[PATCH] Objective-C : Implement NSObject attribute.
Iain Sandoe
iain@sandoe.co.uk
Fri Nov 6 20:18:07 GMT 2020
Hi
Originally, I had this as a Darwin-only patch, however GNUStep
also makes use of NSObject and similar constructs, so this really
needs to be available to linux-gnu as well.
tested across several Darwin versions and on x86_64-linux-gnu.
OK for the c-family changes?
thanks
Iain
=====
This attribute allows pointers to be marked as pointers to
an NSObject-compatible object. This allows for additional
checking of assignment etc. when referring to pointers to
opaque types (or type-erased via a void * cast).
gcc/c-family/ChangeLog:
* c-attribs.c (handle_nsobject_attribute): New.
* c.opt: Add WNSObject-attribute.
gcc/objc/ChangeLog:
* objc-act.c (objc_compare_types): Handle NSObject type
attributes.
(objc_type_valid_for_messaging): Likewise.
gcc/testsuite/ChangeLog:
* obj-c++.dg/attributes/nsobject-01.mm: New test.
* objc.dg/attributes/nsobject-01.m: New test.
---
gcc/c-family/c-attribs.c | 39 +++++++++++
gcc/c-family/c.opt | 4 ++
gcc/objc/objc-act.c | 39 +++++++++--
.../obj-c++.dg/attributes/nsobject-01.mm | 66 +++++++++++++++++++
.../objc.dg/attributes/nsobject-01.m | 66 +++++++++++++++++++
5 files changed, 207 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/obj-c++.dg/attributes/nsobject-01.mm
create mode 100644 gcc/testsuite/objc.dg/attributes/nsobject-01.m
diff --git a/gcc/c-family/c-attribs.c b/gcc/c-family/c-attribs.c
index 65cba5074e5..f1680820ecd 100644
--- a/gcc/c-family/c-attribs.c
+++ b/gcc/c-family/c-attribs.c
@@ -157,6 +157,7 @@ static tree handle_designated_init_attribute (tree *, tree, tree, int, bool *);
static tree handle_patchable_function_entry_attribute (tree *, tree, tree,
int, bool *);
static tree handle_copy_attribute (tree *, tree, tree, int, bool *);
+static tree handle_nsobject_attribute (tree *, tree, tree, int, bool *);
/* Helper to define attribute exclusions. */
#define ATTR_EXCL(name, function, type, variable) \
@@ -509,6 +510,9 @@ const struct attribute_spec c_common_attribute_table[] =
handle_noinit_attribute, attr_noinit_exclusions },
{ "access", 1, 3, false, true, true, false,
handle_access_attribute, NULL },
+ /* Attributes used by Objective-C. */
+ { "NSObject", 0, 0, true, false, false, false,
+ handle_nsobject_attribute, NULL },
{ NULL, 0, 0, false, false, false, false, NULL, NULL }
};
@@ -5124,6 +5128,41 @@ handle_patchable_function_entry_attribute (tree *, tree name, tree args,
return NULL_TREE;
}
+/* Handle a "NSObject" attributes; arguments as in
+ struct attribute_spec.handler. */
+
+static tree
+handle_nsobject_attribute (tree *node, tree name, tree args,
+ int /*flags*/, bool *no_add_attrs)
+{
+ *no_add_attrs = true;
+
+ /* This attribute only applies to typedefs (or field decls for properties),
+ we drop it otherwise - but warn about this if enabled. */
+ if (TREE_CODE (*node) != TYPE_DECL && TREE_CODE (*node) != FIELD_DECL)
+ {
+ warning (OPT_WNSObject_attribute, "%qE attribute may be put on a"
+ " typedef only; attribute is ignored", name);
+ return NULL_TREE;
+ }
+
+ /* The original implementation only allowed pointers to records, however
+ recent implementations also allow void *. */
+ tree type = TREE_TYPE (*node);
+ if (!type || !POINTER_TYPE_P (type)
+ || (TREE_CODE (TREE_TYPE (type)) != RECORD_TYPE
+ && !VOID_TYPE_P (TREE_TYPE (type))))
+ {
+ error ("%qE attribute is for pointer types only", name);
+ return NULL_TREE;
+ }
+
+ tree t = tree_cons (name, args, TYPE_ATTRIBUTES (type));
+ TREE_TYPE (*node) = build_type_attribute_variant (type, t);
+
+ return NULL_TREE;
+}
+
/* Attempt to partially validate a single attribute ATTR as if
it were to be applied to an entity OPER. */
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index ebd07cc8059..fe16357db85 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -256,6 +256,10 @@ U
C ObjC C++ ObjC++ Joined Separate MissingArgError(macro name missing after %qs)
-U<macro> Undefine <macro>.
