std.fmt: breaking API changes

added adapter to AnyWriter and GenericWriter to help bridge the gap
between old and new API

make std.testing.expectFmt work at compile-time

std.fmt no longer has a dependency on std.unicode. Formatted printing
was never properly unicode-aware. Now it no longer pretends to be.

Breakage/deprecations:
* std.fs.File.reader -> std.fs.File.deprecatedReader
* std.fs.File.writer -> std.fs.File.deprecatedWriter
* std.io.GenericReader -> std.io.Reader
* std.io.GenericWriter -> std.io.Writer
* std.io.AnyReader -> std.io.Reader
* std.io.AnyWriter -> std.io.Writer
* std.fmt.format -> std.fmt.deprecatedFormat
* std.fmt.fmtSliceEscapeLower -> std.ascii.hexEscape
* std.fmt.fmtSliceEscapeUpper -> std.ascii.hexEscape
* std.fmt.fmtSliceHexLower -> {x}
* std.fmt.fmtSliceHexUpper -> {X}
* std.fmt.fmtIntSizeDec -> {B}
* std.fmt.fmtIntSizeBin -> {Bi}
* std.fmt.fmtDuration -> {D}
* std.fmt.fmtDurationSigned -> {D}
* {} -> {f} when there is a format method
* format method signature
  - anytype -> *std.io.Writer
  - inferred error set -> error{WriteFailed}
  - options -> (deleted)
* std.fmt.Formatted
  - now takes context type explicitly
  - no fmt string

1 files changed, 3 insertions, 8 deletions

diff --git a/lib/std/Build/Cache/Directory.zig b/lib/std/Build/Cache/Directory.zig
index 4de1cc18f1..cc6b930c23 100644
--- a/lib/std/Build/Cache/Directory.zig
+++ b/lib/std/Build/Cache/Directory.zig
@@ -1,5 +1,6 @@
 const Directory = @This();
 const std = @import("../../std.zig");
+const assert = std.debug.assert;
 const fs = std.fs;
 const fmt = std.fmt;
 const Allocator = std.mem.Allocator;
@@ -55,14 +56,8 @@ pub fn closeAndFree(self: *Directory, gpa: Allocator) void {
     self.* = undefined;
 }
 
-pub fn format(
-    self: Directory,
-    comptime fmt_string: []const u8,
-    options: fmt.FormatOptions,
-    writer: anytype,
-) !void {
-    _ = options;
-    if (fmt_string.len != 0) fmt.invalidFmtError(fmt_string, self);
+pub fn format(self: Directory, writer: *std.io.Writer, comptime f: []const u8) std.io.Writer.Error!void {
+    comptime assert(f.len == 0);
     if (self.path) |p| {
         try writer.writeAll(p);
         try writer.writeAll(fs.path.sep_str);