Imported Upstream version 60.1upstream/60.1

40 files changed, 469 insertions, 49 deletions

diff --git a/doc/devel/release.html b/doc/devel/release.html
index 458a116de..4ce3d37c1 100644
--- a/doc/devel/release.html
+++ b/doc/devel/release.html
@@ -89,6 +89,21 @@ appropriate tag or branch names in their repositories to make their libraries
 more accessible.
 </p>
 
+<h3 id="r60.minor">Minor revisions</h3>
+
+<p>
+r60.1 includes a 
+<a href="http://code.google.com/p/go/source/detail?r=1824581bf62d">linker
+fix</a>, a pair of
+<a href="http://code.google.com/p/go/source/detail?r=9ef4429c2c64">goplay</a>
+<a href="http://code.google.com/p/go/source/detail?r=d42ed8c3098e">fixes</a>,
+and a <code>json</code> package
+<a href="http://code.google.com/p/go/source/detail?r=d5e97874fe84">fix</a> and
+a new
+<a href="http://code.google.com/p/go/source/detail?r=4f0e6269213f">struct tag
+option</a>.
+</p>
+
 <h2 id="r59">r59 (released 2011/08/01)</h2>
 
 <p>
diff --git a/doc/docs.html b/doc/docs.html
index 9fd3dcebe..ce833fdd1 100644
--- a/doc/docs.html
+++ b/doc/docs.html
@@ -29,9 +29,9 @@ Slides from a 3-day course about the Go programming language.
 A more thorough introduction than the tutorial.
 </p>
 <ul>
-<li><a href="GoCourseDay1.pdf">Day 1: Basics</a> <small>[270KB PDF]</small>
-<li><a href="GoCourseDay2.pdf">Day 2: Types, Methods, Interfaces</a> <small>[270KB PDF]</small>
-<li><a href="GoCourseDay3.pdf">Day 3: Concurrency and Communication</a> <small>[180KB PDF]</small>
+<li><a href="GoCourseDay1.pdf">Day 1: Basics</a> <small>[270KB PDF]</small></li>
+<li><a href="GoCourseDay2.pdf">Day 2: Types, Methods, Interfaces</a> <small>[270KB PDF]</small></li>
+<li><a href="GoCourseDay3.pdf">Day 3: Concurrency and Communication</a> <small>[180KB PDF]</small></li>
 </ul>
 
 <h3 id="effective_go"><a href="effective_go.html">Effective Go</a></h3>
@@ -62,12 +62,51 @@ and closures.
 <p>
 Guided tours of Go programs. 
 </p>
+<ul>
+<li><a href="/doc/codewalk/functions">First-Class Functions in Go</a></li>
+<li><a href="/doc/codewalk/markov">Generating arbitrary text: a Markov chain algorithm</a></li>
+<li><a href="/doc/codewalk/sharemem">Share Memory by Communicating</a></li>
+</ul>
 
 <h3 id="go_for_cpp_programmers"><a href="go_for_cpp_programmers.html">Go for C++ Programmers</a></h3>
 <p>
 An introduction to Go for C++ programmers.
 </p>
 
+<h2 id="articles">Go Articles</h2>
+
+<p>
+Notable articles from the <a href="http://blog.golang.org/">Go Blog</a>.
+</p>
+
+<h3>Language</h3>
+
+<ul>
+<li><a href="http://blog.golang.org/2010/04/json-rpc-tale-of-interfaces.html">JSON-RPC: a tale of interfaces</a></li>
+<li><a href="http://blog.golang.org/2010/07/gos-declaration-syntax.html">Go's Declaration Syntax</a></li>
+<li><a href="http://blog.golang.org/2010/08/defer-panic-and-recover.html">Defer, Panic, and Recover</a></li>
+<li><a href="http://blog.golang.org/2010/09/go-concurrency-patterns-timing-out-and.html">Go Concurrency Patterns: Timing out, moving on</a></li>
+<li><a href="http://blog.golang.org/2011/01/go-slices-usage-and-internals.html">Go Slices: usage and internals</a></li>
+<li><a href="http://blog.golang.org/2011/05/gif-decoder-exercise-in-go-interfaces.html">A GIF decoder: an exercise in Go interfaces</a></li>
+<li><a href="http://blog.golang.org/2011/07/error-handling-and-go.html">Error Handling and Go</a></li>
+</ul>
+
+<h3>Packages</h3>
+
+<ul>
+<li><a href="http://blog.golang.org/2011/01/json-and-go.html">JSON and Go</a> - using the <a href="/pkg/json/">json</a> package.</li>
+<li><a href="http://blog.golang.org/2011/03/gobs-of-data.html">Gobs of data</a> - the design and use of the <a href="/pkg/gob/">gob</a> package.</li>
+<li><a href="http://blog.golang.org/2011/09/laws-of-reflection.html">The Laws of Reflection</a> - the fundamentals of the <a href="/pkg/reflect/">reflect</a> package.</li>
+</ul>
+
+<h3>Tools</h3>
+
+<ul>
+<li><a href="http://blog.golang.org/2011/03/c-go-cgo.html">C? Go? Cgo!</a> - linking against C code with <a href="/cmd/cgo/">cgo</a>.</li>
+<li><a href="http://blog.golang.org/2011/03/godoc-documenting-go-code.html">Godoc: documenting Go code</a> - writing good documentation for <a href="/cmd/godoc/">godoc</a>.</li>
+<li><a href="http://blog.golang.org/2011/06/profiling-go-programs.html">Profiling Go Programs</a></li>
+</ul>
+
 <h2 id="tutorials_nonenglish">Non-English Documentation</h2>
 
