Commit 29e438fd1f

Andrew Kelley <andrew@ziglang.org>
2019-11-25 06:30:28
more sentinel-terminated pointers std lib integration
See #3767
1 parent 15d415e
doc/langref.html.in
@@ -4865,7 +4865,7 @@ const mem = std.mem;
 test "cast *[1][*]const u8 to [*]const ?[*]const u8" {
     const window_name = [1][*]const u8{"window name"};
     const x: [*]const ?[*]const u8 = &window_name;
-    assert(mem.eql(u8, std.mem.toSliceConst(u8, x[0].?), "window name"));
+    assert(mem.eql(u8, std.mem.toSliceConst(u8, @ptrCast([*:0]const u8, x[0].?)), "window name"));
 }
       {#code_end#}
       {#header_close#}
lib/std/event/fs.zig
@@ -58,8 +58,7 @@ pub const Request = struct {
         };
 
         pub const Open = struct {
-            /// must be null terminated. TODO https://github.com/ziglang/zig/issues/265
-            path: []const u8,
+            path: [:0]const u8,
             flags: u32,
             mode: File.Mode,
             result: Error!fd_t,
@@ -68,8 +67,7 @@ pub const Request = struct {
         };
 
         pub const WriteFile = struct {
-            /// must be null terminated. TODO https://github.com/ziglang/zig/issues/265
-            path: []const u8,
+            path: [:0]const u8,
             contents: []const u8,
             mode: File.Mode,
             result: Error!void,
lib/std/fs/file.zig
@@ -31,7 +31,7 @@ pub const File = struct {
     }
 
     /// Deprecated; call `std.fs.Dir.openReadC` directly.
-    pub fn openReadC(path_c: [*]const u8) OpenError!File {
+    pub fn openReadC(path_c: [*:0]const u8) OpenError!File {
         return std.fs.Dir.cwd().openReadC(path_c);
     }
 
@@ -61,7 +61,7 @@ pub const File = struct {
 
     /// Same as `openWriteMode` except `path` is null-terminated.
     /// TODO: deprecate this and move it to `std.fs.Dir`.
-    pub fn openWriteModeC(path: [*]const u8, file_mode: Mode) OpenError!File {
+    pub fn openWriteModeC(path: [*:0]const u8, file_mode: Mode) OpenError!File {
         if (builtin.os == .windows) {
             const path_w = try windows.cStrToPrefixedFileW(path);
             return openWriteModeW(&path_w, file_mode);
@@ -74,7 +74,7 @@ pub const File = struct {
 
     /// Same as `openWriteMode` except `path` is null-terminated and UTF16LE encoded
     /// TODO: deprecate this and move it to `std.fs.Dir`.
-    pub fn openWriteModeW(path_w: [*]const u16, file_mode: Mode) OpenError!File {
+    pub fn openWriteModeW(path_w: [*:0]const u16, file_mode: Mode) OpenError!File {
         const handle = try windows.CreateFileW(
             path_w,
             windows.GENERIC_WRITE,
@@ -101,7 +101,7 @@ pub const File = struct {
     }
 
     /// TODO: deprecate this and move it to `std.fs.Dir`.
-    pub fn openWriteNoClobberC(path: [*]const u8, file_mode: Mode) OpenError!File {
+    pub fn openWriteNoClobberC(path: [*:0]const u8, file_mode: Mode) OpenError!File {
         if (builtin.os == .windows) {
             const path_w = try windows.cStrToPrefixedFileW(path);
             return openWriteNoClobberW(&path_w, file_mode);
@@ -113,7 +113,7 @@ pub const File = struct {
     }
 
     /// TODO: deprecate this and move it to `std.fs.Dir`.
-    pub fn openWriteNoClobberW(path_w: [*]const u16, file_mode: Mode) OpenError!File {
+    pub fn openWriteNoClobberW(path_w: [*:0]const u16, file_mode: Mode) OpenError!File {
         const handle = try windows.CreateFileW(
             path_w,
             windows.GENERIC_WRITE,
@@ -142,13 +142,13 @@ pub const File = struct {
 
     /// Same as `access` except the parameter is null-terminated.
     /// TODO: deprecate this and move it to `std.fs.Dir`.
-    pub fn accessC(path: [*]const u8) !void {
+    pub fn accessC(path: [*:0]const u8) !void {
         return os.accessC(path, os.F_OK);
     }
 
     /// Same as `access` except the parameter is null-terminated UTF16LE-encoded.
     /// TODO: deprecate this and move it to `std.fs.Dir`.
-    pub fn accessW(path: [*]const u16) !void {
+    pub fn accessW(path: [*:0]const u16) !void {
         return os.accessW(path, os.F_OK);
     }
 
lib/std/os/bits/darwin.zig
@@ -1205,7 +1205,7 @@ pub const addrinfo = extern struct {
     socktype: i32,
     protocol: i32,
     addrlen: socklen_t,
-    canonname: ?[*]u8,
+    canonname: ?[*:0]u8,
     addr: ?*sockaddr,
     next: ?*addrinfo,
 };
lib/std/os/bits/linux.zig
@@ -1355,7 +1355,7 @@ pub const addrinfo = extern struct {
     protocol: i32,
     addrlen: socklen_t,
     addr: ?*sockaddr,
-    canonname: ?[*]u8,
+    canonname: ?[*:0]u8,
     next: ?*addrinfo,
 };
 
lib/std/os/wasi.zig
@@ -19,13 +19,13 @@ comptime {
 pub const iovec_t = iovec;
 pub const ciovec_t = iovec_const;
 
-pub extern "wasi_unstable" fn args_get(argv: [*][*]u8, argv_buf: [*]u8) errno_t;
+pub extern "wasi_unstable" fn args_get(argv: [*][*:0]u8, argv_buf: [*]u8) errno_t;
 pub extern "wasi_unstable" fn args_sizes_get(argc: *usize, argv_buf_size: *usize) errno_t;
 
 pub extern "wasi_unstable" fn clock_res_get(clock_id: clockid_t, resolution: *timestamp_t) errno_t;
 pub extern "wasi_unstable" fn clock_time_get(clock_id: clockid_t, precision: timestamp_t, timestamp: *timestamp_t) errno_t;
 
