From f37cfdf83742536a81a1878a94126827aeaddf7e Mon Sep 17 00:00:00 2001
From: Dennis <dkorpel@users.noreply.github.com>
Date: Wed, 12 Feb 2025 13:44:16 +0100
Subject: [PATCH] Fix #20831 - Mangle conflict after ImportC statement
 expression gets expanded from macro (#20854)

---
 compiler/src/dmd/identifier.d      |  7 ++++---
 compiler/test/runnable/test20831.c | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)
 create mode 100644 compiler/test/runnable/test20831.c

diff --git a/compiler/src/dmd/identifier.d b/compiler/src/dmd/identifier.d
index 231aa5832f..9ef8285f8e 100644
--- a/compiler/src/dmd/identifier.d
+++ b/compiler/src/dmd/identifier.d
@@ -248,13 +248,14 @@ nothrow:
          * directly, but that would unnecessary lengthen symbols names. See issue:
          * https://issues.dlang.org/show_bug.cgi?id=23722
          */
-        static struct Key { uint fileOffset; string prefix; string parent; }
+        static struct Key { string locKey; string prefix; string parent; }
         __gshared uint[Key] counters;
 
+        string locKey = cast(string) (sl.filename ~ idBuf[]);
         static if (__traits(compiles, counters.update(Key.init, () => 0u, (ref uint a) => 0u)))
         {
             // 2.082+
-            counters.update(Key(loc.fileOffset, prefix, parent),
+            counters.update(Key(locKey, prefix, parent),
                 () => 1u,          // insertion
                 (ref uint counter) // update
                 {
@@ -266,7 +267,7 @@ nothrow:
         }
         else
         {
-            const key = Key(loc.fileOffset, prefix, parent);
+            const key = Key(locKey, prefix, parent);
             if (auto pCounter = key in counters)
             {
                 idBuf.writestring("_");
diff --git a/compiler/test/runnable/test20831.c b/compiler/test/runnable/test20831.c
new file mode 100644
index 0000000000..29a91a9f87
--- /dev/null
+++ b/compiler/test/runnable/test20831.c
@@ -0,0 +1,15 @@
+// https://github.com/dlang/dmd/issues/20831
+#include "assert.h"
+
+int* p;
+
+#define IMPL() \
+f()\
+{\
+    assert(p);\
+    assert(0);\
+}
+
+void IMPL()
+
+void main(void) {}