[dev.regabi] test: add another closure test case

mdempsky · mdempsky · commit bfa97ba48fa2 · 2021-01-01T13:44:37.000Z
When deciding whether a captured variable can be passed by value, the compiler is sensitive to the order that the OCLOSURE node is typechecked relative to the order that the variable is passed to "checkassign". Today, for an assignment like: q, g = 2, func() int { return q } we get this right because we always typecheck the full RHS expression list before calling checkassign on any LHS expression. But I nearly made a change that would interleave this ordering, causing us to call checkassign on q before typechecking the function literal. And alarmingly, there weren't any tests that caught this. So this commit adds one. Change-Id: I66cacd61066c7a229070861a7d973bcc434904cc Reviewed-on: https://go-review.googlesource.com/c/go/+/280998 Trust: Matthew Dempsky <mdempsky@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
diff --git a/test/closure2.go b/test/closure2.go
@@ -9,6 +9,8 @@
 
 package main
 
+var never bool
+
 func main() {
 	{
 		type X struct {
@@ -115,4 +117,16 @@ func main() {
 			panic("g() != 2")
 		}
 	}
+
+	{
+		var g func() int
+		q := 0
+		q, g = 1, func() int { return q }
+		if never {
+			g = func() int { return 2 }
+		}
+		if g() != 1 {
+			panic("g() != 1")
+		}
+	}
 }

Original file line number	Diff line number	Diff line change
`@@ -9,6 +9,8 @@`
`9`	`9`
`10`	`10`	`package main`
`11`	`11`
	`12`	`+var never bool`
	`13`	`+`
`12`	`14`	`func main() {`
`13`	`15`	`{`
`14`	`16`	`type X struct {`
`@@ -115,4 +117,16 @@ func main() {`
`115`	`117`	`panic("g() != 2")`
`116`	`118`	`}`
`117`	`119`	`}`
	`120`	`+`
	`121`	`+ {`
	`122`	`+ var g func() int`
	`123`	`+ q := 0`
	`124`	`+ q, g = 1, func() int { return q }`
	`125`	`+ if never {`
	`126`	`+ g = func() int { return 2 }`
	`127`	`+ }`
	`128`	`+ if g() != 1 {`
	`129`	`+ panic("g() != 1")`
	`130`	`+ }`
	`131`	`+ }`
`118`	`132`	`}`