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Commit e99ef408 by Jakub Jelinek Committed by Jakub Jelinek
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re PR c++/81327 (cast to void* does not suppress -Wclass-memaccess) 

	PR c++/81327
	* call.c (maybe_warn_class_memaccess): Add forward declaration.
	Change last argument from tree * to const vec<tree, va_gc> *, adjust
	args uses and check number of operands too.  Don't strip away any
	nops.  Use maybe_constant_value when looking for INTEGER_CST args.
	Deal with src argument not having pointer type.  Check
	tree_fits_uhwi_p before calling tree_to_uhwi.  Remove useless
	test.
	(build_over_call): Call maybe_warn_class_memaccess here on the
	original arguments.
	(build_cxx_call): Rather than here on converted arguments.

	* g++.dg/Wclass-memaccess-2.C: Don't expect a warning when explicitly
	cast to void *.

From-SVN: r256440
parent 75ce74bb
Showing with 50 additions and 28 deletions
gcc/cp/ChangeLog
2018-01-10 Jakub Jelinek <jakub@redhat.com>
PR c++/81327
* call.c (maybe_warn_class_memaccess): Add forward declaration.
Change last argument from tree * to const vec<tree, va_gc> *, adjust
args uses and check number of operands too. Don't strip away any
nops. Use maybe_constant_value when looking for INTEGER_CST args.
Deal with src argument not having pointer type. Check
tree_fits_uhwi_p before calling tree_to_uhwi. Remove useless
test.
(build_over_call): Call maybe_warn_class_memaccess here on the
original arguments.
(build_cxx_call): Rather than here on converted arguments.
2018-01-10 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/81055
......
gcc/cp/call.c
......@@ -147,6 +147,8 @@ static int equal_functions (tree, tree);
static int joust (struct z_candidate *, struct z_candidate *, bool,
tsubst_flags_t);
static int compare_ics (conversion *, conversion *);
static void maybe_warn_class_memaccess (location_t, tree,
const vec<tree, va_gc> *);
static tree build_over_call (struct z_candidate *, int, tsubst_flags_t);
#define convert_like(CONV, EXPR, COMPLAIN) \
convert_like_real ((CONV), (EXPR), NULL_TREE, 0, \
......@@ -8180,6 +8182,12 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
&& !mark_used (fn, complain))
return error_mark_node;
/* Warn if the built-in writes to an object of a non-trivial type. */
if (warn_class_memaccess
&& vec_safe_length (args) >= 2
&& DECL_BUILT_IN_CLASS (fn) == BUILT_IN_NORMAL)
maybe_warn_class_memaccess (input_location, fn, args);
if (DECL_VINDEX (fn) && (flags & LOOKUP_NONVIRTUAL) == 0
/* Don't mess with virtual lookup in instantiate_non_dependent_expr;
virtual functions can't be constexpr. */
......@@ -8360,7 +8368,8 @@ has_trivial_copy_p (tree type, bool access, bool hasctor[2])
assignments. */
static void
maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
maybe_warn_class_memaccess (location_t loc, tree fndecl,
const vec<tree, va_gc> *args)
{
/* Except for bcopy where it's second, the destination pointer is
the first argument for all functions handled here. Compute
......@@ -8368,15 +8377,10 @@ maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
unsigned dstidx = DECL_FUNCTION_CODE (fndecl) == BUILT_IN_BCOPY;
unsigned srcidx = !dstidx;
tree dest = args[dstidx];
if (!dest || !TREE_TYPE (dest) || !POINTER_TYPE_P (TREE_TYPE (dest)))
tree dest = (*args)[dstidx];
if (!TREE_TYPE (dest) || !POINTER_TYPE_P (TREE_TYPE (dest)))
return;
/* Remove the outermost (usually implicit) conversion to the void*
argument type. */
if (TREE_CODE (dest) == NOP_EXPR)
dest = TREE_OPERAND (dest, 0);
tree srctype = NULL_TREE;
/* Determine the type of the pointed-to object and whether it's
