validate deprecated attrs from static traversals

We can't validate that data from deprecated nested attributes is used in
the configuration, but we can at least catch the simple case where a
deprecated attribute is referenced directly.

internal/configs/configschema/validate_traversal.go

@@ -74,14 +74,34 @@ func (b *Block) StaticValidateTraversal(traversal hcl.Traversal) tfdiags.Diagnos
 	}
 
 	if attrS, exists := b.Attributes[name]; exists {
+		// Check for Deprecated status of this attribute.
+		// We currently can't provide the user with any useful guidance because
+		// the deprecation string is not part of the schema, but we can at
+		// least warn them.
+		//
+		// This purposely does not attempt to recurse into nested attribute
+		// types. Because nested attribute values are often not accessed via a
+		// direct traversal to the leaf attributes, we cannot reliably detect
+		// if a nested, deprecated attribute value is actually used from the
+		// traversal alone. More precise detection of deprecated attributes
+		// would require adding metadata like marks to the cty value itself, to
+		// be caught during evaluation.
+		if attrS.Deprecated {
+			diags = diags.Append(&hcl.Diagnostic{
+				Severity: hcl.DiagWarning,
+				Summary:  `Deprecated attribute`,
+				Detail:   fmt.Sprintf(`The attribute %q is deprecated. Refer to the provider documentation for details.`, name),
+				Subject:  next.SourceRange().Ptr(),
+			})
+		}
+
 		// For attribute validation we will just apply the rest of the
-		// traversal to an unknown value of the attribute type and pass through
-		// HCL's own errors, since we don't want to replicate all of HCL's type
-		// checking rules here.
+		// traversal to an unknown value of the attribute type and pass
+		// through HCL's own errors, since we don't want to replicate all
+		// of HCL's type checking rules here.
 		val := cty.UnknownVal(attrS.ImpliedType())
 		_, hclDiags := after.TraverseRel(val)
-		diags = diags.Append(hclDiags)
-		return diags
+		return diags.Append(hclDiags)
 	}
 
 	if blockS, exists := b.BlockTypes[name]; exists {

internal/configs/configschema/validate_traversal_test.go

@@ -10,9 +10,10 @@ import (
 
 func TestStaticValidateTraversal(t *testing.T) {
 	attrs := map[string]*Attribute{
-		"str":  {Type: cty.String, Optional: true},
-		"list": {Type: cty.List(cty.String), Optional: true},
-		"dyn":  {Type: cty.DynamicPseudoType, Optional: true},
+		"str":        {Type: cty.String, Optional: true},
+		"list":       {Type: cty.List(cty.String), Optional: true},
+		"dyn":        {Type: cty.DynamicPseudoType, Optional: true},
+		"deprecated": {Type: cty.String, Computed: true, Deprecated: true},
 		"nested_single": {
 			Optional: true,
 			NestedType: &Object{
@@ -220,6 +221,10 @@ func TestStaticValidateTraversal(t *testing.T) {
 			`obj.nested_map["key"].optional`,
 			``,
 		},
+		{
+			`obj.deprecated`,
+			`Deprecated attribute: The attribute "deprecated" is deprecated. Refer to the provider documentation for details.`,
+		},
 	}
 
 	for _, test := range tests {
@@ -239,8 +244,9 @@ func TestStaticValidateTraversal(t *testing.T) {
 					t.Errorf("unexpected error: %s", diags.Err().Error())
 				}
 			} else {
-				if diags.HasErrors() {
-					if got := diags.Err().Error(); got != test.WantError {
+				err := diags.ErrWithWarnings()
+				if err != nil {
+					if got := err.Error(); got != test.WantError {
 						t.Errorf("wrong error\ngot:  %s\nwant: %s", got, test.WantError)
 					}
 				} else {