From: Robert Findley <rfindley@google.com>
Date: Fri, 29 Oct 2021 21:47:32 +0000 (-0400)
Subject: go/types: make built-in to accept type sets with single underlying types
X-Git-Tag: go1.18beta1~667
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=3571ab58b8069fd945427ba49c4d8a702325bdb0;p=gostls13.git

go/types: make built-in to accept type sets with single underlying types

This is a straightforward port of CL 357776 to go/types.

Change-Id: I64220840a01f57cd7955f7d956b9aa8227473b46
Reviewed-on: https://go-review.googlesource.com/c/go/+/359874
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
---

diff --git a/src/go/types/builtins.go b/src/go/types/builtins.go
index 29a8339f3e..de7d7e6b5f 100644
--- a/src/go/types/builtins.go
+++ b/src/go/types/builtins.go
@@ -469,13 +469,13 @@ func (check *Checker) builtin(x *operand, call *ast.CallExpr, id builtinId) (_ b
 		}
 
 		var min int // minimum number of arguments
-		switch optype(T).(type) {
+		switch singleUnder(T).(type) {
 		case *Slice:
 			min = 2
 		case *Map, *Chan:
 			min = 1
-		case *top:
-			check.invalidArg(arg0, _InvalidMake, "cannot make %s; type parameter has no structural type", arg0)
+		case nil:
+			check.errorf(arg0, _InvalidMake, "cannot make %s; type set has no single underlying type", arg0)
 			return
 		default:
 			check.invalidArg(arg0, _InvalidMake, "cannot make %s; type must be slice, map, or channel", arg0)
diff --git a/src/go/types/testdata/check/builtins.go2 b/src/go/types/testdata/check/builtins.go2
index f9b6ec7926..7cca6fd714 100644
--- a/src/go/types/testdata/check/builtins.go2
+++ b/src/go/types/testdata/check/builtins.go2
@@ -127,15 +127,18 @@ func _[T M4[K, V], K comparable, V any](m T) {
 
 // make
 
+type myChan chan int
+
 func _[
-	S1 interface{ []int },
-	S2 interface{ []int | chan int },
+	S1 ~[]int,
+	S2 ~[]int | ~chan int,
 
-	M1 interface{ map[string]int },
-	M2 interface{ map[string]int | chan int },
+	M1 ~map[string]int,
+	M2 ~map[string]int | ~chan int,
 
-	C1 interface{ chan int },
-	C2 interface{ chan int | chan string },
+	C1 ~chan int,
+	C2 ~chan int | ~chan string,
+	C3 chan int | myChan, // single underlying type
 ]() {
 	type S0 []int
 	_ = make([]int, 10)
@@ -145,7 +148,7 @@ func _[
 	_ = make /* ERROR expects 2 or 3 arguments */ (S1)
 	_ = make(S1, 10, 20)
 	_ = make /* ERROR expects 2 or 3 arguments */ (S1, 10, 20, 30)
-	_ = make(S2 /* ERROR cannot make .* no structural type */ , 10)
+	_ = make(S2 /* ERROR cannot make .* no single underlying type */ , 10)
 
 	type M0 map[string]int
 	_ = make(map[string]int)
@@ -153,7 +156,7 @@ func _[
 	_ = make(M1)
 	_ = make(M1, 10)
 	_ = make/* ERROR expects 1 or 2 arguments */(M1, 10, 20)
-	_ = make(M2 /* ERROR cannot make .* no structural type */ )
+	_ = make(M2 /* ERROR cannot make .* no single underlying type */ )
 
 	type C0 chan int
 	_ = make(chan int)
@@ -161,7 +164,8 @@ func _[
 	_ = make(C1)
 	_ = make(C1, 10)
 	_ = make/* ERROR expects 1 or 2 arguments */(C1, 10, 20)
-	_ = make(C2 /* ERROR cannot make .* no structural type */ )
+	_ = make(C2 /* ERROR cannot make .* no single underlying type */ )
+	_ = make(C3)
 }
 
 // unsafe.Alignof