Attached is an updated patch with Jason's suggested change to use
handled_component_p(), retested on x86_64-linux and with Glibc.
Adding more tests led to more changes but hopefully also a better
end result.
I've changed the warning suppression from a cast to void* to one
to intptr_t, in part because that's what Clang does, and in part
because I couldn't get it to work consistently between C and C++
(the C front end seems to introduce a NOP_EXPR in some cases even
when there is no cast in the source). In hindsight, a cast to
void* doesn't seem like the most intuitive way to avoid this sort
of warning.
Jeff, I didn't get your reply to my first post for some reason so
let me copy your question here and answer it below:
how does this interact with targets that allow objects at address
0? We have a few targets like that and that makes me wonder if
we should be suppressing some, if not all, of these warnings for
targets that turn on -fno-delete-null-pointer-checks?
I didn't see any code related to -Waddress that tries to handle those
targets. I have very little experience with them but I do know that
AVR makes it possible to pin an object to a fixed address by means
of attribute address. The test case below triggers -Waddress (both
with and without my changes):
__attribute__ ((address (0))) int x;
int f (void)
{
if (&x == 0) return -1; // -Waddress
int *p = &x;
int t = *p;
if (!p) __builtin_abort (); // folded to false
return t;
}
But the optimized code doesn't have the second test so I'm not sure
that the address attribute here does what I think it does (I'd
expect the test to be folded to true). If you have a better test
case or other targets for me to try I can look into it some more.
Martin
On 9/2/21 8:39 AM, Martin Sebor wrote:
On 9/2/21 7:43 AM, Jason Merrill wrote:
On 9/1/21 6:27 PM, Martin Sebor wrote:
On 9/1/21 3:39 PM, Jason Merrill wrote:
On 9/1/21 4:33 PM, Martin Sebor wrote:
On 9/1/21 1:21 PM, Jason Merrill wrote:
On 8/31/21 10:08 PM, Martin Sebor wrote:
A Coverity run recently uncovered a latent bug in GCC that GCC
should
be able to detect itself: comparing the address of a declared object
for equality to null, similar to:
int f (void)
{
int a[2][2];
return &a == 0;
}
GCC issues -Waddress for this code, but the bug Coverity found was
actually closer to the following:
int f (void)
{
int a[2][2];
return a[0] == 0;
}
where the hapless author (yours truly) meant to compare the value
of a[0][0] (as in r12-3268).
This variant is not diagnosed even though the bug in it is the same
and I'd expect more likely to occur in practice. (&a[0] == 0 isn't
diagnosed either, though that's a less likely mistake to make).
The attached patch enhances -Waddress to detect this variant along
with a number of other similar instances of the problem, including
comparing the address of array members to null.
Besides these, the patch also issues -Waddress for null equality
tests of pointer-plus expressions such as in:
int g (int i)
{
return a[0] + i == 0;
}
and in C++ more instances of pointers to members.
Testing on x86_64-linux, besides a few benign issues in GCC sources
a regression test, run shows a failure in gcc.dg/Waddress.c. That's
a test added after GCC for some reason stopped warning for one of
the basic cases that other tools warn about (comparing an array to
null). I suspect the change was unintentional because GCC still
warns for other very similar expressions. The reporter who also
submitted the test in pr36299 argued that the warning wasn't
helpful because tests for arrays sometimes come from macros, and
the test was committed after it was noted that GCC no longer warned
for the reporter's simple case. While it's certainly true that
the warning can be triggered by the null equality tests in macros
(the patch exposed two such instances in GCC) they are easy to
avoid (the patch adds a an additional escape hatch). At the same
time, as is evident from the Coverity bug report and from the two
issues the enhancement exposes in the FORTRAN front end (even if
benign), issuing the warning in these cases does help find bugs
or mistaken assumptions. With that, I've changed the test to
expect the restored -Waddress warning instead.
Testing with Glibc exposed a couple of harmless comparisons of
arrays a large macro in vfprintf-internal.c. I'll submit a fix
to avoid the -Waddress instances if/when this enhancement is
approved.
Testing with Binutils/GDB also turned up a couple of pointless
comparison of arrays to null and a couple of uses in macros that
can be trivially suppressed.
Martin
PS Clang issues a warning for some of the same null pointer tests
the patch diagnoses, including gcc.dg/Waddress.c, except under at
least three different options: some under -Wpointer-bool-conversion,
others under -Wtautological-pointer-compare, and others still under
-Wtautological-compare.
+ while (TREE_CODE (cop) == ARRAY_REF
+ || TREE_CODE (cop) == COMPONENT_REF)
+ {
+ unsigned opno = TREE_CODE (cop) == COMPONENT_REF;
+ cop = TREE_OPERAND (cop, opno);
+ }
1) Maybe 'while (handled_component_p (cop))'?
2) Why handle COMPONENT_REF differently? Operand 1 is the
FIELD_DECL, which doesn't have an address of its own.
This is because the address of a field is never null, regardless of
what the P in in &P->M points to.
True, though I'd change "invalid" to "undefined" in the comment for
decl_with_nonnull_addr_p.
(With the caveat mentioned in
the comment further up about the pointer used to access the member
being nonnull.) So this is diagnosed:
extern struct { int m; } *p;
bool b = &p->m == 0;
Using handled_component_p() in a loop would prevent that.
Would it? p isn't declared weak.
Maybe I misunderstood. This loop:
while (handled_component_p (cop))
cop = TREE_OPERAND (cop, 0);
would unwrap the COMPONENT_REF from cop and terminate with it set
to INDIRECT_REF for which decl_with_nonnull_addr_p() would return
false. But if you meant to keep the body as is and just change
the condition, that would work. If you think that's better,
e.g., because it would handle more cases, I'm all for it.
It's worth considering the other codes in handled_component_p, at
least. BIT_FIELD_REF we shouldn't see an address of. I don't think
the C++ front end produces ARRAY_RANGE_REF. I'd think REALPART_EXPR
and IMAGPART_EXPR would be like COMPONENT_REF. I guess we would want
to look through VIEW_CONVERT_EXPR.
