bug#31003: Test failure on macOS with new Xcode 9.3 command-line tools

[Charles Diza]

Building grep 3.1 on macOS 10.3.3 with the newly-released command-line
tools for Xcode 9.3 causes a test failure:

-------8<-------------------------------------------------------------
FAIL: test-vasnprintf
=====================

FAIL test-vasnprintf (exit status: 132)
------>8--------------------------------------------------------------

gnulib-tests/test-suite.log carries no further information than that.

In configure.log, I find the following:

-------8<-------------------------------------------------------------
configure:7830: checking for vasnprintf
configure:7830: gcc -o conftest -g -O2   conftest.c  >&5
Undefined symbols for architecture x86_64:
  "_vasnprintf", referenced from:
      _main in conftest-b41cac.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see
invocation)
------>8--------------------------------------------------------------


I'm really wondering whether a grep 3.1 that fails this test is safe to
keep using.

The exact same failure happens when building diffutils, and I have emailed
address@hidden to report this.

I'm not sure if this is related or not, but config.log also has:

------>8--------------------------------------------------------------
configure:7830: checking for snprintf
configure:7830: gcc -o conftest -g -O2   conftest.c  >&5
conftest.c:86:6: warning: incompatible redeclaration of library function
'snprintf' [-Wincompatible-library-redeclaration]
char snprintf ();
     ^
conftest.c:86:6: note: 'snprintf' is a builtin with type 'int (char *,
unsigned long, const char *, ...)'
1 warning generated.
------>8--------------------------------------------------------------

I'm also not sure if *this* is related or not, but I see the following
compiler warning during build:

CC       openat.o
obstack.c:351:31: warning: incompatible pointer types initializing 'void
      (*)(void) __attribute__((noreturn))' with an expression of type
      'void (void)' [-Wincompatible-pointer-types]
__attribute_noreturn__ void (*obstack_alloc_failed_handler) (void)
                              ^
1 warning generated.


-Charles