[Bug bootstrap/63622] [5.0 Regression] Bootstrap fails on x86_64-apple-darwin1[34] after revision r216305

[howarth at bromo dot med.uc.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63622

--- Comment #17 from howarth at bromo dot med.uc.edu ---
These warnings are emitted from this code in gcc/config/darwin.h

/* Mach-O supports 'weak imports', and 'weak definitions' in coalesced
   sections.  machopic_select_section ensures that weak variables go in
   coalesced sections.  Weak aliases (or any other kind of aliases) are
   not supported.  Weak symbols that aren't visible outside the .s file
   are not supported.  */
#define ASM_WEAKEN_DECL(FILE, DECL, NAME, ALIAS)                        \
  do {                                                                  \
    if (ALIAS)                                                          \
      {                                                                 \
        warning (0, "alias definitions not supported in Mach-O; ignored");     
\
        break;                                                          \
      }                                                                 \
                                                                        \
    if (! DECL_EXTERNAL (DECL) && TREE_PUBLIC (DECL))                   \
      targetm.asm_out.globalize_label (FILE, NAME);                     \
    if (DECL_EXTERNAL (DECL))                                           \
      fputs ("\t.weak_reference ", FILE);                               \
    else if (lookup_attribute ("weak_import", DECL_ATTRIBUTES (DECL)))  \
      break;                                                            \
    else if (TREE_PUBLIC (DECL))                                        \
      fputs ("\t.weak_definition ", FILE);                              \
    else                                                                \
      break;                                                            \
    assemble_name (FILE, NAME);                                         \
    fputc ('\n', FILE);                                                 \
  } while (0)