Okay, let me update the patch then and repost before committing.
For array_refs, the loop gets us the decl to mention in the warning.
But this should work too and looks cleaner:
cop = TREE_OPERAND (cop, 0);
/* Get the outermost array. */
while (TREE_CODE (cop) == ARRAY_REF)
cop = TREE_OPERAND (cop, 0);
/* Get the member (its address is never null). */
if (TREE_CODE (cop) == COMPONENT_REF)
cop = TREE_OPERAND (cop, 1);
Do you prefer the above instead?
Sure. OK with that change and the comment tweak above.
Thanks. Are you approving the whole patch (including the C FE
changes) or just the C++ part?
My impression was that Jeff approved the rest of the patch, so I was
only really looking at the C++ part.
That's odd (and worrisome). I didn't get that email for some
strange reason but I just found it in the archive. Let me also
respond to Jeff's question in my follow up.
Martin
Enhance -Waddress to detect more suspicious expressions [PR102103].
Resolves:
PR c/102103 - missing warning comparing array address to null
gcc/ChangeLog:
* doc/invoke.texi (-Waddress): Update.
* gcc/gengtype.c (write_types): Avoid -Waddress.
gcc/c-family/ChangeLog:
* c-common.c (decl_with_nonnull_addr_p): Handle members.
Check and perform warning suppression.
(c_common_truthvalue_conversion): Enhance warning suppression.
gcc/c/ChangeLog:
* c-typeck.c (maybe_warn_for_null_address): New function.
(build_binary_op): Call it.
gcc/cp/ChangeLog:
* typeck.c (warn_for_null_address): Enhance.
(cp_build_binary_op): Call it also for member pointers.
gcc/fortran/ChangeLog:
* gcc/fortran/array.c: Remove an unnecessary test.
* gcc/fortran/trans-array.c: Same.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-array-ptr10.C: Suppress a valid warning.
* g++.dg/warn/Wreturn-local-addr-6.C: Correct a cast.
* gcc.dg/Waddress.c: Expect a warning.
* c-c++-common/Waddress-3.c: New test.
* c-c++-common/Waddress-4.c: New test.
* g++.dg/warn/Waddress-5.C: New test.
* g++.dg/warn/Waddress-6.C: New test.
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 017e41537ac..50d9559175e 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -3393,14 +3393,16 @@ c_wrap_maybe_const (tree expr, bool non_const)
return expr;
}
-/* Return whether EXPR is a declaration whose address can never be
- NULL. */
+/* Return whether EXPR is a declaration whose address can never be NULL.
+ The address of the first struct member could be NULL only if it were
+ accessed through a NULL pointer, and such an access would be invalid. */
bool
decl_with_nonnull_addr_p (const_tree expr)
{
return (DECL_P (expr)
- && (TREE_CODE (expr) == PARM_DECL
+ && (TREE_CODE (expr) == FIELD_DECL
+ || TREE_CODE (expr) == PARM_DECL
|| TREE_CODE (expr) == LABEL_DECL
|| !DECL_WEAK (expr)));
}
@@ -3488,13 +3490,17 @@ c_common_truthvalue_conversion (location_t location, tree expr)
case ADDR_EXPR:
{
tree inner = TREE_OPERAND (expr, 0);
- if (decl_with_nonnull_addr_p (inner))
+ if (decl_with_nonnull_addr_p (inner)
+ /* Check both EXPR and INNER for suppression. */
+ && !warning_suppressed_p (expr, OPT_Waddress)
+ && !warning_suppressed_p (inner, OPT_Waddress))
{
- /* Common Ada programmer's mistake. */
+ /* Common Ada programmer's mistake. */
warning_at (location,
OPT_Waddress,
"the address of %qD will always evaluate as %<true%>",
inner);
+ suppress_warning (inner, OPT_Waddress);
return truthvalue_true_node;
}
break;
@@ -3627,8 +3633,17 @@ c_common_truthvalue_conversion (location_t location, tree expr)
break;
/* If this isn't narrowing the argument, we can ignore it. */
if (TYPE_PRECISION (totype) >= TYPE_PRECISION (fromtype))
- return c_common_truthvalue_conversion (location,
- TREE_OPERAND (expr, 0));
+ {
+ tree op0 = TREE_OPERAND (expr, 0);
+ if ((TREE_CODE (fromtype) == POINTER_TYPE
+ && TREE_CODE (totype) == INTEGER_TYPE)
+ || warning_suppressed_p (expr, OPT_Waddress))
+ /* Suppress -Waddress for casts to intptr_t, propagating
+ any suppression from the enclosing expression to its
+ operand. */
+ suppress_warning (op0, OPT_Waddress);
+ return c_common_truthvalue_conversion (location, op0);
+ }
}
break;
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 5849c5ab23d..0e9cf1063c0 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -11545,6 +11545,110 @@ build_vec_cmp (tree_code code, tree type,
return build3 (VEC_COND_EXPR, type, cmp, minus_one_vec, zero_vec);
}
+/* Possibly warn about an address of OP never being NULL in a comparison
+ operation CODE involving null. */
+
+static void
+maybe_warn_for_null_address (location_t loc, tree op, tree_code code)
+{
+ if (!warn_address || warning_suppressed_p (op, OPT_Waddress))
+ return;
+
+ if (TREE_CODE (op) == NOP_EXPR)
+ {
+ /* Allow casts to intptr_t to suppress the warning. */
+ tree type = TREE_TYPE (op);
+ if (TREE_CODE (type) == INTEGER_TYPE)
+ return;
+ op = TREE_OPERAND (op, 0);
+ }
+
+ if (TREE_CODE (op) == POINTER_PLUS_EXPR)
+ {
+ /* Allow a cast to void* to suppress the warning. */
+ tree type = TREE_TYPE (TREE_TYPE (op));
+ if (VOID_TYPE_P (type))
+ return;
+
+ /* Adding any value to a null pointer, including zero, is undefined
+ in C. This includes the expression &p[0] where p is the null
+ pointer, although &p[0] will have been folded to p by this point
+ and so not diagnosed. */
+ if (code == EQ_EXPR)
+ warning_at (loc, OPT_Waddress,
+ "the comparison will always evaluate as %<false%> "
+ "for the pointer operand in %qE must not be NULL",
+ op);
+ else
+ warning_at (loc, OPT_Waddress,
+ "the comparison will always evaluate as %<true%> "
+ "for the pointer operand in %qE must not be NULL",
+ op);
+
+ return;
+ }
+
+ if (TREE_CODE (op) != ADDR_EXPR)
+ return;
+
+ op = TREE_OPERAND (op, 0);
+
+ if (TREE_CODE (op) == IMAGPART_EXPR
+ || TREE_CODE (op) == REALPART_EXPR)
+ {
+ /* The address of either complex part may not be null. */
+ if (code == EQ_EXPR)
+ warning_at (loc, OPT_Waddress,
+ "the comparison will always evaluate as %<false%> "
+ "for the address %qE will never be NULL",
+ op);
+ else
+ warning_at (loc, OPT_Waddress,
+ "the comparison will always evaluate as %<true%> "
+ "for the address %qE will never be NULL",
+ op);
+ return;
+ }
+
+ /* Set to true in the loop below if OP dereferences is operand.
