diff mbox

[PATCHv2] New attribute designated_init: mark a struct as requiring designated init

Message ID 20091011185425.GA8688@feather (mailing list archive)
State Superseded, archived
Headers show

Commit Message

Josh Triplett Oct. 11, 2009, 6:54 p.m. UTC
None
diff mbox

Patch

diff --git a/evaluate.c b/evaluate.c
index 805ae90..28bfd7c 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2366,6 +2366,7 @@  static void handle_list_initializer(struct expression *expr,
 		int lclass;
 
 		if (e->type != EXPR_INDEX && e->type != EXPR_IDENTIFIER) {
+			struct symbol *struct_sym;
 			if (!top) {
 				top = e;
 				last = first_subobject(ctype, class, &top);
@@ -2378,6 +2379,15 @@  static void handle_list_initializer(struct expression *expr,
 				DELETE_CURRENT_PTR(e);
 				continue;
 			}
+			struct_sym = ctype->type == SYM_NODE ? ctype->ctype.base_type : ctype;
+			if (Wdesignated_init && struct_sym->designated_init)
+				warning(e->pos, "%s%.*s%spositional init of field in %s %s, declared with attribute designated_init",
+					ctype->ident ? "in initializer for " : "",
+					ctype->ident ? ctype->ident->len : 0,
+					ctype->ident ? ctype->ident->name : "",
+					ctype->ident ? ": " : "",
+					get_type_name(struct_sym->type),
+					show_ident(struct_sym->ident));
 			if (jumped) {
 				warning(e->pos, "advancing past deep designator");
 				jumped = 0;
diff --git a/lib.c b/lib.c
index 622b547..77a1c33 100644
--- a/lib.c
+++ b/lib.c
@@ -197,6 +197,7 @@  int Wcast_truncate = 1;
 int Wcontext = 1;
 int Wdecl = 1;
 int Wdefault_bitfield_sign = 0;
+int Wdesignated_init = 1;
 int Wdo_while = 0;
 int Wenum_mismatch = 1;
 int Wnon_pointer_null = 1;
@@ -378,6 +379,7 @@  static const struct warning {
 	{ "context", &Wcontext },
 	{ "decl", &Wdecl },
 	{ "default-bitfield-sign", &Wdefault_bitfield_sign },
+	{ "designated-init", &Wdesignated_init },
 	{ "do-while", &Wdo_while },
 	{ "enum-mismatch", &Wenum_mismatch },
 	{ "non-pointer-null", &Wnon_pointer_null },
diff --git a/lib.h b/lib.h
index 25abb80..3ced1bf 100644
--- a/lib.h
+++ b/lib.h
@@ -97,6 +97,7 @@  extern int Wcast_truncate;
 extern int Wcontext;
 extern int Wdecl;
 extern int Wdefault_bitfield_sign;
+extern int Wdesignated_init;
 extern int Wdo_while;
 extern int Wenum_mismatch;
 extern int Wnon_pointer_null;
diff --git a/parse.c b/parse.c
index 5e75242..03fa5d9 100644
--- a/parse.c
+++ b/parse.c
@@ -64,6 +64,7 @@  typedef struct token *attr_t(struct token *, struct symbol *,
 static attr_t
 	attribute_packed, attribute_aligned, attribute_modifier,
 	attribute_address_space, attribute_context,
+	attribute_designated_init,
 	attribute_transparent_union, ignore_attribute,
 	attribute_mode, attribute_force;
 
@@ -319,6 +320,10 @@  static struct symbol_op context_op = {
 	.attribute = attribute_context,
 };
 
+static struct symbol_op designated_init_op = {
+	.attribute = attribute_designated_init,
+};
+
 static struct symbol_op transparent_union_op = {
 	.attribute = attribute_transparent_union,
 };
@@ -453,6 +458,7 @@  static struct init_keyword {
 	{ "address_space",NS_KEYWORD,	.op = &address_space_op },
 	{ "mode",	NS_KEYWORD,	.op = &mode_op },
 	{ "context",	NS_KEYWORD,	.op = &context_op },
+	{ "designated_init",	NS_KEYWORD,	.op = &designated_init_op },
 	{ "__transparent_union__",	NS_KEYWORD,	.op = &transparent_union_op },
 
