Hi,
as analyzed by Jakub in the audit trail, after changes made by Mark back
in 2005, constant_value_1 doesn't return aggregate constants for fear of
inadvertent copies (in general their addresses must be the same
everywhere). However, for the purpose of format checking in
check_format_arg it is safe to do that, and necessary, thus Jakub
suggested adding a parameter to decl_constant_value controlling that
behavior. Which is what I tried to do with the below, tested x86_64-linux.
Ok for mainline?
Thanks,
Paolo.
/////////////////////
/c-family
2011-10-05 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/38980
* c-common.h (decl_constant_value): Add bool parameter.
* c-common.c (decl_constant_value_for_optimization): Adjust call.
* c-format.c (check_format_arg): Likewise.
2011-10-05 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/38980
* c-typeck.c (decl_constant_value): Adjust definition.
/cp
2011-10-05 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/38980
* typeck.c (decay_conversion): Adjust decl_constant_value call.
* call.c (convert_like_real): Likewise.
* init.c (constant_value_1): Add bool parameter.
(integral_constant_value): Adjust call.
(decl_constant_value): Adjust definition.
/testsuite
2011-10-05 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/38980
* g++.dg/warn/format5.C: New.
Index: c-family/c-format.c
===================================================================
--- c-family/c-format.c (revision 179540)
+++ c-family/c-format.c (working copy)
@@ -1529,7 +1529,7 @@ check_format_arg (void *ctx, tree format_tree,
format_tree = TREE_OPERAND (format_tree, 0);
if (TREE_CODE (format_tree) == VAR_DECL
&& TREE_CODE (TREE_TYPE (format_tree)) == ARRAY_TYPE
- && (array_init = decl_constant_value (format_tree)) != format_tree
+ && (array_init = decl_constant_value (format_tree, true)) != format_tree
&& TREE_CODE (array_init) == STRING_CST)
{
/* Extract the string constant initializer. Note that this may include
Index: c-family/c-common.c
===================================================================
--- c-family/c-common.c (revision 179540)
+++ c-family/c-common.c (working copy)
@@ -1443,7 +1443,7 @@ decl_constant_value_for_optimization (tree exp)
|| DECL_MODE (exp) == BLKmode)
return exp;
- ret = decl_constant_value (exp);
+ ret = decl_constant_value (exp, false);
/* Avoid unwanted tree sharing between the initializer and current
function's body where the tree can be modified e.g. by the
gimplifier. */
Index: c-family/c-common.h
===================================================================
--- c-family/c-common.h (revision 179540)
+++ c-family/c-common.h (working copy)
@@ -886,7 +886,7 @@ extern tree default_conversion (tree);
extern tree common_type (tree, tree);
-extern tree decl_constant_value (tree);
+extern tree decl_constant_value (tree, bool);
/* Handle increment and decrement of boolean types. */
extern tree boolean_increment (enum tree_code, tree);
Index: testsuite/g++.dg/warn/format5.C
===================================================================
--- testsuite/g++.dg/warn/format5.C (revision 0)
+++ testsuite/g++.dg/warn/format5.C (revision 0)
@@ -0,0 +1,12 @@
+// PR c++/38980
+// { dg-options "-Wformat" }
+
+extern "C"
+int printf(const char *format, ...) __attribute__((format(printf, 1, 2) ));
+
+const char fmt1[] = "Hello, %s";
+
+void f()
+{
+ printf(fmt1, 3); // { dg-warning "expects argument" }
+}
Index: cp/typeck.c
===================================================================
--- cp/typeck.c (revision 179540)
+++ cp/typeck.c (working copy)
@@ -1827,7 +1827,7 @@ decay_conversion (tree exp)
/* FIXME remove? at least need to remember that this isn't really a
constant expression if EXP isn't decl_constant_var_p, like with
C_MAYBE_CONST_EXPR. */
- exp = decl_constant_value (exp);
+ exp = decl_constant_value (exp, /*return_aggregate_cst_ok_p=*/false);
if (error_operand_p (exp))
return error_mark_node;
Index: cp/init.c
===================================================================
--- cp/init.c (revision 179540)
+++ cp/init.c (working copy)
@@ -1794,10 +1794,11 @@ build_offset_ref (tree type, tree member, bool add
constant initializer, return the initializer (or, its initializers,
recursively); otherwise, return DECL. If INTEGRAL_P, the
initializer is only returned if DECL is an integral
- constant-expression. */
+ constant-expression. If RETURN_AGGREGATE_CST_OK_P, it is ok to
+ return an aggregate constant. */
static tree
-constant_value_1 (tree decl, bool integral_p)
+constant_value_1 (tree decl, bool integral_p, bool return_aggregate_cst_ok_p)
{
while (TREE_CODE (decl) == CONST_DECL
|| (integral_p
@@ -1834,11 +1835,12 @@ static tree
if (!init
|| !TREE_TYPE (init)
|| !TREE_CONSTANT (init)
- || (!integral_p
- /* Do not return an aggregate constant (of which
- string literals are a special case), as we do not
- want to make inadvertent copies of such entities,
- and we must be sure that their addresses are the
+ || (!integral_p && !return_aggregate_cst_ok_p
+ /* Unless RETURN_AGGREGATE_CST_OK_P is true, do not
+ return an aggregate constant (of which string
+ literals are a special case), as we do not want
+ to make inadvertent copies of such entities, and
+ we must be sure that their addresses are the
same everywhere. */
&& (TREE_CODE (init) == CONSTRUCTOR
|| TREE_CODE (init) == STRING_CST)))
@@ -1856,7 +1858,8 @@ static tree
tree
integral_constant_value (tree decl)
{
- return constant_value_1 (decl, /*integral_p=*/true);
+ return constant_value_1 (decl, /*integral_p=*/true,
+ /*return_aggregate_cst_ok_p=*/false);
}
/* A more relaxed version of integral_constant_value, used by the
@@ -1864,10 +1867,10 @@ integral_constant_value (tree decl)
purposes. */
tree
-decl_constant_value (tree decl)
+decl_constant_value (tree decl, bool return_aggregate_cst_ok_p)
{
- return constant_value_1 (decl,
- /*integral_p=*/processing_template_decl);
+ return constant_value_1 (decl, /*integral_p=*/processing_template_decl,
+ return_aggregate_cst_ok_p);
}
/* Common subroutines of build_new and build_vec_delete. */
Index: cp/call.c
===================================================================
--- cp/call.c (revision 179540)
+++ cp/call.c (working copy)
@@ -5703,8 +5703,10 @@ convert_like_real (conversion *convs, tree expr, t
leave it as an lvalue. */
if (inner >= 0)
{
- expr = decl_constant_value (expr);
- if (expr == null_node && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P
(totype))
+ expr = decl_constant_value (expr,
+ /*return_aggregate_cst_ok_p=*/false);
+ if (expr == null_node
+ && INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (totype))
/* If __null has been converted to an integer type, we do not
want to warn about uses of EXPR as an integer, rather than
as a pointer. */
Index: c-typeck.c
===================================================================
--- c-typeck.c (revision 179540)
+++ c-typeck.c (working copy)
@@ -1742,7 +1742,7 @@ c_size_in_bytes (const_tree type)
/* Return either DECL or its known constant value (if it has one). */
tree
-decl_constant_value (tree decl)
+decl_constant_value (tree decl, bool return_aggregate_cst_ok_p
ATTRIBUTE_UNUSED)
{
if (/* Don't change a variable array bound or initial value to a constant
in a place where a variable is invalid. Note that DECL_INITIAL
