Fix bugs in handling multiple simultaneous ambiguities

spec/fixtures/corpus/cpp/statements.txt

@@ -31,7 +31,7 @@ int main() {
     (expression_statement (call_expression (identifier) (string) (string)))))))
 
 ==================================================
-template / relational expression ambiguities
+template function / relational expression ambiguities
 ==================================================
 
 int main() {
@@ -53,3 +53,23 @@ int main() {
       (call_expression
         (template_call (identifier) (type_id (type_specifier (identifier))))
         (identifier)))))))
+
+==================================================
+template class / relational expression ambiguities
+==================================================
+
+int main() {
+  SomeTemplate<SomeType> someVariable = 1;
+}
+
+---
+
+(translation_unit (function_definition
+  (type_specifier (identifier))
+  (declarator (direct_declarator (direct_declarator (identifier))))
+  (function_body (compound_statement
+    (simple_declaration
+      (type_specifier (template_call (identifier) (identifier)))
+      (init_declarator
+        (declarator (direct_declarator (identifier)))
+        (initializer (initializer_clause (number)))))))))

spec/fixtures/grammars/cpp.cc

@@ -138,6 +138,7 @@ extern const Grammar cpp = Grammar({
 
   { "type_specifier", choice({
     sym("scoped_identifier"),
+    sym("template_call"),
     sym("identifier") }) },
 
   { "compound_statement", seq({
@@ -214,9 +215,9 @@ extern const Grammar cpp = Grammar({
   sym("comment"),
   pattern("[ \t\r\n]"),
 }).expected_conflicts({
-  { "template_call", "_expression" },
   { "type_specifier", "_expression" },
-  { "template_argument", "relational_expression" },
+  { "template_call", "_expression" },
+  { "template_call", "relational_expression" },
 });
 
 }  // namespace tree_sitter_examples

src/runtime/lexer.c

@@ -22,7 +22,7 @@ static const char *empty_chunk = "";
 
 static void ts_lexer__get_chunk(TSLexer *self) {
   TSInput input = self->input;
-  if (self->current_position.bytes != self->chunk_start + self->chunk_size)
+  if (!self->chunk || self->current_position.bytes != self->chunk_start + self->chunk_size)
     input.seek_fn(input.payload, self->current_position);
 
   self->chunk_start = self->current_position.bytes;
@@ -113,6 +113,7 @@ void ts_lexer_reset(TSLexer *self, TSLength position) {
   self->token_end_position = position;
   self->current_position = position;
   self->chunk = 0;
+  self->chunk_start = 0;
   self->chunk_size = 0;
   self->lookahead_size = 0;
   self->lookahead = 0;

src/runtime/stack.c

@@ -168,9 +168,8 @@ static int ts_stack__find_or_add_head(Stack *self, StackNode *node) {
 
 void ts_stack_remove_head(Stack *self, int head_index) {
   stack_node_release(self->heads[head_index]);
-  for (int i = head_index; i < self->head_count - 1; i++) {
-    self->heads[head_index] = self->heads[head_index + 1];
-  }
+  for (int i = head_index; i < self->head_count - 1; i++)
+    self->heads[i] = self->heads[i + 1];
   self->head_count--;
 }