Change the n argument of lexer_shift_buffer to size_t from int

Values are all inside the ast struct and require no cleanup other than
freeing the ast struct.

.gitignore

@@ -1,7 +1,5 @@
 *.o
 *.d
 /core
-/oas
-/oas-asan
-/oas-msan
+/build
 /reports

src/ast.c

@@ -17,10 +17,6 @@ error_t *ast_node_alloc(ast_node_t **output) {
     return nullptr;
 }
 
-void ast_node_free_value(ast_node_t *node) {
-    // TODO: decide how value ownership will work and clean it up here
-}
-
 void ast_node_free(ast_node_t *node) {
     if (node == nullptr)
         return;
@@ -30,8 +26,6 @@ void ast_node_free(ast_node_t *node) {
         free(node->children);
     }
 
-    ast_node_free_value(node);
-
     memset(node, 0, sizeof(ast_node_t));
     free(node);
 }

src/lexer.c

@@ -136,7 +136,7 @@ error_t *lexer_open(lexer_t *lex, char *path) {
  *
  * @pre There must be at least n characters in the input buffer
  */
-void lexer_shift_buffer(lexer_t *lex, int n) {
+void lexer_shift_buffer(lexer_t *lex, size_t n) {
     assert(lex->buffer_count >= n);
     lex->buffer_count -= n;
     memmove(lex->buffer, lex->buffer + n, lex->buffer_count);