From bb2bafadbc44f4b1ef0b6cc26111093c335f8783 Mon Sep 17 00:00:00 2001
From: Harry Gillanders <contact@harrygillanders.com>
Date: Fri, 3 Jul 2026 22:07:24 +0100
Subject: [PATCH] Fix Issue #23356 - ImportC: The preprocessor is improperly
 invoked, on macOS, when cross-compiling.

---
 compiler/src/dmd/link.d              |  2 +-
 compiler/test/compilable/test23356.c | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 compiler/test/compilable/test23356.c

diff --git a/compiler/src/dmd/link.d b/compiler/src/dmd/link.d
index a04d4401ae4c..99823757f632 100644
--- a/compiler/src/dmd/link.d
+++ b/compiler/src/dmd/link.d
@@ -1196,7 +1196,7 @@ public int runPreprocessor(Loc loc, const(char)[] cpp, const(char)[] filename, c
         // need to redefine some macros in importc.h
         argv.push("-Wno-builtin-macro-redefined");
 
-        if (target.os == Target.OS.OSX)
+        version (OSX)
         {
             argv.push("-fno-blocks");       // disable clang blocks extension
             argv.push("-E");                // run preprocessor only for clang
diff --git a/compiler/test/compilable/test23356.c b/compiler/test/compilable/test23356.c
new file mode 100644
index 000000000000..e1fc0c63ea37
--- /dev/null
+++ b/compiler/test/compilable/test23356.c
@@ -0,0 +1,14 @@
+// DISABLED: win linux freebsd openbsd netbsd dragonflybsd hurd
+// REQUIRED_ARGS: -os=linux
+// If clang is invoked improperly as a preprocessor,
+// then this will fail to compile and link due to `__check` being undefined.
+// If clang is invoked properly as a preprocessor then this will succeed
+// as clang won't attempt to compile nor link the file.
+
+// https://github.com/dlang/dmd/issues/23356
+
+int main(void)
+{
+    __check(1);
+    return 0;
+}