From 4bd8fe585518ef33d1280918e774748a87a61c88 Mon Sep 17 00:00:00 2001
From: James Turner <zakalawe@mac.com>
Date: Tue, 27 May 2014 10:05:17 +0100
Subject: [PATCH] =?UTF-8?q?Fix=20bad=20Nasal=20parse=20of=20=E2=80=98foo[]?=
 =?UTF-8?q?=E2=80=99.?=
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When a vector subscript is empty, don’t parse it as ‘[foo]’, instead
print a parse error.

Fix by Nicholas Scheel & Thomas Geymayer.
---
 simgear/nasal/codegen.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/simgear/nasal/codegen.c b/simgear/nasal/codegen.c
index 8636fbb9..bc36a817 100644
--- a/simgear/nasal/codegen.c
+++ b/simgear/nasal/codegen.c
@@ -7,6 +7,7 @@
 // These are more sensical predicate names in most contexts in this file
 #define LEFT(tok)   ((tok)->children)
 #define RIGHT(tok)  ((tok)->lastChild)
+#define UNARY(tok)  (LEFT(tok) && LEFT(tok) == RIGHT(tok))
 #define BINARY(tok) (LEFT(tok) && RIGHT(tok) && LEFT(tok)->next == RIGHT(tok))
 
 // Forward references for recursion
@@ -634,12 +635,16 @@ static void genExpr(struct Parser* p, struct Token* t)
         else genExpr(p, LEFT(t));
         break;
     case TOK_LBRA:
-        if(BINARY(t)) {
-            genExtract(p, t);
-        } else {
+        if(UNARY(t)) {
             emit(p, OP_NEWVEC);
             genList(p, LEFT(t), 1);
         }
+        else if(BINARY(t)) {
+            genExtract(p, t);
+        } else {
+            // forbid usage as 'vec[]'
+            naParseError(p, "missing index or slice expression(s)", t->line);
+        }
         break;
     case TOK_LCURL:
         emit(p, OP_NEWHASH);