+ In such a case the ultimate target need not be a decl for
+ the null [in]equality test to be constant. */
+ bool deref = false;
+
+ /* Get the outermost array or object, or member. */
+ while (handled_component_p (op))
+ {
+ if (TREE_CODE (op) == COMPONENT_REF)
+ {
+ /* Get the member (its address is never null). */
+ op = TREE_OPERAND (op, 1);
+ break;
+ }
+
+ /* Get the outer array/object to refer to in the warning. */
+ op = TREE_OPERAND (op, 0);
+ deref = true;
+ }
+
+ if ((!deref && !decl_with_nonnull_addr_p (op))
+ || from_macro_expansion_at (loc))
+ return;
+
+ if (code == EQ_EXPR)
+ warning_at (loc, OPT_Waddress,
+ "the comparison will always evaluate as %<false%> "
+ "for the address of %qE will never be NULL",
+ op);
+ else
+ warning_at (loc, OPT_Waddress,
+ "the comparison will always evaluate as %<true%> "
+ "for the address of %qE will never be NULL",
+ op);
+
+ if (DECL_P (op))
+ inform (DECL_SOURCE_LOCATION (op), "%qD declared here", op);
+}
+
/* Build a binary-operation expression without default conversions.
CODE is the kind of expression to build.
LOCATION is the operator's location.
@@ -12180,44 +12284,12 @@ build_binary_op (location_t location, enum tree_code code,
short_compare = 1;
else if (code0 == POINTER_TYPE && null_pointer_constant_p (orig_op1))
{
- if (TREE_CODE (op0) == ADDR_EXPR
- && decl_with_nonnull_addr_p (TREE_OPERAND (op0, 0))
- && !from_macro_expansion_at (location))
- {
- if (code == EQ_EXPR)
- warning_at (location,
- OPT_Waddress,
- "the comparison will always evaluate as %<false%> "
- "for the address of %qD will never be NULL",
- TREE_OPERAND (op0, 0));
- else
- warning_at (location,
- OPT_Waddress,
- "the comparison will always evaluate as %<true%> "
- "for the address of %qD will never be NULL",
- TREE_OPERAND (op0, 0));
- }
+ maybe_warn_for_null_address (location, op0, code);
result_type = type0;
}
else if (code1 == POINTER_TYPE && null_pointer_constant_p (orig_op0))
{
- if (TREE_CODE (op1) == ADDR_EXPR
- && decl_with_nonnull_addr_p (TREE_OPERAND (op1, 0))
- && !from_macro_expansion_at (location))
- {
- if (code == EQ_EXPR)
- warning_at (location,
- OPT_Waddress,
- "the comparison will always evaluate as %<false%> "
- "for the address of %qD will never be NULL",
- TREE_OPERAND (op1, 0));
- else
- warning_at (location,
- OPT_Waddress,
- "the comparison will always evaluate as %<true%> "
- "for the address of %qD will never be NULL",
- TREE_OPERAND (op1, 0));
- }
+ maybe_warn_for_null_address (location, op1, code);
result_type = type1;
}
else if (code0 == POINTER_TYPE && code1 == POINTER_TYPE)
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index cc61b509f8a..293c292d9b2 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4622,28 +4622,94 @@ warn_for_null_address (location_t location, tree op, tsubst_flags_t complain)
if (!warn_address
|| (complain & tf_warning) == 0
|| c_inhibit_evaluation_warnings != 0
- || warning_suppressed_p (op, OPT_Waddress))
+ || warning_suppressed_p (op, OPT_Waddress)
+ || processing_template_decl != 0)
return;
tree cop = fold_for_warn (op);
- if (TREE_CODE (cop) == ADDR_EXPR
- && decl_with_nonnull_addr_p (TREE_OPERAND (cop, 0))
- && !warning_suppressed_p (cop, OPT_Waddress))
- warning_at (location, OPT_Waddress, "the address of %qD will never "
- "be NULL", TREE_OPERAND (cop, 0));
+ if (TREE_CODE (cop) == NON_LVALUE_EXPR)
+ /* Unwrap the expression for C++ 98. */
+ cop = TREE_OPERAND (cop, 0);
- if (CONVERT_EXPR_P (op)
+ if (TREE_CODE (cop) == PTRMEM_CST)
+ {
+ /* The address of a nonstatic data member is never null. */
+ warning_at (location, OPT_Waddress,
+ "the address %qE will never be NULL",
+ cop);
+ return;
+ }
+
+ if (TREE_CODE (cop) == NOP_EXPR)
+ {
+ /* Allow casts to intptr_t to suppress the warning. */
+ tree type = TREE_TYPE (cop);
+ if (TREE_CODE (type) == INTEGER_TYPE)
+ return;
+
+ STRIP_NOPS (cop);
+ }
+
+ bool warned = false;
+ if (TREE_CODE (cop) == ADDR_EXPR)
+ {
+ cop = TREE_OPERAND (cop, 0);
+
+ /* Set to true in the loop below if OP dereferences its operand.