 <h3 id="docs_be">Belarusian &mdash; Беларуская</h3>
diff --git a/misc/goplay/goplay.go b/misc/goplay/goplay.go
index bbc388ba4..a1eb61795 100644
--- a/misc/goplay/goplay.go
+++ b/misc/goplay/goplay.go
@@ -145,7 +145,7 @@ func run(cmd ...string) ([]byte, os.Error) {
 var frontPage = template.Must(template.New("frontPage").Parse(frontPageText)) // HTML template
 var output = template.Must(template.New("output").Parse(outputText))          // HTML template
 
-var outputText = `<pre>{{html .}}</pre>`
+var outputText = `<pre>{{printf "%s" . |html}}</pre>`
 
 var frontPageText = `<!doctype html>
 <html>
@@ -256,7 +256,7 @@ function compileUpdate() {
 </head>
 <body>
 <table width="100%"><tr><td width="60%" valign="top">
-<textarea autofocus="true" id="edit" spellcheck="false" onkeydown="keyHandler(event);" onkeyup="autocompile();">{{html .}}</textarea>
+<textarea autofocus="true" id="edit" spellcheck="false" onkeydown="keyHandler(event);" onkeyup="autocompile();">{{printf "%s" . |html}}</textarea>
 <div class="hints">
 (Shift-Enter to compile and run.)&nbsp;&nbsp;&nbsp;&nbsp;
 <input type="checkbox" id="autocompile" value="checked" /> Compile and run after each keystroke
diff --git a/src/cmd/cgo/doc.go b/src/cmd/cgo/doc.go
index 63413825a..a4219867c 100644
--- a/src/cmd/cgo/doc.go
+++ b/src/cmd/cgo/doc.go
@@ -92,5 +92,8 @@ process of using cgo.  See $GOROOT/misc/cgo/stdio and
 $GOROOT/misc/cgo/gmp for examples.
 
 Cgo does not yet work with gccgo.
+
+See "C? Go? Cgo!" for an introduction to using cgo:
+http://blog.golang.org/2011/03/c-go-cgo.html
 */
 package documentation
diff --git a/src/cmd/gc/obj.c b/src/cmd/gc/obj.c
index 456aabb88..f99f93bda 100644
--- a/src/cmd/gc/obj.c
+++ b/src/cmd/gc/obj.c
@@ -127,7 +127,6 @@ static void
 outhist(Biobuf *b)
 {
 	Hist *h;
-	int i, depth = 0;
 	char *p, ds[] = {'c', ':', '/', 0};
 
 	for(h = hist; h != H; h = h->link) {
@@ -164,14 +163,7 @@ outhist(Biobuf *b)
 					outzfile(b, p);
 				}
 			}
-			if(h->offset > 0) {
-				//line directive
-				depth++;
-			}
-		} else if(depth > 0) {
-			for(i = 0; i < depth; i++)
-				zhist(b, h->line, h->offset);
-			depth = 0;
+		
 		}
 		zhist(b, h->line, h->offset);
 	}
diff --git a/src/cmd/godoc/doc.go b/src/cmd/godoc/doc.go
index dc98b0eca..088889d2a 100644
--- a/src/cmd/godoc/doc.go
+++ b/src/cmd/godoc/doc.go
@@ -126,5 +126,8 @@ one may run godoc as follows:
 