-pub extern "wasi_unstable" fn environ_get(environ: [*]?[*]u8, environ_buf: [*]u8) errno_t;
+pub extern "wasi_unstable" fn environ_get(environ: [*]?[*:0]u8, environ_buf: [*]u8) errno_t;
 pub extern "wasi_unstable" fn environ_sizes_get(environ_count: *usize, environ_buf_size: *usize) errno_t;
 
 pub extern "wasi_unstable" fn fd_advise(fd: fd_t, offset: filesize_t, len: filesize_t, advice: advice_t) errno_t;
lib/std/os/windows.zig
@@ -192,7 +192,7 @@ pub const FindFirstFileError = error{
 };
 
 pub fn FindFirstFile(dir_path: []const u8, find_file_data: *WIN32_FIND_DATAW) FindFirstFileError!HANDLE {
-    const dir_path_w = try sliceToPrefixedSuffixedFileW(dir_path, [_]u16{ '\\', '*', 0 });
+    const dir_path_w = try sliceToPrefixedSuffixedFileW(dir_path, [_]u16{ '\\', '*'});
     const handle = kernel32.FindFirstFileW(&dir_path_w, find_file_data);
 
     if (handle == INVALID_HANDLE_VALUE) {
@@ -919,18 +919,18 @@ pub fn nanoSecondsToFileTime(ns: i64) FILETIME {
     };
 }
 
-pub fn cStrToPrefixedFileW(s: [*]const u8) ![PATH_MAX_WIDE + 1]u16 {
+pub fn cStrToPrefixedFileW(s: [*:0]const u8) ![PATH_MAX_WIDE:0]u16 {
     return sliceToPrefixedFileW(mem.toSliceConst(u8, s));
 }
 
-pub fn sliceToPrefixedFileW(s: []const u8) ![PATH_MAX_WIDE + 1]u16 {
-    return sliceToPrefixedSuffixedFileW(s, [_]u16{0});
+pub fn sliceToPrefixedFileW(s: []const u8) ![PATH_MAX_WIDE:0]u16 {
+    return sliceToPrefixedSuffixedFileW(s, &[_]u16{});
 }
 
 /// Assumes an absolute path.
-pub fn wToPrefixedFileW(s: []const u16) ![PATH_MAX_WIDE + 1]u16 {
+pub fn wToPrefixedFileW(s: []const u16) ![PATH_MAX_WIDE:0]u16 {
     // TODO https://github.com/ziglang/zig/issues/2765
-    var result: [PATH_MAX_WIDE + 1]u16 = undefined;
+    var result: [PATH_MAX_WIDE:0]u16 = undefined;
 
     const start_index = if (mem.startsWith(u16, s, [_]u16{'\\', '?'})) 0 else blk: {
         const prefix = [_]u16{ '\\', '?', '?', '\\' };
@@ -945,9 +945,9 @@ pub fn wToPrefixedFileW(s: []const u16) ![PATH_MAX_WIDE + 1]u16 {
 
 }
 
-pub fn sliceToPrefixedSuffixedFileW(s: []const u8, comptime suffix: []const u16) ![PATH_MAX_WIDE + suffix.len]u16 {
+pub fn sliceToPrefixedSuffixedFileW(s: []const u8, comptime suffix: []const u16) ![PATH_MAX_WIDE + suffix.len:0]u16 {
     // TODO https://github.com/ziglang/zig/issues/2765
-    var result: [PATH_MAX_WIDE + suffix.len]u16 = undefined;
+    var result: [PATH_MAX_WIDE + suffix.len:0]u16 = undefined;
     // > File I/O functions in the Windows API convert "/" to "\" as part of
     // > converting the name to an NT-style name, except when using the "\\?\"
     // > prefix as detailed in the following sections.
lib/std/c.zig
@@ -102,7 +102,7 @@ pub extern "c" fn execve(path: [*]const u8, argv: [*]const ?[*]const u8, envp: [
 pub extern "c" fn dup(fd: fd_t) c_int;
 pub extern "c" fn dup2(old_fd: fd_t, new_fd: fd_t) c_int;
 pub extern "c" fn readlink(noalias path: [*]const u8, noalias buf: [*]u8, bufsize: usize) isize;
-pub extern "c" fn realpath(noalias file_name: [*]const u8, noalias resolved_name: [*]u8) ?[*]u8;
+pub extern "c" fn realpath(noalias file_name: [*]const u8, noalias resolved_name: [*]u8) ?[*:0]u8;
 pub extern "c" fn sigprocmask(how: c_int, noalias set: *const sigset_t, noalias oset: ?*sigset_t) c_int;
 pub extern "c" fn gettimeofday(noalias tv: ?*timeval, noalias tz: ?*timezone) c_int;
 pub extern "c" fn sigaction(sig: c_int, noalias act: *const Sigaction, noalias oact: ?*Sigaction) c_int;
lib/std/debug.zig
@@ -401,7 +401,7 @@ fn printSourceAtAddressWindows(di: *DebugInfo, out_stream: var, relocated_addres
                 const vaddr_start = coff_section.header.virtual_address + proc_sym.CodeOffset;
                 const vaddr_end = vaddr_start + proc_sym.CodeSize;
                 if (relative_address >= vaddr_start and relative_address < vaddr_end) {
-                    break mem.toSliceConst(u8, @ptrCast([*]u8, proc_sym) + @sizeOf(pdb.ProcSym));
+                    break mem.toSliceConst(u8, @ptrCast([*:0]u8, proc_sym) + @sizeOf(pdb.ProcSym));
                 }
             },
             else => {},
@@ -703,9 +703,9 @@ fn printSourceAtAddressMacOs(di: *DebugInfo, out_stream: var, address: usize, tt
         return;
     };
 