+ In such a case the ultimate target need not be a decl for
+ the null [in]equality test to be necessarily constant. */
+ bool deref = false;
+
+ /* Get the outermost array or object, or member. */
+ while (handled_component_p (cop))
+ {
+ if (TREE_CODE (cop) == COMPONENT_REF)
+ {
+ /* Get the member (its address is never null). */
+ cop = TREE_OPERAND (cop, 1);
+ break;
+ }
+
+ /* Get the outer array/object to refer to in the warning. */
+ cop = TREE_OPERAND (cop, 0);
+ deref = true;
+ }
+
+ if ((!deref && !decl_with_nonnull_addr_p (cop))
+ || from_macro_expansion_at (location)
+ || warning_suppressed_p (cop, OPT_Waddress))
+ return;
+
+ warned = warning_at (location, OPT_Waddress,
+ "the address of %qD will never be NULL", cop);
+ op = cop;
+ }
+ else if (TREE_CODE (cop) == POINTER_PLUS_EXPR)
+ {
+ /* Adding zero to the null pointer is well-defined in C++. When
+ the offset is unknown (i.e., not a constant) warn anyway since
+ it's less likely that the pointer operand is null than not. */
+ tree off = TREE_OPERAND (cop, 1);
+ if (!integer_zerop (off)
+ && !warning_suppressed_p (cop, OPT_Waddress))
+ warning_at (location, OPT_Waddress, "comparing the result of pointer "
+ "addition %qE and NULL", cop);
+ return;
+ }
+ else if (CONVERT_EXPR_P (op)
&& TYPE_REF_P (TREE_TYPE (TREE_OPERAND (op, 0))))
{
- tree inner_op = op;
- STRIP_NOPS (inner_op);
+ STRIP_NOPS (op);
- if (DECL_P (inner_op))
- warning_at (location, OPT_Waddress,
- "the compiler can assume that the address of "
- "%qD will never be NULL", inner_op);
+ if (DECL_P (op))
+ warned = warning_at (location, OPT_Waddress,
+ "the compiler can assume that the address of "
+ "%qD will never be NULL", op);
}
+
+ if (warned && DECL_P (op))
+ inform (DECL_SOURCE_LOCATION (op), "%qD declared here", op);
}
/* Warn about [expr.arith.conv]/2: If one operand is of enumeration type and
@@ -5433,6 +5499,8 @@ cp_build_binary_op (const op_location_t &location,
op1 = cp_convert (TREE_TYPE (op0), op1, complain);
}
result_type = TREE_TYPE (op0);
+
+ warn_for_null_address (location, orig_op0, complain);
}
else if (TYPE_PTRMEMFUNC_P (type1) && null_ptr_cst_p (orig_op0))
return cp_build_binary_op (location, code, op1, op0, complain);
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 8969bac664d..cba5fefb027 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -8547,17 +8547,43 @@ by @option{-Wall}.
@item -Waddress
@opindex Waddress
@opindex Wno-address
-Warn about suspicious uses of memory addresses. These include using
-the address of a function in a conditional expression, such as
-@code{void func(void); if (func)}, and comparisons against the memory
-address of a string literal, such as @code{if (x == "abc")}. Such
-uses typically indicate a programmer error: the address of a function
-always evaluates to true, so their use in a conditional usually
-indicate that the programmer forgot the parentheses in a function
-call; and comparisons against string literals result in unspecified
-behavior and are not portable in C, so they usually indicate that the
-programmer intended to use @code{strcmp}. This warning is enabled by
-@option{-Wall}.
+Warn about suspicious uses of address expressions. These include comparing
+the address of a function or a declared object to the null pointer constant
+such as in
+@smallexample
+void f (void);
+void g (void)
+@{
+ if (!func) // warning: expression evaluates to false
+ abort ();
+@}
+@end smallexample
+comparisons of a pointer to a string literal, such as in
+@smallexample
+void f (const char *x)
+@{
+ if (x == "abc") // warning: expression evaluates to false
+ puts ("equal");
+@}
+@end smallexample
+and tests of the results of pointer addition or subtraction for equality
+to null, such as in
+@smallexample
+void f (const int *p, int i)
+@{
+ return p + i == NULL;
+@}
+@end smallexample
+Such uses typically indicate a programmer error: the address of most
+functions and objects necessarily evaluates to true (the exception are
+weak symbols), so their use in a conditional might indicate missing
+parentheses in a function call or a missing dereference in an array
+expression. The subset of the warning for object pointers can be
+suppressed by casting the pointer operand to an integer type such
+as @code{inptr_t} or @code{uinptr_t}.
+Comparisons against string literals result in unspecified behavior
+and are not portable, and suggest the intent was to call @code{strcmp}.
+@option{-Waddress} warning is enabled by @option{-Wall}.
