Hello,
This patch fixes fixes an erroneous -Wnonnull warning when calling a
constructor declared with __attribute__ ((nonnull (1))). The issue is
that a NULL pointer is used as the placeholder object for the "this"
parameter of the constructor method call until a target object is
determined and substituted for the placeholder object during
gimplification. Meanwhile, check_function_arguments is called in
build_over_call which notices that there is a NULL pointer argument for
a parameter that's been marked nonnull, thus issuing the -Wnonnull
warning.
This patch modifies the C++ frontend to use build_dummy_object() instead
of a NULL pointer as the placeholder object to a constructor method
call. This suppresses the warning issued by check_function_arguments
because the object returned by build_dummy_object() is not determined to
be a NULL pointer.
I bootstrapped and regtested this patch on x86_64-unknown-linux-gnu.
PR c++/60764
* call.c (build_user_type_coversion): Use build_dummy_object
to create the placeholder object for a constructor method call.
(build_special_member_call): Likewise.
(build_over_call): Check for the placeholder object with
is_dummy_object.
(build_new_method_call_1): Likewise. Don't attempt to resolve
a dummy object for a constructor method call.
---
gcc/cp/call.c | 14 +++++---------
gcc/testsuite/g++.dg/warn/nonnull2.C | 10 ++++++++++
2 files changed, 15 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/warn/nonnull2.C
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index ae0d4ff..ff5c834 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -3519,8 +3519,7 @@ build_user_type_conversion_1 (tree totype, tree expr, int
flags,
{
int ctorflags = flags;
- first_arg = build_int_cst (build_pointer_type (totype), 0);
- first_arg = build_fold_indirect_ref (first_arg);
+ first_arg = build_dummy_object (totype);
/* We should never try to call the abstract or base constructor
from here. */
@@ -7096,7 +7095,7 @@ build_over_call (struct z_candidate *cand, int flags,
tsubst_flags_t complain)
ctor is trivial, do a bitwise copy with a simple TARGET_EXPR for a
temp or an INIT_EXPR otherwise. */
fa = argarray[0];
- if (integer_zerop (fa))
+ if (is_dummy_object (fa))
{
if (TREE_CODE (arg) == TARGET_EXPR)
return arg;
@@ -7434,10 +7433,7 @@ build_special_member_call (tree instance, tree name,
vec<tree, va_gc> **args,
/* Handle the special case where INSTANCE is NULL_TREE. */
if (name == complete_ctor_identifier && !instance)
- {
- instance = build_int_cst (build_pointer_type (class_type), 0);
- instance = build1 (INDIRECT_REF, class_type, instance);
- }
+ instance = build_dummy_object (class_type);
else
{
if (name == complete_dtor_identifier
@@ -7747,8 +7743,7 @@ build_new_method_call_1 (tree instance, tree fns,
vec<tree, va_gc> **args,
if (init)
{
- if (INDIRECT_REF_P (instance)
- && integer_zerop (TREE_OPERAND (instance, 0)))
+ if (is_dummy_object (instance))
return get_target_expr_sfinae (init, complain);
init = build2 (INIT_EXPR, TREE_TYPE (instance), instance, init);
TREE_SIDE_EFFECTS (init) = true;
@@ -7847,6 +7842,7 @@ build_new_method_call_1 (tree instance, tree fns,
vec<tree, va_gc> **args,
}
if (TREE_CODE (TREE_TYPE (fn)) == METHOD_TYPE
+ && !DECL_CONSTRUCTOR_P (fn)
&& is_dummy_object (instance))
{
instance = maybe_resolve_dummy (instance);
diff --git a/gcc/testsuite/g++.dg/warn/nonnull2.C
b/gcc/testsuite/g++.dg/warn/nonnull2.C
new file mode 100644
index 0000000..10515a4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/nonnull2.C
@@ -0,0 +1,10 @@
+// PR c++/60764
+// { dg-options "-Wall" }
+
+struct foo
+{
+ foo () __attribute__ ((nonnull (1)));
+};
+
+const foo &x = foo (); // { dg-bogus "null argument" }
+foo y = foo (); // { dg-bogus "null argument" }
--
1.9.1