-    const symbol_name = mem.toSliceConst(u8, di.strings.ptr + symbol.nlist.n_strx);
+    const symbol_name = mem.toSliceConst(u8, @ptrCast([*:0]const u8, di.strings.ptr + symbol.nlist.n_strx));
     const compile_unit_name = if (symbol.ofile) |ofile| blk: {
-        const ofile_path = mem.toSliceConst(u8, di.strings.ptr + ofile.n_strx);
+        const ofile_path = mem.toSliceConst(u8, @ptrCast([*:0]const u8, di.strings.ptr + ofile.n_strx));
         break :blk fs.path.basename(ofile_path);
     } else "???";
     if (getLineNumberInfoMacOs(di, symbol.*, adjusted_addr)) |line_info| {
@@ -915,7 +915,7 @@ fn openSelfDebugInfoWindows(allocator: *mem.Allocator) !DebugInfo {
         for (present) |_| {
             const name_offset = try pdb_stream.stream.readIntLittle(u32);
             const name_index = try pdb_stream.stream.readIntLittle(u32);
-            const name = mem.toSlice(u8, name_bytes.ptr + name_offset);
+            const name = mem.toSlice(u8, @ptrCast([*:0]u8, name_bytes.ptr + name_offset));
             if (mem.eql(u8, name, "/names")) {
                 break :str_tab_index name_index;
             }
@@ -1708,7 +1708,7 @@ fn getLineNumberInfoMacOs(di: *DebugInfo, symbol: MachoSymbol, target_address: u
     const gop = try di.ofiles.getOrPut(ofile);
     const mach_o_file = if (gop.found_existing) &gop.kv.value else blk: {
         errdefer _ = di.ofiles.remove(ofile);
-        const ofile_path = mem.toSliceConst(u8, di.strings.ptr + ofile.n_strx);
+        const ofile_path = mem.toSliceConst(u8, @ptrCast([*:0]const u8, di.strings.ptr + ofile.n_strx));
 
         gop.kv.value = MachOFile{
             .bytes = try std.fs.Dir.cwd().readFileAllocAligned(
@@ -1741,7 +1741,7 @@ fn getLineNumberInfoMacOs(di: *DebugInfo, symbol: MachoSymbol, target_address: u
             if (sect.flags & macho.SECTION_TYPE == macho.S_REGULAR and
                 (sect.flags & macho.SECTION_ATTRIBUTES) & macho.S_ATTR_DEBUG == macho.S_ATTR_DEBUG)
             {
-                const sect_name = mem.toSliceConst(u8, &sect.sectname);
+                const sect_name = mem.toSliceConst(u8, @ptrCast([*:0]const u8, &sect.sectname));
                 if (mem.eql(u8, sect_name, "__debug_line")) {
                     gop.kv.value.sect_debug_line = sect;
                 } else if (mem.eql(u8, sect_name, "__debug_info")) {
@@ -2323,8 +2323,8 @@ fn readInitialLengthMem(ptr: *[*]const u8, is_64: *bool) !u64 {
     }
 }
 
-fn readStringMem(ptr: *[*]const u8) []const u8 {
-    const result = mem.toSliceConst(u8, ptr.*);
+fn readStringMem(ptr: *[*]const u8) [:0]const u8 {
+    const result = mem.toSliceConst(u8, @ptrCast([*:0]const u8, ptr.*));
     ptr.* += result.len + 1;
     return result;
 }
lib/std/dynamic_library.zig
@@ -140,7 +140,7 @@ pub const LinuxDynLib = struct {
 };
 
 pub const ElfLib = struct {
-    strings: [*]u8,
+    strings: [*:0]u8,
     syms: [*]elf.Sym,
     hashtab: [*]os.Elf_Symndx,
     versym: ?[*]u16,
@@ -175,7 +175,7 @@ pub const ElfLib = struct {
         const dynv = maybe_dynv orelse return error.MissingDynamicLinkingInformation;
         if (base == maxInt(usize)) return error.BaseNotFound;
 
-        var maybe_strings: ?[*]u8 = null;
+        var maybe_strings: ?[*:0]u8 = null;
         var maybe_syms: ?[*]elf.Sym = null;
         var maybe_hashtab: ?[*]os.Elf_Symndx = null;
         var maybe_versym: ?[*]u16 = null;
@@ -186,7 +186,7 @@ pub const ElfLib = struct {
             while (dynv[i] != 0) : (i += 2) {
                 const p = base + dynv[i + 1];
                 switch (dynv[i]) {
-                    elf.DT_STRTAB => maybe_strings = @intToPtr([*]u8, p),
+                    elf.DT_STRTAB => maybe_strings = @intToPtr([*:0]u8, p),
                     elf.DT_SYMTAB => maybe_syms = @intToPtr([*]elf.Sym, p),
                     elf.DT_HASH => maybe_hashtab = @intToPtr([*]os.Elf_Symndx, p),
                     elf.DT_VERSYM => maybe_versym = @intToPtr([*]u16, p),
@@ -230,7 +230,7 @@ pub const ElfLib = struct {
     }
 };
 
-fn checkver(def_arg: *elf.Verdef, vsym_arg: i32, vername: []const u8, strings: [*]u8) bool {
+fn checkver(def_arg: *elf.Verdef, vsym_arg: i32, vername: []const u8, strings: [*:0]u8) bool {
     var def = def_arg;
     const vsym = @bitCast(u32, vsym_arg) & 0x7fff;
     while (true) {
lib/std/fs.zig
@@ -28,6 +28,7 @@ pub const GetAppDataDirError = @import("fs/get_app_data_dir.zig").GetAppDataDirE
 /// This represents the maximum size of a UTF-8 encoded file path.
 /// All file system operations which return a path are guaranteed to
 /// fit into a UTF-8 encoded array of this length.
+/// The byte count includes room for a null sentinel byte.
 pub const MAX_PATH_BYTES = switch (builtin.os) {
     .linux, .macosx, .ios, .freebsd, .netbsd, .dragonfly => os.PATH_MAX,
     // Each UTF-16LE character may be expanded to 3 UTF-8 bytes.
@@ -227,7 +228,7 @@ pub const AtomicFile = struct {
             try crypto.randomBytes(rand_buf[0..]);
             b64_fs_encoder.encode(tmp_path_buf[dirname_component_len..tmp_path_len], rand_buf);
 
