[Stdlib] Remove SwiftPrivate's dependency on Darwin.

stdlib/private/SwiftPrivate/IO.swift

@@ -11,7 +11,6 @@
 //===----------------------------------------------------------------------===//
 
 import SwiftShims
-import SwiftOverlayShims
 
 public struct _FDInputStream {
   public let fd: CInt

stdlib/public/SwiftShims/LibcOverlayShims.h

@@ -29,7 +29,6 @@ typedef int mode_t;
 #include <semaphore.h>
 #include <sys/ioctl.h>
 #include <sys/types.h>
-#include <unistd.h>
 #endif
 
 #include <errno.h>
@@ -114,32 +113,6 @@ int static inline _swift_stdlib_openat(int fd, const char *path, int oflag,
 }
 #endif
 
-static inline __swift_ssize_t
-_swift_stdlib_read(int fd, void *buf, size_t nbyte) {
-#if defined(_WIN32)
-  return _read(fd, buf, nbyte);
-#else
-  return read(fd, buf, nbyte);
-#endif
-}
-
-static inline __swift_ssize_t
-_swift_stdlib_write(int fd, const void *buf, size_t nbyte) {
-#if defined(_WIN32)
-  return _write(fd, buf, nbyte);
-#else
-  return write(fd, buf, nbyte);
-#endif
-}
-
-static inline int _swift_stdlib_close(int fd) {
-#if defined(_WIN32)
-  return _close(fd);
-#else
-  return close(fd);
-#endif
-}
-
 #if __has_feature(nullability)
 #pragma clang assume_nonnull end
 #endif

stdlib/public/SwiftShims/LibcShims.h

@@ -62,6 +62,14 @@ static inline void _swift_stdlib_free(void *ptr) {
   free(ptr);
 }
 
+// <unistd.h>
+SWIFT_RUNTIME_STDLIB_SPI
+__swift_ssize_t _swift_stdlib_read(int fd, void *buf, __swift_size_t nbyte);
+SWIFT_RUNTIME_STDLIB_SPI
+__swift_ssize_t _swift_stdlib_write(int fd, const void *buf, __swift_size_t nbyte);
+SWIFT_RUNTIME_STDLIB_SPI
+int _swift_stdlib_close(int fd);
+
 // String handling <string.h>
 SWIFT_READONLY
 static inline __swift_size_t _swift_stdlib_strlen(const char *s) {

stdlib/public/stubs/LibcShims.cpp

@@ -23,6 +23,7 @@
 
 #include <stdio.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 #include <type_traits>
 
@@ -50,3 +51,32 @@ __swift_size_t swift::_swift_stdlib_fwrite_stdout(const void *ptr,
                                                   __swift_size_t nitems) {
     return fwrite(ptr, size, nitems, stdout);
 }
+
+SWIFT_RUNTIME_STDLIB_SPI
+__swift_ssize_t
+swift::_swift_stdlib_read(int fd, void *buf, __swift_size_t nbyte) {
+#if defined(_WIN32)
+  return _read(fd, buf, nbyte);
+#else
+  return read(fd, buf, nbyte);
+#endif
+}
+
+SWIFT_RUNTIME_STDLIB_SPI
+__swift_ssize_t
+swift::_swift_stdlib_write(int fd, const void *buf, __swift_size_t nbyte) {
+#if defined(_WIN32)
+  return _write(fd, buf, nbyte);
+#else
+  return write(fd, buf, nbyte);
+#endif
+}
+
+SWIFT_RUNTIME_STDLIB_SPI
+int swift::_swift_stdlib_close(int fd) {
+#if defined(_WIN32)
+  return _close(fd);
+#else
+  return close(fd);
+#endif
+}