fix(parser): reset dotted-key and array records per array-of-tables element

Assisted-by: GLM 5.3

CHANGELOG.md

@@ -46,6 +46,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   check covered `[table]` headers and dotted keys but not the intermediate
   steps of an array-of-tables header, so such a document silently extended the
   inline table.
+- A new element of an array of tables starts a fresh scope for dotted-key paths
+  and nested arrays of tables: `[[a]]`, `b.c = 1`, `[[a]]`, `[a.b]` parses, as
+  the TOML examples in the spec shape it. The records of the previous element
+  falsely rejected the same paths in the next one.
 - A float with an exponent marker but no digits (`1e`, `0.0E`) is rejected;
   the exponent requires at least one digit.
 - A date-time offset outside 00:00 through 23:59 is rejected; such offsets

interpres_test.go

@@ -498,6 +498,36 @@ func TestRejectsInlineTableExtension(t *testing.T) {
 	}
 }
 
+// A new element of an array of tables starts a fresh scope: sub-table headers,
+// nested arrays of tables, and dotted-key paths recorded for the previous
+// element must not block the same paths in the next one.
+func TestArrayOfTablesFreshScopePerElement(t *testing.T) {
+	cases := map[string]string{
+		"nested array of tables": "[[a]]\n[[a.b]]\nx = 1\n[[a]]\n[a.b]\ny = 2\n",
+		"dotted key":             "[[a]]\nb.c = 1\n[[a]]\n[a.b]\nd = 2\n",
+	}
+	for name, doc := range cases {
+		tree, err := Parse([]byte(doc))
+		if err != nil {
+			t.Errorf("%s: %v", name, err)
+			continue
+		}
+		elements := tree["a"].([]map[string]any)
+		if len(elements) != 2 {
+			t.Errorf("%s: len(a) = %d, want 2", name, len(elements))
+		}
+	}
+	// Within one element the redefinition rules keep applying.
+	for name, doc := range map[string]string{
+		"header over dotted in one element": "[[a]]\nb.c = 1\n[a.b]\nd = 2\n",
+		"table over nested array":           "[[a]]\n[[a.b]]\n[a.b]\nx = 1\n",
+	} {
+		if _, err := Parse([]byte(doc)); err == nil {
+			t.Errorf("%s: expected an error, got none", name)
+		}
+	}
+}
+
 func TestRejectsSpecInvalid(t *testing.T) {
 	cases := map[string]string{
 		"single-digit hour":       "a = 2023-10-01T1:32:00Z\n",

parser.go

@@ -274,19 +274,18 @@ func (p *parser) freezeInline(path []string, val any) {
 	}
 }
 
-// resetScopeUnder forgets the header and freeze records nested under key, which
-// belong to the previous element of an array of tables.
+// resetScopeUnder forgets the definition records nested under key, which
+// belong to the previous element of an array of tables: headers, frozen
+// inline tables, dotted-key paths, and nested arrays of tables all start
+// fresh in the new element.
 func (p *parser) resetScopeUnder(key []string) {
 	prefix := pathKey(key) + "\x00"
-	for k := range p.headers {
+	for _, m := range []map[string]bool{p.headers, p.frozen, p.dotted, p.arrays} {
+		for k := range m {
 			if strings.HasPrefix(k, prefix) {
-			delete(p.headers, k)
+				delete(m, k)
 			}
 		}
-	for k := range p.frozen {
-		if strings.HasPrefix(k, prefix) {
-			delete(p.frozen, k)
-		}
 	}
 }