+WNSObject-attribute
+C ObjC C++ ObjC++ LTO Var(warn_nsobject_attribute) Warning Init(1)
+Warn if the NSObject attribute is applied to a non-typedef.
+
Wabi
C ObjC C++ ObjC++ LTO Var(warn_abi) Warning
Warn about things that will change when compiling with an ABI-compliant compiler.
diff --git a/gcc/objc/objc-act.c b/gcc/objc/objc-act.c
index 68d829fd773..8be4beadf3b 100644
--- a/gcc/objc/objc-act.c
+++ b/gcc/objc/objc-act.c
@@ -2476,9 +2476,14 @@ objc_compare_types (tree ltyp, tree rtyp, int argno, tree callee)
if (!POINTER_TYPE_P (ltyp) || !POINTER_TYPE_P (rtyp))
return false;
+ tree ltyp_attr, rtyp_attr;
do
{
- ltyp = TREE_TYPE (ltyp); /* Remove indirections. */
+ /* Remove indirections, but keep the type attributes from the innermost
+ pointer type, to check for NSObject. */
+ ltyp_attr = TYPE_ATTRIBUTES (ltyp);
+ ltyp = TREE_TYPE (ltyp);
+ rtyp_attr = TYPE_ATTRIBUTES (rtyp);
rtyp = TREE_TYPE (rtyp);
}
while (POINTER_TYPE_P (ltyp) && POINTER_TYPE_P (rtyp));
@@ -2523,17 +2528,23 @@ objc_compare_types (tree ltyp, tree rtyp, int argno, tree callee)
return true;
}
+ /* We might have void * with NSObject type attr. */
+ bool l_NSObject_p = ltyp_attr && lookup_attribute ("NSObject", ltyp_attr);
+ bool r_NSObject_p = rtyp_attr && lookup_attribute ("NSObject", rtyp_attr);
+
/* Past this point, we are only interested in ObjC class instances,
- or 'id' or 'Class'. */
- if (TREE_CODE (ltyp) != RECORD_TYPE || TREE_CODE (rtyp) != RECORD_TYPE)
+ or 'id' or 'Class' (except if the user applied the NSObject type
+ attribute). */
+ if ((TREE_CODE (ltyp) != RECORD_TYPE && !l_NSObject_p)
+ || (TREE_CODE (rtyp) != RECORD_TYPE && !r_NSObject_p))
return false;
if (!objc_is_object_id (ltyp) && !objc_is_class_id (ltyp)
- && !TYPE_HAS_OBJC_INFO (ltyp))
+ && !TYPE_HAS_OBJC_INFO (ltyp) && !l_NSObject_p)
return false;
if (!objc_is_object_id (rtyp) && !objc_is_class_id (rtyp)
- && !TYPE_HAS_OBJC_INFO (rtyp))
+ && !TYPE_HAS_OBJC_INFO (rtyp) && !r_NSObject_p)
return false;
/* Past this point, we are committed to returning 'true' to the caller
@@ -2567,12 +2578,15 @@ objc_compare_types (tree ltyp, tree rtyp, int argno, tree callee)
rcls = NULL_TREE;
/* If either type is an unqualified 'id', we're done. This is because
- an 'id' can be assigned to or from any type with no warnings. */
+ an 'id' can be assigned to or from any type with no warnings. When
+ the pointer has NSObject attribute, consider that to be equivalent. */
if (argno != -5)
{
if ((!lproto && objc_is_object_id (ltyp))
|| (!rproto && objc_is_object_id (rtyp)))
return true;
+ if (l_NSObject_p || r_NSObject_p)
+ return true;
}
else
{
@@ -2580,7 +2594,7 @@ objc_compare_types (tree ltyp, tree rtyp, int argno, tree callee)
general type of object, hence if you try to specialize an
'NSArray *' (ltyp) property with an 'id' (rtyp) one, we need
to warn. */
- if (!lproto && objc_is_object_id (ltyp))