 	godoc -http=:6060 -zip=go.zip -goroot=$HOME/go
 
+
+See "Godoc: documenting Go code" for how to write good comments for godoc:
+http://blog.golang.org/2011/03/godoc-documenting-go-code.html
 */
 package documentation
diff --git a/src/cmd/ld/dwarf.c b/src/cmd/ld/dwarf.c
index d8ca27ace..77536018a 100644
--- a/src/cmd/ld/dwarf.c
+++ b/src/cmd/ld/dwarf.c
@@ -1578,13 +1578,16 @@ addhistfile(char *zentry)
 		histfile[histfilesize++] = "<eof>";
 
 	fname = decodez(zentry);
+//	print("addhistfile %d: %s\n", histfilesize, fname);
 	if (fname == 0)
 		return -1;
+
 	// Don't fill with duplicates (check only top one).
 	if (strcmp(fname, histfile[histfilesize-1]) == 0) {
 		free(fname);
 		return histfilesize - 1;
 	}
+
 	histfile[histfilesize++] = fname;
 	return histfilesize - 1;
 }
@@ -1608,11 +1611,13 @@ finddebugruntimepath(void)
 }
 
 // Go's runtime C sources are sane, and Go sources nest only 1 level,
-// so 16 should be plenty.
+// so a handful would be plenty, if it weren't for the fact that line
+// directives can push an unlimited number of them.
 static struct {
 	int file;
 	vlong line;
-} includestack[16];
+} *includestack;
+static int includestacksize;
 static int includetop;
 static vlong absline;
 
@@ -1629,17 +1634,15 @@ static Linehist *linehist;
 static void
 checknesting(void)
 {
-	int i;
-
 	if (includetop < 0) {
 		diag("dwarf: corrupt z stack");
 		errorexit();
 	}
-	if (includetop >= nelem(includestack)) {
-		diag("dwarf: nesting too deep");
-		for (i = 0; i < nelem(includestack); i++)
-			diag("\t%s", histfile[includestack[i].file]);
-		errorexit();
+	if (includetop >= includestacksize) {
+		includestacksize += 1;
+		includestacksize <<= 2;
+//		print("checknesting: growing to %d\n", includestacksize);
+		includestack = realloc(includestack, includestacksize * sizeof *includestack);	       
 	}
 }
 
@@ -1669,6 +1672,7 @@ inithist(Auto *a)
 	// Clear the history.
 	clearhistfile();
 	includetop = 0;
+	checknesting();
 	includestack[includetop].file = 0;
 	includestack[includetop].line = -1;
 	absline = 0;
@@ -1682,10 +1686,10 @@ inithist(Auto *a)
 	for (; a; a = a->link) {
 		if (a->type == D_FILE) {  // 'z'
 			int f = addhistfile(a->asym->name);
-			if (f < 0) {	   // pop file
+			if (f < 0) {	// pop file
 				includetop--;
 				checknesting();
-			} else if(f != includestack[includetop].file) { // pushed a new file
+			} else {	// pushed a file (potentially same)
 				includestack[includetop].line += a->aoffset - absline;
 				includetop++;
 				checknesting();
diff --git a/src/pkg/gob/doc.go b/src/pkg/gob/doc.go
index 35d882afb..a9284ced7 100644
--- a/src/pkg/gob/doc.go
+++ b/src/pkg/gob/doc.go
@@ -221,6 +221,9 @@ In summary, a gob stream looks like
 
 where * signifies zero or more repetitions and the type id of a value must
 be predefined or be defined before the value in the stream.
+
+See "Gobs of data" for a design discussion of the gob wire format:
+http://blog.golang.org/2011/03/gobs-of-data.html
 */
 package gob
 
diff --git a/src/pkg/json/Makefile b/src/pkg/json/Makefile
index 4e5a8a139..28ed62bc4 100644
--- a/src/pkg/json/Makefile
+++ b/src/pkg/json/Makefile
@@ -11,5 +11,6 @@ GOFILES=\
 	indent.go\
 	scanner.go\
 	stream.go\
+	tags.go\
 
 include ../../Make.pkg
diff --git a/src/pkg/json/decode.go b/src/pkg/json/decode.go
index 4f6562bd5..b7129f984 100644
--- a/src/pkg/json/decode.go
+++ b/src/pkg/json/decode.go
@@ -140,6 +140,7 @@ type decodeState struct {
 	scan       scanner
 	nextscan   scanner // for calls to nextValue
 	savedError os.Error
+	tempstr    string // scratch space to avoid some allocations
 }
 
 // errPhase is used for errors that should not happen unless
@@ -470,6 +471,8 @@ func (d *decodeState) object(v reflect.Value) {
 
