stdlib: add modulemap for Musl, add Musl platform module

stdlib/public/Platform/CMakeLists.txt

@@ -98,6 +98,22 @@ add_swift_target_library(swiftGlibc ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_O
     INSTALL_IN_COMPONENT sdk-overlay
     DEPENDS glibc_modulemap)
 
+add_swift_target_library(swiftMusl ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVERLAY
+    ${swift_platform_sources}
+    POSIXError.swift
+
+    GYB_SOURCES
+      ${swift_platform_gyb_sources}
+      Musl.swift.gyb
+
+    SWIFT_COMPILE_FLAGS
+      ${SWIFT_RUNTIME_SWIFT_COMPILE_FLAGS}
+      ${SWIFT_STANDARD_LIBRARY_SWIFT_FLAGS}
+      ${swift_platform_compile_flags}
+    LINK_FLAGS "${SWIFT_RUNTIME_SWIFT_LINK_FLAGS}"
+    TARGET_SDKS MUSL
+    INSTALL_IN_COMPONENT sdk-overlay)
+
 add_swift_target_library(swiftCRT ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_SDK_OVERLAY
     ucrt.swift
     ${swift_platform_sources}

stdlib/public/Platform/Musl.swift.gyb

@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2022 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
+//
+//===----------------------------------------------------------------------===//
+
+@_exported import SwiftMusl // Clang module
+
+public let MAP_FAILED: UnsafeMutableRawPointer! = UnsafeMutableRawPointer(bitPattern: -1)
+
+//  Constants defined by <math.h>
+@available(swift, deprecated: 3.0, message: "Please use 'Double.pi' or '.pi' to get the value of correct type and avoid casting.")
+public let M_PI = Double.pi
+
+@available(swift, deprecated: 3.0, message: "Please use 'Double.pi / 2' or '.pi / 2' to get the value of correct type and avoid casting.")
+public let M_PI_2 = Double.pi / 2
+
+@available(swift, deprecated: 3.0, message: "Please use 'Double.pi / 4' or '.pi / 4' to get the value of correct type and avoid casting.")
+public let M_PI_4 = Double.pi / 4
+
+@available(swift, deprecated: 3.0, message: "Please use '2.squareRoot()'.")
+public let M_SQRT2 = 2.squareRoot()
+
+@available(swift, deprecated: 3.0, message: "Please use '0.5.squareRoot()'.")
+public let M_SQRT1_2 = 0.5.squareRoot()
+
+//  Constants defined by <float.h>
+@available(swift, deprecated: 3.0, message: "Please use 'T.radix' to get the radix of a FloatingPoint type 'T'.")
+public let FLT_RADIX = Double.radix
+
+%for type, prefix in [('Float', 'FLT'), ('Double', 'DBL'), ('Float80', 'LDBL')]:
+% if type == "Float80":
+#if !os(Android) && (arch(i386) || arch(x86_64))
+% end
+//  Where does the 1 come from? C counts the usually-implicit leading
+//  significand bit, but Swift does not. Neither is really right or wrong.
+@available(swift, deprecated: 3.0, message: "Please use '${type}.significandBitCount + 1'.")
+public let ${prefix}_MANT_DIG = ${type}.significandBitCount + 1
+
+//  Where does the 1 come from? C models floating-point numbers as having a
+//  significand in [0.5, 1), but Swift (following IEEE 754) considers the
+//  significand to be in [1, 2). This rationale applies to ${prefix}_MIN_EXP
+//  as well.
+@available(swift, deprecated: 3.0, message: "Please use '${type}.greatestFiniteMagnitude.exponent + 1'.")
+public let ${prefix}_MAX_EXP = ${type}.greatestFiniteMagnitude.exponent + 1
+
+@available(swift, deprecated: 3.0, message: "Please use '${type}.leastNormalMagnitude.exponent + 1'.")
+public let ${prefix}_MIN_EXP = ${type}.leastNormalMagnitude.exponent + 1
+
+@available(swift, deprecated: 3.0, message: "Please use '${type}.greatestFiniteMagnitude' or '.greatestFiniteMagnitude'.")
+public let ${prefix}_MAX = ${type}.greatestFiniteMagnitude
+
+@available(swift, deprecated: 3.0, message: "Please use '${type}.ulpOfOne' or '.ulpOfOne'.")
+public let ${prefix}_EPSILON = ${type}.ulpOfOne
+
+@available(swift, deprecated: 3.0, message: "Please use '${type}.leastNormalMagnitude' or '.leastNormalMagnitude'.")
+public let ${prefix}_MIN = ${type}.leastNormalMagnitude
+
+@available(swift, deprecated: 3.0, message: "Please use '${type}.leastNonzeroMagnitude' or '.leastNonzeroMagnitude'.")
+public let ${prefix}_TRUE_MIN = ${type}.leastNonzeroMagnitude
+
+% if type == "Float80":
+#endif
+% end
+%end