+ if (!lproto && (objc_is_object_id (ltyp) || l_NSObject_p))
return true;
}
@@ -8659,11 +8673,19 @@ objc_type_valid_for_messaging (tree type, bool accept_classes)
if (!POINTER_TYPE_P (type))
return false;
+ /* We will check for an NSObject type attribute on the pointer if other
+ tests fail. */
+ tree type_attr = TYPE_ATTRIBUTES (type);
+
/* Remove the pointer indirection; don't remove more than one
otherwise we'd consider "NSObject **" a valid type for messaging,
which it isn't. */
type = TREE_TYPE (type);
+ /* We allow void * to have an NSObject type attr. */
+ if (VOID_TYPE_P (type) && type_attr)
+ return lookup_attribute ("NSObject", type_attr) != NULL_TREE;
+
if (TREE_CODE (type) != RECORD_TYPE)
return false;
@@ -8676,6 +8698,9 @@ objc_type_valid_for_messaging (tree type, bool accept_classes)
if (TYPE_HAS_OBJC_INFO (type))
return true;
+ if (type_attr)
+ return lookup_attribute ("NSObject", type_attr) != NULL_TREE;
+
return false;
}
diff --git a/gcc/testsuite/obj-c++.dg/attributes/nsobject-01.mm b/gcc/testsuite/obj-c++.dg/attributes/nsobject-01.mm
new file mode 100644
index 00000000000..498fbc7e8fd
--- /dev/null
+++ b/gcc/testsuite/obj-c++.dg/attributes/nsobject-01.mm
@@ -0,0 +1,66 @@
+/* Test handling of the NSObject attribute. */
+/* { dg-additional-options "-fsyntax-only " } */
+
+typedef struct AnObj * __attribute__ ((NSObject)) AnObjRef;
+typedef struct AnObj * __attribute__ ((__NSObject__)) AnotherObjRef;
+
+/* We allow a void * to be labeled as NSObject. */
+typedef void * __attribute__((NSObject)) AnonRef;
+
+typedef struct AnObj * __attribute__((NSObject("foo"))) Bad; // { dg-error {wrong number of arguments specified for 'NSObject' attribute} }
+typedef struct AnObj * __attribute__((NSObject(42))) Wrong; // { dg-error {wrong number of arguments specified for 'NSObject' attribute} }
+
+/* Must be a pointer. */
+typedef struct AnObj __attribute__((NSObject)) BadRef; // { dg-error {'NSObject' attribute is for pointer types only} }
+
+typedef void * VPtr;
+
+@interface CheckAttrNSObject
+{
+@public
+ AnObjRef aor;
+ /* TODO: synthesize without pre-defined ivars. */
+ VPtr obj_v;
+ int bar;
+ /* TODO: This should warn, even tho the property does not */
+ __attribute__((NSObject)) struct AnObj *Thing;
+}
+
+@property(copy) AnObjRef aor;
+
+typedef struct AnObj * __attribute__((NSObject)) AnObjPtr3;
+@property (nonatomic, retain) AnObjPtr3 obj_3;
+
+@property (retain) __attribute__((NSObject)) VPtr obj_v;
+
+//@property (strong, nullable) AnObjPtr3 objp_4;
+
+@property(retain) __attribute__((NSObject)) int bar;
+ // { dg-error {'NSObject' attribute is for pointer types only} "" { target *-*-* } .-1 }
+ // { dg-error {'retain' attribute is only valid for Objective-C objects} "" { target *-*-* } .-2 }
+
+@end
+
+void foo ()
+{
