Fix diags non-assignment bugs

Fix places where diags was not reassigned when diags were added.

lang/eval.go

@@ -323,10 +323,10 @@ func (s *Scope) evalContext(refs []*addrs.Reference, selfAddr addrs.Referenceabl
 			switch k := subj.Key.(type) {
 			case addrs.IntKey:
 				self, hclDiags = hcl.Index(val, cty.NumberIntVal(int64(k)), ref.SourceRange.ToHCL().Ptr())
-				diags.Append(hclDiags)
+				diags = diags.Append(hclDiags)
 			case addrs.StringKey:
 				self, hclDiags = hcl.Index(val, cty.StringVal(string(k)), ref.SourceRange.ToHCL().Ptr())
-				diags.Append(hclDiags)
+				diags = diags.Append(hclDiags)
 			default:
 				self = val
 			}

terraform/context_validate_test.go

@@ -546,7 +546,7 @@ func TestContext2Validate_orphans(t *testing.T) {
 	p.ValidateResourceTypeConfigFn = func(req providers.ValidateResourceTypeConfigRequest) providers.ValidateResourceTypeConfigResponse {
 		var diags tfdiags.Diagnostics
 		if req.Config.GetAttr("foo").IsNull() {
-			diags.Append(errors.New("foo is not set"))
+			diags = diags.Append(errors.New("foo is not set"))
 		}
 		return providers.ValidateResourceTypeConfigResponse{
 			Diagnostics: diags,
@@ -810,7 +810,7 @@ func TestContext2Validate_provisionerConfig_good(t *testing.T) {
 	pr.ValidateProvisionerConfigFn = func(req provisioners.ValidateProvisionerConfigRequest) provisioners.ValidateProvisionerConfigResponse {
 		var diags tfdiags.Diagnostics
 		if req.Config.GetAttr("test_string").IsNull() {
-			diags.Append(errors.New("test_string is not set"))
+			diags = diags.Append(errors.New("test_string is not set"))
 		}
 		return provisioners.ValidateProvisionerConfigResponse{
 			Diagnostics: diags,
@@ -943,7 +943,7 @@ func TestContext2Validate_tainted(t *testing.T) {
 	p.ValidateResourceTypeConfigFn = func(req providers.ValidateResourceTypeConfigRequest) providers.ValidateResourceTypeConfigResponse {
 		var diags tfdiags.Diagnostics
 		if req.Config.GetAttr("foo").IsNull() {
-			diags.Append(errors.New("foo is not set"))
+			diags = diags.Append(errors.New("foo is not set"))
 		}
 		return providers.ValidateResourceTypeConfigResponse{
 			Diagnostics: diags,