-            const file = File.openWriteNoClobberC(&tmp_path_buf, mode) catch |err| switch (err) {
+            const file = File.openWriteNoClobberC(@ptrCast([*:0]u8, &tmp_path_buf), mode) catch |err| switch (err) {
                 error.PathAlreadyExists => continue,
                 // TODO zig should figure out that this error set does not include PathAlreadyExists since
                 // it is handled in the above switch
@@ -247,7 +248,7 @@ pub const AtomicFile = struct {
     pub fn deinit(self: *AtomicFile) void {
         if (!self.finished) {
             self.file.close();
-            deleteFileC(&self.tmp_path_buf) catch {};
+            deleteFileC(@ptrCast([*:0]u8, &self.tmp_path_buf)) catch {};
             self.finished = true;
         }
     }
@@ -258,11 +259,11 @@ pub const AtomicFile = struct {
         self.finished = true;
         if (builtin.os == .windows) {
             const dest_path_w = try os.windows.sliceToPrefixedFileW(self.dest_path);
-            const tmp_path_w = try os.windows.cStrToPrefixedFileW(&self.tmp_path_buf);
+            const tmp_path_w = try os.windows.cStrToPrefixedFileW(@ptrCast([*:0]u8, &self.tmp_path_buf));
             return os.renameW(&tmp_path_w, &dest_path_w);
         }
         const dest_path_c = try os.toPosixPath(self.dest_path);
-        return os.renameC(&self.tmp_path_buf, &dest_path_c);
+        return os.renameC(@ptrCast([*:0]u8, &self.tmp_path_buf), &dest_path_c);
     }
 };
 
@@ -274,12 +275,12 @@ pub fn makeDir(dir_path: []const u8) !void {
 }
 
 /// Same as `makeDir` except the parameter is a null-terminated UTF8-encoded string.
-pub fn makeDirC(dir_path: [*]const u8) !void {
+pub fn makeDirC(dir_path: [*:0]const u8) !void {
     return os.mkdirC(dir_path, default_new_dir_mode);
 }
 
 /// Same as `makeDir` except the parameter is a null-terminated UTF16LE-encoded string.
-pub fn makeDirW(dir_path: [*]const u16) !void {
+pub fn makeDirW(dir_path: [*:0]const u16) !void {
     return os.mkdirW(dir_path, default_new_dir_mode);
 }
 
@@ -327,12 +328,12 @@ pub fn deleteDir(dir_path: []const u8) !void {
 }
 
 /// Same as `deleteDir` except the parameter is a null-terminated UTF8-encoded string.
-pub fn deleteDirC(dir_path: [*]const u8) !void {
+pub fn deleteDirC(dir_path: [*:0]const u8) !void {
     return os.rmdirC(dir_path);
 }
 
 /// Same as `deleteDir` except the parameter is a null-terminated UTF16LE-encoded string.
-pub fn deleteDirW(dir_path: [*]const u16) !void {
+pub fn deleteDirW(dir_path: [*:0]const u16) !void {
     return os.rmdirW(dir_path);
 }
 
@@ -688,7 +689,7 @@ pub const Dir = struct {
     }
 
     /// Same as `open` except the parameter is null-terminated.
-    pub fn openC(dir_path_c: [*]const u8) OpenError!Dir {
+    pub fn openC(dir_path_c: [*:0]const u8) OpenError!Dir {
         return cwd().openDirC(dir_path_c);
     }
 
@@ -708,7 +709,7 @@ pub const Dir = struct {
     }
 
     /// Call `File.close` on the result when done.
-    pub fn openReadC(self: Dir, sub_path: [*]const u8) File.OpenError!File {
+    pub fn openReadC(self: Dir, sub_path: [*:0]const u8) File.OpenError!File {
         if (builtin.os == .windows) {
             const path_w = try os.windows.cStrToPrefixedFileW(sub_path);
             return self.openReadW(&path_w);
@@ -719,7 +720,7 @@ pub const Dir = struct {
         return File.openHandle(fd);
     }
 
-    pub fn openReadW(self: Dir, sub_path_w: [*]const u16) File.OpenError!File {
+    pub fn openReadW(self: Dir, sub_path_w: [*:0]const u16) File.OpenError!File {
         const w = os.windows;
 
         var result = File{ .handle = undefined };
@@ -786,7 +787,7 @@ pub const Dir = struct {
     }
 
     /// Same as `openDir` except the parameter is null-terminated.
-    pub fn openDirC(self: Dir, sub_path_c: [*]const u8) OpenError!Dir {
+    pub fn openDirC(self: Dir, sub_path_c: [*:0]const u8) OpenError!Dir {
         if (builtin.os == .windows) {
             const sub_path_w = try os.windows.cStrToPrefixedFileW(sub_path_c);
             return self.openDirW(&sub_path_w);
@@ -805,7 +806,7 @@ pub const Dir = struct {
 
     /// Same as `openDir` except the path parameter is UTF16LE, NT-prefixed.
     /// This function is Windows-only.
-    pub fn openDirW(self: Dir, sub_path_w: [*]const u16) OpenError!Dir {
+    pub fn openDirW(self: Dir, sub_path_w: [*:0]const u16) OpenError!Dir {
         const w = os.windows;
 
         var result = Dir{
@@ -868,7 +869,7 @@ pub const Dir = struct {
     }
 
     /// Same as `deleteFile` except the parameter is null-terminated.
-    pub fn deleteFileC(self: Dir, sub_path_c: [*]const u8) DeleteFileError!void {
+    pub fn deleteFileC(self: Dir, sub_path_c: [*:0]const u8) DeleteFileError!void {
         os.unlinkatC(self.fd, sub_path_c, 0) catch |err| switch (err) {
             error.DirNotEmpty => unreachable, // not passing AT_REMOVEDIR
             else => |e| return e,
@@ -903,7 +904,7 @@ pub const Dir = struct {
     }
 
