libunwind cannot be used in C programs due to __cxxabi_config.h include

[iid_iunknown]

Summary

Hello,

The public libunwind's headers include <__cxxabi_config.h> that is installed into C++ headers directory.
libunwind.h / unwind.h cannot be used from C code for this reason.

The patch introduces libunwind specific <libunwind_config.h> header instead and removes dependency on <__cxxabi_config.h>.

[asl]

include/libunwind_config.h

15

Should we use LIBUNWIND_ARM_EHABI here and everywhere below?

[iid_iunknown]

include/libunwind_config.h

15

Yes, this sounds reasonable.
However, my thought behind leaving it same-named is that if anyone decides to change the conditions when LIBCXXABI_ARM_EHABI is defined, it could be helpful to see the change can and should affect libunwind, since the meaning of LIBCXXABI_ARM_EHABI and LIBUNWIND_ARM_EHABI is the same. One will find all the dependent logic by searching the code for LIBCXXABI_ARM_EHABI.

Please let me know if the name is to be changed anyway.

[iid_iunknown]

Were you able to review this?
Thanks.

[compnerd]

Isn't this obsoleted by the change which Logan made a few days ago?

include/libunwind.h

 //===----------------------------------------------------------------------===//
 
 #ifndef __LIBUNWIND__
 #define __LIBUNWIND__
 
 #include <stdint.h>
 #include <stddef.h>
 
-#include <__cxxabi_config.h>
+#include <libunwind_config.h>
 
 #ifdef __APPLE__
   #include <Availability.h>
     #ifdef __arm__
        #define LIBUNWIND_AVAIL __attribute__((unavailable))
     #else
       #define LIBUNWIND_AVAIL __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_5_0)
     #endif

include/libunwind_config.h

+//===-------------------------- libunwind_config.h -------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef ____LIBUNWIND_CONFIG_H
+#define ____LIBUNWIND_CONFIG_H
+
+#if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) && \
+    !defined(__ARM_DWARF_EH__)
+#define LIBCXXABI_ARM_EHABI 1
+#else
+#define LIBCXXABI_ARM_EHABI 0
+#endif
+
+#endif // ____LIBUNWIND_CONFIG_H

include/unwind.h

 #include <stddef.h>
 
 #if defined(__APPLE__)
 #define LIBUNWIND_UNAVAIL __attribute__ (( unavailable ))
 #else
 #define LIBUNWIND_UNAVAIL
 #endif
 
-#include <__cxxabi_config.h>
+#include <libunwind_config.h>
 
 typedef enum {
   _URC_NO_REASON = 0,
   _URC_OK = 0,
   _URC_FOREIGN_EXCEPTION_CAUGHT = 1,
   _URC_FATAL_PHASE2_ERROR = 2,
   _URC_FATAL_PHASE1_ERROR = 3,
   _URC_NORMAL_STOP = 4,

src/Unwind-EHABI.h

 //===------------------------- Unwind-EHABI.hpp ---------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef __UNWIND_EHABI_H__
 #define __UNWIND_EHABI_H__
 
-#include <__cxxabi_config.h>
+#include <libunwind_config.h>
 
 #if LIBCXXABI_ARM_EHABI
 
 #include <stdint.h>
 #include <unwind.h>
 
 // Unable to unwind in the ARM index table (section 5 EHABI).
 #define UNW_EXIDX_CANTUNWIND 0x1