internal/enc: add test cases for MetadataName and Unescape

The metadata name 123 is distinguished from
metadata IDs by escaping the first digit. This
is not my invention, but how it seem to be
done by LLVM.

Author: mewmew

internal/enc/enc_test.go

@@ -188,6 +188,8 @@ func TestMetadataName(t *testing.T) {
 		{s: "foo世bar", want: `!foo\E4\B8\96bar`},
 		// i=9
 		{s: "qux\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2A\x2B\x2C\x2D\x2E\x2F\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3A\x3B\x3C\x3D\x3E\x3F\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4A\x4B\x4C\x4D\x4E\x4F\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5A\x5B\x5C\x5D\x5E\x5F\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6A\x6B\x6C\x6D\x6E\x6F\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7A\x7B\x7C\x7D\x7E\x7F\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8A\x8B\x8C\x8D\x8E\x8F\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9A\x9B\x9C\x9D\x9E\x9F\xA0\xA1\xA2\xA3\xA4\xA5\xA6\xA7\xA8\xA9\xAA\xAB\xAC\xAD\xAE\xAF\xB0\xB1\xB2\xB3\xB4\xB5\xB6\xB7\xB8\xB9\xBA\xBB\xBC\xBD\xBE\xBF\xC0\xC1\xC2\xC3\xC4\xC5\xC6\xC7\xC8\xC9\xCA\xCB\xCC\xCD\xCE\xCF\xD0\xD1\xD2\xD3\xD4\xD5\xD6\xD7\xD8\xD9\xDA\xDB\xDC\xDD\xDE\xDF\xE0\xE1\xE2\xE3\xE4\xE5\xE6\xE7\xE8\xE9\xEA\xEB\xEC\xED\xEE\xEF\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7\xF8\xF9\xFA\xFB\xFC\xFD\xFE\xFF", want: `!qux\01\02\03\04\05\06\07\08\09\0A\0B\0C\0D\0E\0F\10\11\12\13\14\15\16\17\18\19\1A\1B\1C\1D\1E\1F\20\21\22\23$\25\26\27\28\29\2A\2B\2C-.\2F0123456789\3A\3B\3C\3D\3E\3F\40ABCDEFGHIJKLMNOPQRSTUVWXYZ\5B\5C\5D\5E_\60abcdefghijklmnopqrstuvwxyz\7B\7C\7D\7E\7F\80\81\82\83\84\85\86\87\88\89\8A\8B\8C\8D\8E\8F\90\91\92\93\94\95\96\97\98\99\9A\9B\9C\9D\9E\9F\A0\A1\A2\A3\A4\A5\A6\A7\A8\A9\AA\AB\AC\AD\AE\AF\B0\B1\B2\B3\B4\B5\B6\B7\B8\B9\BA\BB\BC\BD\BE\BF\C0\C1\C2\C3\C4\C5\C6\C7\C8\C9\CA\CB\CC\CD\CE\CF\D0\D1\D2\D3\D4\D5\D6\D7\D8\D9\DA\DB\DC\DD\DE\DF\E0\E1\E2\E3\E4\E5\E6\E7\E8\E9\EA\EB\EC\ED\EE\EF\F0\F1\F2\F3\F4\F5\F6\F7\F8\F9\FA\FB\FC\FD\FE\FF`},
+		// i=10
+		{s: "123", want: `!\3123`},
 	}
 	for i, g := range golden {
 		got := MetadataName(g.s)
@@ -323,8 +325,10 @@ func TestUnescape(t *testing.T) {
 		// i=10
 		{s: `foo \5C bar`, want: []byte(`foo \ bar`)},
 		// i=11
+		{s: `foo \5c bar`, want: []byte(`foo \ bar`)},
+		// i=12
 		{s: `foo \\ bar`, want: []byte(`foo \ bar`)},
-		// i=12 (arbitrary data, invalid UTF-8)
+		// i=13 (arbitrary data, invalid UTF-8)
 		{s: `foo\81\82bar`, want: []byte{'f', 'o', 'o', 0x81, 0x82, 'b', 'a', 'r'}},
 	}
 	for i, g := range golden {

ir/metadata/metadata.go

@@ -35,7 +35,7 @@ func (md *NamedDef) String() string {
 func (md *NamedDef) Def() string {
 	// Name=MetadataName '=' '!' '{' MDNodes=(MetadataNode separator ',')* '}'
 	buf := &strings.Builder{}
-	fmt.Fprintf(buf, "%s = !{", enc.MetadataName(md.Name))
+	fmt.Fprintf(buf, "%s = !{", md)
 	for i, node := range md.Nodes {
 		if i != 0 {
 			buf.WriteString(", ")