 		// Figure out field corresponding to key.
 		var subv reflect.Value
+		destring := false // whether the value is wrapped in a string to be decoded first
+
 		if mv.IsValid() {
 			elemType := mv.Type().Elem()
 			if !mapElem.IsValid() {
@@ -486,7 +489,8 @@ func (d *decodeState) object(v reflect.Value) {
 			if isValidTag(key) {
 				for i := 0; i < sv.NumField(); i++ {
 					f = st.Field(i)
-					if f.Tag.Get("json") == key {
+					tagName, _ := parseTag(f.Tag.Get("json"))
+					if tagName == key {
 						ok = true
 						break
 					}
@@ -508,6 +512,8 @@ func (d *decodeState) object(v reflect.Value) {
 				} else {
 					subv = sv.FieldByIndex(f.Index)
 				}
+				_, opts := parseTag(f.Tag.Get("json"))
+				destring = opts.Contains("string")
 			}
 		}
 
@@ -520,8 +526,12 @@ func (d *decodeState) object(v reflect.Value) {
 		}
 
 		// Read value.
-		d.value(subv)
-
+		if destring {
+			d.value(reflect.ValueOf(&d.tempstr))
+			d.literalStore([]byte(d.tempstr), subv)
+		} else {
+			d.value(subv)
+		}
 		// Write value back to map;
 		// if using struct, subv points into struct already.
 		if mv.IsValid() {
@@ -550,8 +560,12 @@ func (d *decodeState) literal(v reflect.Value) {
 	// Scan read one byte too far; back up.
 	d.off--
 	d.scan.undo(op)
-	item := d.data[start:d.off]
 
+	d.literalStore(d.data[start:d.off], v)
+}
+
+// literalStore decodes a literal stored in item into v.
+func (d *decodeState) literalStore(item []byte, v reflect.Value) {
 	// Check for unmarshaler.
 	wantptr := item[0] == 'n' // null
 	unmarshaler, pv := d.indirect(v, wantptr)
diff --git a/src/pkg/json/decode_test.go b/src/pkg/json/decode_test.go
index a855d6048..5f6c3f5b8 100644
--- a/src/pkg/json/decode_test.go
+++ b/src/pkg/json/decode_test.go
@@ -262,7 +262,10 @@ type All struct {
 	Float32 float32
 	Float64 float64
 
-	Foo string `json:"bar"`
+	Foo  string `json:"bar"`
+	Foo2 string `json:"bar2,dummyopt"`
+
+	IntStr int64 `json:",string"`
 
 	PBool    *bool
 	PInt     *int
@@ -331,6 +334,8 @@ var allValue = All{
 	Float32: 14.1,
 	Float64: 15.1,
 	Foo:     "foo",
+	Foo2:    "foo2",
+	IntStr:  42,
 	String:  "16",
 	Map: map[string]Small{
 		"17": {Tag: "tag17"},
@@ -391,6 +396,8 @@ var allValueIndent = `{
 	"Float32": 14.1,
 	"Float64": 15.1,
 	"bar": "foo",
+	"bar2": "foo2",
+	"IntStr": "42",
 	"PBool": null,
 	"PInt": null,
 	"PInt8": null,
@@ -481,6 +488,8 @@ var pallValueIndent = `{
 	"Float32": 0,
 	"Float64": 0,
 	"bar": "",
+	"bar2": "",
+        "IntStr": "0",
 	"PBool": true,
 	"PInt": 2,
 	"PInt8": 3,
diff --git a/src/pkg/json/encode.go b/src/pkg/json/encode.go
index 3e593fec1..16be5e2af 100644
--- a/src/pkg/json/encode.go
+++ b/src/pkg/json/encode.go
@@ -4,6 +4,9 @@
 
 // Package json implements encoding and decoding of JSON objects as defined in
 // RFC 4627.
+//
+// See "JSON and Go" for an introduction to this package:
+// http://blog.golang.org/2011/01/json-and-go.html
 package json
 
 import (
@@ -14,7 +17,6 @@ import (
 	"runtime"
 	"sort"
 	"strconv"
-	"strings"
 	"unicode"
 	"utf8"
 )
@@ -59,6 +61,12 @@ import (
 //   // Note the leading comma.
 //   Field int `json:",omitempty"`
 //
+// The "string" option signals that a field is stored as JSON inside a
+// JSON-encoded string.  This extra level of encoding is sometimes
+// used when communicating with JavaScript programs:
+//
+//    Int64String int64 `json:",string"`
+//
 // The key name will be used if it's a non-empty string consisting of
 // only Unicode letters, digits, dollar signs, hyphens, and underscores.
 //
@@ -221,6 +229,12 @@ func isEmptyValue(v reflect.Value) bool {
 }
 
