From 2a417b50ee350589efd3018fb75ec8a6f1993d7a Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Sun, 7 Apr 2019 04:09:25 +0200
Subject: [PATCH] Detect invalid VLA decls

see testcase, when the inner array dimension of multi-dimensional
VLAs isn't given TCC was generating invalid vstack accesses.
Those are actually invalid, so just diagnose them.
---
 tccgen.c                                   | 3 +++
 tests/tests2/60_errors_and_warnings.c      | 6 ++++++
 tests/tests2/60_errors_and_warnings.expect | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/tccgen.c b/tccgen.c
index 39f9a28d..cab801ae 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -4521,6 +4521,7 @@ static int post_type(CType *type, AttributeDef *ad, int storage, int td)
             } else {
                 if (!is_integer_btype(vtop->type.t & VT_BTYPE))
                     tcc_error("size of variable length array should be an integer");
+                n = 0;
                 t1 = VT_VLA;
             }
         }
@@ -4532,6 +4533,8 @@ static int post_type(CType *type, AttributeDef *ad, int storage, int td)
         t1 |= type->t & VT_VLA;
         
         if (t1 & VT_VLA) {
+            if (n < 0)
+              tcc_error("need explicit inner array size in VLAs");
             loc -= type_size(&int_type, &align);
             loc &= -align;
             n = loc;
diff --git a/tests/tests2/60_errors_and_warnings.c b/tests/tests2/60_errors_and_warnings.c
index 44f7f67e..61561b8e 100644
--- a/tests/tests2/60_errors_and_warnings.c
+++ b/tests/tests2/60_errors_and_warnings.c
@@ -166,4 +166,10 @@ union u {
         int i;
     } m;
 };
+#elif defined test_vla_1
+int X=1;
+
+int main(void) {
+  int t[][][X];
+}
 #endif
diff --git a/tests/tests2/60_errors_and_warnings.expect b/tests/tests2/60_errors_and_warnings.expect
index 3b34fef9..e4ddd9de 100644
--- a/tests/tests2/60_errors_and_warnings.expect
+++ b/tests/tests2/60_errors_and_warnings.expect
@@ -77,3 +77,6 @@
 
 [test_nested_types]
 60_errors_and_warnings.c:166: error: struct/union/enum already defined
+
+[test_vla_1]
+60_errors_and_warnings.c:173: error: need explicit inner array size in VLAs