     /// Same as `deleteDir` except the parameter is null-terminated.
-    pub fn deleteDirC(self: Dir, sub_path_c: [*]const u8) DeleteDirError!void {
+    pub fn deleteDirC(self: Dir, sub_path_c: [*:0]const u8) DeleteDirError!void {
         os.unlinkatC(self.fd, sub_path_c, os.AT_REMOVEDIR) catch |err| switch (err) {
             error.IsDir => unreachable, // not possible since we pass AT_REMOVEDIR
             else => |e| return e,
@@ -912,7 +913,7 @@ pub const Dir = struct {
 
     /// Same as `deleteDir` except the parameter is UTF16LE, NT prefixed.
     /// This function is Windows-only.
-    pub fn deleteDirW(self: Dir, sub_path_w: [*]const u16) DeleteDirError!void {
+    pub fn deleteDirW(self: Dir, sub_path_w: [*:0]const u16) DeleteDirError!void {
         os.unlinkatW(self.fd, sub_path_w, os.AT_REMOVEDIR) catch |err| switch (err) {
             error.IsDir => unreachable, // not possible since we pass AT_REMOVEDIR
             else => |e| return e,
@@ -927,7 +928,7 @@ pub const Dir = struct {
     }
 
     /// Same as `readLink`, except the `pathname` parameter is null-terminated.
-    pub fn readLinkC(self: Dir, sub_path_c: [*]const u8, buffer: *[MAX_PATH_BYTES]u8) ![]u8 {
+    pub fn readLinkC(self: Dir, sub_path_c: [*:0]const u8, buffer: *[MAX_PATH_BYTES]u8) ![]u8 {
         return os.readlinkatC(self.fd, sub_path_c, buffer);
     }
 
@@ -1250,7 +1251,8 @@ pub fn openSelfExe() OpenSelfExeError!File {
     var buf: [MAX_PATH_BYTES]u8 = undefined;
     const self_exe_path = try selfExePath(&buf);
     buf[self_exe_path.len] = 0;
-    return File.openReadC(self_exe_path.ptr);
+    // TODO avoid @ptrCast here using slice syntax with https://github.com/ziglang/zig/issues/3731
+    return File.openReadC(@ptrCast([*:0]u8, self_exe_path.ptr));
 }
 
 test "openSelfExe" {
@@ -1277,7 +1279,7 @@ pub fn selfExePath(out_buffer: *[MAX_PATH_BYTES]u8) SelfExePathError![]u8 {
         var u32_len: u32 = out_buffer.len;
         const rc = std.c._NSGetExecutablePath(out_buffer, &u32_len);
         if (rc != 0) return error.NameTooLong;
-        return mem.toSlice(u8, out_buffer);
+        return mem.toSlice(u8, @ptrCast([*:0]u8, out_buffer));
     }
     switch (builtin.os) {
         .linux => return os.readlinkC("/proc/self/exe", out_buffer),
@@ -1306,9 +1308,9 @@ pub fn selfExePath(out_buffer: *[MAX_PATH_BYTES]u8) SelfExePathError![]u8 {
 }
 
 /// The result is UTF16LE-encoded.
-pub fn selfExePathW() []const u16 {
+pub fn selfExePathW() [:0]const u16 {
     const image_path_name = &os.windows.peb().ProcessParameters.ImagePathName;
-    return mem.toSliceConst(u16, image_path_name.Buffer);
+    return mem.toSliceConst(u16, @ptrCast([*:0]const u16, image_path_name.Buffer));
 }
 
 /// `selfExeDirPath` except allocates the result on the heap.
lib/std/os.zig
@@ -655,8 +655,7 @@ pub fn open(file_path: []const u8, flags: u32, perm: usize) OpenError!fd_t {
 
 /// Open and possibly create a file. Keeps trying if it gets interrupted.
 /// See also `open`.
-/// TODO https://github.com/ziglang/zig/issues/265
-pub fn openC(file_path: [*]const u8, flags: u32, perm: usize) OpenError!fd_t {
+pub fn openC(file_path: [*:0]const u8, flags: u32, perm: usize) OpenError!fd_t {
     while (true) {
         const rc = system.open(file_path, flags, perm);
         switch (errno(rc)) {
@@ -697,7 +696,7 @@ pub fn openat(dir_fd: fd_t, file_path: []const u8, flags: u32, mode: usize) Open
 /// Open and possibly create a file. Keeps trying if it gets interrupted.
 /// `file_path` is relative to the open directory handle `dir_fd`.
 /// See also `openat`.
-pub fn openatC(dir_fd: fd_t, file_path: [*]const u8, flags: u32, mode: usize) OpenError!fd_t {
+pub fn openatC(dir_fd: fd_t, file_path: [*:0]const u8, flags: u32, mode: usize) OpenError!fd_t {
     while (true) {
         const rc = system.openat(dir_fd, file_path, flags, mode);
         switch (errno(rc)) {
@@ -757,7 +756,7 @@ pub const ExecveError = error{
 /// Like `execve` except the parameters are null-terminated,
 /// matching the syscall API on all targets. This removes the need for an allocator.
 /// This function ignores PATH environment variable. See `execvpeC` for that.
-pub fn execveC(path: [*]const u8, child_argv: [*]const ?[*]const u8, envp: [*]const ?[*]const u8) ExecveError {
+pub fn execveC(path: [*:0]const u8, child_argv: [*:null]const ?[*:0]const u8, envp: [*:null]const ?[*:0]const u8) ExecveError {
     switch (errno(system.execve(path, child_argv, envp))) {
         0 => unreachable,
         EFAULT => unreachable,
@@ -784,7 +783,7 @@ pub fn execveC(path: [*]const u8, child_argv: [*]const ?[*]const u8, envp: [*]co
 /// matching the syscall API on all targets. This removes the need for an allocator.
 /// This function also uses the PATH environment variable to get the full path to the executable.
 /// If `file` is an absolute path, this is the same as `execveC`.
-pub fn execvpeC(file: [*:0]const u8, child_argv: [*]const ?[*:0]const u8, envp: [*]const ?[*:0]const u8) ExecveError {
+pub fn execvpeC(file: [*:0]const u8, child_argv: [*:null]const ?[*:0]const u8, envp: [*:null]const ?[*:0]const u8) ExecveError {
     const file_slice = mem.toSliceConst(u8, file);
     if (mem.indexOfScalar(u8, file_slice, '/') != null) return execveC(file, child_argv, envp);
 
