Hi,
Instead of adding the parameter, let's have the C++ front end call a
different function that doesn't try to pull out the value from
aggregate variables, like C has decl_constant_value_for_optimization.
Ok. The below lives entirely inside the C++ front-end (actually I had
already experimented with something similar)
Note I'm using the name decl_constant_value_safe, thus I'm not
overloading the name decl_constant_value_for_optimization, because the
latter is only used by the C front-end but still exported by c-family. I
could move back that decl_constant_value_for_optimization currently in
c-common.c to the C front-end, but callers, also C front-end only, would
remain in c-family. I'd rather not fiddle further with all of that
(looks like long term people would like to have more shared code in
c-common.c, seems indeed an excellent idea, but at the moment large
chunks are actually used by the C front-end only...).
Tested x86_64-linux.
Paolo.
/////////////////////
/cp
2011-10-07 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/38980
* init.c (constant_value_1): Add bool parameter.
(decl_constant_value_safe): Add.
(integral_constant_value): Adjust.
(decl_constant_value): Adjust.
* cp-tree.h (decl_constant_value_safe): Declare.
* typeck.c (decay_conversion): Use decl_constant_value_safe.
* call.c (convert_like_real): Likewise.
/testsuite
2011-10-07 Paolo Carlini <paolo.carl...@oracle.com>
PR c++/38980
* g++.dg/warn/format5.C: New.
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 179649)
+++ 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_safe (exp);
if (error_operand_p (exp))
return error_mark_node;
Index: cp/init.c
===================================================================
--- cp/init.c (revision 179649)
+++ 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
@@ -1834,12 +1835,13 @@ 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
- same everywhere. */
+ || (!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)))
break;
@@ -1856,19 +1858,29 @@ 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
- common C/C++ code and by the C++ front end for optimization
- purposes. */
+ common C/C++ code. */
tree
decl_constant_value (tree decl)
{
- 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=*/true);
}
+
+/* A version of integral_constant_value used by the C++ front end for
+ optimization purposes. */
+
+tree
+decl_constant_value_safe (tree decl)
+{
+ return constant_value_1 (decl, /*integral_p=*/processing_template_decl,
+ /*return_aggregate_cst_ok_p=*/false);
+}
/* Common subroutines of build_new and build_vec_delete. */
Index: cp/call.c
===================================================================
--- cp/call.c (revision 179649)
+++ cp/call.c (working copy)
@@ -5703,7 +5703,7 @@ convert_like_real (conversion *convs, tree expr, t
leave it as an lvalue. */
if (inner >= 0)
{
- expr = decl_constant_value (expr);
+ expr = decl_constant_value_safe (expr);
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
Index: cp/cp-tree.h
===================================================================
--- cp/cp-tree.h (revision 179649)
+++ cp/cp-tree.h (working copy)
@@ -5097,6 +5097,7 @@ extern tree create_temporary_var (tree);
extern void initialize_vtbl_ptrs (tree);
extern tree build_java_class_ref (tree);
extern tree integral_constant_value (tree);
+extern tree decl_constant_value_safe (tree);
extern int diagnose_uninitialized_cst_or_ref_member (tree, bool, bool);
/* in lex.c */
