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[PATCH]: PR c/22476 -Wmissing-format-attribute [take 3]


 > The warning in c_common_post_options for -Wmissing-format-attribute 
 > without -Wformat will need rewording, and "warning (0," in the patch 
 > should use OPT_Wmissing_format_attribute instead of 0.

This version addresses your comments above and passed regression
testing.  This post for reference only, I'm going to split
-Wmissing-format-attribute and -Wformat next as per your message here:
http://gcc.gnu.org/ml/gcc-patches/2005-07/msg01092.html

		--Kaveh


2005-07-16  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>

	PR c/22476
	* c-opts.c (c_common_post_options): Update diagnostic for
	-Wmissing-format-attribute.
	* c-typeck.c (convert_for_assignment): Detect additional cases for
	-Wmissing-format-attribute.
	* doc/invoke.texi (-Wmissing-format-attribute): Document new
	behavior.

testsuite:
	* gcc.dg/format/miss-3.c, gcc.dg/format/miss-4.c,
	gcc.dg/format/miss-5.c, gcc.dg/format/miss-6.c: New.
	* gcc.dg/format/opt-6.c: Update.
	
diff -rup orig/egcc-CVS20050716/gcc/c-opts.c egcc-CVS20050716/gcc/c-opts.c
--- orig/egcc-CVS20050716/gcc/c-opts.c	2005-06-25 22:37:13.000000000 -0400
+++ egcc-CVS20050716/gcc/c-opts.c	2005-07-16 11:12:30.000000000 -0400
@@ -992,7 +992,7 @@ c_common_post_options (const char **pfil
       warning (OPT_Wformat_security,
 	       "-Wformat-security ignored without -Wformat");
       warning (OPT_Wmissing_format_attribute,
-	       "-Wmissing-format-attribute ignored without -Wformat");
+	       "-Wmissing-format-attribute is less effective without -Wformat");
     }
 
   /* C99 requires special handling of complex multiplication and division;
diff -rup orig/egcc-CVS20050716/gcc/c-typeck.c egcc-CVS20050716/gcc/c-typeck.c
--- orig/egcc-CVS20050716/gcc/c-typeck.c	2005-07-16 10:38:02.000000000 -0400
+++ egcc-CVS20050716/gcc/c-typeck.c	2005-07-16 10:57:01.000000000 -0400
@@ -3793,6 +3793,55 @@ convert_for_assignment (tree type, tree 
         warning (OPT_Wc___compat, "request for implicit conversion from "
                  "%qT to %qT not permitted in C++", rhstype, type);
 
