From 97ca7117735044673da6c89ee9dff544a3526f70 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sun, 6 Aug 2017 15:16:04 +0200
Subject: Resolve if-else block ambiguity

---
 build2/parser.cxx           | 14 +++++++++-----
 old-tests/if-else/buildfile |  9 +++++++++
 old-tests/if-else/test.out  |  1 +
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/build2/parser.cxx b/build2/parser.cxx
index 0c45e17..66af0a5 100644
--- a/build2/parser.cxx
+++ b/build2/parser.cxx
@@ -1396,13 +1396,17 @@ namespace build2
         fail (t) << "expected newline instead of " << t << " after " << k
                  << (k != "else" ? "-expression" : "");
 
-      // This can be a block or a single line.
+      // This can be a block or a single line. The block part is a bit
+      // tricky, consider:
       //
-      if (next (t, tt) == type::lcbrace)
+      // else
+      //   {hxx cxx}{options}: install = false
+      //
+      // So we treat it as a block if it's followed immediately by newline.
+      //
+      if (next (t, tt) == type::lcbrace && peek () == type::newline)
       {
-        if (next (t, tt) != type::newline)
-          fail (t) << "expected newline after {";
-
+        next (t, tt); // Get newline.
         next (t, tt);
 
         if (take)
diff --git a/old-tests/if-else/buildfile b/old-tests/if-else/buildfile
index 25fabf0..16a49fb 100644
--- a/old-tests/if-else/buildfile
+++ b/old-tests/if-else/buildfile
@@ -148,6 +148,15 @@ if true
   else
     print 1
 
+# Brace ambiguity.
+#
+if false
+  {dir}{.}: x = 0
+else
+  {dir}{.}: x = 1
+
+print $(dir{.}:x)
+
 # EOF test.
 #
 ./:
diff --git a/old-tests/if-else/test.out b/old-tests/if-else/test.out
index 58501cb..4cce943 100644
--- a/old-tests/if-else/test.out
+++ b/old-tests/if-else/test.out
@@ -14,3 +14,4 @@
 1
 1
 1
+1
-- 
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