[C++] Do not evaluate recursive variable in ifdef

This fixes #79

2 files changed, 9 insertions, 2 deletions

diff --git a/eval.cc b/eval.cc
index 5c9055c..3e885bb 100644
--- a/eval.cc
+++ b/eval.cc
@@ -201,8 +201,7 @@ void Evaluator::EvalIf(const IfStmt* stmt) {
       if (lhs.str().find_first_of(" \t") != string::npos)
         Error("*** invalid syntax in conditional.");
       Var* v = LookupVarInCurrentScope(lhs);
-      const string&& s = v->Eval(this);
-      is_true = (s.empty() == (stmt->op == CondOp::IFNDEF));
+      is_true = (v->String().empty() == (stmt->op == CondOp::IFNDEF));
       break;
     }
     case CondOp::IFEQ:
diff --git a/testcase/ifdef_rec_var.mk b/testcase/ifdef_rec_var.mk
new file mode 100644
index 0000000..0874d2e
--- /dev/null
+++ b/testcase/ifdef_rec_var.mk
@@ -0,0 +1,8 @@
+empty=$(info FAIL)
+rec=$(empty)
+
+ifdef rec
+$(info PASS)
+else
+$(info FAIL)
+endif