......@@ -8436,7 +8440,7 @@ maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
switch (DECL_FUNCTION_CODE (fndecl))
{
case BUILT_IN_MEMSET:
if (!integer_zerop (args[1]))
if (!integer_zerop (maybe_constant_value ((*args)[1])))
{
/* Diagnose setting non-copy-assignable or non-trivial types,
or types with a private member, to (potentially) non-zero
......@@ -8497,8 +8501,11 @@ maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
case BUILT_IN_MEMMOVE:
case BUILT_IN_MEMPCPY:
/* Determine the type of the source object. */
srctype = STRIP_NOPS (args[srcidx]);
srctype = TREE_TYPE (TREE_TYPE (srctype));
srctype = TREE_TYPE ((*args)[srcidx]);
if (!srctype || !POINTER_TYPE_P (srctype))
srctype = void_type_node;
else
srctype = TREE_TYPE (srctype);
/* Since it's impossible to determine wheter the byte copy is
being used in place of assignment to an existing object or
......@@ -8547,13 +8554,16 @@ maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
"assignment or copy-initialization instead",
fndecl, desttype, access, fld, srctype);
}
else if (!trivial && TREE_CODE (args[2]) == INTEGER_CST)
else if (!trivial && vec_safe_length (args) > 2)
{
tree sz = maybe_constant_value ((*args)[2]);
if (!tree_fits_uhwi_p (sz))
break;
/* Finally, warn on partial copies. */
unsigned HOST_WIDE_INT typesize
= tree_to_uhwi (TYPE_SIZE_UNIT (desttype));
if (unsigned HOST_WIDE_INT partial
= tree_to_uhwi (args[2]) % typesize)
if (unsigned HOST_WIDE_INT partial = tree_to_uhwi (sz) % typesize)
warned = warning_at (loc, OPT_Wclass_memaccess,
(typesize - partial > 1
? G_("%qD writing to an object of "
......@@ -8577,16 +8587,17 @@ maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
else if (!get_dtor (desttype, tf_none))
warnfmt = G_("%qD moving an object of type %#qT with deleted "
"destructor");
else if (!trivial
&& TREE_CODE (args[1]) == INTEGER_CST
&& tree_int_cst_lt (args[1], TYPE_SIZE_UNIT (desttype)))
else if (!trivial)
{
tree sz = maybe_constant_value ((*args)[1]);
if (TREE_CODE (sz) == INTEGER_CST
&& tree_int_cst_lt (sz, TYPE_SIZE_UNIT (desttype)))
/* Finally, warn on reallocation into insufficient space. */
warned = warning_at (loc, OPT_Wclass_memaccess,
"%qD moving an object of non-trivial type "
"%#qT and size %E into a region of size %E",
fndecl, desttype, TYPE_SIZE_UNIT (desttype),
args[1]);
sz);
}
break;
......@@ -8594,9 +8605,6 @@ maybe_warn_class_memaccess (location_t loc, tree fndecl, tree *args)
return;
}
if (!warned && !warnfmt)
return;
if (warnfmt)
{
if (suggest)
......@@ -8643,10 +8651,6 @@ build_cxx_call (tree fn, int nargs, tree *argarray,
if (!check_builtin_function_arguments (EXPR_LOCATION (fn), vNULL, fndecl,
nargs, argarray))
return error_mark_node;
/* Warn if the built-in writes to an object of a non-trivial type. */
if (nargs)
maybe_warn_class_memaccess (loc, fndecl, argarray);
}
if (VOID_TYPE_P (TREE_TYPE (fn)))
......
gcc/testsuite/ChangeLog
2018-01-10 Jakub Jelinek <jakub@redhat.com>
PR c++/81327
* g++.dg/Wclass-memaccess-2.C: Don't expect a warning when explicitly
cast to void *.
2018-01-10 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/81055
......
gcc/testsuite/g++.dg/Wclass-memaccess-2.C
......@@ -53,9 +53,7 @@ void c_cast_uchar (NonTrivial *p)
__builtin_memset ((unsigned char*)p, 0, sizeof *p);
}
// A cast to void* does not suppress the warning. That is (or can be)
// considered a feature.
void c_cast_void (NonTrivial *p)
{
__builtin_memset ((void*)p, 0, sizeof *p); // { dg-warning "\\\[-Wclass-memaccess]" }
__builtin_memset ((void*)p, 0, sizeof *p); // { dg-bogus "\\\[-Wclass-memaccess]" }
}
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