fix regression of flock being called on wasi targets

* common symbols are now public from std.c even if they live in
  std.posix
* LOCK is now one of the common symbols since it is the same on 100% of
  operating systems.
* flock is now void value on wasi and windows
* std.fs.Dir now uses flock being void as feature detection, avoiding
  trying to call it on wasi and windows

lib/std/c.zig

@@ -4,9 +4,6 @@ const c = @This();
 const maxInt = std.math.maxInt;
 const assert = std.debug.assert;
 const page_size = std.mem.page_size;
-const iovec = std.posix.iovec;
-const iovec_const = std.posix.iovec_const;
-const winsize = std.posix.winsize;
 const native_abi = builtin.abi;
 const native_arch = builtin.cpu.arch;
 const native_os = builtin.os.tag;
@@ -23,6 +20,14 @@ const dragonfly = @import("c/dragonfly.zig");
 const haiku = @import("c/haiku.zig");
 const openbsd = @import("c/openbsd.zig");
 
+// These constants are shared among all operating systems even when not linking
+// libc.
+
+pub const iovec = std.posix.iovec;
+pub const iovec_const = std.posix.iovec_const;
+pub const LOCK = std.posix.LOCK;
+pub const winsize = std.posix.winsize;
+
 /// The value of the link editor defined symbol _MH_EXECUTE_SYM is the address
 /// of the mach header in a Mach-O executable file type.  It does not appear in
 /// any file type other than a MH_EXECUTE file type.  The type of the symbol is
@@ -1330,16 +1335,6 @@ pub const KERN = switch (native_os) {
     },
     else => void,
 };
-pub const LOCK = switch (native_os) {
-    .linux => linux.LOCK,
-    .emscripten => emscripten.LOCK,
-    else => struct {
-        pub const SH = 1;
-        pub const EX = 2;
-        pub const NB = 4;
-        pub const UN = 8;
-    },
-};
 pub const MADV = switch (native_os) {
     .linux => linux.MADV,
     .emscripten => emscripten.MADV,
@@ -9032,6 +9027,11 @@ pub const sf_hdtr = switch (native_os) {
     else => void,
 };
 
+pub const flock = switch (native_os) {
+    .windows, .wasi => {},
+    else => private.flock,
+};
+
 pub extern "c" var environ: [*:null]?[*:0]u8;
 
 pub extern "c" fn fopen(noalias filename: [*:0]const u8, noalias modes: [*:0]const u8) ?*FILE;
@@ -9116,7 +9116,6 @@ pub extern "c" fn sysctlnametomib(name: [*:0]const u8, mibp: ?*c_int, sizep: ?*u
 pub extern "c" fn tcgetattr(fd: fd_t, termios_p: *termios) c_int;
 pub extern "c" fn tcsetattr(fd: fd_t, optional_action: TCSA, termios_p: *const termios) c_int;
 pub extern "c" fn fcntl(fd: fd_t, cmd: c_int, ...) c_int;
-pub extern "c" fn flock(fd: fd_t, operation: c_int) c_int;
 pub extern "c" fn ioctl(fd: fd_t, request: c_int, ...) c_int;
 pub extern "c" fn uname(buf: *utsname) c_int;
 
@@ -9396,6 +9395,9 @@ pub extern "c" fn pthread_getthreadid_np() c_int;
 pub extern "c" fn pthread_set_name_np(thread: pthread_t, name: [*:0]const u8) void;
 pub extern "c" fn pthread_get_name_np(thread: pthread_t, name: [*:0]u8, len: usize) void;
 
+// OS-specific bits. These are protected from being used on the wrong OS by
+// comptime assertions inside each OS-specific file.
+
 pub const AF_SUN = solaris.AF_SUN;
 pub const AT_SUN = solaris.AT_SUN;
 pub const FILE_EVENT = solaris.FILE_EVENT;
@@ -9675,6 +9677,7 @@ const private = struct {
     extern "c" fn clock_getres(clk_id: clockid_t, tp: *timespec) c_int;
     extern "c" fn clock_gettime(clk_id: clockid_t, tp: *timespec) c_int;
     extern "c" fn copy_file_range(fd_in: fd_t, off_in: ?*i64, fd_out: fd_t, off_out: ?*i64, len: usize, flags: c_uint) isize;
+    extern "c" fn flock(fd: fd_t, operation: c_int) c_int;
     extern "c" fn fork() c_int;
     extern "c" fn fstat(fd: fd_t, buf: *Stat) c_int;
     extern "c" fn fstatat(dirfd: fd_t, path: [*:0]const u8, buf: *Stat, flag: u32) c_int;

lib/std/fs/Dir.zig

@@ -881,7 +881,7 @@ pub fn openFileZ(self: Dir, sub_path: [*:0]const u8, flags: File.OpenFlags) File
     const fd = try posix.openatZ(self.fd, sub_path, os_flags, 0);
     errdefer posix.close(fd);
 