 func (e *encodeState) reflectValue(v reflect.Value) {
+	e.reflectValueQuoted(v, false)
+}
+
+// reflectValueQuoted writes the value in v to the output.
+// If quoted is true, the serialization is wrapped in a JSON string.
+func (e *encodeState) reflectValueQuoted(v reflect.Value, quoted bool) {
 	if !v.IsValid() {
 		e.WriteString("null")
 		return
@@ -238,26 +252,39 @@ func (e *encodeState) reflectValue(v reflect.Value) {
 		return
 	}
 
+	writeString := (*encodeState).WriteString
+	if quoted {
+		writeString = (*encodeState).string
+	}
+
 	switch v.Kind() {
 	case reflect.Bool:
 		x := v.Bool()
 		if x {
-			e.WriteString("true")
+			writeString(e, "true")
 		} else {
-			e.WriteString("false")
+			writeString(e, "false")
 		}
 
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		e.WriteString(strconv.Itoa64(v.Int()))
+		writeString(e, strconv.Itoa64(v.Int()))
 
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-		e.WriteString(strconv.Uitoa64(v.Uint()))
+		writeString(e, strconv.Uitoa64(v.Uint()))
 
 	case reflect.Float32, reflect.Float64:
-		e.WriteString(strconv.FtoaN(v.Float(), 'g', -1, v.Type().Bits()))
+		writeString(e, strconv.FtoaN(v.Float(), 'g', -1, v.Type().Bits()))
 
 	case reflect.String:
-		e.string(v.String())
+		if quoted {
+			sb, err := Marshal(v.String())
+			if err != nil {
+				e.error(err)
+			}
+			e.string(string(sb))
+		} else {
+			e.string(v.String())
+		}
 
 	case reflect.Struct:
 		e.WriteByte('{')
@@ -269,17 +296,14 @@ func (e *encodeState) reflectValue(v reflect.Value) {
 			if f.PkgPath != "" {
 				continue
 			}
-			tag, omitEmpty := f.Name, false
+			tag, omitEmpty, quoted := f.Name, false, false
 			if tv := f.Tag.Get("json"); tv != "" {
-				ss := strings.SplitN(tv, ",", 2)
-				if isValidTag(ss[0]) {
-					tag = ss[0]
-				}
-				if len(ss) > 1 {
-					// Currently the only option is omitempty,
-					// so parsing is trivial.
-					omitEmpty = ss[1] == "omitempty"
+				name, opts := parseTag(tv)
+				if isValidTag(name) {
+					tag = name
 				}
+				omitEmpty = opts.Contains("omitempty")
+				quoted = opts.Contains("string")
 			}
 			fieldValue := v.Field(i)
 			if omitEmpty && isEmptyValue(fieldValue) {
@@ -292,7 +316,7 @@ func (e *encodeState) reflectValue(v reflect.Value) {
 			}
 			e.string(tag)
 			e.WriteByte(':')
-			e.reflectValue(fieldValue)
+			e.reflectValueQuoted(fieldValue, quoted)
 		}
 		e.WriteByte('}')
 
@@ -380,7 +404,8 @@ func (sv stringValues) Swap(i, j int)      { sv[i], sv[j] = sv[j], sv[i] }
 func (sv stringValues) Less(i, j int) bool { return sv.get(i) < sv.get(j) }
 func (sv stringValues) get(i int) string   { return sv[i].String() }
 
-func (e *encodeState) string(s string) {
+func (e *encodeState) string(s string) (int, os.Error) {
+	len0 := e.Len()
 	e.WriteByte('"')
 	start := 0
 	for i := 0; i < len(s); {
@@ -425,4 +450,5 @@ func (e *encodeState) string(s string) {
 		e.WriteString(s[start:])
 	}
 	e.WriteByte('"')
+	return e.Len() - len0, nil
 }
diff --git a/src/pkg/json/encode_test.go b/src/pkg/json/encode_test.go
index 0e4b63770..012e9f143 100644
--- a/src/pkg/json/encode_test.go
+++ b/src/pkg/json/encode_test.go
@@ -5,6 +5,8 @@
 package json
 
 import (
+	"bytes"
+	"reflect"
 	"testing"
 )
 
