[PATCH] fix typos behind incorrect destination buffer length in -Wformat-length warning (77762)

[Martin Sebor <msebor at gmail dot com>]

The attached patch corrects a couple of typos in argument numbers
in the handling of __builtin__vsnprintf_chk calls in the gimple-
ssa-sprintf pass, and another couple of typos in the test for
this that were masking this failure.

As an aside, the patch also fixes the off-by-one line test failures
introduced in r240503.  If there is a way to make the line numbers
relative (as suggested in
https://gcc.gnu.org/ml/gcc-patches/2016-09/msg02070.html) I'm happy
to update the -Wformat-length tests to make use of them (and document
it on the Wiki) if someone can point me at an example (or
documentation).  I couldn't find examples of dg-warning directives
that use the feature.

Thanks
Martin

PR c/77762 - Incorrect destination buffer length in -Wformat-length warning

gcc/testsuite/ChangeLog:
2016-09-27  Martin Sebor  <msebor@redhat.com>

	PR c/77762
	* gcc.dg/tree-ssa/builtin-sprintf-warn-1.c (test_vsnprintf_chk_s):
	Call __builtin___vsnprintf_chk, not __builtin___snprintf_chk.
	(test_sprintf_p_const): Adjust line numbers to avoid failures
	introduced in r240503.

gcc/ChangeLog:
2016-09-27  Martin Sebor  <msebor@redhat.com>

	PR c/77762
	* gimple-ssa-sprintf.c (pass_sprintf_length::handle_gimple_call):
	Fix typos.

Index: gcc/gimple-ssa-sprintf.c
===================================================================
--- gcc/gimple-ssa-sprintf.c	(revision 240556)
+++ gcc/gimple-ssa-sprintf.c	(working copy)
@@ -2536,8 +2536,8 @@ pass_sprintf_length::handle_gimple_call (gimple_st
       // Signature:
       //   __builtin___vsnprintf_chk (dst, size, ost, objsize, format, va)
       idx_dstsize = 1;
-      idx_objsize = 2;
-      idx_format = 3;
+      idx_objsize = 3;
+      idx_format = 4;
       info.argidx = -1;
       info.bounded = true;
       break;
Index: gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-1.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-1.c	(revision 240556)
+++ gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-1.c	(working copy)
@@ -95,7 +95,7 @@ void test_sprintf_p_const (void)
      format null pointers as 0 or 0x0 and so the following will only be
      diagnosed on the former targets.  */
   T (5, "%p",     (void*)0);
-  /* { dg-warning "nul past the end" "(nil)" { target *-linux-gnu *-*-uclinux } 96 } */
+  /* { dg-warning "nul past the end" "(nil)" { target *-linux-gnu *-*-uclinux } 97 } */
 
   /* The exact output for %p is unspecified by C.  Two formats are known:
      same as %tx (for example AIX) and same as %#tx (for example Solaris).  */
@@ -107,8 +107,8 @@ void test_sprintf_p_const (void)
      as with signed integer conversions (i.e., it prepends a space).  Other
      known implementations ignore it.  */
   T (6, "% p",    (void*)0x234);  /* { dg-warning ". . flag used with .%p." } */
-  /* { dg-warning "nul past the end" "Glibc %p" { target *-linux-gnu } 108 } */
-  /* { dg-warning "nul past the end" "Generic %p" { target *-*-uclinux } 108 } */
+  /* { dg-warning "nul past the end" "Glibc %p" { target *-linux-gnu } 109 } */
+  /* { dg-warning "nul past the end" "Generic %p" { target *-*-uclinux } 109 } */
 }
 
 /* Verify that no warning is issued for calls that write into a flexible
@@ -1404,9 +1404,9 @@ void test_vsnprintf_chk_s (__builtin_va_list va)
   /* Verify that specifying a size of the destination buffer that's
      bigger than its actual size (normally determined and passed to
      the function by __builtin_object_size) is diagnosed.  */
-  __builtin___snprintf_chk (buffer, 123, 0, 122, " ");   /* { dg-warning "always overflow|specified size 123 exceeds the size 122 of the destination object" } */
+  __builtin___vsnprintf_chk (buffer, 123, 0, 122, "%-s", va);   /* { dg-warning "always overflow|specified size 123 exceeds the size 122 of the destination object" } */
 
-  __builtin___snprintf_chk (buffer, __SIZE_MAX__, 0, 2, " ");   /* { dg-warning "always overflow|destination size .\[0-9\]+. too large" } */
+  __builtin___vsnprintf_chk (buffer, __SIZE_MAX__, 0, 2, "%-s", va);   /* { dg-warning "always overflow|destination size .\[0-9\]+. too large" } */
 
   T (0, "%s");
   T (1, "%s");