@@ -799,7 +798,8 @@ pub fn execvpeC(file: [*:0]const u8, child_argv: [*]const ?[*:0]const u8, envp:
         path_buf[search_path.len] = '/';
         mem.copy(u8, path_buf[search_path.len + 1 ..], file_slice);
         path_buf[search_path.len + file_slice.len + 1] = 0;
-        err = execveC(&path_buf, child_argv, envp);
+        // TODO avoid @ptrCast here using slice syntax with https://github.com/ziglang/zig/issues/3731
+        err = execveC(@ptrCast([*:0]u8, &path_buf), child_argv, envp);
         switch (err) {
             error.AccessDenied => seen_eacces = true,
             error.FileNotFound, error.NotDir => {},
@@ -842,10 +842,13 @@ pub fn execvpe(
     const envp_buf = try createNullDelimitedEnvMap(allocator, env_map);
     defer freeNullDelimitedEnvMap(allocator, envp_buf);
 
-    return execvpeC(argv_buf.ptr[0].?, argv_buf.ptr, envp_buf.ptr);
+    // TODO avoid @ptrCast here using slice syntax with https://github.com/ziglang/zig/issues/3731
+    const argv_ptr = @ptrCast([*:null]?[*:0]u8, argv_buf.ptr);
+
+    return execvpeC(argv_buf.ptr[0].?, argv_ptr, envp_buf.ptr);
 }
 
-pub fn createNullDelimitedEnvMap(allocator: *mem.Allocator, env_map: *const std.BufMap) ![]?[*:0]u8 {
+pub fn createNullDelimitedEnvMap(allocator: *mem.Allocator, env_map: *const std.BufMap) ![:null]?[*:0]u8 {
     const envp_count = env_map.count();
     const envp_buf = try allocator.alloc(?[*:0]u8, envp_count + 1);
     mem.set(?[*:0]u8, envp_buf, null);
@@ -860,13 +863,14 @@ pub fn createNullDelimitedEnvMap(allocator: *mem.Allocator, env_map: *const std.
             @memcpy(env_buf.ptr + pair.key.len + 1, pair.value.ptr, pair.value.len);
             env_buf[env_buf.len - 1] = 0;
 
-            // TODO avoid @ptrCast using slice syntax with https://github.com/ziglang/zig/issues/3731
+            // TODO avoid @ptrCast here using slice syntax with https://github.com/ziglang/zig/issues/3731
             envp_buf[i] = @ptrCast([*:0]u8, env_buf.ptr);
         }
         assert(i == envp_count);
     }
+    // TODO avoid @ptrCast here using slice syntax with https://github.com/ziglang/zig/issues/3731
     assert(envp_buf[envp_count] == null);
-    return envp_buf;
+    return @ptrCast([*:null]?[*:0]u8, envp_buf.ptr)[0..envp_count];
 }
 
 pub fn freeNullDelimitedEnvMap(allocator: *mem.Allocator, envp_buf: []?[*:0]u8) void {
@@ -967,7 +971,7 @@ pub fn symlink(target_path: []const u8, sym_link_path: []const u8) SymLinkError!
 
 /// This is the same as `symlink` except the parameters are null-terminated pointers.
 /// See also `symlink`.
-pub fn symlinkC(target_path: [*]const u8, sym_link_path: [*]const u8) SymLinkError!void {
+pub fn symlinkC(target_path: [*:0]const u8, sym_link_path: [*:0]const u8) SymLinkError!void {
     if (builtin.os == .windows) {
         const target_path_w = try windows.cStrToPrefixedFileW(target_path);
         const sym_link_path_w = try windows.cStrToPrefixedFileW(sym_link_path);
@@ -999,7 +1003,7 @@ pub fn symlinkat(target_path: []const u8, newdirfd: fd_t, sym_link_path: []const
     return symlinkatC(target_path_c, newdirfd, sym_link_path_c);
 }
 
-pub fn symlinkatC(target_path: [*]const u8, newdirfd: fd_t, sym_link_path: [*]const u8) SymLinkError!void {
+pub fn symlinkatC(target_path: [*:0]const u8, newdirfd: fd_t, sym_link_path: [*:0]const u8) SymLinkError!void {
     switch (errno(system.symlinkat(target_path, newdirfd, sym_link_path))) {
         0 => return,
         EFAULT => unreachable,
@@ -1053,7 +1057,7 @@ pub fn unlink(file_path: []const u8) UnlinkError!void {
 }
 
 /// Same as `unlink` except the parameter is a null terminated UTF8-encoded string.
-pub fn unlinkC(file_path: [*]const u8) UnlinkError!void {
+pub fn unlinkC(file_path: [*:0]const u8) UnlinkError!void {
     if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path);
         return windows.DeleteFileW(&file_path_w);
@@ -1093,7 +1097,7 @@ pub fn unlinkat(dirfd: fd_t, file_path: []const u8, flags: u32) UnlinkatError!vo
 }
 
 /// Same as `unlinkat` but `file_path` is a null-terminated string.
-pub fn unlinkatC(dirfd: fd_t, file_path_c: [*]const u8, flags: u32) UnlinkatError!void {
+pub fn unlinkatC(dirfd: fd_t, file_path_c: [*:0]const u8, flags: u32) UnlinkatError!void {
     if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path_c);
         return unlinkatW(dirfd, &file_path_w, flags);
@@ -1122,7 +1126,7 @@ pub fn unlinkatC(dirfd: fd_t, file_path_c: [*]const u8, flags: u32) UnlinkatErro
 }
 
