[glibc/maskray/grte] Work around clang mishandling of assert functions in resolver buffer allocation, fixes random error

[glibc/maskray/grte] Work around clang mishandling of assert functions in resolver buffer allocation, fixes random error

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=090479eb8ce8eecbcb78a72b8070549762f80c1b

commit 090479eb8ce8eecbcb78a72b8070549762f80c1b
Author: Stan Shebs <stanshebs@google.com>
Date:   Fri Apr 20 14:44:54 2018 -0700

    Work around clang mishandling of assert functions in resolver buffer allocation, fixes random error returns in resolv/ tests.

Diff:
---
 include/alloc_buffer.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/alloc_buffer.h b/include/alloc_buffer.h
index 4167584f6f..a06980e6d2 100644
--- a/include/alloc_buffer.h
+++ b/include/alloc_buffer.h
@@ -213,6 +213,10 @@ alloc_buffer_alloc_bytes (struct alloc_buffer *buf, size_t length)
 static __always_inline size_t
 __alloc_buffer_assert_size (size_t size)
 {
+  /* clang does not presently support the __error__ attribute, and for
+     some reason the fallback case for __errordecl results in error()
+     being called unconditionally.  So skip over this for now.  */
+#ifndef __clang__
   if (!__builtin_constant_p (size))
     {
       __errordecl (error, "type size is not constant");
@@ -223,6 +227,7 @@ __alloc_buffer_assert_size (size_t size)
       __errordecl (error, "type size is zero");
       error ();
     }
+#endif
   return size;
 }
 
@@ -231,6 +236,8 @@ __alloc_buffer_assert_size (size_t size)
 static __always_inline size_t
 __alloc_buffer_assert_align (size_t align)
 {
+  /* As above - skip until we have a better idea for clang here.  */
+#ifndef __clang__
   if (!__builtin_constant_p (align))
     {
       __errordecl (error, "type alignment is not constant");
@@ -246,6 +253,7 @@ __alloc_buffer_assert_align (size_t align)
       __errordecl (error, "type alignment is not a power of two");
       error ();
     }
+#endif
   return align;
 }