From 4cdc65d32a3f0378cc508e8eb395063b83683fd4 Mon Sep 17 00:00:00 2001
From: Keith Randall <khr@golang.org>
Date: Thu, 22 Jul 2021 15:30:01 -0700
Subject: [PATCH] [dev.typeparams] cmd/compile/internal/types: format union
 types

Previously it was just printing <S>. Now it prints things like int32|~int64.

Change-Id: I960b011ce8ed360020a49ae7809d85d1d1fdbfb2
Reviewed-on: https://go-review.googlesource.com/c/go/+/336692
Trust: Keith Randall <khr@golang.org>
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Dan Scales <danscales@google.com>
---
 src/cmd/compile/internal/types/fmt.go | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/cmd/compile/internal/types/fmt.go b/src/cmd/compile/internal/types/fmt.go
index a52dd060a0..0824f6d093 100644
--- a/src/cmd/compile/internal/types/fmt.go
+++ b/src/cmd/compile/internal/types/fmt.go
@@ -590,6 +590,18 @@ func tconv2(b *bytes.Buffer, t *Type, verb rune, mode fmtMode, visited map[*Type
 			b.WriteString(fmt.Sprintf("%p", t))
 		}
 
+	case TUNION:
+		for i := 0; i < t.NumTerms(); i++ {
+			if i > 0 {
+				b.WriteString("|")
+			}
+			elem, tilde := t.Term(i)
+			if tilde {
+				b.WriteString("~")
+			}
+			tconv2(b, elem, 0, mode, visited)
+		}
+
 	case Txxx:
 		b.WriteString("Txxx")