 	{ "__mode__",	NS_KEYWORD,	.op = &mode_op },
@@ -1127,6 +1133,15 @@  static struct token *attribute_context(struct token *token, struct symbol *attr,
 	return token;
 }
 
+static struct token *attribute_designated_init(struct token *token, struct symbol *attr, struct decl_state *ctx)
+{
+	if (ctx->ctype.base_type && ctx->ctype.base_type->type == SYM_STRUCT)
+		ctx->ctype.base_type->designated_init = 1;
+	else
+		warning(token->pos, "attribute designated_init applied to non-structure type");
+	return token;
+}
+
 static struct token *attribute_transparent_union(struct token *token, struct symbol *attr, struct decl_state *ctx)
 {
 	if (Wtransparent_union)
diff --git a/sparse.1 b/sparse.1
index d7fe444..1054712 100644
--- a/sparse.1
+++ b/sparse.1
@@ -134,6 +134,30 @@  explicitly.
 Sparse does not issue these warnings by default.
 .
 .TP
+.B \-Wdesignated\-init
+Warn about positional initialization of structs marked as requiring designated
+initializers.
+
+Sparse allows an attribute
+.BI __attribute__((designated_init))
+which marks a struct as requiring designated initializers.  Sparse will warn
+about positional initialization of a struct variable or struct literal of a
+type that has this attribute.
+
+Requiring designated initializers for a particular struct type will insulate
+code using that struct type from changes to the layout of the type, avoiding
+the need to change initializers for that type unless they initialize a removed
+or incompatibly changed field.
+
+Common examples of this type of struct include collections of function pointers
+for the implementations of a class of related operations, for which the default
+NULL for an unmentioned field in a designated initializer will correctly
+indicate the absence of that operation.
+
+Sparse issues these warnings by default.  To turn them off, use
+\fB\-Wno\-designated\-init\fR.
+.
+.TP
 .B \-Wdo\-while
 Warn about do-while loops that do not delimit the loop body with braces.
 
