[release-branch.go1.12] fmtsort: sort interfaces deterministically
Previously, the result of sorting a map[interface{}] containing
multiple concrete types was non-deterministic. To ensure consistent
results, sort first by type name, then by concrete value.
Fixes #30484
Change-Id: I10fd4b6a74eefbc87136853af6b2e689bc76ae9d
GitHub-Last-Rev: 1b07f0c275716e1b2834f74f9c67f897bae82882
GitHub-Pull-Request: golang/go#30406
Reviewed-on: https://go-review.googlesource.com/c/163745
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
(cherry picked from commit 9d40fadb1c3245a318b155ee3e19a4de139401dc)
Reviewed-on: https://go-review.googlesource.com/c/go/+/164617
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/src/internal/fmtsort/sort.go b/src/internal/fmtsort/sort.go
index c959cbe..70a305a 100644
--- a/src/internal/fmtsort/sort.go
+++ b/src/internal/fmtsort/sort.go
@@ -167,7 +167,7 @@
if c, ok := nilCompare(aVal, bVal); ok {
return c
}
- c := compare(reflect.ValueOf(aType), reflect.ValueOf(bType))
+ c := compare(reflect.ValueOf(aVal.Elem().Type()), reflect.ValueOf(bVal.Elem().Type()))
if c != 0 {
return c
}
diff --git a/src/internal/fmtsort/sort_test.go b/src/internal/fmtsort/sort_test.go
index 6b10c77..e060d4b 100644
--- a/src/internal/fmtsort/sort_test.go
+++ b/src/internal/fmtsort/sort_test.go
@@ -126,10 +126,6 @@
map[[2]int]string{{7, 2}: "72", {7, 1}: "71", {3, 4}: "34"},
"[3 4]:34 [7 1]:71 [7 2]:72",
},
- {
- map[interface{}]string{7: "7", 4: "4", 3: "3", nil: "nil"},
- "<nil>:nil 3:3 4:4 7:7",
- },
}
func sprint(data interface{}) string {
@@ -210,3 +206,41 @@
}
}
}
+
+func TestInterface(t *testing.T) {
+ // A map containing multiple concrete types should be sorted by type,
+ // then value. However, the relative ordering of types is unspecified,
+ // so test this by checking the presence of sorted subgroups.
+ m := map[interface{}]string{
+ [2]int{1, 0}: "",
+ [2]int{0, 1}: "",
+ true: "",
+ false: "",
+ 3.1: "",
+ 2.1: "",
+ 1.1: "",
+ math.NaN(): "",
+ 3: "",
+ 2: "",
+ 1: "",
+ "c": "",
+ "b": "",
+ "a": "",
+ struct{ x, y int }{1, 0}: "",
+ struct{ x, y int }{0, 1}: "",
+ }
+ got := sprint(m)
+ typeGroups := []string{
+ "NaN: 1.1: 2.1: 3.1:", // float64
+ "false: true:", // bool
+ "1: 2: 3:", // int
+ "a: b: c:", // string
+ "[0 1]: [1 0]:", // [2]int
+ "{0 1}: {1 0}:", // struct{ x int; y int }
+ }
+ for _, g := range typeGroups {
+ if !strings.Contains(got, g) {
+ t.Errorf("sorted map should contain %q", g)
+ }
+ }
+}
