMAKE_COMMAND}" "-E" "copy" ${interface_file} ${interface_file_static}
+        ${command_copy_interface_file}
         OUTPUT ${module_outputs_static}
         DEPENDS
           "${module_dependency_target}"

stdlib/public/core/Mirror.swift

@@ -481,19 +481,31 @@ public struct Mirror {
     children: C,
     displayStyle: DisplayStyle? = nil,
     ancestorRepresentation: AncestorRepresentation = .generated
-  ) where C.Element == Child { Builtin.unreachable() }
+  ) where C.Element == Child {
+    // Can't use Builtin.unreachable() due to
+    // https://bugs.swift.org/browse/SR-15300
+    self.init(reflecting: subject)
+  }
   public init<Subject, C: Collection>(
     _ subject: Subject,
     unlabeledChildren: C,
     displayStyle: DisplayStyle? = nil,
     ancestorRepresentation: AncestorRepresentation = .generated
-  ) { Builtin.unreachable() }
+  ) {
+    // Can't use Builtin.unreachable() due to
+    // https://bugs.swift.org/browse/SR-15300
+    self.init(reflecting: subject)
+  }
   public init<Subject>(
     _ subject: Subject,
     children: KeyValuePairs<String, Any>,
     displayStyle: DisplayStyle? = nil,
     ancestorRepresentation: AncestorRepresentation = .generated
-  ) { Builtin.unreachable() }
+  ) {
+    // Can't use Builtin.unreachable() due to
+    // https://bugs.swift.org/browse/SR-15300
+    self.init(reflecting: subject)
+  }
   public let subjectType: Any.Type
   public let children: Children
   public let displayStyle: DisplayStyle?

test/SIL/crash-sr-15300.swift

@@ -0,0 +1,12 @@
+// RUN: %target-swift-frontend -Osize -parse-stdlib -enable-ossa-modules -emit-sil %s
+
+// https://bugs.swift.org/browse/SR-15300
+// XFAIL: *
+
+import Swift
+
+public struct A {
+  public init(_ pairs: KeyValuePairs<Any, Any>) {
+    Builtin.unreachable()
+  }
+}

test/lit.cfg

@@ -941,6 +941,10 @@ if run_vendor == 'apple':
         # Build all "freestanding" tests with -disable-objc-interop
         swift_execution_tests_extra_flags += ' -Xfrontend -disable-objc-interop'
 
+        # The Concurrency module is not available in "freestanding" mode.
+        swift_execution_tests_extra_flags += \
+                ' -Xfrontend -disable-implicit-concurrency-module-import'
+
         # Link all "freestanding" tests with -dead_strip, which can effectively
         # even remove parts of the stdlib and runtime, if it's not needed. Since
         # it's a very desired behavior, let's enable it for all executable tests.

utils/build-presets.ini

@@ -2463,6 +2463,7 @@ build-swift-static-stdlib=1
 swift-objc-interop=0
 swift-enable-compatibility-overrides=0
 swift-enable-reflection=0
+swift-stdlib-stable-abi=0
 swift-stdlib-has-dladdr=0
 swift-stdlib-supports-backtrace-reporting=0
 swift-stdlib-has-darwin-libmalloc=0