+      /* Check if the right-hand side has a format attribute but the
+	 left-hand side doesn't.  */
+      if (warn_missing_format_attribute)
+        {
+	  tree rattrs = TYPE_ATTRIBUTES (ttr), ra;
+	  for (ra = rattrs; ra; ra = TREE_CHAIN (ra))
+	    {
+	      if (is_attribute_p ("format", TREE_PURPOSE (ra)))
+		break;
+	    }
+	  if (ra)
+	    {
+	      tree lattrs = TYPE_ATTRIBUTES (ttl), la;
+	      for (la = lattrs; la; la = TREE_CHAIN (la))
+	      {
+		if (is_attribute_p ("format", TREE_PURPOSE (la)))
+		  break;
+	      }
+	      if (!la)
+		switch (errtype)
+		  {
+		  case ic_argpass:
+		  case ic_argpass_nonproto:
+		    warning (OPT_Wmissing_format_attribute,
+			     "argument %d of %qE might be "
+			     "a candidate for a format attribute",
+			     parmnum, rname);
+		    break;
+		  case ic_assign:
+		    warning (OPT_Wmissing_format_attribute,
+			     "assignment left-hand side might be "
+			     "a candidate for a format attribute");
+		    break;
+		  case ic_init:
+		    warning (OPT_Wmissing_format_attribute,
+			     "initialization left-hand side might be "
+			     "a candidate for a format attribute");
+		    break;
+		  case ic_return:
+		    warning (OPT_Wmissing_format_attribute,
+			     "return type might be "
+			     "a candidate for a format attribute");
+		    break;
+		  default:
+		    gcc_unreachable ();
+		  }
+	    }
+	}
+      
       /* Any non-function converts to a [const][volatile] void *
 	 and vice versa; otherwise, targets must be the same.
 	 Meanwhile, the lhs target must have all the qualifiers of the rhs.  */
diff -rup orig/egcc-CVS20050716/gcc/doc/invoke.texi egcc-CVS20050716/gcc/doc/invoke.texi
--- orig/egcc-CVS20050716/gcc/doc/invoke.texi	2005-07-13 21:43:26.000000000 -0400
+++ egcc-CVS20050716/gcc/doc/invoke.texi	2005-07-16 10:51:40.000000000 -0400
@@ -3126,14 +3126,23 @@ hosted C environments.
 @item -Wmissing-format-attribute
 @opindex Wmissing-format-attribute
 @opindex Wformat
-If @option{-Wformat} is enabled, also warn about functions which might be
-candidates for @code{format} attributes.  Note these are only possible
-candidates, not absolute ones.  GCC will guess that @code{format}
-attributes might be appropriate for any function that calls a function
-like @code{vprintf} or @code{vscanf}, but this might not always be the
-case, and some functions for which @code{format} attributes are
-appropriate may not be detected.  This option has no effect unless
-@option{-Wformat} is enabled (possibly by @option{-Wall}).
+Warn about function pointers which might be candidates for @code{format}
+attributes.  Note these are only possible candidates, not absolute ones.
+GCC will guess that function pointers with @code{format} attributes that
+are used in assignment, initialization, parameter passing or return
+statements should have a corresponding @code{format} attribute in the
+resulting type.  I.e.@: the left-hand side of the assignment or
+initialization, the type of the parameter variable, or the return type
+of the containing function respectively should also have a @code{format}
+attribute to avoid the warning.
+
+If @option{-Wformat} is enabled (possibly by @option{-Wall}), also warn
+about function definitions which might be candidates for @code{format}
+attributes.  Again, these are only possible candidates.  GCC will guess
+that @code{format} attributes might be appropriate for any function that
+calls a function like @code{vprintf} or @code{vscanf}, but this might
+not always be the case, and some functions for which @code{format}
+attributes are appropriate may not be detected.
 
