internal/reflectlite: include Kind in ValueError message

The implementation has been ported from reflect, but to avoid
introducing a dependency on strconv, Kind.String() falls back to
"invalid" if the Kind is unknown rather than "kind" + strconv.Itoa(int(k))

Fixes #39286

Change-Id: I82277242a6c41d0146dabd9d20339fe72d562500
Reviewed-on: https://go-review.googlesource.com/c/go/+/235522
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Trust: Dmitri Shuralyov <dmitshur@golang.org>

2 files changed, 42 insertions, 1 deletions

diff --git a/src/internal/reflectlite/type.go b/src/internal/reflectlite/type.go
index eb7f1a4b78..15ba30da36 100644
--- a/src/internal/reflectlite/type.go
+++ b/src/internal/reflectlite/type.go
@@ -384,6 +384,44 @@ const (
 	kindMask        = (1 << 5) - 1
 )
 
+// String returns the name of k.
+func (k Kind) String() string {
+	if int(k) < len(kindNames) {
+		return kindNames[k]
+	}
+	return kindNames[0]
+}
+
+var kindNames = []string{
+	Invalid:       "invalid",
+	Bool:          "bool",
+	Int:           "int",
+	Int8:          "int8",
+	Int16:         "int16",
+	Int32:         "int32",
+	Int64:         "int64",
+	Uint:          "uint",
+	Uint8:         "uint8",
+	Uint16:        "uint16",
+	Uint32:        "uint32",
+	Uint64:        "uint64",
+	Uintptr:       "uintptr",
+	Float32:       "float32",
+	Float64:       "float64",
+	Complex64:     "complex64",
+	Complex128:    "complex128",
+	Array:         "array",
+	Chan:          "chan",
+	Func:          "func",
+	Interface:     "interface",
+	Map:           "map",
+	Ptr:           "ptr",
+	Slice:         "slice",
+	String:        "string",
+	Struct:        "struct",
+	UnsafePointer: "unsafe.Pointer",
+}
+
 func (t *uncommonType) methods() []method {
 	if t.mcount == 0 {
 		return nil
diff --git a/src/internal/reflectlite/value.go b/src/internal/reflectlite/value.go
index 85beea606c..0365eeeabf 100644
--- a/src/internal/reflectlite/value.go
+++ b/src/internal/reflectlite/value.go
@@ -160,7 +160,10 @@ type ValueError struct {
 }
 
 func (e *ValueError) Error() string {
-	return "reflect: call of " + e.Method + " on zero Value"
+	if e.Kind == 0 {
+		return "reflect: call of " + e.Method + " on zero Value"
+	}
+	return "reflect: call of " + e.Method + " on " + e.Kind.String() + " Value"
 }
 
 // methodName returns the name of the calling method,