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)
