core: Fix schema loading for deleted resources

Resource instances removed from the configuration would previously use
the implied provider address. This is correct for default providers, but
incorrect for those from other namespaces or hosts. The fix here is to
use the stored provider config if it is present.

internal/terraform/node_resource_abstract_instance.go

@@ -136,6 +136,9 @@ func (n *NodeAbstractResourceInstance) Provider() addrs.Provider {
 	if n.Config != nil {
 		return n.Config.Provider
 	}
+	if n.storedProviderConfig.Provider.Type != "" {
+		return n.storedProviderConfig.Provider
+	}
 	return addrs.ImpliedProviderForUnqualifiedType(n.Addr.Resource.ContainingResource().ImpliedProvider())
 }
 

internal/terraform/node_resource_abstract_instance_test.go

@@ -15,6 +15,7 @@ func TestNodeAbstractResourceInstanceProvider(t *testing.T) {
 	tests := []struct {
 		Addr                 addrs.AbsResourceInstance
 		Config               *configs.Resource
+		StoredProviderConfig addrs.AbsProviderConfig
 		Want                 addrs.Provider
 	}{
 		{
@@ -87,6 +88,28 @@ func TestNodeAbstractResourceInstanceProvider(t *testing.T) {
 				Type:      "happycloud",
 			},
 		},
+		{
+			Addr: addrs.Resource{
+				Mode: addrs.DataResourceMode,
+				Type: "null_resource",
+				Name: "baz",
+			}.Instance(addrs.NoKey).Absolute(addrs.RootModuleInstance),
+			Config: nil,
+			StoredProviderConfig: addrs.AbsProviderConfig{
+				Module: addrs.RootModule,
+				Provider: addrs.Provider{
+					Hostname:  addrs.DefaultProviderRegistryHost,
+					Namespace: "awesomecorp",
+					Type:      "null",
+				},
+			},
+			// The stored provider config overrides the default behavior.
+			Want: addrs.Provider{
+				Hostname:  addrs.DefaultProviderRegistryHost,
+				Namespace: "awesomecorp",
+				Type:      "null",
+			},
+		},
 	}
 
 	for _, test := range tests {
@@ -104,6 +127,7 @@ func TestNodeAbstractResourceInstanceProvider(t *testing.T) {
 				NodeAbstractResource: NodeAbstractResource{
 					Config: test.Config,
 				},
+				storedProviderConfig: test.StoredProviderConfig,
 			}
 			got := node.Provider()
 			if got != test.Want {