[Platform] Update musl modulemap and improve musl platform support.

stdlib/public/Platform/CMakeLists.txt

@@ -161,8 +161,9 @@ add_swift_target_library(swiftMusl ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OV
       ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
       ${swift_platform_compile_flags}
     LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
-    TARGET_SDKS MUSL
-    INSTALL_IN_COMPONENT sdk-overlay)
+    TARGET_SDKS LINUX_STATIC
+    INSTALL_IN_COMPONENT sdk-overlay
+    DEPENDS musl_modulemap)
 
 add_swift_target_library(swiftWASILibc ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVERLAY
     ${swift_platform_sources}
@@ -198,6 +199,80 @@ add_swift_target_library(swiftCRT ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVE
     TARGET_SDKS WINDOWS
     INSTALL_IN_COMPONENT sdk-overlay)
 
+foreach(sdk ${SWIFT_SDKS})
+  # Add more platforms supporting Musl to these checks,
+  if(NOT "${sdk}" STREQUAL "LINUX_STATIC")
+    continue()
+  endif()
+
+  set(musl_modulemap "musl.modulemap")
+  set(musl_header "SwiftMusl.h")
+
+  foreach(arch ${SWIFT_SDK_${sdk}_ARCHITECTURES})
+    set(arch_subdir "${SWIFT_SDK_${sdk}_LIB_SUBDIR}/${arch}")
+    set(module_dir "${SWIFTLIB_DIR}/${arch_subdir}")
+    set(module_dir_static "${SWIFTSTATICLIB_DIR}/${arch_subdir}")
+
+    set(musl_modulemap_out "${module_dir}/${musl_modulemap}")
+    set(musl_modulemap_out_static "${module_dir_static}/${musl_modulemap}")
+    set(musl_header_out "${module_dir}/${musl_header}")
+    set(musl_header_out_static "${module_dir_static}/${musl_header}")
+
+    add_custom_command_target(
+      copy_musl_modulemap
+      COMMAND
+        "${CMAKE_COMMAND}" "-E" "make_directory" ${module_dir}
+      COMMAND
+        "${CMAKE_COMMAND}" "-E" "copy"
+          ${CMAKE_CURRENT_LIST_DIR}/${musl_modulemap}
+          ${musl_modulemap_out}
+      COMMAND
+        "${CMAKE_COMMAND}" "-E" "copy"
+          ${CMAKE_CURRENT_LIST_DIR}/${musl_header}
+          ${musl_header_out}
+      OUTPUT ${musl_modulemap_out} ${musl_header_out}
+      COMMENT "Copying Musl modulemap to resources")
+
+    list(APPEND musl_modulemap_target_list ${copy_musl_modulemap})
+
+    if(SWIFT_BUILD_STATIC_STDLIB OR SWIFT_SDK_${sdk}_STATIC_ONLY)
+      add_custom_command_target(
+        copy_musl_modulemap_static
+        COMMAND
+          "${CMAKE_COMMAND}" "-E" "make_directory" ${module_dir_static}
+        COMMAND
+          "${CMAKE_COMMAND}" "-E" "copy"
+            ${CMAKE_CURRENT_LIST_DIR}/${musl_modulemap}
+            ${musl_modulemap_out_static}
+        COMMAND
+          "${CMAKE_COMMAND}" "-E" "copy"
+            ${CMAKE_CURRENT_LIST_DIR}/${musl_header}
+            ${musl_header_out_static}
+        OUTPUT ${musl_modulemap_out_static} ${musl_header_out_static}
+        COMMENT "Copying Musl modulemap to static resources")
+
+      list(APPEND musl_modulemap_target_list ${copy_musl_modulemap_static})
+
+      swift_install_in_component(FILES "${musl_modulemap_out_static}"
+                                 DESTINATION "lib/swift_static/${arch_subdir}"
+                                 COMPONENT sdk-overlay)
+      swift_install_in_component(FILES "${musl_header_out_static}"
+                                 DESTINATION "lib/swift_static/${arch_subdir}"
+                                 COMPONENT sdk-overlay)
+    endif()
+
+    swift_install_in_component(FILES "${musl_modulemap_out}"
+                               DESTINATION "lib/swift/${arch_subdir}"
+                               COMPONENT sdk-overlay)
+    swift_install_in_component(FILES "${musl_header_out}"
+                               DESTINATION "lib/swift/${arch_subdir}"
+                               COMPONENT sdk-overlay)
+  endforeach()
+endforeach()
+add_custom_target(musl_modulemap DEPENDS ${musl_modulemap_target_list})
+set_property(TARGET musl_modulemap PROPERTY FOLDER "Miscellaneous")
+add_dependencies(sdk-overlay musl_modulemap)
+
 set(glibc_modulemap_target_list)
 foreach(sdk ${SWIFT_SDKS})
   if(NOT "${sdk}" STREQUAL "LINUX" AND
@@ -238,7 +313,7 @@ foreach(sdk ${SWIFT_SDKS})
         FLAGS "-DCMAKE_SDK=${sdk}")
     list(APPEND glibc_modulemap_target_list ${glibc_header_target})
 
