From 9656560f144380bcebade03a6c10b8c186ad3874 Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Sat, 3 Sep 2016 23:55:54 +0200
Subject: [PATCH] Fix sizeof(char[a])

The sizes of VLAs need to be evaluated even inside sizeof,
i.e. when nocode_wanted is set.
---
 tccgen.c        | 27 +++++++++++++++------------
 tests/tcctest.c | 10 ++++++++++
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/tccgen.c b/tccgen.c
index f79d30e..410dcb7 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -3792,7 +3792,7 @@ static int asm_label_instr(void)
     return v;
 }
 
-static void post_type(CType *type, AttributeDef *ad)
+static void post_type(CType *type, AttributeDef *ad, int storage)
 {
     int n, l, t1, arg_size, align;
     Sym **plast, *s, *first;
@@ -3870,6 +3870,7 @@ static void post_type(CType *type, AttributeDef *ad)
         type->t = VT_FUNC;
         type->ref = s;
     } else if (tok == '[') {
+	int saved_nocode_wanted = nocode_wanted;
         /* array definition */
         next();
         if (tok == TOK_RESTRICT1)
@@ -3877,9 +3878,16 @@ static void post_type(CType *type, AttributeDef *ad)
         n = -1;
         t1 = 0;
         if (tok != ']') {
-            if (!local_stack || nocode_wanted)
-                 vpushi(expr_const());
-            else gexpr();
+            if (!local_stack || (storage & VT_STATIC))
+                vpushi(expr_const());
+            else {
+		/* VLAs (which can only happen with local_stack && !VT_STATIC)
+		   length must always be evaluated, even under nocode_wanted,
+		   so that its size slot is initialized (e.g. under sizeof
+		   or typeof).  */
+		nocode_wanted = 0;
+		gexpr();
+	    }
             if ((vtop->r & (VT_VALMASK | VT_LVAL | VT_SYM)) == VT_CONST) {
                 n = vtop->c.i;
                 if (n < 0)
@@ -3892,7 +3900,7 @@ static void post_type(CType *type, AttributeDef *ad)
         }
         skip(']');
         /* parse next post type */
-        post_type(type, ad);
+        post_type(type, ad, storage);
         if (type->t == VT_FUNC)
             tcc_error("declaration of an array of functions");
         t1 |= type->t & VT_VLA;
@@ -3910,6 +3918,7 @@ static void post_type(CType *type, AttributeDef *ad)
         }
         if (n != -1)
             vpop();
+	nocode_wanted = saved_nocode_wanted;
                 
         /* we push an anonymous symbol which will contain the array
            element type */
@@ -3984,13 +3993,7 @@ static void type_decl(CType *type, AttributeDef *ad, int *v, int td)
     }
     storage = type->t & VT_STORAGE;
     type->t &= ~VT_STORAGE;
-    if (storage & VT_STATIC) {
-        int saved_nocode_wanted = nocode_wanted;
-        nocode_wanted = 1;
-        post_type(type, ad);
-        nocode_wanted = saved_nocode_wanted;
-    } else
-        post_type(type, ad);
+    post_type(type, ad, storage);
     type->t |= storage;
     if (tok == TOK_ATTRIBUTE1 || tok == TOK_ATTRIBUTE2)
         parse_attribute(ad);
diff --git a/tests/tcctest.c b/tests/tcctest.c
index daf788c..4e51ea1 100644
--- a/tests/tcctest.c
+++ b/tests/tcctest.c
@@ -2456,6 +2456,16 @@ void sizeof_test(void)
     printf("__alignof__(char) = %d\n", __alignof__(char));
     printf("__alignof__(unsigned char) = %d\n", __alignof__(unsigned char));
     printf("__alignof__(func) = %d\n", __alignof__ sizeof_test());
+
+    /* sizes of VLAs need to be evaluated even inside sizeof: */
+    a = 2;
+    printf("sizeof(char[1+2*a]) = %d\n", sizeof(char[1+2*a]));
+    /* And checking if sizeof compound literal works.  Parenthesized: */
+    printf("sizeof( (struct {int i; int j;}){4,5} ) = %d\n",
+	   sizeof( (struct {int i; int j;}){4,5} ));
+    /* And as direct sizeof argument (as unary expression): */
+    printf("sizeof (struct {short i; short j;}){4,5} = %d\n",
+	   sizeof (struct {short i; short j;}){4,5} );
 }
 
 void typeof_test(void)