Add test and fix bug leading to infinite recursion.

The test case here is simply "#define foo foo" and "#define bar foo"
and then attempting to expand "bar".

Previously, our termination condition for the recursion was overly
simple---just looking for the single identifier that began the
expansion. We now fix this to maintain a stack of identifiers and
terminate when any one of them occurs in the replacement list.

1 files changed, 3 insertions, 0 deletions

diff --git a/tests/024-define-chain-to-self-recursion.c b/tests/024-define-chain-to-self-recursion.c
new file mode 100644
index 0000000000..e788adce30
--- /dev/null
+++ b/tests/024-define-chain-to-self-recursion.c
@@ -0,0 +1,3 @@
+#define  foo foo
+#define  bar foo
+bar