-    if(SWIFT_BUILD_STATIC_STDLIB)
+    if(SWIFT_BUILD_STATIC_STDLIB OR SWIFT_SDK_${sdk}_STATIC_ONLY)
       add_custom_command_target(
         copy_glibc_modulemap_header_static
         COMMAND
@@ -287,7 +362,7 @@ foreach(sdk ${SWIFT_SDKS})
                                DESTINATION "lib/swift/${arch_subdir}"
                                COMPONENT sdk-overlay)
 
-    if(SWIFT_BUILD_STATIC_STDLIB)
+    if(SWIFT_BUILD_STATIC_STDLIB OR SWIFT_SDK_${sdk}_STATIC_ONLY)
       swift_install_in_component(FILES "${glibc_modulemap_out}"
                                  DESTINATION "lib/swift_static/${arch_subdir}"
                                  COMPONENT sdk-overlay)

stdlib/public/Platform/Platform.swift

@@ -344,7 +344,9 @@ public var SIG_IGN: sig_t { return unsafeBitCast(1, to: sig_t.self) }
 public var SIG_ERR: sig_t { return unsafeBitCast(-1, to: sig_t.self) }
 public var SIG_HOLD: sig_t { return unsafeBitCast(3, to: sig_t.self) }
 #elseif os(Linux) || os(FreeBSD) || os(PS4) || os(Android) || os(Haiku)
+#if !canImport(SwiftMusl)
 public typealias sighandler_t = __sighandler_t
+#endif
 
 public var SIG_DFL: sighandler_t? { return nil }
 public var SIG_IGN: sighandler_t {
@@ -487,7 +489,7 @@ extension Duration {
 public var environ: UnsafeMutablePointer<UnsafeMutablePointer<CChar>?> {
   return _swift_stdlib_getEnviron()
 }
-#elseif os(Linux)
+#elseif os(Linux) && !canImport(SwiftMusl)
 public var environ: UnsafeMutablePointer<UnsafeMutablePointer<CChar>?> {
   return __environ
 }