 /// Same as `unlinkat` but `sub_path_w` is UTF16LE, NT prefixed. Windows only.
-pub fn unlinkatW(dirfd: fd_t, sub_path_w: [*]const u16, flags: u32) UnlinkatError!void {
+pub fn unlinkatW(dirfd: fd_t, sub_path_w: [*:0]const u16, flags: u32) UnlinkatError!void {
     const w = windows;
 
     const want_rmdir_behavior = (flags & AT_REMOVEDIR) != 0;
@@ -1217,7 +1221,7 @@ pub fn rename(old_path: []const u8, new_path: []const u8) RenameError!void {
 }
 
 /// Same as `rename` except the parameters are null-terminated byte arrays.
-pub fn renameC(old_path: [*]const u8, new_path: [*]const u8) RenameError!void {
+pub fn renameC(old_path: [*:0]const u8, new_path: [*:0]const u8) RenameError!void {
     if (builtin.os == .windows) {
         const old_path_w = try windows.cStrToPrefixedFileW(old_path);
         const new_path_w = try windows.cStrToPrefixedFileW(new_path);
@@ -1249,7 +1253,7 @@ pub fn renameC(old_path: [*]const u8, new_path: [*]const u8) RenameError!void {
 
 /// Same as `rename` except the parameters are null-terminated UTF16LE encoded byte arrays.
 /// Assumes target is Windows.
-pub fn renameW(old_path: [*]const u16, new_path: [*]const u16) RenameError!void {
+pub fn renameW(old_path: [*:0]const u16, new_path: [*:0]const u16) RenameError!void {
     const flags = windows.MOVEFILE_REPLACE_EXISTING | windows.MOVEFILE_WRITE_THROUGH;
     return windows.MoveFileExW(old_path, new_path, flags);
 }
@@ -1283,7 +1287,7 @@ pub fn mkdir(dir_path: []const u8, mode: u32) MakeDirError!void {
 }
 
 /// Same as `mkdir` but the parameter is a null-terminated UTF8-encoded string.
-pub fn mkdirC(dir_path: [*]const u8, mode: u32) MakeDirError!void {
+pub fn mkdirC(dir_path: [*:0]const u8, mode: u32) MakeDirError!void {
     if (builtin.os == .windows) {
         const dir_path_w = try windows.cStrToPrefixedFileW(dir_path);
         return windows.CreateDirectoryW(&dir_path_w, null);
@@ -1333,7 +1337,7 @@ pub fn rmdir(dir_path: []const u8) DeleteDirError!void {
 }
 
 /// Same as `rmdir` except the parameter is null-terminated.
-pub fn rmdirC(dir_path: [*]const u8) DeleteDirError!void {
+pub fn rmdirC(dir_path: [*:0]const u8) DeleteDirError!void {
     if (builtin.os == .windows) {
         const dir_path_w = try windows.cStrToPrefixedFileW(dir_path);
         return windows.RemoveDirectoryW(&dir_path_w);
@@ -1380,7 +1384,7 @@ pub fn chdir(dir_path: []const u8) ChangeCurDirError!void {
 }
 
 /// Same as `chdir` except the parameter is null-terminated.
-pub fn chdirC(dir_path: [*]const u8) ChangeCurDirError!void {
+pub fn chdirC(dir_path: [*:0]const u8) ChangeCurDirError!void {
     if (builtin.os == .windows) {
         const dir_path_w = try windows.cStrToPrefixedFileW(dir_path);
         @compileError("TODO implement chdir for Windows");
@@ -1422,7 +1426,7 @@ pub fn readlink(file_path: []const u8, out_buffer: []u8) ReadLinkError![]u8 {
 }
 
 /// Same as `readlink` except `file_path` is null-terminated.
-pub fn readlinkC(file_path: [*]const u8, out_buffer: []u8) ReadLinkError![]u8 {
+pub fn readlinkC(file_path: [*:0]const u8, out_buffer: []u8) ReadLinkError![]u8 {
     if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path);
         @compileError("TODO implement readlink for Windows");
@@ -1443,7 +1447,7 @@ pub fn readlinkC(file_path: [*]const u8, out_buffer: []u8) ReadLinkError![]u8 {
     }
 }
 
-pub fn readlinkatC(dirfd: fd_t, file_path: [*]const u8, out_buffer: []u8) ReadLinkError![]u8 {
+pub fn readlinkatC(dirfd: fd_t, file_path: [*:0]const u8, out_buffer: []u8) ReadLinkError![]u8 {
     if (builtin.os == .windows) {
         const file_path_w = try windows.cStrToPrefixedFileW(file_path);
         @compileError("TODO implement readlink for Windows");
@@ -2130,7 +2134,7 @@ pub fn inotify_add_watch(inotify_fd: i32, pathname: []const u8, mask: u32) INoti
 }
 
 /// Same as `inotify_add_watch` except pathname is null-terminated.
-pub fn inotify_add_watchC(inotify_fd: i32, pathname: [*]const u8, mask: u32) INotifyAddWatchError!i32 {
+pub fn inotify_add_watchC(inotify_fd: i32, pathname: [*:0]const u8, mask: u32) INotifyAddWatchError!i32 {
     const rc = system.inotify_add_watch(inotify_fd, pathname, mask);
     switch (errno(rc)) {
         0 => return @intCast(i32, rc),
@@ -2287,7 +2291,7 @@ pub fn access(path: []const u8, mode: u32) AccessError!void {
 }
 
