-Winvalid-offsetof was introduced before __builtin_offsetof, and the
comments both in the code and the testsuite note that even though
offsetof on a non-standard-layout type is undefined, the usual expansion
seems to be well-defined. So -Winvalid-offsetof should move to
offsetof-specific code, and we can upgrade the warning to a pedwarn.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit faa1550a6c8075c4190143a48d92f6f52e746356
Author: Jason Merrill <ja...@redhat.com>
Date: Mon Sep 8 13:21:41 2014 -0400
* typeck.c (build_class_member_access_expr): Move
-Winvalid-offsetof code...
* semantics.c (finish_offsetof): ...here.
* parser.c (cp_parser_builtin_offsetof): Remember the location of
the type argument.
* pt.c (tsubst_copy_and_build) [OFFSETOF_EXPR]: Preserve it.
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 05fa86a..204ed42 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -8577,6 +8577,7 @@ cp_parser_builtin_offsetof (cp_parser *parser)
/* Consume the opening `('. */
cp_parser_require (parser, CPP_OPEN_PAREN, RT_OPEN_PAREN);
/* Parse the type-id. */
+ location_t loc = cp_lexer_peek_token (parser->lexer)->location;
type = cp_parser_type_id (parser);
/* Look for the `,'. */
cp_parser_require (parser, CPP_COMMA, RT_COMMA);
@@ -8630,6 +8631,9 @@ cp_parser_builtin_offsetof (cp_parser *parser)
}
success:
+ if (CAN_HAVE_LOCATION_P (expr))
+ SET_EXPR_LOCATION (expr, loc);
+
/* If we're processing a template, we can't finish the semantics yet.
Otherwise we can fold the entire expression now. */
if (processing_template_decl)
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 38093ec..b778644 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -15440,7 +15440,12 @@ tsubst_copy_and_build (tree t,
}
case OFFSETOF_EXPR:
- RETURN (finish_offsetof (RECUR (TREE_OPERAND (t, 0))));
+ {
+ tree expr = RECUR (TREE_OPERAND (t, 0));
+ if (CAN_HAVE_LOCATION_P (expr))
+ SET_EXPR_LOCATION (expr, EXPR_LOCATION (TREE_OPERAND (t, 0)));
+ RETURN (finish_offsetof (expr));
+ }
case TRAIT_EXPR:
{
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 776fa26..cd43384 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -3816,6 +3816,7 @@ finish_bases (tree type, bool direct)
tree
finish_offsetof (tree expr)
{
+ location_t loc = EXPR_LOCATION (expr);
if (TREE_CODE (expr) == PSEUDO_DTOR_EXPR)
{
error ("cannot apply %<offsetof%> to destructor %<~%T%>",
@@ -3846,6 +3847,13 @@ finish_offsetof (tree expr)
tree object = TREE_OPERAND (expr, 0);
if (!complete_type_or_else (TREE_TYPE (object), object))
return error_mark_node;
+ if (warn_invalid_offsetof
+ && CLASS_TYPE_P (TREE_TYPE (object))
+ && CLASSTYPE_NON_STD_LAYOUT (TREE_TYPE (object))
+ && cp_unevaluated_operand == 0)
+ pedwarn (loc, OPT_Winvalid_offsetof,
+ "offsetof within non-standard-layout type %qT is undefined",
+ TREE_TYPE (object));
}
return fold_offsetof (expr);
}
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 05fd48e..aa82f1c 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -2359,10 +2359,8 @@ build_class_member_access_expr (tree object, tree member,
{
if (complain & tf_error)
{
- error ("invalid access to non-static data member %qD of "
- "NULL object",
- member);
- error ("(perhaps the %<offsetof%> macro was used incorrectly)");
+ error ("invalid access to non-static data member %qD in "
+ "virtual base of NULL object", member);
}
return error_mark_node;
}
@@ -2375,27 +2373,6 @@ build_class_member_access_expr (tree object, tree member,
gcc_assert (object != error_mark_node);
}
- /* Complain about other invalid uses of offsetof, even though they will
- give the right answer. Note that we complain whether or not they
- actually used the offsetof macro, since there's no way to know at this
- point. So we just give a warning, instead of a pedwarn. */
- /* Do not produce this warning for base class field references, because
- we know for a fact that didn't come from offsetof. This does occur
- in various testsuite cases where a null object is passed where a
- vtable access is required. */
- if (null_object_p && warn_invalid_offsetof
- && CLASSTYPE_NON_STD_LAYOUT (object_type)
- && !DECL_FIELD_IS_BASE (member)
- && cp_unevaluated_operand == 0
- && (complain & tf_warning))
- {
- warning (OPT_Winvalid_offsetof,
- "invalid access to non-static data member %qD "
- " of NULL object", member);
- warning (OPT_Winvalid_offsetof,
- "(perhaps the %<offsetof%> macro was used incorrectly)");
- }
-
/* If MEMBER is from an anonymous aggregate, we have converted
OBJECT so that it refers to the class containing the
anonymous union. Generate a reference to the anonymous union
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 55e6d56..a4a345d 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -5097,12 +5097,10 @@ warnings produced by @option{-Winline} to appear or disappear.