 @item -Wno-multichar
 @opindex Wno-multichar
diff -rup orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-3.c egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-3.c
--- orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-3.c	2005-07-16 10:52:12.000000000 -0400
+++ egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-3.c	2005-07-16 10:51:40.000000000 -0400
@@ -0,0 +1,26 @@
+/* Test warnings for missing format attributes on function pointers.  */
+/* Origin: Kaveh Ghazi <ghazi@caip.rutgers.edu> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat -Wmissing-format-attribute" } */
+
+#include "format.h"
+
+typedef void (*noattr_t) (const char *, ...);
+typedef noattr_t __attribute__ ((__format__(__printf__, 1, 2))) attr_t;
+
+typedef void (*vnoattr_t) (const char *, va_list);
+typedef vnoattr_t __attribute__ ((__format__(__printf__, 1, 0))) vattr_t;
+
+void
+foo1 (noattr_t na, attr_t a, vnoattr_t vna, vattr_t va)
+{
+  noattr_t na1 = na;
+  noattr_t na2 = a; /* { dg-warning "candidate" "initialization warning" } */
+  attr_t a1 = na;
+  attr_t a2 = a;
+  
+  vnoattr_t vna1 = vna;
+  vnoattr_t vna2 = va; /* { dg-warning "candidate" "initialization warning" } */
+  vattr_t va1 = vna;
+  vattr_t va2 = va;
+}
diff -rup orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-4.c egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-4.c
--- orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-4.c	2005-07-16 10:52:15.000000000 -0400
+++ egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-4.c	2005-07-16 10:51:40.000000000 -0400
@@ -0,0 +1,32 @@
+/* Test warnings for missing format attributes on function pointers.  */
+/* Origin: Kaveh Ghazi <ghazi@caip.rutgers.edu> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat -Wmissing-format-attribute" } */
+
+#include "format.h"
+
+typedef void (*noattr_t) (const char *, ...);
+typedef noattr_t __attribute__ ((__format__(__printf__, 1, 2))) attr_t;
+
+typedef void (*vnoattr_t) (const char *, va_list);
+typedef vnoattr_t __attribute__ ((__format__(__printf__, 1, 0))) vattr_t;
+
+void
+foo1 (noattr_t na, attr_t a, vnoattr_t vna, vattr_t va)
+{
+  noattr_t na1, na2;
+  attr_t a1, a2;
+  
+  vnoattr_t vna1, vna2;
+  vattr_t va1, va2;
+
+  na1 = na;
+  na2 = a; /* { dg-warning "candidate" "assignment warning" } */
+  a1 = na;
+  a2 = a;
+  
+  vna1 = vna;
+  vna2 = va; /* { dg-warning "candidate" "assignment warning" } */
+  va1 = vna;
+  va1 = va;
+}
diff -rup orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-5.c egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-5.c
--- orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-5.c	2005-07-16 10:52:17.000000000 -0400
+++ egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-5.c	2005-07-16 10:51:40.000000000 -0400
@@ -0,0 +1,48 @@
+/* Test warnings for missing format attributes on function pointers.  */
+/* Origin: Kaveh Ghazi <ghazi@caip.rutgers.edu> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat -Wmissing-format-attribute" } */
+
+#include "format.h"
+
+typedef void (*noattr_t) (const char *, ...);
+typedef noattr_t __attribute__ ((__format__(__printf__, 1, 2))) attr_t;
+
+typedef void (*vnoattr_t) (const char *, va_list);
+typedef vnoattr_t __attribute__ ((__format__(__printf__, 1, 0))) vattr_t;
+
+noattr_t
+foo1 (noattr_t na, attr_t a, int i)
+{
+  if (i)
+    return na;
+  else
+    return a; /* { dg-warning "candidate" "return type warning" } */
+}
+
+attr_t
+foo2 (noattr_t na, attr_t a, int i)
+{
+  if (i)
+    return na;
+  else
+    return a;
+}
+
+vnoattr_t
+foo3 (vnoattr_t vna, vattr_t va, int i)
+{
+  if (i)
+    return vna;
+  else
+    return va; /* { dg-warning "candidate" "return type warning" } */
+}
+
+vattr_t
+foo4 (vnoattr_t vna, vattr_t va, int i)
+{
+  if (i)
+    return vna;
+  else
+    return va;
+}
diff -rup orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-6.c egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-6.c
--- orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-6.c	2005-07-16 10:52:19.000000000 -0400
+++ egcc-CVS20050716/gcc/testsuite/gcc.dg/format/miss-6.c	2005-07-16 10:51:40.000000000 -0400
@@ -0,0 +1,31 @@
+/* Test warnings for missing format attributes on function pointers.  */
+/* Origin: Kaveh Ghazi <ghazi@caip.rutgers.edu> */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wformat -Wmissing-format-attribute" } */
+
+#include "format.h"
+
+typedef void (*noattr_t) (const char *, ...);
+typedef noattr_t __attribute__ ((__format__(__printf__, 1, 2))) attr_t;
+
+typedef void (*vnoattr_t) (const char *, va_list);
+typedef vnoattr_t __attribute__ ((__format__(__printf__, 1, 0))) vattr_t;
+
+extern void foo1 (noattr_t);
+extern void foo2 (attr_t);
+extern void foo3 (vnoattr_t);
+extern void foo4 (vattr_t);
+
+void
+foo (noattr_t na, attr_t a, vnoattr_t vna, vattr_t va)
+{
+  foo1 (na);
+  foo1 (a); /* { dg-warning "candidate" "parameter passing warning" } */
+  foo2 (na);
+  foo2 (a);
+  
+  foo3 (vna);
+  foo3 (va); /* { dg-warning "candidate" "parameter passing warning" } */
+  foo4 (vna);
+  foo4 (va);
+}
diff -rup orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/opt-6.c egcc-CVS20050716/gcc/testsuite/gcc.dg/format/opt-6.c
--- orig/egcc-CVS20050716/gcc/testsuite/gcc.dg/format/opt-6.c	2004-11-27 21:16:57.000000000 -0500
+++ egcc-CVS20050716/gcc/testsuite/gcc.dg/format/opt-6.c	2005-07-16 11:14:15.000000000 -0400
@@ -4,4 +4,4 @@
 /* { dg-do compile } */
 /* { dg-options "-Wmissing-format-attribute" } */
 
-/* { dg-warning "warning: -Wmissing-format-attribute ignored without -Wformat" "ignored" { target *-*-* } 0 } */
+/* { dg-warning "warning: -Wmissing-format-attribute is less effective without -Wformat" "ignored" { target *-*-* } 0 } */


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