 /// Same as `access` except `path` is null-terminated.
-pub fn accessC(path: [*]const u8, mode: u32) AccessError!void {
+pub fn accessC(path: [*:0]const u8, mode: u32) AccessError!void {
     if (builtin.os == .windows) {
         const path_w = try windows.cStrToPrefixedFileW(path);
         _ = try windows.GetFileAttributesW(&path_w);
@@ -2314,7 +2318,7 @@ pub fn accessC(path: [*]const u8, mode: u32) AccessError!void {
 /// Call from Windows-specific code if you already have a UTF-16LE encoded, null terminated string.
 /// Otherwise use `access` or `accessC`.
 /// TODO currently this ignores `mode`.
-pub fn accessW(path: [*]const u16, mode: u32) windows.GetFileAttributesError!void {
+pub fn accessW(path: [*:0]const u16, mode: u32) windows.GetFileAttributesError!void {
     const ret = try windows.GetFileAttributesW(path);
     if (ret != windows.INVALID_FILE_ATTRIBUTES) {
         return;
@@ -2381,7 +2385,7 @@ pub fn sysctl(
 }
 
 pub fn sysctlbynameC(
-    name: [*]const u8,
+    name: [*:0]const u8,
     oldp: ?*c_void,
     oldlenp: ?*usize,
     newp: ?*c_void,
@@ -2563,7 +2567,7 @@ pub fn realpath(pathname: []const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPathE
 }
 
 /// Same as `realpath` except `pathname` is null-terminated.
-pub fn realpathC(pathname: [*]const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPathError![]u8 {
+pub fn realpathC(pathname: [*:0]const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPathError![]u8 {
     if (builtin.os == .windows) {
         const pathname_w = try windows.cStrToPrefixedFileW(pathname);
         return realpathW(&pathname_w, out_buffer);
@@ -2572,10 +2576,10 @@ pub fn realpathC(pathname: [*]const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPat
         const fd = try openC(pathname, linux.O_PATH | linux.O_NONBLOCK | linux.O_CLOEXEC, 0);
         defer close(fd);
 
-        var procfs_buf: ["/proc/self/fd/-2147483648\x00".len]u8 = undefined;
+        var procfs_buf: ["/proc/self/fd/-2147483648".len:0]u8 = undefined;
         const proc_path = std.fmt.bufPrint(procfs_buf[0..], "/proc/self/fd/{}\x00", fd) catch unreachable;
 
-        return readlinkC(proc_path.ptr, out_buffer);
+        return readlinkC(@ptrCast([*:0]const u8, proc_path.ptr), out_buffer);
     }
     const result_path = std.c.realpath(pathname, out_buffer) orelse switch (std.c._errno().*) {
         EINVAL => unreachable,
@@ -2594,7 +2598,7 @@ pub fn realpathC(pathname: [*]const u8, out_buffer: *[MAX_PATH_BYTES]u8) RealPat
 }
 
 /// Same as `realpath` except `pathname` is null-terminated and UTF16LE-encoded.
-pub fn realpathW(pathname: [*]const u16, out_buffer: *[MAX_PATH_BYTES]u8) RealPathError![]u8 {
+pub fn realpathW(pathname: [*:0]const u16, out_buffer: *[MAX_PATH_BYTES]u8) RealPathError![]u8 {
     const h_file = try windows.CreateFileW(
         pathname,
         windows.GENERIC_READ,
@@ -2749,8 +2753,8 @@ pub fn sched_getaffinity(pid: pid_t) SchedGetAffinityError!cpu_set_t {
 
 /// Used to convert a slice to a null terminated slice on the stack.
 /// TODO https://github.com/ziglang/zig/issues/287
-pub fn toPosixPath(file_path: []const u8) ![PATH_MAX]u8 {
-    var path_with_null: [PATH_MAX]u8 = undefined;
+pub fn toPosixPath(file_path: []const u8) ![PATH_MAX-1:0]u8 {
+    var path_with_null: [PATH_MAX-1:0]u8 = undefined;
     // >= rather than > to make room for the null byte
     if (file_path.len >= PATH_MAX) return error.NameTooLong;
     mem.copy(u8, &path_with_null, file_path);
@@ -2855,7 +2859,7 @@ pub const GetHostNameError = error{PermissionDenied} || UnexpectedError;
 pub fn gethostname(name_buffer: *[HOST_NAME_MAX]u8) GetHostNameError![]u8 {
     if (builtin.link_libc) {
         switch (errno(system.gethostname(name_buffer, name_buffer.len))) {
-            0 => return mem.toSlice(u8, name_buffer),
+            0 => return mem.toSlice(u8, @ptrCast([*:0]u8, name_buffer)),
             EFAULT => unreachable,
             ENAMETOOLONG => unreachable, // HOST_NAME_MAX prevents this
             EPERM => return error.PermissionDenied,
lib/std/process.zig
@@ -77,7 +77,7 @@ pub fn getEnvMap(allocator: *Allocator) !BufMap {
 
         // TODO: Verify that the documentation is incorrect
         // https://github.com/WebAssembly/WASI/issues/27
-        var environ = try allocator.alloc(?[*]u8, environ_count + 1);
+        var environ = try allocator.alloc(?[*:0]u8, environ_count + 1);
         defer allocator.free(environ);
         var environ_buf = try std.heap.wasm_allocator.alloc(u8, environ_buf_size);
         defer allocator.free(environ_buf);
@@ -397,7 +397,7 @@ pub fn argsAlloc(allocator: *mem.Allocator) ![][]u8 {
             return os.unexpectedErrno(args_sizes_get_ret);
         }
 
-        var argv = try allocator.alloc([*]u8, count);
+        var argv = try allocator.alloc([*:0]u8, count);
         defer allocator.free(argv);
 
         var argv_buf = try allocator.alloc(u8, buf_size);
src/analyze.cpp
@@ -6550,7 +6550,7 @@ static bool const_values_equal_array(CodeGen *g, ConstExprValue *a, ConstExprVal
 }
 
 bool const_values_equal(CodeGen *g, ConstExprValue *a, ConstExprValue *b) {
-    assert(a->type->id == b->type->id);
+    if (a->type->id != b->type->id) return false;
     assert(a->special == ConstValSpecialStatic);
     assert(b->special == ConstValSpecialStatic);
     if (a->type == b->type) {