@item -Wno-address-of-packed-member
@opindex Waddress-of-packed-member
diff --git a/gcc/fortran/array.c b/gcc/fortran/array.c
index b858bada18a..341290f91b8 100644
--- a/gcc/fortran/array.c
+++ b/gcc/fortran/array.c
@@ -2578,7 +2578,7 @@ gfc_array_dimen_size (gfc_expr *array, int dimen, mpz_t *result)
}
}
- if (array->shape && array->shape[dimen])
+ if (array->shape)
{
mpz_init_set (*result, array->shape[dimen]);
return true;
diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index 0d013defdbb..5147509fbe7 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -5104,7 +5104,6 @@ set_loop_bounds (gfc_loopinfo *loop)
if (info->shape)
{
- gcc_assert (info->shape[dim]);
/* The frontend has worked out the size for us. */
if (!loopspec[n]
|| !specinfo->shape
diff --git a/gcc/gengtype.c b/gcc/gengtype.c
index 31d4bf4e5d0..a77cfd92bfa 100644
--- a/gcc/gengtype.c
+++ b/gcc/gengtype.c
@@ -3685,8 +3685,8 @@ write_types (outf_p output_header, type_p structures,
output_mangled_typename (output_header, s);
oprintf (output_header, "(X) do { \\\n");
oprintf (output_header,
- " if (X != NULL) gt_%sx_%s (X);\\\n", wtd->prefix,
- s_id_for_tag);
+ " if ((intptr_t)(X) != 0) gt_%sx_%s (X);\\\n",
+ wtd->prefix, s_id_for_tag);
oprintf (output_header, " } while (0)\n");
for (opt = s->u.s.opt; opt; opt = opt->next)
diff --git a/gcc/poly-int.h b/gcc/poly-int.h
index f47f9e436a8..94e7b701f64 100644
--- a/gcc/poly-int.h
+++ b/gcc/poly-int.h
@@ -324,10 +324,10 @@ struct poly_result<T1, T2, 2>
routine can take the address of RES rather than the address of
a temporary.
- The dummy comparison against a null C * is just a way of checking
+ The dummy self-comparison against C * is just a way of checking
that C gives the right type. */
#define POLY_SET_COEFF(C, RES, I, VALUE) \
- ((void) (&(RES).coeffs[0] == (C *) 0), \
+ ((void) (&(RES).coeffs[0] == (C *) (void *) &(RES).coeffs[0]), \
wi::int_traits<C>::precision_type == wi::FLEXIBLE_PRECISION \
? (void) ((RES).coeffs[I] = VALUE) \
: (void) ((RES).coeffs[I].~C (), new (&(RES).coeffs[I]) C (VALUE)))
diff --git a/gcc/testsuite/c-c++-common/Waddress-3.c b/gcc/testsuite/c-c++-common/Waddress-3.c
new file mode 100644
index 00000000000..9a13a444045
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Waddress-3.c
@@ -0,0 +1,125 @@
+/* PR c/102103 - missing warning comparing array address to null
+ { dg-do compile }
+ { dg-options "-Wall" } */
+
+typedef __INTPTR_TYPE__ intptr_t;
+typedef __UINTPTR_TYPE__ uintptr_t;
+
+#ifndef __cplusplus
+# define bool _Bool
+#endif
+
+struct S { void *p, *a1[2], *a2[2][2]; } s, *p;
+
+extern const void *a1[2];
+extern void *a2[2][2], *ax[];
+
+void T (bool);
+
+void test_array_eq_0 (int i)
+{
+ // Verify that casts intptr_t suppress the warning.
+ T ((intptr_t)a1 == 0);
+ T ((uintptr_t)a1 == 0);
+ T (a1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &a1); // { dg-warning "-Waddress" }
+ // Verify that casts to other pointer types don't suppress it.
+ T ((void *)a1 == 0); // { dg-warning "-Waddress" }
+ T ((char *)a1 == 0); // { dg-warning "-Waddress" }
+ T (a1[0] == 0);
+ T (0 == (intptr_t)&a1[0]);
+ T (0 == &a1[0]); // { dg-warning "-Waddress" }
+ T (a1[i] == 0);
+ T (0 == (uintptr_t)&a1[i]);
+ T (0 == &a1[i]); // { dg-warning "-Waddress" }
+
+ T ((intptr_t)a2 == 0);
+ T (a2 == 0); // { dg-warning "-Waddress" }
+ T (0 == &a2); // { dg-warning "-Waddress" }
+ T (a2[0] == 0); // { dg-warning "-Waddress" }
+ T (0 == &a1[0]); // { dg-warning "-Waddress" }
+ T (a2[i] == 0); // { dg-warning "-Waddress" }
+ T (0 == &a2[i]); // { dg-warning "-Waddress" }
+ T (a2[0][0] == 0);
+ T (0 == &a2[0][0]); // { dg-warning "-Waddress" }
+ T (&ax == 0); // { dg-warning "-Waddress" }
+ T (0 == &ax); // { dg-warning "-Waddress" }
+ T (&ax[0] == 0); // { dg-warning "-Waddress" }
+ T (0 == ax[0]);
+}
+
+
+void test_array_neq_0 (int i)
+{
+ // Verify that casts to intptr_t suppress the warning.
+ T ((uintptr_t)a1);
+
+ T (a1); // { dg-warning "-Waddress" }
+ T ((void *)a1); // { dg-warning "-Waddress" }
+ T (&a1 != 0); // { dg-warning "-Waddress" }
+ T (a1[0]);
+ T (&a1[0] != 0); // { dg-warning "-Waddress" }
+ T (a1[i]);
+ T (&a1[i] != 0); // { dg-warning "-Waddress" }
+
+ T ((intptr_t)a2);
+ T (a2); // { dg-warning "-Waddress" }
+ T ((void *)a2); // { dg-warning "-Waddress" }
+ T ((char *)a2); // { dg-warning "-Waddress" }
+ T (&a2 != 0); // { dg-warning "-Waddress" }
+ T (a2[0]); // { dg-warning "-Waddress" }
+ T (&a1[0] != 0); // { dg-warning "-Waddress" }
+ T (a2[i]); // { dg-warning "-Waddress" }
+ T (&a2[i] != 0); // { dg-warning "-Waddress" }
+ T (a2[0][0]);
+ T (&a2[0][0] != 0); // { dg-warning "-Waddress" }
+}
+
+
+void test_member_array_eq_0 (int i)
+{
+ // Verify that casts to intptr_t suppress the warning.
