From f43d01bdc789328437e88927c2e2ecf4a8648390 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Tue, 6 Aug 2019 11:40:23 +0200
Subject: [PATCH] compiler: make struct types more unique

There are a lot more fields that are important when comparing structs
with each other. Take them into account when building the unique ID per
struct type.

Example code that differs between the compilers:
https://play.golang.org/p/nDX4tSHOf_T
---
 compiler/interface.go  |  9 ++++++++-
 testdata/interface.go  | 12 ++++++++++++
 testdata/interface.txt |  2 ++
 3 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/compiler/interface.go b/compiler/interface.go
index 94a60f3dc..beda21a68 100644
--- a/compiler/interface.go
+++ b/compiler/interface.go
@@ -161,7 +161,14 @@ func getTypeCodeName(t types.Type) string {
 			panic("cgo unions are not allowed in interfaces")
 		}
 		for i := 0; i < t.NumFields(); i++ {
-			elems[i] = getTypeCodeName(t.Field(i).Type())
+			embedded := ""
+			if t.Field(i).Embedded() {
+				embedded = "#"
+			}
+			elems[i] = embedded + t.Field(i).Name() + ":" + getTypeCodeName(t.Field(i).Type())
+			if t.Tag(i) != "" {
+				elems[i] += "`" + t.Tag(i) + "`"
+			}
 		}
 		return "struct:" + "{" + strings.Join(elems, ",") + "}"
 	default:
diff --git a/testdata/interface.go b/testdata/interface.go
index 69c3b32cf..88b0944ba 100644
--- a/testdata/interface.go
+++ b/testdata/interface.go
@@ -11,6 +11,10 @@ func main() {
 	printItf(*thing)
 	printItf(thing)
 	printItf(Stringer(thing))
+	printItf(struct{ n int }{})
+	printItf(struct {
+		n int `foo:"bar"`
+	}{})
 	printItf(Number(3))
 	array := Array([4]uint32{1, 7, 11, 13})
 	printItf(array)
@@ -47,6 +51,14 @@ func printItf(val interface{}) {
 		println("is Thing:", val.String())
 	case *Thing:
 		println("is *Thing:", val.String())
+	case struct{ i int }:
+		println("is struct{i int}")
+	case struct{ n int }:
+		println("is struct{n int}")
+	case struct {
+		n int `foo:"bar"`
+	}:
+		println("is struct{n int `foo:\"bar\"`}")
 	case Foo:
 		println("is Foo:", val)
 	default:
diff --git a/testdata/interface.txt b/testdata/interface.txt
index 3f3989747..83ee80b07 100644
--- a/testdata/interface.txt
+++ b/testdata/interface.txt
@@ -7,6 +7,8 @@ is Foo: 18
 is Thing: foo
 is *Thing: foo
 is *Thing: foo
+is struct{n int}
+is struct{n int `foo:"bar"`}
 is Doubler: 6
 is Tuple: 1 7 11 13
 Array len: 4