add more comments

wgtmac · wgtmac · commit 530918e2c973 · 2025-05-22T14:28:03.000+08:00
diff --git a/src/iceberg/schema_util.cc b/src/iceberg/schema_util.cc
@@ -36,7 +36,8 @@ namespace {
 
 Status ValidateSchemaEvolution(const Type& expected_type, const Type& source_type) {
   if (expected_type.is_nested()) {
-    // Nested type requires identical type ids.
+    // Nested type requires identical type ids but their sub-fields are checked
+    // recursively and individually.
     if (source_type.type_id() != expected_type.type_id()) {
       return NotSupported("Cannot read {} from {}", expected_type, source_type);
     }

Original file line number	Diff line number	Diff line change
`@@ -36,7 +36,8 @@ namespace {`
`36`	`36`
`37`	`37`	`Status ValidateSchemaEvolution(const Type& expected_type, const Type& source_type) {`
`38`	`38`	`if (expected_type.is_nested()) {`
`39`		`- // Nested type requires identical type ids.`
	`39`	`+ // Nested type requires identical type ids but their sub-fields are checked`
	`40`	`+ // recursively and individually.`
`40`	`41`	`if (source_type.type_id() != expected_type.type_id()) {`
`41`	`42`	`return NotSupported("Cannot read {} from {}", expected_type, source_type);`
`42`	`43`	`}`