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-rw-r--r--test/fixedbugs/issue4909b.go80
1 files changed, 80 insertions, 0 deletions
diff --git a/test/fixedbugs/issue4909b.go b/test/fixedbugs/issue4909b.go
new file mode 100644
index 0000000..0f594e3
--- /dev/null
+++ b/test/fixedbugs/issue4909b.go
@@ -0,0 +1,80 @@
+// errorcheckoutput
+
+package main
+
+import "fmt"
+
+// We are going to define 256 types T(n),
+// such that T(n) embeds T(2n) and *T(2n+1).
+
+func main() {
+ fmt.Printf("// errorcheck\n\n")
+ fmt.Printf("package p\n\n")
+ fmt.Println(`import "unsafe"`)
+
+ // Dump types.
+ for n := 1; n < 256; n++ {
+ writeStruct(n)
+ }
+ // Dump leaves
+ for n := 256; n < 512; n++ {
+ fmt.Printf("type T%d int\n", n)
+ }
+
+ fmt.Printf("var t T1\n")
+ fmt.Printf("var p *T1\n")
+
+ // Simple selectors
+ for n := 2; n < 256; n++ {
+ writeDot(n)
+ }
+
+ // Double selectors
+ for n := 128; n < 256; n++ {
+ writeDot(n/16, n)
+ }
+
+ // Triple selectors
+ for n := 128; n < 256; n++ {
+ writeDot(n/64, n/8, n)
+ }
+}
+
+const structTpl = `
+type T%d struct {
+ A%d int
+ T%d
+ *T%d
+}
+`
+
+func writeStruct(n int) {
+ fmt.Printf(structTpl, n, n, 2*n, 2*n+1)
+}
+
+func writeDot(ns ...int) {
+ for _, root := range []string{"t", "p"} {
+ fmt.Printf("const _ = unsafe.Offsetof(%s", root)
+ for _, n := range ns {
+ fmt.Printf(".T%d", n)
+ }
+ // Does it involve an indirection?
+ nlast := ns[len(ns)-1]
+ nprev := 1
+ if len(ns) > 1 {
+ nprev = ns[len(ns)-2]
+ }
+ isIndirect := false
+ for n := nlast / 2; n > nprev; n /= 2 {
+ if n%2 == 1 {
+ isIndirect = true
+ break
+ }
+ }
+ fmt.Print(")")
+ if isIndirect {
+ fmt.Print(` // ERROR "indirection"`)
+ }
+ fmt.Print("\n")
+ }
+}