From 4d827b4e57a9d3e15d10fba88a227cd93c994ba3 Mon Sep 17 00:00:00 2001
From: Ary Borenszweig <asterite@gmail.com>
Date: Tue, 21 Aug 2018 23:34:28 -0300
Subject: [PATCH] Macros: evaluate yield expressions

---
 spec/compiler/semantic/macro_spec.cr       | 12 ++++++++++++
 src/compiler/crystal/macros/interpreter.cr |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/spec/compiler/semantic/macro_spec.cr b/spec/compiler/semantic/macro_spec.cr
index 836744b5783b..32d2d4761d09 100644
--- a/spec/compiler/semantic/macro_spec.cr
+++ b/spec/compiler/semantic/macro_spec.cr
@@ -1321,4 +1321,16 @@ describe "Semantic: macro" do
       {% end %}
       )) { int32 }
   end
+
+  it "evaluates yield expression (#2924)" do
+    assert_type(%(
+      macro a(b)
+        {{yield b}}
+      end
+
+      a("foo") do |c|
+        {{c}}
+      end
+      )) { string }
+  end
 end
diff --git a/src/compiler/crystal/macros/interpreter.cr b/src/compiler/crystal/macros/interpreter.cr
index 09ced3441ffe..d7447704ad6c 100644
--- a/src/compiler/crystal/macros/interpreter.cr
+++ b/src/compiler/crystal/macros/interpreter.cr
@@ -388,7 +388,7 @@ module Crystal
           block_vars = {} of String => ASTNode
           node.exps.each_with_index do |exp, i|
             if block_arg = block.args[i]?
-              block_vars[block_arg.name] = exp.clone
+              block_vars[block_arg.name] = accept exp.clone
             end
           end
           @last = replace_block_vars block.body.clone, block_vars