@@ -42,3 +44,39 @@ func TestOmitEmpty(t *testing.T) {
 		t.Errorf(" got: %s\nwant: %s\n", got, optionalsExpected)
 	}
 }
+
+type StringTag struct {
+	BoolStr bool   `json:",string"`
+	IntStr  int64  `json:",string"`
+	StrStr  string `json:",string"`
+}
+
+var stringTagExpected = `{
+ "BoolStr": "true",
+ "IntStr": "42",
+ "StrStr": "\"xzbit\""
+}`
+
+func TestStringTag(t *testing.T) {
+	var s StringTag
+	s.BoolStr = true
+	s.IntStr = 42
+	s.StrStr = "xzbit"
+	got, err := MarshalIndent(&s, "", " ")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got := string(got); got != stringTagExpected {
+		t.Fatalf(" got: %s\nwant: %s\n", got, stringTagExpected)
+	}
+
+	// Verify that it round-trips.
+	var s2 StringTag
+	err = NewDecoder(bytes.NewBuffer(got)).Decode(&s2)
+	if err != nil {
+		t.Fatalf("Decode: %v", err)
+	}
+	if !reflect.DeepEqual(s, s2) {
+		t.Fatalf("decode didn't match.\nsource: %#v\nEncoded as:\n%s\ndecode: %#v", s, string(got), s2)
+	}
+}
diff --git a/src/pkg/json/tags.go b/src/pkg/json/tags.go
new file mode 100644
index 000000000..58cda2027
--- /dev/null
+++ b/src/pkg/json/tags.go
@@ -0,0 +1,44 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package json
+
+import (
+	"strings"
+)
+
+// tagOptions is the string following a comma in a struct field's "json"
+// tag, or the empty string. It does not include the leading comma.
+type tagOptions string
+
+// parseTag splits a struct field's json tag into its name and
+// comma-separated options.
+func parseTag(tag string) (string, tagOptions) {
+	if idx := strings.Index(tag, ","); idx != -1 {
+		return tag[:idx], tagOptions(tag[idx+1:])
+	}
+	return tag, tagOptions("")
+}
+
+// Contains returns whether checks that a comma-separated list of options
+// contains a particular substr flag. substr must be surrounded by a
+// string boundary or commas.
+func (o tagOptions) Contains(optionName string) bool {
+	if len(o) == 0 {
+		return false
+	}
+	s := string(o)
+	for s != "" {
+		var next string
+		i := strings.Index(s, ",")
+		if i >= 0 {
+			s, next = s[:i], s[i+1:]
+		}
+		if s == optionName {
+			return true
+		}
+		s = next
+	}
+	return false
+}
diff --git a/src/pkg/json/tags_test.go b/src/pkg/json/tags_test.go
new file mode 100644
index 000000000..91fb18831
--- /dev/null
+++ b/src/pkg/json/tags_test.go
@@ -0,0 +1,28 @@
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package json
+
+import (
+	"testing"
+)
+
+func TestTagParsing(t *testing.T) {
+	name, opts := parseTag("field,foobar,foo")
+	if name != "field" {
+		t.Fatalf("name = %q, want field", name)
+	}
+	for _, tt := range []struct {
+		opt  string
+		want bool
+	}{
+		{"foobar", true},
+		{"foo", true},
+		{"bar", false},
+	} {
+		if opts.Contains(tt.opt) != tt.want {
+			t.Errorf("Contains(%q) = %v", tt.opt, !tt.want)
+		}
+	}
+}
diff --git a/src/pkg/reflect/type.go b/src/pkg/reflect/type.go
index 4c377e1fe..ef0fb87ea 100644
--- a/src/pkg/reflect/type.go
+++ b/src/pkg/reflect/type.go
@@ -10,6 +10,9 @@
 // A call to ValueOf returns a Value representing the run-time data.
 // Zero takes a Type and returns a Value representing a zero value
 // for that type.
+//
+// See "The Laws of Reflection" for an introduction to reflection in Go:
+// http://blog.golang.org/2011/09/laws-of-reflection.html
 package reflect
 