+ T ((intptr_t)s.a1 == 0);
+ T (s.a1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &a1); // { dg-warning "-Waddress" }
+ T (s.a1[0] == 0);
+ T ((void*)s.a1); // { dg-warning "-Waddress" }
+ T (0 == &a1[0]); // { dg-warning "-Waddress" }
+ T (s.a1[i] == 0);
+ T (0 == &a1[i]); // { dg-warning "-Waddress" }
+
+ T ((uintptr_t)s.a2 == 0);
+ T (s.a2 == 0); // { dg-warning "-Waddress" }
+ T (0 == &a2); // { dg-warning "-Waddress" }
+ T ((void *)s.a2 == 0);// { dg-warning "-Waddress" }
+ T (s.a2[0] == 0); // { dg-warning "-Waddress" }
+ T (0 == &a1[0]); // { dg-warning "-Waddress" }
+ T (s.a2[i] == 0); // { dg-warning "-Waddress" }
+ T (0 == &a2[i]); // { dg-warning "-Waddress" }
+ T (s.a2[0][0] == 0);
+ T (0 == &a2[0][0]); // { dg-warning "-Waddress" }
+}
+
+
+void test_member_array_neq_0 (int i)
+{
+ // Verify that casts to intptr_t suppress the warning.
+ T ((uintptr_t)s.a1);
+ T (s.a1); // { dg-warning "-Waddress" }
+ T (&s.a1 != 0); // { dg-warning "-Waddress" }
+ T ((void *)&s.a1[0]); // { dg-warning "-Waddress" }
+ T (s.a1[0]);
+ T (&s.a1[0] != 0); // { dg-warning "-Waddress" }
+ T (s.a1[i]);
+ T (&s.a1[i] != 0); // { dg-warning "-Waddress" }
+
+ T ((intptr_t)s.a2);
+ T (s.a2); // { dg-warning "-Waddress" }
+ T (&s.a2 != 0); // { dg-warning "-Waddress" }
+ T (s.a2[0]); // { dg-warning "-Waddress" }
+ T (&s.a1[0] != 0); // { dg-warning "-Waddress" }
+ T (s.a2[i]); // { dg-warning "-Waddress" }
+ T (&s.a2[i] != 0); // { dg-warning "-Waddress" }
+ T (s.a2[0][0]);
+ T (&s.a2[0][0] != 0); // { dg-warning "-Waddress" }
+}
diff --git a/gcc/testsuite/c-c++-common/Waddress-4.c b/gcc/testsuite/c-c++-common/Waddress-4.c
new file mode 100644
index 00000000000..7b32503f84e
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/Waddress-4.c
@@ -0,0 +1,106 @@
+/* PR c/102103 - missing warning comparing array address to null
+ { dg-do compile }
+ { dg-options "-Wall" } */
+
+typedef __INTPTR_TYPE__ intptr_t;
+typedef __INTPTR_TYPE__ uintptr_t;
+
+extern char *ax[], *a2[][2];
+
+void T (int);
+
+void test_ax_plus_eq_0 (int i)
+{
+ // Verify that casts to intptr_t suppress the warning.
+ T ((intptr_t)(ax + 0) == 0);
+ T ((uintptr_t)(ax + 1) == 0);
+
+ T (ax + 0 == 0); // { dg-warning "-Waddress" }
+ T (&ax[0] == 0); // { dg-warning "-Waddress" }
+ T (ax - 1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &ax[-1]); // { dg-warning "-Waddress" }
+ T ((void *)(&ax[0] + 2) == 0); // { dg-warning "-Waddress" }
+ T (&ax[0] + 2 == 0); // { dg-warning "-Waddress" }
+ T (ax + 3 == 0); // { dg-warning "-Waddress" }
+ T (0 == &ax[-4]); // { dg-warning "-Waddress" }
+ T (ax - i == 0); // { dg-warning "-Waddress" }
+ T (&ax[i] == 0); // { dg-warning "-Waddress" }
+ T (0 == &ax[1] + i); // { dg-warning "-Waddress" }
+}
+
+void test_a2_plus_eq_0 (int i)
+{
+ // Verify that casts to intptr_t suppress the warning.
+ T ((intptr_t)(a2 + 0) == 0);
+ T ((uintptr_t)(a2 + 1) == 0);
+
+ T (a2 + 0 == 0); // { dg-warning "-Waddress" }
+ // Verify that a cast to another pointer type doesn't suppress it.
+ T ((void*)(a2 + 0) == 0); // { dg-warning "-Waddress" }
+ T ((char*)a2 + 1 == 0); // { dg-warning "-Waddress" }
+ T (&a2[0] == 0); // { dg-warning "-Waddress" }
+ T (a2 - 1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &a2[-1]); // { dg-warning "-Waddress" }
+ T (a2 + 2 == 0); // { dg-warning "-Waddress" }
+ T (0 == &a2[-2]); // { dg-warning "-Waddress" }
+ T (a2 - i == 0); // { dg-warning "-Waddress" }
+ T (&a2[i] == 0); // { dg-warning "-Waddress" }
+}
+
+// Exercise a pointer.
+void test_p_plus_eq_0 (int *p, int i)
+{
+ /* P + 0 and equivalently &P[0] are invalid for a null P but they're
+ folded to p before the warning has a chance to trigger. */
+ T (p + 0 == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+ T (&p[0] == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+
+ T (p - 1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &p[-1]); // { dg-warning "-Waddress" }
+ T (p + 2 == 0); // { dg-warning "-Waddress" }
+ T (0 == &p[-2]); // { dg-warning "-Waddress" }
+ T (p - i == 0); // { dg-warning "-Waddress" }
+ T (&p[i] == 0); // { dg-warning "-Waddress" }
+}
+
+// Exercise pointer to array.
+void test_pa_plus_eq_0 (int (*p)[], int (*p2)[][2], int i)
+{
+ // The array pointer may be null.
+ T (*p == 0);
+ /* &**P is equivalent to *P and might be the result od macro expansion.