@opindex Wno-invalid-offsetof
@opindex Winvalid-offsetof
Suppress warnings from applying the @samp{offsetof} macro to a non-POD
-type. According to the 1998 ISO C++ standard, applying @samp{offsetof}
-to a non-POD type is undefined. In existing C++ implementations,
-however, @samp{offsetof} typically gives meaningful results even when
-applied to certain kinds of non-POD types (such as a simple
-@samp{struct} that fails to be a POD type only by virtue of having a
-constructor). This flag is for users who are aware that they are
+type. According to the 2014 ISO C++ standard, applying @samp{offsetof}
+to a non-standard-layout type is undefined. In existing C++ implementations,
+however, @samp{offsetof} typically gives meaningful results.
+This flag is for users who are aware that they are
writing nonportable code and who have deliberately chosen to ignore the
warning about it.
diff --git a/gcc/testsuite/g++.dg/abi/offsetof.C b/gcc/testsuite/g++.dg/abi/offsetof.C
index d6a53e6..5a66511 100644
--- a/gcc/testsuite/g++.dg/abi/offsetof.C
+++ b/gcc/testsuite/g++.dg/abi/offsetof.C
@@ -4,7 +4,6 @@
// implementation thereof.
// Yes, this is bad, naughty, evil code. But it seems to be well-formed.
-// So we'll just warn.
// { dg-do run }
@@ -18,5 +17,5 @@ struct C: public B { };
int main ()
{
- return ((__SIZE_TYPE__) &((C*)0)->i) != sizeof(void*); // { dg-warning "offsetof|invalid" "" }
+ return ((__SIZE_TYPE__) &((C*)0)->i) != sizeof(void*);
}
diff --git a/gcc/testsuite/g++.dg/other/offsetof3.C b/gcc/testsuite/g++.dg/other/offsetof3.C
index 5946c81..8d98242 100644
--- a/gcc/testsuite/g++.dg/other/offsetof3.C
+++ b/gcc/testsuite/g++.dg/other/offsetof3.C
@@ -1,7 +1,6 @@
-/* Verify that offsetof warns if given a non-standard-layout class */
+/* Verify that offsetof complains if given a non-standard-layout class. */
/* Copyright (C) 2003 Free Software Foundation, Inc. */
/* Contributed by Matt Austern <aust...@apple.com> 15 May 2003 */
-/* { dg-do compile } */
struct X
{
@@ -13,5 +12,4 @@ protected:
typedef X* pX;
typedef __SIZE_TYPE__ size_t;
-size_t yoff = size_t(&(pX(0)->y)); /* { dg-warning "invalid access" "" } */
-/* { dg-warning "macro was used incorrectly" "macro" { target *-*-* } 16 } */
+size_t yoff = __builtin_offsetof (X, y); /* { dg-error "35:non-standard-layout" } */
diff --git a/gcc/testsuite/g++.dg/other/offsetof5.C b/gcc/testsuite/g++.dg/other/offsetof5.C
index b53b06f..86b1448 100644
--- a/gcc/testsuite/g++.dg/other/offsetof5.C
+++ b/gcc/testsuite/g++.dg/other/offsetof5.C
@@ -9,14 +9,14 @@ struct A
int &i;
};
-int j = offsetof (A, i); // { dg-warning "invalid access|offsetof" }
+int j = offsetof (A, i); // { dg-error "offsetof" }
template <typename T>
struct S
{
T h;
T &i;
- static const int j = offsetof (S, i); // { dg-warning "invalid access|offsetof" }
+ static const int j = offsetof (S, i); // { dg-error "offsetof" }
};
int k = S<int>::j; // { dg-message "required from here" }