stdlib/public/Platform/SwiftMusl.h

@@ -0,0 +1,187 @@
+//===--- SwiftMusl.h ------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+#include <assert.h>
+#include <float.h>
+#include <iso646.h>
+#include <limits.h>
+#include <stdalign.h>
+#include <stdarg.h>
+#include <stdatomic.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <time.h>
+#include <tgmath.h>
+#include <complex.h>
+#include <ctype.h>
+#include <errno.h>
+#include <fenv.h>
+#include <inttypes.h>
+#include <locale.h>
+#include <math.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdnoreturn.h>
+#include <string.h>
+#include <threads.h>
+#include <uchar.h>
+#include <wchar.h>
+#include <wctype.h>
+#include <aio.h>
+#include <arpa/inet.h>
+#include <arpa/ftp.h>
+#include <arpa/nameser.h>
+#include <arpa/nameser_compat.h>
+#include <arpa/telnet.h>
+#include <arpa/tftp.h>
+#include <cpio.h>
+#include <dirent.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <fmtmsg.h>
+#include <fnmatch.h>
+#include <ftw.h>
+#include <glob.h>
+#include <grp.h>
+#include <iconv.h>
+#include <langinfo.h>
+#include <libgen.h>
+#include <monetary.h>
+#include <mqueue.h>
+#include <net/if.h>
+#include <net/ethernet.h>
+#include <net/if_arp.h>
+#include <net/route.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <netinet/ether.h>
+#include <netinet/icmp6.h>
+#include <netinet/if_ether.h>
+#include <netinet/igmp.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/ip_icmp.h>
+#include <netinet/udp.h>
+#include <nl_types.h>
+#include <poll.h>
+#include <pthread.h>
+#include <pwd.h>
+#include <regex.h>
+#include <sched.h>
+#include <search.h>
+#include <semaphore.h>
+#include <spawn.h>
+#include <strings.h>
+#include <stropts.h>
+#include <sys/ipc.h>
+#include <sys/mman.h>
+#include <sys/msg.h>
+#include <sys/resource.h>
+#include <sys/select.h>
+#include <sys/sem.h>
+#include <sys/shm.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/time.h>
+#include <sys/times.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/un.h>
+#include <sys/utsname.h>
+#include <sys/wait.h>
+#include <sys/acct.h>
+#include <sys/auxv.h>
+#include <sys/cachectl.h>
+#include <sys/dir.h>
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+#include <sys/fanotify.h>
+#include <sys/file.h>
+#include <sys/fsuid.h>
+#include <sys/inotify.h>
+#include <sys/ioctl.h>
+#include <sys/io.h>
+#include <sys/klog.h>
+#include <sys/membarrier.h>
+#include <sys/mount.h>
+#include <sys/mtio.h>
+#include <sys/param.h>
+#include <sys/personality.h>
+#include <sys/prctl.h>
+#include <sys/procfs.h>
+#include <sys/ptrace.h>
+#include <sys/quota.h>
+#include <sys/random.h>
+#include <sys/reboot.h>
+#include <sys/reg.h>
+#include <sys/sendfile.h>
+#include <sys/signalfd.h>
+#include <sys/statfs.h>
+#include <sys/stropts.h>
+#include <sys/swap.h>
+#include <sys/syscall.h>
+#include <sys/sysinfo.h>
+#include <sys/syslog.h>
+#include <sys/sysmacros.h>
+#include <sys/timeb.h>
+#include <sys/timerfd.h>
+#include <sys/timex.h>
+#include <sys/ttydefaults.h>
+#include <sys/ucontext.h>
+#include <sys/user.h>
+#include <sys/vfs.h>
+#include <sys/xattr.h>
+#include <syslog.h>
+#include <tar.h>
+#include <termios.h>
+#include <ucontext.h>
+#include <unistd.h>
+#include <ulimit.h>
+#include <utime.h>
+#include <utmpx.h>
+#include <alloca.h>
+#include <ar.h>
+#include <byteswap.h>
+#include <crypt.h>
+#include <elf.h>
+#include <endian.h>
+#include <err.h>
+#include <getopt.h>
+#include <ifaddrs.h>
+#include <lastlog.h>
+#include <libintl.h>
+#include <link.h>
+#include <malloc.h>
+#include <memory.h>
+#include <mntent.h>
+#include <netpacket/packet.h>
+#include <paths.h>
+#include <pty.h>
+#include <resolv.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/sg.h>
+#include <shadow.h>
+#include <stdio_ext.h>
+#include <syscall.h>
+#include <sysexits.h>
+#include <utmp.h>
+#include <values.h>
+#include <unwind.h>
+#include <wordexp.h>
+#include <fts.h>