From 48eda22835e58ec1f14f6333e444ccc8a32244b7 Mon Sep 17 00:00:00 2001
From: Kevin Atkinson <kevina@cs.utah.edu>
Date: Fri, 10 Feb 2012 17:27:35 -0700
Subject: [PATCH] Bug fix to accept $ in 0th pos, (ie #ast{$(x) + ...}).

Note: part from Niko Matsakis commit: rewrite assert to accept a $ in
0th pos.
---
 src/comp/syntax/ext/qquote.rs | 9 +++++----
 src/test/run-pass/qquote.rs   | 7 +++++++
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/comp/syntax/ext/qquote.rs b/src/comp/syntax/ext/qquote.rs
index 8899ff64f57..1d5022d1903 100644
--- a/src/comp/syntax/ext/qquote.rs
+++ b/src/comp/syntax/ext/qquote.rs
@@ -184,11 +184,12 @@ fn finish<T: qq_helper>
     let sp = node.span();
     let qcx = gather_anti_quotes(sp.lo, node);
     let cx = qcx;
-    let prev = 0u;
-    for {lo: lo, _} in cx.gather {
-        assert lo > prev;
-        prev = lo;
+
+    // assert that the vector is sorted by position:
+    uint::range(1u, vec::len(cx.gather)) {|i|
+        assert cx.gather[i-1u].lo < cx.gather[i].lo;
     }
+
     let str2 = "";
     enum state {active, skip(uint), blank};
     let state = active;
diff --git a/src/test/run-pass/qquote.rs b/src/test/run-pass/qquote.rs
index ef10f03129b..46330d119b6 100644
--- a/src/test/run-pass/qquote.rs
+++ b/src/test/run-pass/qquote.rs
@@ -81,6 +81,13 @@ fn main() {
     let x = #ast{1};
     let test1 = #ast{1+$(x)};
     check_pp(test1, pprust::print_expr, "1 + 1");
+
+    let test2 = #ast{$(x)+1};
+    check_pp(test2, pprust::print_expr, "1 + 1");
+
+    let y = #ast{2};
+    let test3 = #ast{$(x) + $(y)};
+    check_pp(test3, pprust::print_expr, "1 + 2");
 }
 
 fn check_pp<T>(expr: T, f: fn(pprust::ps, T), expect: str) {