-    if (!has_flock_open_flags and flags.lock != .none) {
+    if (have_flock and !has_flock_open_flags and flags.lock != .none) {
         // TODO: integrate async I/O
         const lock_nonblocking: i32 = if (flags.lock_nonblocking) posix.LOCK.NB else 0;
         try posix.flock(fd, switch (flags.lock) {
@@ -1029,7 +1029,7 @@ pub fn createFileZ(self: Dir, sub_path_c: [*:0]const u8, flags: File.CreateFlags
     const fd = try posix.openatZ(self.fd, sub_path_c, os_flags, flags.mode);
     errdefer posix.close(fd);
 
-    if (!has_flock_open_flags and flags.lock != .none) {
+    if (have_flock and !has_flock_open_flags and flags.lock != .none) {
         // TODO: integrate async I/O
         const lock_nonblocking: i32 = if (flags.lock_nonblocking) posix.LOCK.NB else 0;
         try posix.flock(fd, switch (flags.lock) {
@@ -2702,3 +2702,4 @@ const Allocator = std.mem.Allocator;
 const assert = std.debug.assert;
 const windows = std.os.windows;
 const native_os = builtin.os.tag;
+const have_flock = @TypeOf(posix.system.flock) != void;

lib/std/os/linux.zig

@@ -69,7 +69,6 @@ pub const Elf_Symndx = arch_bits.Elf_Symndx;
 pub const F = arch_bits.F;
 pub const Flock = arch_bits.Flock;
 pub const HWCAP = arch_bits.HWCAP;
-pub const LOCK = arch_bits.LOCK;
 pub const MMAP2_UNIT = arch_bits.MMAP2_UNIT;
 pub const REG = arch_bits.REG;
 pub const SC = arch_bits.SC;

lib/std/os/linux/arm-eabi.zig

@@ -167,13 +167,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const VDSO = struct {
     pub const CGT_SYM = "__vdso_clock_gettime";
     pub const CGT_VER = "LINUX_2.6";

lib/std/os/linux/arm64.zig

@@ -149,13 +149,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const VDSO = struct {
     pub const CGT_SYM = "__kernel_clock_gettime";
     pub const CGT_VER = "LINUX_2.6.39";

lib/std/os/linux/mips.zig

@@ -239,13 +239,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const MMAP2_UNIT = 4096;
 
 pub const VDSO = struct {

lib/std/os/linux/mips64.zig

@@ -224,13 +224,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const MMAP2_UNIT = 4096;
 
 pub const VDSO = struct {

lib/std/os/linux/powerpc.zig

@@ -168,13 +168,6 @@ pub const F = struct {
     pub const UNLCK = 2;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const VDSO = struct {
     pub const CGT_SYM = "__kernel_clock_gettime";
     pub const CGT_VER = "LINUX_2.6.15";

lib/std/os/linux/powerpc64.zig

@@ -168,13 +168,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const VDSO = struct {
     pub const CGT_SYM = "__kernel_clock_gettime";
     pub const CGT_VER = "LINUX_2.6.15";

lib/std/os/linux/riscv64.zig

@@ -134,13 +134,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const UN = 8;
-    pub const NB = 4;
-};
-
 pub const blksize_t = i32;
 pub const nlink_t = u32;
 pub const time_t = isize;

lib/std/os/linux/sparc64.zig

@@ -218,13 +218,6 @@ pub const F = struct {
     pub const GETOWNER_UIDS = 17;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const NB = 4;
-    pub const UN = 8;
-};
-
 pub const VDSO = struct {
     pub const CGT_SYM = "__vdso_clock_gettime";
     pub const CGT_VER = "LINUX_2.6";

lib/std/os/linux/x86.zig

@@ -181,13 +181,6 @@ pub const F = struct {
     pub const UNLCK = 2;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const NB = 4;
-    pub const UN = 8;
-};
-
 pub const MMAP2_UNIT = 4096;
 
 pub const VDSO = struct {

lib/std/os/linux/x86_64.zig

@@ -195,13 +195,6 @@ pub const REG = struct {
     pub const CR2 = 22;
 };
 
-pub const LOCK = struct {
-    pub const SH = 1;
-    pub const EX = 2;
-    pub const NB = 4;
-    pub const UN = 8;
-};
-
 pub const Flock = extern struct {
     type: i16,
     whence: i16,

lib/std/posix.zig

@@ -70,7 +70,6 @@ pub const IOV_MAX = system.IOV_MAX;
 pub const IPPROTO = system.IPPROTO;
 pub const KERN = system.KERN;
 pub const Kevent = system.Kevent;
-pub const LOCK = system.LOCK;
 pub const MADV = system.MADV;
 pub const MAP = system.MAP;
 pub const MAX_ADDR_LEN = system.MAX_ADDR_LEN;
@@ -202,6 +201,13 @@ pub const winsize = extern struct {
     ypixel: u16,
 };
 
+pub const LOCK = struct {
+    pub const SH = 1;
+    pub const EX = 2;
+    pub const NB = 4;
+    pub const UN = 8;
+};
+
 pub const LOG = struct {
     /// system is unusable
     pub const EMERG = 0;