+ Verify it doesn't cause a warning. */
+ T (&**p == 0);
+
+ /* *P + 0 is invalid but folded to *P before the warning has a chance
+ to trigger. */
+ T (*p + 0 == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+
+ T (&(*p)[0] == 0); // { dg-warning "-Waddress" }
+ T (*p - 1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &(*p)[-1]); // { dg-warning "-Waddress" }
+ T (*p + 2 == 0); // { dg-warning "-Waddress" }
+ T (0 == &(*p)[-2]); // { dg-warning "-Waddress" }
+ T (*p - i == 0); // { dg-warning "-Waddress" }
+ T (&(*p)[i] == 0); // { dg-warning "-Waddress" }
+
+
+ /* Similar to the above but for a pointer to a two-dimensional array,
+ referring to the higher-level element (i.e., an array itself). */
+ T (*p2 == 0);
+ T (**p2 == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+ T (&**p2 == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+ T (&***p2 == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+ T (&**p2 == 0);
+
+ T (*p2 + 0 == 0); // { dg-warning "-Waddress" "pr??????" { xfail *-*-* } }
+ T (&(*p2)[0] == 0); // { dg-warning "-Waddress" }
+ T (&(*p2)[0][1] == 0); // { dg-warning "-Waddress" }
+ T (*p2 - 1 == 0); // { dg-warning "-Waddress" }
+ T (0 == &(*p2)[-1]); // { dg-warning "-Waddress" }
+ T (0 == &(*p2)[1][2]); // { dg-warning "-Waddress" }
+ T (*p2 + 2 == 0); // { dg-warning "-Waddress" }
+ T (0 == &(*p2)[-2]); // { dg-warning "-Waddress" }
+ T (*p2 - i == 0); // { dg-warning "-Waddress" }
+ T (&(*p2)[i] == 0); // { dg-warning "-Waddress" }
+}
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-array-ptr10.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-array-ptr10.C
index 5224bb14234..63295230d51 100644
--- a/gcc/testsuite/g++.dg/cpp0x/constexpr-array-ptr10.C
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-array-ptr10.C
@@ -85,8 +85,11 @@ extern __attribute__ ((weak)) int i;
constexpr int *p1 = &i + 1;
#pragma GCC diagnostic push
+// Suppress warning: ordered comparison of pointer with integer zero.
#pragma GCC diagnostic ignored "-Wextra"
-// Suppress warning: ordered comparison of pointer with integer zero
+// Also suppress -Waddress for comparisons of constant addresses to
+// to null.
+#pragma GCC diagnostic ignored "-Waddress"
constexpr bool b0 = p1; // { dg-error "not a constant expression" }
constexpr bool b1 = p1 == 0; // { dg-error "not a constant expression" }
diff --git a/gcc/testsuite/g++.dg/warn/Waddress-5.C b/gcc/testsuite/g++.dg/warn/Waddress-5.C
new file mode 100644
index 00000000000..3390cda563b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Waddress-5.C
@@ -0,0 +1,87 @@
+/* PR c/102103 - missing warning comparing array address to null
+ { dg-do compile }
+ { dg-options "-Wall" } */
+
+#if __cplusplus < 201103L
+# define nullptr __null
+#endif
+
+struct A
+{
+ void f ();
+ virtual void vf ();
+ virtual void pvf () = 0;
+
+ void sf ();
+
+ int *p;
+ int a[2];
+};
+
+void T (bool);
+
+void warn_memptr_if ()
+{
+ // Exercise warnings for addresses of nonstatic member functions.
+ if (&A::f == 0) // { dg-warning "-Waddress" }
+ T (0);
+
+ if (&A::vf) // { dg-warning "-Waddress" }
+ T (0);
+
+ if (&A::pvf != 0) // { dg-warning "-Waddress" }
+ T (0);
+
+ // Exercise warnings for addresses of static member functions.
+ if (&A::sf == 0) // { dg-warning "-Waddress" }
+ T (0);
+
+ if (&A::sf) // { dg-warning "-Waddress" }
+ T (0);
+
+ // Exercise warnings for addresses of nonstatic data members.
+ if (&A::p == 0) // { dg-warning "-Waddress" }
+ T (0);
+
+ if (&A::a == nullptr) // { dg-warning "-Waddress" }
+ T (0);
+}
+
+void warn_memptr_bool ()
+{
+ // Exercise warnings for addresses of nonstatic member functions.
+ T (&A::f == 0); // { dg-warning "-Waddress" }
+ T (&A::vf); // { dg-warning "-Waddress" }
+ T (&A::pvf != 0); // { dg-warning "-Waddress" }
+
+ // Exercise warnings for addresses of static member functions.
+ T (&A::sf == 0); // { dg-warning "-Waddress" }
+ T (&A::sf); // { dg-warning "-Waddress" }
+
+ // Exercise warnings for addresses of nonstatic data members.
+ T (&A::p == 0); // { dg-warning "-Waddress" }
+ T (&A::a == nullptr); // { dg-warning "-Waddress" }
+}
+
+
+// Verify that no warnings are issued for an uninstantiated template.
+
+template <int>
+struct B
+{
+ // This is why.
+ struct F { void* operator& () const { return 0; } } f;
+};
+
+template <int N>
+void nowarn_template ()
+{
+ T (&B<N>::f == 0);
+
+ /* Like in the case above, the address-of operator could be a member
+ of B<N>::vf that returns zero. */
+ T (&B<N>::vf);
+ T (&B<N>::pvf != 0);
+ T (&B<N>::p == 0);
+ T (&B<N>::a == 0);
+}
diff --git a/gcc/testsuite/g++.dg/warn/Waddress-6.C b/gcc/testsuite/g++.dg/warn/Waddress-6.C
new file mode 100644
index 00000000000..b4f6b4f4b52
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Waddress-6.C
@@ -0,0 +1,79 @@
+/* PR c/102103 - missing warning comparing array address to null
+ { dg-do compile }
+ Verify -Waddress for member arrays of structs and notes.
