reflect: fix FieldByNameFunc
The existing algorithm did not properly propagate the type
count from one level to the next, and as a consequence it
missed collisions.
Properly propagate multiplicity (count) information to the
next level.
benchmark old ns/op new ns/op delta
BenchmarkFieldByName1 182 180 -1.10%
BenchmarkFieldByName2 6273 6183 -1.43%
BenchmarkFieldByName3 49267 46784 -5.04%
Fixes #4355.
R=rsc
CC=golang-dev
https://golang.org/cl/6821094
diff --git a/src/pkg/reflect/all_test.go b/src/pkg/reflect/all_test.go
index 1cfab81..12cdbe1 100644
--- a/src/pkg/reflect/all_test.go
+++ b/src/pkg/reflect/all_test.go
@@ -1694,6 +1694,20 @@
S8
}
+// The X in S15.S11.S1 and S16.S11.S1 annihilate.
+type S14 struct {
+ S15
+ S16
+}
+
+type S15 struct {
+ S11
+}
+
+type S16 struct {
+ S11
+}
+
var fieldTests = []FTest{
{struct{}{}, "", nil, 0},
{struct{}{}, "Foo", nil, 0},
@@ -1719,6 +1733,7 @@
{S5{}, "Y", []int{2, 0, 1}, 0},
{S10{}, "X", nil, 0},
{S10{}, "Y", []int{2, 0, 0, 1}, 0},
+ {S14{}, "X", nil, 0},
}
func TestFieldByIndex(t *testing.T) {
diff --git a/src/pkg/reflect/type.go b/src/pkg/reflect/type.go
index 0b029d7..1101419 100644
--- a/src/pkg/reflect/type.go
+++ b/src/pkg/reflect/type.go
@@ -913,19 +913,22 @@
// Queue embedded struct fields for processing with next level,
// but only if we haven't seen a match yet at this level and only
- // if the embedded types haven't alredy been queued.
+ // if the embedded types haven't already been queued.
if ok || ntyp == nil || ntyp.Kind() != Struct {
continue
}
styp := (*structType)(unsafe.Pointer(ntyp))
if nextCount[styp] > 0 {
- nextCount[styp]++
+ nextCount[styp] = 2 // exact multiple doesn't matter
continue
}
if nextCount == nil {
nextCount = map[*structType]int{}
}
nextCount[styp] = 1
+ if count[t] > 1 {
+ nextCount[styp] = 2 // exact multiple doesn't matter
+ }
var index []int
index = append(index, scan.index...)
index = append(index, i)
