Implement -Wimplicit-fallthrough (version 9)

[Eric Botcazou]

> testing completed successfully, so I've installed the patch with this
> ChangeLog entry:
> 
> 2016-09-26  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
> 
> 	gcc:
> 	* config/i386/i386.c (ix86_print_operand)
> 	[HAVE_AS_IX86_CMOV_SUN_SYNTAX]: Add gcc_fallthrough.
> 	* config/sparc/sparc.c (check_pic): Add fallthrough comment.
> 	(epilogue_renumber): Likewise.
> 
> 	gcc/ada:
> 	* gcc-interface/decl.c: Fix fall through comment formatting.
> 	* gcc-interface/misc.c: Likewise.
> 	* gcc-interface/trans.c: Likewise.
> 	* gcc-interface/utils.c: Likewise.
> 	* gcc-interface/utils2.c: Likewise.

This is a revealing example of how excessive pickiness in warnings can be 
counter-productive: after Jakub's latest patches (thanks!) accepting the 
original formatting of gcc-interface, I reverted part #2 of the above patch... 
only to discover that bootstrap was still broken because of a -Wimplicit-
fallthrough warning, but this time for a missing break:

Index: gcc-interface/utils.c
===================================================================
--- gcc-interface/utils.c	(revision 324591)
+++ gcc-interface/utils.c	(working copy)
@@ -4289,6 +4289,7 @@ convert (tree type, tree expr)
 	  TREE_TYPE (expr) = type;
 	  return expr;
 	}
+      break;
 
     case CONSTRUCTOR:
       /* If we are converting a CONSTRUCTOR to a mere type variant, or to

So the issue went unnoticed among the slew of false positives the first time 
and a genuine error was overlooked...

Tested on x86_64-suse-linux, applied on the mainline.


2016-10-08  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc-interface/utils.c (convert) <VECTOR_CST>: Add missing break.

	Revert
	2016-09-26  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	* gcc-interface/decl.c: Fix fall through comment formatting.
	* gcc-interface/misc.c: Likewise.
	* gcc-interface/trans.c: Likewise.
	* gcc-interface/utils.c: Likewise.
	* gcc-interface/utils2.c: Likewise.


-- 
Eric Botcazou
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