[Bug d/91666] New: _builtin function no work with GDC

[ray_linn at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91666

            Bug ID: 91666
           Summary: _builtin function no work with GDC
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: ray_linn at hotmail dot com
  Target Milestone: ---

when compiling libphobos with MinGW-W64, I got the following errors on thread.d

/bin/sh ../libtool --tag=D   --mode=compile /home/alpha/gcc-build/./gcc/gdc
-B/home/alpha/gcc-build/./gcc/ -L/mingw64/x86_64-w64-mingw32/lib
-L/mingw64/mingw/lib -isystem /mingw64/x86_64-w64-mingw32/include -isystem
/mingw64/mingw/include -B/mingw64/x86_64-w64-mingw32/bin/
-B/mingw64/x86_64-w64-mingw32/lib/ -isystem /mingw64/x86_64-w64-mingw32/include
-isystem /mingw64/x86_64-w64-mingw32/sys-include     -O2 -g  -nostdinc -I
../../../../gcc-9.2.0/libphobos/libdruntime -I . -c -o core/thread.lo
../../../../gcc-9.2.0/libphobos/libdruntime/core/thread.d
libtool: compile:  /home/alpha/gcc-build/./gcc/gdc
-B/home/alpha/gcc-build/./gcc/ -L/mingw64/x86_64-w64-mingw32/lib
-L/mingw64/mingw/lib -isystem /mingw64/x86_64-w64-mingw32/include -isystem
/mingw64/mingw/include -B/mingw64/x86_64-w64-mingw32/bin/
-B/mingw64/x86_64-w64-mingw32/lib/ -isystem /mingw64/x86_64-w64-mingw32/include
-isystem /mingw64/x86_64-w64-mingw32/sys-include -O2 -g -nostdinc -I
../../../../gcc-9.2.0/libphobos/libdruntime -I . -c
../../../../gcc-9.2.0/libphobos/libdruntime/core/thread.d -o core/thread.o
../../../../gcc-9.2.0/libphobos/libdruntime/core/thread.d:2430:13: error:
undefined identifier '__builtin_unwind_init'
 2430 |             __builtin_unwind_init();
      |             ^
../../../../gcc-9.2.0/libphobos/libdruntime/core/thread.d:3220:16: error:
undefined identifier '__builtin_frame_address'
 3220 |         return __builtin_frame_address(0);
      |                ^
...

it looks' the built-in function does not work here.