From cd06572c4fda7b0771215193358d677799e26263 Mon Sep 17 00:00:00 2001
From: Martin Atkins <mart@degeneration.co.uk>
Date: Mon, 12 Jul 2021 16:30:31 -0700
Subject: [PATCH] addrs: ModuleInstance and AbsResourceInstance are
 UniqueKeyers

Since these address types are not directly comparable themselves, we use
an unexported named type around the string representation, whereby the
special type can avoid any ambiguity between string representations of
different types and thus each type only needs to worry about possible
ambiguity of its _own_ string representation.
---
 internal/addrs/module_instance.go | 8 ++++++++
 internal/addrs/resource.go        | 8 ++++++++
 internal/addrs/unique_key_test.go | 8 ++++++++
 3 files changed, 24 insertions(+)

diff --git a/internal/addrs/module_instance.go b/internal/addrs/module_instance.go
index 2eb57948de..21afcb077b 100644
--- a/internal/addrs/module_instance.go
+++ b/internal/addrs/module_instance.go
@@ -275,6 +275,14 @@ func (m ModuleInstance) String() string {
 	return buf.String()
 }
 
+type moduleInstanceKey string
+
+func (m ModuleInstance) UniqueKey() UniqueKey {
+	return moduleInstanceKey(m.String())
+}
+
+func (mk moduleInstanceKey) uniqueKeySigil() {}
+
 // Equal returns true if the receiver and the given other value
 // contains the exact same parts.
 func (m ModuleInstance) Equal(o ModuleInstance) bool {
diff --git a/internal/addrs/resource.go b/internal/addrs/resource.go
index f22db05cbb..a7b7ee308d 100644
--- a/internal/addrs/resource.go
+++ b/internal/addrs/resource.go
@@ -292,6 +292,14 @@ func (r AbsResourceInstance) Less(o AbsResourceInstance) bool {
 	}
 }
 
+type absResourceInstanceKey string
+
+func (r AbsResourceInstance) UniqueKey() UniqueKey {
+	return absResourceInstanceKey(r.String())
+}
+
+func (r absResourceInstanceKey) uniqueKeySigil() {}
+
 func (r AbsResourceInstance) absMoveableSigil() {
 	// AbsResourceInstance is moveable
 }
diff --git a/internal/addrs/unique_key_test.go b/internal/addrs/unique_key_test.go
index 416899ca4d..0926a0c377 100644
--- a/internal/addrs/unique_key_test.go
+++ b/internal/addrs/unique_key_test.go
@@ -46,6 +46,14 @@ func TestUniqueKeyer(t *testing.T) {
 			},
 			Key: IntKey(1),
 		},
+		RootModuleInstance,
+		RootModuleInstance.Child("foo", NoKey),
+		RootModuleInstance.ResourceInstance(
+			DataResourceMode,
+			"boop",
+			"beep",
+			NoKey,
+		),
 		Self,
 	}