On 30 May 2018 at 18:12, Jason Merrill <ja...@redhat.com> wrote:
> Hmm, why doesn't maybe_warn_zero_as_null_pointer_constant check
> null_node_p like it does NULLPTR_TYPE_P?
Now it does. This passes all the Wzero-as-null-pointer-constant tests in warn/
and cpp0x/, running full suite on Linux-PPC64. Ok for trunk if the tests
pass?
2018-05-30 Ville Voutilainen <ville.voutilai...@gmail.com>
gcc/cp/
Do not warn about zero-as-null when NULL is used.
* typeck.c (cp_build_binary_op): Diagnose zero as null here..
* call.c (conversion_null_warnings): ..and here..
* cvt.c (cp_convert_to_pointer): ..not here.
* tree.c (maybe_warn_zero_as_null_pointer_constant): Also
check null_node_p.
testsuite/
Do not warn about zero-as-null when NULL is used.
* g++.dg/warn/Wzero-as-null-pointer-constant-7.C: New.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 7aadd64..0c7e462 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6517,6 +6517,7 @@ build_temp (tree expr, tree type, int flags,
}
/* Perform warnings about peculiar, but valid, conversions from/to NULL.
+ Also handle a subset of zero as null warnings.
EXPR is implicitly converted to type TOTYPE.
FN and ARGNUM are used for diagnostics. */
@@ -6551,6 +6552,16 @@ conversion_null_warnings (tree totype, tree expr, tree fn, int argnum)
warning_at (input_location, OPT_Wconversion_null,
"converting %<false%> to pointer type %qT", totype);
}
+ /* Handle zero as null pointer warnings for cases other
+ than EQ_EXPR and NE_EXPR */
+ else if (null_ptr_cst_p (expr)
+ && (TYPE_PTRMEMFUNC_P (totype) || TYPE_PTRDATAMEM_P (totype)
+ || TYPE_PTR_P (totype)))
+ {
+ source_location loc =
+ expansion_point_location_if_in_system_header (input_location);
+ maybe_warn_zero_as_null_pointer_constant (expr, loc);
+ }
}
/* We gave a diagnostic during a conversion. If this was in the second
diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c
index f29dacd..e2f8579 100644
--- a/gcc/cp/cvt.c
+++ b/gcc/cp/cvt.c
@@ -208,9 +208,6 @@ cp_convert_to_pointer (tree type, tree expr, bool dofold,
return build_ptrmemfunc (TYPE_PTRMEMFUNC_FN_TYPE (type), expr, 0,
/*c_cast_p=*/false, complain);
- if (complain & tf_warning)
- maybe_warn_zero_as_null_pointer_constant (expr, loc);
-
/* A NULL pointer-to-data-member is represented by -1, not by
zero. */
tree val = (TYPE_PTRDATAMEM_P (type)
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index f21daac..332d51d 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -5423,7 +5423,7 @@ bool
maybe_warn_zero_as_null_pointer_constant (tree expr, location_t loc)
{
if (c_inhibit_evaluation_warnings == 0
- && !NULLPTR_TYPE_P (TREE_TYPE (expr)))
+ && !null_node_p (expr) && !NULLPTR_TYPE_P (TREE_TYPE (expr)))
{
warning_at (loc, OPT_Wzero_as_null_pointer_constant,
"zero as null pointer constant");
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 3df043e..d65b39f 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -4353,6 +4353,21 @@ cp_build_binary_op (location_t location,
warning_at (loc, OPT_Wpointer_arith, "NULL used in arithmetic");
}
+ /* Handle zero as null pointer warnings for pointer comparisons */
+ if (code == EQ_EXPR || code == NE_EXPR)
+ {
+ source_location loc =
+ expansion_point_location_if_in_system_header (input_location);
+ if ((TYPE_PTRMEMFUNC_P (type0) || TYPE_PTRDATAMEM_P (type0)
+ || TYPE_PTR_P (type0))
+ && null_ptr_cst_p (op1))
+ maybe_warn_zero_as_null_pointer_constant (op1, loc);
+ else if ((TYPE_PTRMEMFUNC_P (type1) || TYPE_PTRDATAMEM_P (type1)
+ || TYPE_PTR_P (type1))
+ && null_ptr_cst_p (op0))
+ maybe_warn_zero_as_null_pointer_constant (op0, loc);
+ }
+
/* In case when one of the operands of the binary operation is
a vector and another is a scalar -- convert scalar to vector. */
if ((code0 == VECTOR_TYPE) != (code1 == VECTOR_TYPE))
@@ -4833,9 +4848,6 @@ cp_build_binary_op (location_t location,
integer_one_node,
complain);
- if (complain & tf_warning)
- maybe_warn_zero_as_null_pointer_constant (op1, input_location);
-
e2 = cp_build_binary_op (location,
EQ_EXPR, e2, integer_zero_node,
complain);
diff --git a/gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C b/gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C
new file mode 100644
index 0000000..0d06dbf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wzero-as-null-pointer-constant-7.C
@@ -0,0 +1,13 @@
+// { dg-options "-Wzero-as-null-pointer-constant" }
+// { dg-do compile { target c++11 } }
+
+#include <cstddef>
+
+void test01()
+{
+ char* x(NULL);
+ char* x2{NULL};
+ char* x3 = NULL;
+ char* x4(0); // { dg-warning "zero as null pointer" }
+ char* x5 = 0; // { dg-warning "zero as null pointer" }
+}
