chibicc - Simple c compiler block {} node

Commit history for block feature

expected an expression error after adding block {} node

Problem:

{ a=3; return a; }
   ^ expected an expression
make: *** [Makefile:12: test] Error 1

Root cause:

// compound_stmt = stmt* "}"
static Node* compound_stmt(Token** rest, Token* tok) {
  Node head = {};
  Node* cur = &head;
  while(!equal(tok, "}")) {
    // This is the bug, should be tok not tok->next;
    cur = cur->next = stmt(&tok, tok->next);
  }
  Node* node = new_node(ND_BLOCK);
  node->body = head.next;
  *rest = tok->next;

  return node;

}

Fix:

// compound_stmt = stmt* "}"
static Node* compound_stmt(Token** rest, Token* tok) {
  Node head = {};
  Node* cur = &head;
  while(!equal(tok, "}")) {
    cur = cur->next = stmt(&tok, tok);
  }
  Node* node = new_node(ND_BLOCK);
  node->body = head.next;
  *rest = tok->next;

  return node;

}

What is done to introduce block concept?

Introduce another node in node struct called body to store the code content inside block

No change is made to tokenizer

For parser, introduce compound_stmt production/grammar rule for stmt generation rule.

For code generator, start generating code from Function->body part which is a block itself. Each body inside each block has its own list of nodes. Previously we only have on list of nodes. Now we have one list of nodes for each block node.

I guess this is for variable scope purpose, althought this has not been done in this commit history.