 import (
diff --git a/test/dwarf/linedirectives.go b/test/dwarf/linedirectives.go
new file mode 100755
index 000000000..68434f0ab
--- /dev/null
+++ b/test/dwarf/linedirectives.go
@@ -0,0 +1,83 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//line foo/bar.y:4
+package main
+//line foo/bar.y:60
+func main() { 
+//line foo/bar.y:297
+	f, l := 0, 0
+//line yacctab:1
+	f, l = 1, 1
+//line yaccpar:1
+	f, l = 2, 1
+//line foo/bar.y:82
+	f, l = 3, 82
+//line foo/bar.y:90
+	f, l = 3, 90
+//line foo/bar.y:92
+	f, l = 3, 92
+//line foo/bar.y:100
+	f, l = 3, 100
+//line foo/bar.y:104
+	l = 104
+//line foo/bar.y:112
+	l = 112
+//line foo/bar.y:117
+	l = 117
+//line foo/bar.y:121
+	l = 121
+//line foo/bar.y:125
+	l = 125
+//line foo/bar.y:133
+	l = 133
+//line foo/bar.y:146
+	l = 146
+//line foo/bar.y:148
+//line foo/bar.y:153
+//line foo/bar.y:155
+	l = 155
+//line foo/bar.y:160
+
+//line foo/bar.y:164
+//line foo/bar.y:173
+
+//line foo/bar.y:178
+//line foo/bar.y:180
+//line foo/bar.y:185
+//line foo/bar.y:195
+//line foo/bar.y:197
+//line foo/bar.y:202
+//line foo/bar.y:204
+//line foo/bar.y:208
+//line foo/bar.y:211
+//line foo/bar.y:213
+//line foo/bar.y:215
+//line foo/bar.y:217
+//line foo/bar.y:221
+//line foo/bar.y:229
+//line foo/bar.y:236
+//line foo/bar.y:238
+//line foo/bar.y:240
+//line foo/bar.y:244
+//line foo/bar.y:249
+//line foo/bar.y:253
+//line foo/bar.y:257
+//line foo/bar.y:262
+//line foo/bar.y:267
+//line foo/bar.y:272
+	if l == f {
+//line foo/bar.y:277
+	panic("aie!")
+//line foo/bar.y:281
+	}
+//line foo/bar.y:285
+	return
+//line foo/bar.y:288
+//line foo/bar.y:290
+}
+//line foo/bar.y:293
+//line foo/bar.y:295
diff --git a/test/dwarf/main.go b/test/dwarf/main.go
new file mode 100644
index 000000000..7f2ec4c00
--- /dev/null
+++ b/test/dwarf/main.go
@@ -0,0 +1,29 @@
+// $G $D/$F.go $D/z*.go && $L $F.$A && ./$A.out
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+func main() {
+F1()
+F2()
+F3()
+F4()
+F5()
+F6()
+F7()
+F8()
+F9()
+F10()
+F11()
+F12()
+F13()
+F14()
+F15()
+F16()
+F17()
+F18()
+F19()
+F20()
+}
diff --git a/test/dwarf/z1.go b/test/dwarf/z1.go
new file mode 100644
index 000000000..7f163e9a1
--- /dev/null
+++ b/test/dwarf/z1.go
@@ -0,0 +1,5 @@
+
+
+//line x1.go:4
+package main
+func F1() {}
diff --git a/test/dwarf/z10.go b/test/dwarf/z10.go
new file mode 100644
index 000000000..19c70020e
--- /dev/null
+++ b/test/dwarf/z10.go
@@ -0,0 +1,6 @@
+
+
+
+//line x10.go:4
+package main
+func F10() {}
diff --git a/test/dwarf/z11.go b/test/dwarf/z11.go
new file mode 100644
index 000000000..c1d2f9180
--- /dev/null
+++ b/test/dwarf/z11.go
@@ -0,0 +1,4 @@
+
+//line x11.go:4
+package main
+func F11() {}
diff --git a/test/dwarf/z12.go b/test/dwarf/z12.go
new file mode 100644
index 000000000..7455f1894
--- /dev/null
+++ b/test/dwarf/z12.go
@@ -0,0 +1,4 @@
+
+//line x12.go:4
+package main
+func F12() {}
diff --git a/test/dwarf/z13.go b/test/dwarf/z13.go
new file mode 100644
index 000000000..ecb3c4c8c
--- /dev/null
+++ b/test/dwarf/z13.go
@@ -0,0 +1,4 @@
+
+//line x13.go:4
+package main
+func F13() {}
diff --git a/test/dwarf/z14.go b/test/dwarf/z14.go
new file mode 100644
index 000000000..134b39b64
--- /dev/null
+++ b/test/dwarf/z14.go
@@ -0,0 +1,4 @@
+
+//line x14.go:4
+package main
+func F14() {}
diff --git a/test/dwarf/z15.go b/test/dwarf/z15.go
