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, 3 deletions

diff --git a/src/link/Elf/Archive.zig b/src/link/Elf/Archive.zig
index 0d177bc21a..17cd2dc104 100644
--- a/src/link/Elf/Archive.zig
+++ b/src/link/Elf/Archive.zig
@@ -44,8 +44,8 @@ pub fn parse(
         pos += @sizeOf(elf.ar_hdr);
 
         if (!mem.eql(u8, &hdr.ar_fmag, elf.ARFMAG)) {
-            return diags.failParse(path, "invalid archive header delimiter: {s}", .{
-                std.fmt.fmtSliceEscapeLower(&hdr.ar_fmag),
+            return diags.failParse(path, "invalid archive header delimiter: {f}", .{
+                std.ascii.hexEscape(&hdr.ar_fmag, .lower),
             });
         }
 
@@ -288,7 +288,7 @@ pub const ArStrtab = struct {
     ) !void {
         _ = unused_fmt_string;
         _ = options;
-        try writer.print("{s}", .{std.fmt.fmtSliceEscapeLower(ar.buffer.items)});
+        try writer.print("{f}", .{std.ascii.hexEscape(ar.buffer.items, .lower)});
     }
 };