[errors] Greatly simplify common/errors package.

common/errors/annotate_example_test.go

Index: common/errors/annotate_example_test.go
diff --git a/common/errors/annotate_example_test.go b/common/errors/annotate_example_test.go
index 58ee286c2b573d2f982751630daf2fec2774669f..13b5490a82740054b17779173f2e062c2bd368d6 100644
--- a/common/errors/annotate_example_test.go
+++ b/common/errors/annotate_example_test.go
@@ -11,11 +11,11 @@ import (
 func someProcessingFunction(val int) error {
 	if val == 1 {
 		// New and Reason automatically include stack information.
-		return Reason("bad number: %(val)d").D("val", val).Err()
+		return Reason("bad number: %d", val).Err()
 	}
 	if err := someProcessingFunction(val - 1); err != nil {
 		// correctly handles recursion
-		return Annotate(err).D("val", val).Err()
+		return Annotate(err, "").InternalReason("val(%d)", val).Err()
 	}
 	return nil
 }
@@ -23,10 +23,8 @@ func someProcessingFunction(val int) error {
 func someLibFunc(vals ...int) error {
 	for i, v := range vals {
 		if err := someProcessingFunction(v); err != nil {
-			return (Annotate(err).Reason("processing %(val)d").
-				D("val", v).
-				D("i", i).
-				D("secret", "value", "%s").Err())
+			return Annotate(err, "processing %d", v).
+				InternalReason("secret(%s)/i(%d)", "value", i).Err()
 		}
 	}
 	return nil
@@ -48,7 +46,7 @@ func someIntermediateFunc(vals ...int) error {
 	errch := make(chan error)
 	go func() {
 		defer close(errch)
-		errch <- Annotate(errorWrapper(someLibFunc(vals...))).Reason("could not process").Err()
+		errch <- Annotate(errorWrapper(someLibFunc(vals...)), "could not process").Err()
 	}()
 	me := MultiError(nil)
 	for err := range errch {
@@ -57,17 +55,17 @@ func someIntermediateFunc(vals ...int) error {
 		}
 	}
 	if me != nil {
-		return Annotate(me).Reason("while processing %(vals)v").D("vals", vals).Err()
+		return Annotate(me, "while processing %v", vals).Err()
 	}
 	return nil
 }
 
 func ExampleAnnotate() {
 	if err := someIntermediateFunc(3); err != nil {
-		err = Annotate(err).Reason("top level").Err()
+		err = Annotate(err, "top level").Err()
 		fmt.Println("Public-facing error:\n ", err)
 		fmt.Println("\nfull error:")
-		for _, l := range FixForTest(RenderStack(err).ToLines("runtime", "_test")) {
+		for _, l := range FixForTest(RenderStack(err, "runtime", "_test")) {
 			fmt.Println(l)
 		}
 	}
@@ -79,41 +77,35 @@ func ExampleAnnotate() {
 	// full error:
 	// GOROUTINE LINE
 	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:14 - errors.someProcessingFunction()
-	//   reason: "bad number: 1"
-	//   "val" = 1
+	//   reason: bad number: 1
 	//
 	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:16 - errors.someProcessingFunction()
-	//   "val" = 2
+	//   internal reason: val(2)
 	//
 	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:16 - errors.someProcessingFunction()
-	//   "val" = 3
+	//   internal reason: val(3)
 	//
 	// From frame 2 to 3, the following wrappers were found:
 	//   unknown wrapper *errors.MiscWrappedError
 	//
 	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:25 - errors.someLibFunc()
-	//   reason: "processing 3"
-	//   "i" = 0
-	//   "secret" = value
-	//   "val" = 3
+	//   reason: processing 3
+	//   internal reason: secret(value)/i(0)
 	//
 	// From frame 3 to 4, the following wrappers were found:
-	//   MultiError 1/1: following first non-nil error.
-	//     "non-nil" = 1
-	//     "total" = 1
+	//   internal reason: MultiError 1/1: following first non-nil error.
 	//
-	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:51 - errors.someIntermediateFunc.func1()
-	//   reason: "could not process"
+	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:49 - errors.someIntermediateFunc.func1()
+	//   reason: could not process
 	//
 	// ... skipped SOME frames in pkg "runtime"...
 	//
 	// GOROUTINE LINE
-	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:60 - errors.someIntermediateFunc()
-	//   reason: "while processing [3]"
-	//   "vals" = []int{3}
+	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:58 - errors.someIntermediateFunc()
+	//   reason: while processing [3]
 	//
-	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:66 - errors.ExampleAnnotate()
-	//   reason: "top level"
+	// #? github.com/luci/luci-go/common/errors/annotate_example_test.go:64 - errors.ExampleAnnotate()
+	//   reason: top level
 	//
 	// #? testing/example.go:XXX - testing.runExample()
 	// #? testing/example.go:XXX - testing.runExamples()