new file mode 100644
index 000000000..d73819b44
--- /dev/null
+++ b/test/dwarf/z15.go
@@ -0,0 +1,4 @@
+
+//line x15.go:4
+package main
+func F15() {}
diff --git a/test/dwarf/z16.go b/test/dwarf/z16.go
new file mode 100644
index 000000000..6c31651ba
--- /dev/null
+++ b/test/dwarf/z16.go
@@ -0,0 +1,4 @@
+
+//line x16.go:4
+package main
+func F16() {}
diff --git a/test/dwarf/z17.go b/test/dwarf/z17.go
new file mode 100644
index 000000000..b742d1672
--- /dev/null
+++ b/test/dwarf/z17.go
@@ -0,0 +1,4 @@
+
+//line x17.go:4
+package main
+func F17() {}
diff --git a/test/dwarf/z18.go b/test/dwarf/z18.go
new file mode 100644
index 000000000..84150ff0a
--- /dev/null
+++ b/test/dwarf/z18.go
@@ -0,0 +1,5 @@
+
+
+//line x18.go:4
+package main
+func F18() {}
diff --git a/test/dwarf/z19.go b/test/dwarf/z19.go
new file mode 100644
index 000000000..bb2e29684
--- /dev/null
+++ b/test/dwarf/z19.go
@@ -0,0 +1,4 @@
+
+//line x19.go:4
+package main
+func F19() {}
diff --git a/test/dwarf/z2.go b/test/dwarf/z2.go
new file mode 100644
index 000000000..68bd58257
--- /dev/null
+++ b/test/dwarf/z2.go
@@ -0,0 +1,4 @@
+
+//line x2.go:4
+package main
+func F2() {}
diff --git a/test/dwarf/z20.go b/test/dwarf/z20.go
new file mode 100644
index 000000000..03111e184
--- /dev/null
+++ b/test/dwarf/z20.go
@@ -0,0 +1,4 @@
+
+//line x20.go:4
+package main
+func F20() {}
diff --git a/test/dwarf/z3.go b/test/dwarf/z3.go
new file mode 100644
index 000000000..5e4ad3ae2
--- /dev/null
+++ b/test/dwarf/z3.go
@@ -0,0 +1,4 @@
+
+//line x3.go:4
+package main
+func F3() {}
diff --git a/test/dwarf/z4.go b/test/dwarf/z4.go
new file mode 100644
index 000000000..1f28465c5
--- /dev/null
+++ b/test/dwarf/z4.go
@@ -0,0 +1,4 @@
+
+//line x4.go:4
+package main
+func F4() {}
diff --git a/test/dwarf/z5.go b/test/dwarf/z5.go
new file mode 100644
index 000000000..7f4eeb419
--- /dev/null
+++ b/test/dwarf/z5.go
@@ -0,0 +1,4 @@
+
+//line x5.go:4
+package main
+func F5() {}
diff --git a/test/dwarf/z6.go b/test/dwarf/z6.go
new file mode 100644
index 000000000..241791dff
--- /dev/null
+++ b/test/dwarf/z6.go
@@ -0,0 +1,4 @@
+
+//line x6.go:4
+package main
+func F6() {}
diff --git a/test/dwarf/z7.go b/test/dwarf/z7.go
new file mode 100644
index 000000000..68c1ad0c2
--- /dev/null
+++ b/test/dwarf/z7.go
@@ -0,0 +1,4 @@
+
+//line x7.go:4
+package main
+func F7() {}
diff --git a/test/dwarf/z8.go b/test/dwarf/z8.go
new file mode 100644
index 000000000..16eed32a2
--- /dev/null
+++ b/test/dwarf/z8.go
@@ -0,0 +1,4 @@
+
+//line x8.go:4
+package main
+func F8() {}
diff --git a/test/dwarf/z9.go b/test/dwarf/z9.go
new file mode 100644
index 000000000..cbb94b4d2
--- /dev/null
+++ b/test/dwarf/z9.go
@@ -0,0 +1,4 @@
+
+//line x9.go:4
+package main
+func F9() {}
diff --git a/test/golden.out b/test/golden.out
index 655ceda56..1618ef68e 100644
--- a/test/golden.out
+++ b/test/golden.out
@@ -124,6 +124,8 @@ panic: interface conversion: *main.S is not main.I2: missing method Name
 
 == syntax/
 
+== dwarf/
+
 == fixedbugs/
 
 =========== fixedbugs/bug027.go
diff --git a/test/run b/test/run
index bc31d2f71..fce4d012f 100755
--- a/test/run
+++ b/test/run
@@ -53,7 +53,7 @@ filterout() {
 	grep '^'"$2"'$' $1 >/dev/null
 }
 
-for dir in . ken chan interface nilptr syntax fixedbugs bugs
+for dir in . ken chan interface nilptr syntax dwarf fixedbugs bugs
 do
 	echo
 	echo '==' $dir'/'