+ __attribute__((NSObject)) struct AnObj *AnotherThing; // { dg-warning {'NSObject' attribute may be put on a typedef only; attribute is ignored} }
+}
+
+void
+setProperty(id self, id value)
+{
+ ((CheckAttrNSObject *)self)->aor = value;
+}
+
+id
+getProperty(id self)
+{
+ return (id)((CheckAttrNSObject *)self)->aor;
+}
+
+@implementation CheckAttrNSObject
+@synthesize aor;
+@dynamic obj_3;
+@synthesize obj_v;
+@synthesize bar;
+@end // { dg-error {invalid conversion} }
diff --git a/gcc/testsuite/objc.dg/attributes/nsobject-01.m b/gcc/testsuite/objc.dg/attributes/nsobject-01.m
new file mode 100644
index 00000000000..5b568490391
--- /dev/null
+++ b/gcc/testsuite/objc.dg/attributes/nsobject-01.m
@@ -0,0 +1,66 @@
+/* Test handling of the NSObject attribute. */
+/* { dg-additional-options "-fsyntax-only " } */
+
+typedef struct AnObj * __attribute__ ((NSObject)) AnObjRef;
+typedef struct AnObj * __attribute__ ((__NSObject__)) AnotherObjRef;
+
+/* We allow a void * to be labeled as NSObject. */
+typedef void * __attribute__((NSObject)) AnonRef;
+
+typedef struct AnObj * __attribute__((NSObject("foo"))) Bad; // { dg-error {wrong number of arguments specified for 'NSObject' attribute} }
+typedef struct AnObj * __attribute__((NSObject(42))) Wrong; // { dg-error {wrong number of arguments specified for 'NSObject' attribute} }
+
+/* Must be a pointer. */
+typedef struct AnObj __attribute__((NSObject)) BadRef; // { dg-error {'NSObject' attribute is for pointer types only} }
+
+typedef void * VPtr;
+
+@interface CheckAttrNSObject
+{
+@public
+ AnObjRef aor;
+ /* TODO: synthesize without pre-defined ivars. */
+ VPtr obj_v;
+ int bar;
+ /* TODO: This should warn, even tho the property does not */
+ __attribute__((NSObject)) struct AnObj *Thing;
+}
+
+@property(copy) AnObjRef aor;
+
+typedef struct AnObj * __attribute__((NSObject)) AnObjPtr3;
+@property (nonatomic, retain) AnObjPtr3 obj_3;
+
+@property (retain) __attribute__((NSObject)) VPtr obj_v;
+
+//@property (strong, nullable) AnObjPtr3 objp_4;
+
+@property(retain) __attribute__((NSObject)) int bar;
+ // { dg-error {'NSObject' attribute is for pointer types only} "" { target *-*-* } .-1 }
+ // { dg-error {'retain' attribute is only valid for Objective-C objects} "" { target *-*-* } .-2 }
+
+@end
+
+void foo ()
+{
+ __attribute__((NSObject)) struct AnObj *AnotherThing; // { dg-warning {'NSObject' attribute may be put on a typedef only; attribute is ignored} }
+}
+
+void
+setProperty(id self, id value)
+{
+ ((CheckAttrNSObject *)self)->aor = value;
+}
+
+id
+getProperty(id self)
+{
+ return (id)((CheckAttrNSObject *)self)->aor;
+}
+
+@implementation CheckAttrNSObject
+@synthesize aor;
+@dynamic obj_3;
+@synthesize obj_v;
+@synthesize bar; // { dg-warning {returning 'id' from a function with return type 'int'} }
+@end // { dg-warning {passing argument} }
--
2.24.1
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