test: add more tests for const decls with ommitted RHS expressions

Add analogous tests to go/types and types2 test suites.
Make sure "assert" built-in is available in type-checker
tests.

For #49157.
For #53585.

Change-Id: I092901ecb43eb4833c09bd8f5e38efbe0285babe
Reviewed-on: https://go-review.googlesource.com/c/go/+/414795
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/test/const8.go b/test/const8.go
new file mode 100644
index 0000000000..9c04cc7e2c
--- /dev/null
+++ b/test/const8.go
@@ -0,0 +1,36 @@
+// run
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test that identifiers in implicit (omitted) RHS
+// expressions of constant declarations are resolved
+// in the correct context; see issues #49157, #53585.
+
+package main
+
+const X = 2
+
+func main() {
+	const (
+		A    = iota // 0
+		iota = iota // 1
+		B           // 1 (iota is declared locally on prev. line)
+		C           // 1
+	)
+	if A != 0 || B != 1 || C != 1 {
+		println("got", A, B, C, "want 0 1 1")
+		panic("FAILED")
+	}
+
+	const (
+		X = X + X
+		Y
+		Z = iota
+	)
+	if X != 4 || Y != 8 || Z != 1 {
+		println("got", X, Y, Z, "want 4 8 1")
+		panic("FAILED")
+	}
+}