From 7c978669d4f04c061634da31dd3d976685e2489d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?=
 <daniel.marjamaki@cppchecksolutions.com>
Date: Fri, 10 Apr 2026 16:04:32 +0200
Subject: [PATCH] Fix #590 (Incorrect expansion of functional macros)

---
 simplecpp.cpp |  2 ++
 simplecpp.h   |  3 +++
 test.cpp      | 11 +++++++++++
 3 files changed, 16 insertions(+)

diff --git a/simplecpp.cpp b/simplecpp.cpp
index b59f773c..a0e8caa8 100644
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -2204,6 +2204,8 @@ namespace simplecpp {
             }
 
             output.push_back(newMacroToken(tok->str(), loc, true, tok));
+            if (it != macros.end())
+                output.back()->markExpandedFrom(&it->second);
             return tok->next;
         }
 
diff --git a/simplecpp.h b/simplecpp.h
index 49aa600b..b744e62d 100644
--- a/simplecpp.h
+++ b/simplecpp.h
@@ -213,6 +213,9 @@ namespace simplecpp {
         bool isExpandedFrom(const Macro* m) const {
             return mExpandedFrom.find(m) != mExpandedFrom.end();
         }
+        void markExpandedFrom(const Macro* m) {
+            mExpandedFrom.insert(m);
+        }
 
         void printAll() const;
         void printOut() const;
diff --git a/test.cpp b/test.cpp
index b0bf0b4f..bc8cb4d5 100644
--- a/test.cpp
+++ b/test.cpp
@@ -946,6 +946,16 @@ static void define_define_23() // #403 crash (infinite recursion)
     ASSERT_EQUALS("\n\n\n\nYdieZ ( void ) ;", preprocess(code));
 }
 
+static void define_define_24() // #590
+{
+    const char code[] = "#define B A\n"
+                        "#define A x(B)\n"
+                        "#define C(s) s\n"
+                        "#define D(s) C(s)\n"
+                        "D(A)\n";
+    ASSERT_EQUALS("\n\n\n\nx ( A )", preprocess(code));
+}
+
 static void define_va_args_1()
 {
     const char code[] = "#define A(fmt...) dostuff(fmt)\n"
@@ -3671,6 +3681,7 @@ int main(int argc, char **argv)
     TEST_CASE(define_define_21);
     TEST_CASE(define_define_22); // #400
     TEST_CASE(define_define_23); // #403 - crash, infinite recursion
+    TEST_CASE(define_define_24); // #590
     TEST_CASE(define_va_args_1);
     TEST_CASE(define_va_args_2);
     TEST_CASE(define_va_args_3);