BIT-1785: fix scripts able to access uninitialized variables.

src/Frame.cc

@@ -33,6 +33,15 @@ Frame::~Frame()
 	Release();
 	}
 
+void Frame::Reset(int startIdx)
+	{
+	for ( int i = startIdx; i < size; ++i )
+		{
+		Unref(frame[i]);
+		frame[i] = 0;
+		}
+	}
+
 void Frame::Release()
 	{
 	for ( int i = 0; i < size; ++i )

src/Frame.h

@@ -24,6 +24,7 @@ public:
 		frame[n] = v;
 		}
 
+	void Reset(int startIdx);
 	void Release();
 
 	void Describe(ODesc* d) const;

src/Func.cc

@@ -397,6 +397,7 @@ Val* BroFunc::Call(val_list* args, Frame* parent) const
 				bodies[i].stmts->GetLocationInfo());
 
 		Unref(result);
+		f->Reset(args->length());
 
 		try
 			{

testing/btest/Baseline/language.uninitialized-local2/out

@@ -0,0 +1,2 @@
+error in /home/jon/projects/bro/bro/testing/btest/.tmp/language.uninitialized-local2/uninitialized-local2.bro, line 19: value used but not set (var_b)
+var_a is, baz

testing/btest/language/uninitialized-local2.bro

@@ -0,0 +1,25 @@
+# @TEST-EXEC: bro -b %INPUT >out 2>&1
+# @TEST-EXEC: TEST_DIFF_CANONIFIER=$SCRIPTS/diff-remove-abspath btest-diff out
+
+event test()
+	{
+	local var_a: string = "foo";
+	}
+
+event test()
+	{
+	if ( F )
+		{
+		local var_b: string = "bar";
+		}
+
+	local var_a: string = "baz";
+
+	print "var_a is", var_a;
+	print "var_b is", var_b;
+	}
+
+event bro_init()
+	{
+	event test();
+	}