From 1fb5091f757f07940824c422e24fffd961c32025 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Wed, 21 Aug 2019 20:18:08 +0900
Subject: [PATCH] Add _Alignof

---
 parse.c    |  8 ++++++++
 tests      | 10 ++++++++++
 tokenize.c |  2 +-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/parse.c b/parse.c
index bbdf6d0..6dbd5d5 100644
--- a/parse.c
+++ b/parse.c
@@ -1705,6 +1705,7 @@ static Node *func_args(void) {
 //         | "(" expr ")"
 //         | "sizeof" "(" type-name ")"
 //         | "sizeof" unary
+//         | "_Alignof" "(" type-name ")"
 //         | ident func-args?
 //         | str
 //         | num
@@ -1739,6 +1740,13 @@ static Node *primary(void) {
     return new_num(node->ty->size, tok);
   }
 
+  if (tok = consume("_Alignof")) {
+    expect("(");
+    Type *ty = type_name();
+    expect(")");
+    return new_num(ty->align, tok);
+  }
+
   if (tok = consume_ident()) {
     // Function call
     if (consume("(")) {
diff --git a/tests b/tests
index 9c43e50..52bb2f6 100644
--- a/tests
+++ b/tests
@@ -632,6 +632,16 @@ int main() {
 
   ;
 
+  assert(1, _Alignof(char), "_Alignof(char)");
+  assert(2, _Alignof(short), "_Alignof(short)");
+  assert(4, _Alignof(int), "_Alignof(int)");
+  assert(8, _Alignof(long), "_Alignof(long)");
+  assert(8, _Alignof(long long), "_Alignof(long long)");
+  assert(1, _Alignof(char[3]), "_Alignof(char[3])");
+  assert(4, _Alignof(int[3]), "_Alignof(int[3])");
+  assert(1, _Alignof(struct {char a; char b;}[2]), "_Alignof(struct {char a; char b;}[2])");
+  assert(8, _Alignof(struct {char a; long b;}[2]), "_Alignof(struct {char a; long b;}[2])");
+
   printf("OK\n");
   return 0;
 }
diff --git a/tokenize.c b/tokenize.c
index e8c3ba9..54f1cea 100644
--- a/tokenize.c
+++ b/tokenize.c
@@ -151,7 +151,7 @@ static char *starts_with_reserved(char *p) {
                        "char", "sizeof", "struct", "typedef", "short",
                        "long", "void", "_Bool", "enum", "static", "break",
                        "continue", "goto", "switch", "case", "default",
-                       "extern"};
+                       "extern", "_Alignof"};
 
   for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++) {
     int len = strlen(kw[i]);
-- 
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