gcc statement expressions do array decay

git-svn-id: svn+ssh://svn.cprover.org/srv/svn/cbmc/trunk@4556 6afb6bc1-c8e4-404c-8f48-9ae832c5b171

regression/cbmc/gcc_statement_expression4/test.desc

@@ -1,4 +1,4 @@
-KNOWNBUG
+CORE
 main.c
 
 ^EXIT=0$

regression/cbmc/gcc_statement_expression5/main.c

@@ -0,0 +1,13 @@
+#include <assert.h>
+
+int main()
+{
+  char array[40];
+
+  // arrays turn into pointers
+  assert(sizeof(({ array; }))==sizeof(char *));
+  assert(sizeof(array)==40);
+
+  // but it's not promotion
+  assert(sizeof(({ (char)1; }))==sizeof(char));
+}

regression/cbmc/gcc_statement_expression5/test.desc

@@ -0,0 +1,7 @@
+CORE
+main.c
+
+^EXIT=0$
+^SIGNAL=0$
+^VERIFICATION SUCCESSFUL$
+--

src/ansi-c/c_typecheck_expr.cpp

@@ -930,10 +930,19 @@ void c_typecheck_baset::typecheck_side_effect_statement_expression(
   if(last_statement==ID_expression)
   {
     assert(last->operands().size()==1);
-    expr.type()=last->op0().type();
+    exprt &op=last->op0();
+
+    // arrays here turn into pointers (array decay)
+    if(op.type().id()==ID_array)
+      implicit_typecast(op, pointer_typet(op.type().subtype()));
+
+    expr.type()=op.type();    
   }
   else if(last_statement==ID_function_call)
   {
+    // this is suspected to be dead
+    assert(false);
+  
     // make the last statement an expression
 
     code_function_callt &fc=to_code_function_call(*last);