stdlib/public/Platform/musl.modulemap

@@ -0,0 +1,111 @@
+//===--- musl.modulemap ---------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2017 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
+//
+//===----------------------------------------------------------------------===//
+
+module SwiftMusl [system] {
+  header "stdc-predef.h"
+  header "features.h"
+
+  // C standard library
+  header "complex.h"
+  header "ctype.h"
+  header "errno.h"
+  header "fenv.h"
+  header "float.h"
+  header "inttypes.h"
+  header "iso646.h"
+  header "limits.h"
+  header "locale.h"
+  header "math.h"
+  header "pty.h"
+  header "setjmp.h"
+  header "signal.h"
+  header "stdarg.h"
+  header "stdbool.h"
+  header "stddef.h"
+  header "stdint.h"
+  header "stdio.h"
+  header "stdlib.h"
+  header "string.h"
+  header "tgmath.h"
+  header "time.h"
+  header "utmp.h"
+
+  // POSIX
+  header "aio.h"
+  header "arpa/inet.h"
+  header "cpio.h"
+  header "dirent.h"
+  header "dlfcn.h"
+  header "fcntl.h"
+  header "fmtmsg.h"
+  header "fnmatch.h"
+  header "ftw.h"
+  header "glob.h"
+  header "grp.h"
+  header "iconv.h"
+  header "ifaddrs.h"
+  header "langinfo.h"
+  header "libgen.h"
+  header "link.h"
+  header "monetary.h"
+  header "net/if.h"
+  header "netdb.h"
+  header "netinet/in.h"
+  header "netinet/tcp.h"
+  header "nl_types.h"
+  header "poll.h"
+  header "pthread.h"
+  header "pwd.h"
+  header "regex.h"
+  header "sched.h"
+  header "search.h"
+  header "semaphore.h"
+  header "spawn.h"
+  header "strings.h"
+  header "sys/file.h"
+  header "sys/inotify.h"
+  header "sys/ioctl.h"
+  header "sys/ipc.h"
+  header "sys/mman.h"
+  header "sys/mount.h"
+  header "sys/msg.h"
+  header "sys/resource.h"
+  header "sys/select.h"
+  header "sys/sem.h"
+  header "sys/sendfile.h"
+  header "sys/shm.h"
+  header "sys/socket.h"
+  header "sys/stat.h"
+  header "sys/statvfs.h"
+  header "sys/time.h"
+  header "sys/times.h"
+  header "sys/types.h"
+  header "sys/uio.h"
+  header "sys/un.h"
+  header "sys/user.h"
+  header "sys/utsname.h"
+  header "sys/wait.h"
+  header "sysexits.h"
+  header "syslog.h"
+  header "tar.h"
+  header "termios.h"
+  header "ulimit.h"
+  header "unistd.h"
+  header "utime.h"
+  header "utmpx.h"
+  header "wordexp.h"
+
+  // <assert.h>'s use of NDEBUG requires textual inclusion. 
+  textual header "assert.h"
+
+  export *
+}