From 1dc85fbbdfb70cae498c9577b364a53d3921c2cc Mon Sep 17 00:00:00 2001
From: Laurent Huberdeau <laurenthuberd@gmail.com>
Date: Thu, 6 Feb 2025 12:34:16 -0500
Subject: [PATCH] Don't re-expand macro if current macro is unnamed

macro_is_already_expanding had a small bug where
if the currently expanding macro was unnamed, it
returned false even if the macro was present
somewhere on the stack.
---
 pnut.c                                           |  7 +++++--
 tests/_all/preprocessor/macro/self-reference.c   | 16 +++++++++++++++-
 .../preprocessor/macro/self-reference.golden     |  1 +
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/pnut.c b/pnut.c
index 6a662aa9..b8540464 100644
--- a/pnut.c
+++ b/pnut.c
@@ -1660,8 +1660,11 @@ void begin_macro_expansion(int ident, int tokens, int args) {
 // Search the macro stack to see if the macro is already expanding.
 bool macro_is_already_expanding(int ident) {
   int i = macro_stack_ix;
-  if (ident == 0 || macro_ident == 0) return false; // Unnamed macro or no macro is expanding
-  if (ident == macro_ident)           return true;  // The same macro is already expanding
+  // Unnamed macro (i.e. replaying tokens or playing a macro argument)
+  if (ident == 0)           return false;
+
+  // The macro is currently expanding
+  if (ident == macro_ident) return true;
 
   // Traverse the stack to see if the macro is already expanding
   while (i > 0) {
diff --git a/tests/_all/preprocessor/macro/self-reference.c b/tests/_all/preprocessor/macro/self-reference.c
index 04859f9e..f1e21003 100644
--- a/tests/_all/preprocessor/macro/self-reference.c
+++ b/tests/_all/preprocessor/macro/self-reference.c
@@ -1,7 +1,7 @@
 // tests for recursion depth of macros
 
-// putchar
 #include <stdio.h>
+#include <stdlib.h>
 
 int test1 = 1;
 int test2 = 2;
@@ -33,7 +33,21 @@ void B(int a, int b) {
 #define B(a1, a2) C(a1, a2)
 #define C(a1, a2) B(a1, a2)
 
+struct STATE {
+  int regA;
+  int regB;
+};
+
+struct STATE *global_state;
+
+#define struct_field(sym) global_state->sym
+#define regA              struct_field(regA)
+
 void main() {
+  global_state = malloc(sizeof (struct STATE));
+  regA = 'A';
+  putchar(regA); putchar('\n');
+
   putdigit(test1);
   putdigit(test2);
   putdigit(test3);
diff --git a/tests/_all/preprocessor/macro/self-reference.golden b/tests/_all/preprocessor/macro/self-reference.golden
index 05578747..afef4903 100644
--- a/tests/_all/preprocessor/macro/self-reference.golden
+++ b/tests/_all/preprocessor/macro/self-reference.golden
@@ -1,3 +1,4 @@
+A
 1
 2
 3