From 8683be35f6b45b4c53f56573f6eca9936f714df2 Mon Sep 17 00:00:00 2001
From: Thomas Pelletier <pelletier.thomas@gmail.com>
Date: Mon, 8 Nov 2021 21:53:02 -0500
Subject: [PATCH] seen: check inline tables (#660)

Fixes #658
---
 internal/tracker/seen.go | 33 ++++++++++++++++++++++++---------
 unmarshaler_test.go      |  6 ++++++
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/internal/tracker/seen.go b/internal/tracker/seen.go
index 8990dae..8adc4dc 100644
--- a/internal/tracker/seen.go
+++ b/internal/tracker/seen.go
@@ -65,7 +65,7 @@ type entry struct {
 	explicit bool
 }
 
-// Remove all descendent of node at position idx.
+// Remove all descendants of node at position idx.
 func (s *SeenTracker) clear(idx int) {
 	p := s.entries[idx].id
 	rest := clear(p, s.entries[idx+1:])
@@ -102,19 +102,21 @@ func (s *SeenTracker) create(parentIdx int, name []byte, kind keyKind, explicit
 	return idx
 }
 
-// CheckExpression takes a top-level node and checks that it does not contain keys
-// that have been seen in previous calls, and validates that types are consistent.
+// CheckExpression takes a top-level node and checks that it does not contain
+// keys that have been seen in previous calls, and validates that types are
+// consistent.
 func (s *SeenTracker) CheckExpression(node *ast.Node) error {
 	if s.entries == nil {
-		// Skip ID = 0 to remove the confusion between nodes whose parent has
-		// id 0 and root nodes (parent id is 0 because it's the zero value).
+		// Skip ID = 0 to remove the confusion between nodes whose
+		// parent has id 0 and root nodes (parent id is 0 because it's
+		// the zero value).
 		s.nextID = 1
 		// Start unscoped, so idx is negative.
 		s.currentIdx = -1
 	}
 	switch node.Kind {
 	case ast.KeyValue:
-		return s.checkKeyValue(node)
+		return s.checkKeyValue(s.currentIdx, node)
 	case ast.Table:
 		return s.checkTable(node)
 	case ast.ArrayTable:
@@ -206,11 +208,9 @@ func (s *SeenTracker) checkArrayTable(node *ast.Node) error {
 	return nil
 }
 
-func (s *SeenTracker) checkKeyValue(node *ast.Node) error {
+func (s *SeenTracker) checkKeyValue(parentIdx int, node *ast.Node) error {
 	it := node.Key()
 
-	parentIdx := s.currentIdx
-
 	for it.Next() {
 		k := it.Node().Data
 
@@ -230,12 +230,27 @@ func (s *SeenTracker) checkKeyValue(node *ast.Node) error {
 	}
 
 	kind := valueKind
+	var err error
 
 	if node.Value().Kind == ast.InlineTable {
 		kind = tableKind
+		err = s.checkInlineTable(parentIdx, node.Value())
 	}
+
 	s.entries[parentIdx].kind = kind
 
+	return err
+}
+
+func (s *SeenTracker) checkInlineTable(parentIdx int, node *ast.Node) error {
+	it := node.Children()
+	for it.Next() {
+		n := it.Node()
+		err := s.checkKeyValue(parentIdx, n)
+		if err != nil {
+			return err
+		}
+	}
 	return nil
 }
 
diff --git a/unmarshaler_test.go b/unmarshaler_test.go
index ee23808..26ea732 100644
--- a/unmarshaler_test.go
+++ b/unmarshaler_test.go
@@ -1910,6 +1910,12 @@ func TestIssue564(t *testing.T) {
 	require.Equal(t, uuid{0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA, 0xAA}, config.ID)
 }
 
+func TestIssue658(t *testing.T) {
+	var v map[string]interface{}
+	err := toml.Unmarshal([]byte("e={b=1,b=4}"), &v)
+	require.Error(t, err)
+}
+
 //nolint:funlen
 func TestUnmarshalDecodeErrors(t *testing.T) {
 	examples := []struct {