aix: fix ASM_OUTPUT_DEF warning

ASM_OUTPUT_DEF is used by GCC as a proxy to enable alias support.  But
the macro does not provide the necessary implementation for symbol aliasing
on AIX, which uses a different implementation.  On AIX, the macro was empty.
Because the macro is empty, none of the macro argument are used, which
means that some of the variables in the function that calls the macro are
never used.  This causes a warning when building varasm.c, and -Werror
converts that into a fatal error.

This patch references the macro arguments as (void) to prevent the
warning.

2020-12-05  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
	    David Edelsohn  <dje.gcc@gmail.com>

gcc/ChangeLog:

	* config/rs6000/xcoff.h (ASM_OUTPUT_DEF): Reference macro arguments.

diff --git a/gcc/config/rs6000/xcoff.h b/gcc/config/rs6000/xcoff.h
index 0f40b45b27b83736bb749a665e27c82804b01c08..fe6221aae09e5b813cff2932db52d677d06fb1fa 100644 (file)
--- a/gcc/config/rs6000/xcoff.h
+++ b/gcc/config/rs6000/xcoff.h
@@ -273,7 +273,9 @@
    We still need to define this macro to let middle-end know that aliases are
    supported.
  */
-#define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2) do { } while (0)
+#define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2) do { (void) (FILE); \
+                                               (void) (LABEL1); \
+                                               (void) (LABEL2); } while (0)
 
 /* Used by rs6000_assemble_integer, among others.  */