From 95781b8d80c98b37ecce87a8a4771013aa89add9 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Sun, 11 Aug 2019 09:53:31 +0900
Subject: [PATCH] Add void type

---
 chibicc.h  |  2 ++
 parse.c    | 13 +++++++++----
 tests      |  2 ++
 tokenize.c |  2 +-
 type.c     |  8 ++++++++
 5 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/chibicc.h b/chibicc.h
index 509d595..30a26fd 100644
--- a/chibicc.h
+++ b/chibicc.h
@@ -164,6 +164,7 @@ Program *program();
 //
 
 typedef enum {
+  TY_VOID,
   TY_CHAR,
   TY_SHORT,
   TY_INT,
@@ -192,6 +193,7 @@ struct Member {
 };
 
 int align_to(int n, int align);
+Type *void_type();
 Type *char_type();
 Type *short_type();
 Type *int_type();
diff --git a/parse.c b/parse.c
index 7557efd..03e8eeb 100644
--- a/parse.c
+++ b/parse.c
@@ -170,11 +170,13 @@ Program *program() {
 }
 
 // type-specifier = builtin-type | struct-decl | typedef-name
-// builtin-type   = "char" | "short" | "int" | "long"
+// builtin-type   = "void" | "char" | "short" | "int" | "long"
 Type *type_specifier() {
   if (!is_typename(token))
     error_tok(token, "typename expected");
 
+  if (consume("void"))
+    return void_type();
   if (consume("char"))
     return char_type();
   if (consume("short"))
@@ -364,8 +366,11 @@ Node *declaration() {
   char *name = NULL;
   ty = declarator(ty, &name);
   ty = type_suffix(ty);
-  Var *var = push_var(name, ty, true);
 
+  if (ty->kind == TY_VOID)
+    error_tok(tok, "variable declared void");
+
+  Var *var = push_var(name, ty, true);
   if (consume(";"))
     return new_node(ND_NULL, tok);
 
@@ -383,8 +388,8 @@ Node *read_expr_stmt() {
 }
 
 bool is_typename() {
-  return peek("char") || peek("short") || peek("int") || peek("long") ||
-         peek("struct") || find_typedef(token);
+  return peek("void") || peek("char") || peek("short") || peek("int") ||
+         peek("long") || peek("struct") || find_typedef(token);
 }
 
 // stmt = "return" expr ";"
diff --git a/tests b/tests
index 6aec64f..bb0073a 100644
--- a/tests
+++ b/tests
@@ -273,6 +273,8 @@ int main() {
 
   assert(3, *g1_ptr(), "*g1_ptr()");
 
+  { void *x; }
+
   printf("OK\n");
   return 0;
 }
diff --git a/tokenize.c b/tokenize.c
index 3eae8c5..8acdfdf 100644
--- a/tokenize.c
+++ b/tokenize.c
@@ -153,7 +153,7 @@ char *starts_with_reserved(char *p) {
   // Keyword
   static char *kw[] = {"return", "if", "else", "while", "for", "int",
                        "char", "sizeof", "struct", "typedef", "short",
-                       "long"};
+                       "long", "void"};
 
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++) {
     int len = strlen(kw[i]);
diff --git a/type.c b/type.c
index 5c6bb8b..403cfbc 100644
--- a/type.c
+++ b/type.c
@@ -11,6 +11,10 @@ Type *new_type(TypeKind kind, int align) {
   return ty;
 }
 
+Type *void_type() {
+  return new_type(TY_VOID, 1);
+}
+
 Type *char_type() {
   return new_type(TY_CHAR, 1);
 }
@@ -47,6 +51,8 @@ Type *array_of(Type *base, int size) {
 }
 
 int size_of(Type *ty) {
+  assert(ty->kind != TY_VOID);
+
   switch (ty->kind) {
   case TY_CHAR:
     return 1;
@@ -144,6 +150,8 @@ void visit(Node *node) {
     if (!node->lhs->ty->base)
       error_tok(node->tok, "invalid pointer dereference");
     node->ty = node->lhs->ty->base;
+    if (node->ty->kind == TY_VOID)
+      error_tok(node->tok, "dereferencing a void pointer");
     return;
   case ND_SIZEOF:
     node->kind = ND_NUM;
-- 
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