+ { dg-options "-Wall" } */
+
+#if __cplusplus < 201103L
+# define nullptr __null
+#endif
+
+void T (bool);
+
+struct A
+{
+ int n;
+ int ia[]; // { dg-message "'A::ia' declared here" }
+};
+
+struct B
+{
+ A a[3]; // { dg-message "'B::a' declared here" }
+};
+
+struct C
+{
+ B b[3]; // { dg-message "'C::b' declared here" }
+};
+
+struct D
+{
+ C c[3]; // { dg-message "'D::c' declared here" }
+};
+
+
+void test_waddress_1d ()
+{
+ D d[2]; // { dg-message "'d' declared here" }
+
+ T (d); // { dg-warning "address of 'd'" }
+ T (d == nullptr); // { dg-warning "address of 'd'" }
+ T (&d); // { dg-warning "address of 'd'" }
+ T (d->c); // { dg-warning "address of 'D::c'" }
+ T (d->c != nullptr); // { dg-warning "address of 'D::c'" }
+ T (d->c->b); // { dg-warning "address of 'C::b'" }
+ T (d->c[1].b->a); // { dg-warning "address of 'B::a'" }
+ T (d->c->b[2].a->ia); // { dg-warning "address of 'A::ia'" }
+
+ if (d->c->b[2].a[1].ia) // { dg-warning "address of 'A::ia'" }
+ T (0);
+
+ if (bool b = d->c->b[1].a) // { dg-warning "address of 'A::ia'" }
+ T (b);
+
+ /* The following is represented as a declaration of P followed
+ by an if statement and so it isn't diagnosed. It's not clear
+ that it should be since the pointer is then used.
+ void *p = d->c->b[2].a;
+ if (p) ...
+ */
+ if (void *p = d->c->b[2].a) // { dg-warning "address of 'A::ia'" "" { xfail *-*-* } }
+ T (p);
+}
+
+
+void test_waddress_2d (int i)
+{
+ D d[2][3]; // { dg-message "'d' declared here" }
+
+ T (d); // { dg-warning "address of 'd'" }
+ T (d == nullptr); // { dg-warning "address of 'd'" }
+ T (&d); // { dg-warning "address of 'd'" }
+ T (*d); // { dg-warning "address of 'd'" }
+ T (d[1] != nullptr); // { dg-warning "address of 'd'" }
+ T (&d[1]->c); // { dg-warning "address of 'D::c'" }
+ T (d[1]->c); // { dg-warning "address of 'D::c'" }
+ T (d[1]->c == nullptr); // { dg-warning "address of 'D::c'" }
+ T (d[i]->c[1].b); // { dg-warning "address of 'C::b'" }
+ T ((*(d + i))->c->b->a); // { dg-warning "address of 'B::a'" }
+ T (d[1][2].c->b->a->ia); // { dg-warning "address of 'A::ia'" }
+}
diff --git a/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C b/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C
index bfe14457547..fae8b7e766f 100644
--- a/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C
+++ b/gcc/testsuite/g++.dg/warn/Wreturn-local-addr-6.C
@@ -9,7 +9,7 @@ const intptr_t&
return_addr_label_as_intref (void)
{
label:
- if ((const intptr_t*)&&label == 0)
+ if ((const intptr_t)&&label == 0)
__builtin_exit (1);
return *(const intptr_t*)&&label; // { dg-warning "\\\[-Wreturn-local-addr]" } */
@@ -19,7 +19,7 @@ const intptr_t&
return_addr_local_as_intref (void)
{
int a[1];
- if ((const intptr_t*)a == 0)
+ if ((const intptr_t)a == 0)
__builtin_exit (1);
return (const intptr_t&)a; // { dg-warning "\\\[-Wreturn-local-addr]" } */
diff --git a/gcc/testsuite/gcc.dg/Waddress-3.c b/gcc/testsuite/gcc.dg/Waddress-3.c
new file mode 100644
index 00000000000..1bf0050b000
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Waddress-3.c
@@ -0,0 +1,36 @@
+/* PR c/102103 - missing warning comparing array address to null
+ { dg-do compile }
+ { dg-options "-Wall" } */
+
+typedef _Complex float Cflt;
+
+extern Cflt cf, cfa[], cfa2[][2];
+
+Cflt *pcf (void);
+
+void T (int);
+
+void test_complex (Cflt *p, int i)
+{
+ T (&__real__ cf == 0); // { dg-warning "-Waddress" }
+ T (&__imag__ cf == 0); // { dg-warning "-Waddress" }
+
+ T (0 != &__real__ cf); // { dg-warning "-Waddress" }
+ T (0 != &__imag__ cf); // { dg-warning "-Waddress" }
+
+ T (&__real__ cfa[0] == 0); // { dg-warning "-Waddress" }
+ T (&__imag__ cfa[1] == 0); // { dg-warning "-Waddress" }
+
+ T (0 != &__real__ cfa2[i][i]); // { dg-warning "-Waddress" }
+ T (0 != &__imag__ cfa2[i][i]); // { dg-warning "-Waddress" }
+
+ T (0 == &__real__ *p); // { dg-warning "-Waddress" }
+ T (0 == &__imag__ *p); // { dg-warning "-Waddress" }
+
+ T (0 == &__real__ p[i]); // { dg-warning "-Waddress" }
+ T (0 == &__imag__ p[i]); // { dg-warning "-Waddress" }
+
+ T (&__real__ *pcf () == 0); // { dg-warning "-Waddress" }
+ T (0 != &__imag__ *pcf ()); // { dg-warning "-Waddress" }
+}
+
diff --git a/gcc/testsuite/gcc.dg/Waddress.c b/gcc/testsuite/gcc.dg/Waddress.c
index 146b1a932df..b26e7b1f329 100644
--- a/gcc/testsuite/gcc.dg/Waddress.c
+++ b/gcc/testsuite/gcc.dg/Waddress.c
@@ -6,5 +6,5 @@ int
foo(void)
{
char a[1];
- return a == 0;
+ return a == 0; // { dg-warning "-Waddress" }
}
