From 5ac2a26666406c3bb591176e5790de83b0a2557b Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Sun, 7 Apr 2019 03:15:05 +0200
Subject: [PATCH] Don't endlessly recurse on invalid nested typedefs

see testcase.
---
 tccgen.c                                   | 3 ++-
 tests/tests2/60_errors_and_warnings.c      | 6 ++++++
 tests/tests2/60_errors_and_warnings.expect | 3 +++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/tccgen.c b/tccgen.c
index 6c341e0..39f9a28 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -2782,7 +2782,7 @@ ST_FUNC int type_size(CType *type, int *a)
             *a = PTR_SIZE;
             return PTR_SIZE;
         }
-    } else if (IS_ENUM(type->t) && type->ref->c == -1) {
+    } else if (IS_ENUM(type->t) && type->ref->c < 0) {
         return -1; /* incomplete enum */
     } else if (bt == VT_LDOUBLE) {
         *a = LDOUBLE_ALIGN;
@@ -3934,6 +3934,7 @@ do_decl:
         next();
         if (s->c != -1)
             tcc_error("struct/union/enum already defined");
+        s->c = -2;
         /* cannot be empty */
         /* non empty enums are not allowed */
         ps = &s->next;
diff --git a/tests/tests2/60_errors_and_warnings.c b/tests/tests2/60_errors_and_warnings.c
index 556278c..44f7f67 100644
--- a/tests/tests2/60_errors_and_warnings.c
+++ b/tests/tests2/60_errors_and_warnings.c
@@ -160,4 +160,10 @@ void foo(void) {
         i = 42.2;
       }
 }
+#elif defined test_nested_types
+union u {
+    union u {
+        int i;
+    } m;
+};
 #endif
diff --git a/tests/tests2/60_errors_and_warnings.expect b/tests/tests2/60_errors_and_warnings.expect
index 25b5c66..3b34fef 100644
--- a/tests/tests2/60_errors_and_warnings.expect
+++ b/tests/tests2/60_errors_and_warnings.expect
@@ -74,3 +74,6 @@
 
 [test_conflicting_types]
 60_errors_and_warnings.c:159: error: conflicting types for 'i'
+
+[test_nested_types]
+60_errors_and_warnings.c:166: error: struct/union/enum already defined