From beb5ab5b7b18e82cc2d73ed23639cf9aa1a8ec6f Mon Sep 17 00:00:00 2001
From: Martell Malone <martellmalone@gmail.com>
Date: Fri, 18 Aug 2017 19:59:20 +0100
Subject: [PATCH] crt: Handle .ctors and .dtors within mingw-w64

When building with clang we currently assume you will be
linking with llvm's lld or a bleeding edge binutils.
In future this will become the default method once
binutils support has settled and bumped a few versions.
---
This patch is up for review at
https://sourceforge.net/p/mingw-w64/mailman/message/36002789/.
---

diff --git a/mingw-w64-crt/crt/crtdll.c b/mingw-w64-crt/crt/crtdll.c
index 07a18408..85035d49 100644
--- a/mingw-w64-crt/crt/crtdll.c
+++ b/mingw-w64-crt/crt/crtdll.c
@@ -40,6 +40,13 @@ extern _CRTALLOC(".CRT$XIZ") _PIFV __xi_z[];
 extern _CRTALLOC(".CRT$XCA") _PVFV __xc_a[];
 extern _CRTALLOC(".CRT$XCZ") _PVFV __xc_z[];
 
+#ifdef __clang__
+__attribute__ (( __section__ (".ctors"), __used__ , aligned(sizeof(void *)))) const void * __CTOR_LIST__ = (void *) -1;
+__attribute__ (( __section__ (".dtors"), __used__ , aligned(sizeof(void *)))) const void * __DTOR_LIST__ = (void *) -1;
+__attribute__ (( __section__ (".ctors$zzz"), __used__ , aligned(sizeof(void *)))) const void * __CTOR_END__ = (void *) 0;
+__attribute__ (( __section__ (".dtors$zzz"), __used__ , aligned(sizeof(void *)))) const void * __DTOR_END__ = (void *) 0;
+#endif
+
 /* TLS initialization hook.  */
 extern const PIMAGE_TLS_CALLBACK __dyn_tls_init_callback;
 
diff --git a/mingw-w64-crt/crt/crtexe.c b/mingw-w64-crt/crt/crtexe.c
index ae37e0fe..e3a84784 100644
--- a/mingw-w64-crt/crt/crtexe.c
+++ b/mingw-w64-crt/crt/crtexe.c
@@ -60,6 +60,13 @@ extern _CRTALLOC(".CRT$XIZ") _PIFV __xi_z[];
 extern _CRTALLOC(".CRT$XCA") _PVFV __xc_a[];
 extern _CRTALLOC(".CRT$XCZ") _PVFV __xc_z[];
 
+#ifdef __clang__
+__attribute__ (( __section__ (".ctors"), __used__ , aligned(sizeof(void *)))) const void * __CTOR_LIST__ = (void *) -1;
+__attribute__ (( __section__ (".dtors"), __used__ , aligned(sizeof(void *)))) const void * __DTOR_LIST__ = (void *) -1;
+__attribute__ (( __section__ (".ctors$zzz"), __used__ , aligned(sizeof(void *)))) const void * __CTOR_END__ = (void *) 0;
+__attribute__ (( __section__ (".dtors$zzz"), __used__ , aligned(sizeof(void *)))) const void * __DTOR_END__ = (void *) 0;
+#endif
+
 /* TLS initialization hook.  */
 extern const PIMAGE_TLS_CALLBACK __dyn_tls_init_callback;
 
diff --git a/mingw-w64-crt/crt/gccmain.c b/mingw-w64-crt/crt/gccmain.c
index fc0e3500..54cbf02b 100644
--- a/mingw-w64-crt/crt/gccmain.c
+++ b/mingw-w64-crt/crt/gccmain.c
@@ -28,6 +28,23 @@ __do_global_dtors (void)
     }
 }
 
+#ifdef __clang__
+extern func_ptr __CTOR_END__[];
+extern func_ptr __DTOR_END__[];
+
+void __do_global_ctors (void)
+{
+  static func_ptr *p = __CTOR_END__ - 1;
+  while (*p != (func_ptr) -1) {
+    (*(p))();
+    p--;
+  }
+  atexit (__do_global_dtors);
+}
+
+#else
+// old method that iterates the list twice because old linker scripts do not have __CTOR_END__
+
 void
 __do_global_ctors (void)
 {
@@ -47,6 +64,8 @@ __do_global_ctors (void)
   atexit (__do_global_dtors);
 }
 
+#endif
+
 static int initialized = 0;
 
 void
-- 
2.14.1