diff --git a/symbol.h b/symbol.h
index 60fdad0..83b3d4b 100644
--- a/symbol.h
+++ b/symbol.h
@@ -156,7 +156,8 @@  struct symbol {
 					examined:1,
 					expanding:1,
 					evaluated:1,
-					string:1;
+					string:1,
+					designated_init:1;
 			struct expression *array_size;
 			struct ctype ctype;
 			struct symbol_list *arguments;
diff --git a/validation/designated-init.c b/validation/designated-init.c
new file mode 100644
index 0000000..23423e9
--- /dev/null
+++ b/validation/designated-init.c
@@ -0,0 +1,195 @@ 
+struct s1 {
+	int x;
+	int y;
+};
+
+struct s2 {
+	int x;
+	int y;
+} __attribute__((designated_init));
+
+struct nest1 {
+	struct s1 s1;
+	struct s2 s2;
+};
+
+struct nest2 {
+	struct s1 s1;
+	struct s2 s2;
+} __attribute__((designated_init));
+
+static struct s1 s1_positional = { 5, 10 };
+static struct s1 s1_designated = { .x = 5, .y = 10 };
+static struct s2 s2_positional = { 5, 10 };
+static struct s2 s2_designated = { .x = 5, .y = 10 };
+static struct nest1 nest1_positional = {
+	{ 5, 10 },
+	{ 5, 10 },
+};
+static struct nest1 nest1_designated_outer = {
+	.s1 = { 5, 10 },
+	.s2 = { 5, 10 },
+};
+static struct nest1 nest1_designated_inner = {
+	{ .x = 5, .y = 10 },
+	{ .x = 5, .y = 10 },
+};
+static struct nest1 nest1_designated_both = {
+	.s1 = { .x = 5, .y = 10 },
+	.s2 = { .x = 5, .y = 10 },
+};
+static struct nest2 nest2_positional = {
+	{ 5, 10 },
+	{ 5, 10 },
+};
+static struct nest2 nest2_designated_outer = {
+	.s1 = { 5, 10 },
+	.s2 = { 5, 10 },
+};
+static struct nest2 nest2_designated_inner = {
+	{ .x = 5, .y = 10 },
+	{ .x = 5, .y = 10 },
+};
+static struct nest2 nest2_designated_both = {
+	.s1 = { .x = 5, .y = 10 },
+	.s2 = { .x = 5, .y = 10 },
+};
+
+static struct {
+	int x;
+	int y;
+} __attribute__((designated_init))
+	anon_positional = { 5, 10 },
+	anon_designated = { .x = 5, .y = 10};
+
+static struct s1 s1_array[] = {
+	{ 5, 10 },
+	{ .x = 5, .y = 10 },
+};
+
+static struct s2 s2_array[] = {
+	{ 5, 10 },
+	{ .x = 5, .y = 10 },
+};
+
+static struct s1 ret_s1_positional(void)
+{
+	return ((struct s1){ 5, 10 });
+}
+
+static struct s1 ret_s1_designated(void)
+{
+	return ((struct s1){ .x = 5, .y = 10 });
+}
+
+static struct s2 ret_s2_positional(void)
+{
+	return ((struct s2){ 5, 10 });
+}
+
+static struct s2 ret_s2_designated(void)
+{
+	return ((struct s2){ .x = 5, .y = 10 });
+}
+
+static struct nest1 ret_nest1_positional(void)
+{
+	return ((struct nest1){
+			{ 5, 10 },
+			{ 5, 10 },
+		});
+}
+
+static struct nest1 ret_nest1_designated_outer(void)
+{
+	return ((struct nest1){
+			.s1 = { 5, 10 },
+			.s2 = { 5, 10 },
+		});
+}
+
+static struct nest1 ret_nest1_designated_inner(void)
+{
+	return ((struct nest1){
+			{ .x = 5, .y = 10 },
+			{ .x = 5, .y = 10 },
+		});
+}
+
+static struct nest1 ret_nest1_designated_both(void)
+{
+	return ((struct nest1){
+			.s1 = { .x = 5, .y = 10 },
+			.s2 = { .x = 5, .y = 10 },
+		});
+}
+
+static struct nest2 ret_nest2_positional(void)
+{
+	return ((struct nest2){
+			{ 5, 10 },
+			{ 5, 10 },
+		});
+}
+
+static struct nest2 ret_nest2_designated_outer(void)
+{
+	return ((struct nest2){
+			.s1 = { 5, 10 },
+			.s2 = { 5, 10 },
+		});
+}
+
+static struct nest2 ret_nest2_designated_inner(void)
+{
+	return ((struct nest2){
+			{ .x = 5, .y = 10 },
+			{ .x = 5, .y = 10 },
+		});
+}
+
+static struct nest2 ret_nest2_designated_both(void)
+{
+	return ((struct nest2){
+			.s1 = { .x = 5, .y = 10 },
+			.s2 = { .x = 5, .y = 10 },
+		});
+}
+/*
+ * check-name: designated_init attribute
+ *
+ * check-error-start
+designated-init.c:23:36: warning: in initializer for s2_positional: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:23:39: warning: in initializer for s2_positional: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:27:11: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:27:14: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:31:17: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:31:20: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:42:9: warning: in initializer for nest2_positional: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:43:9: warning: in initializer for nest2_positional: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:43:11: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:43:14: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:47:17: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:47:20: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:50:9: warning: in initializer for nest2_designated_inner: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:51:9: warning: in initializer for nest2_designated_inner: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:62:29: warning: in initializer for anon_positional: positional init of field in struct <noident>, declared with attribute designated_init
+designated-init.c:62:32: warning: in initializer for anon_positional: positional init of field in struct <noident>, declared with attribute designated_init
+designated-init.c:71:11: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:71:14: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:87:30: warning: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:87:33: warning: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:99:27: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:99:30: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:107:33: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:107:36: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:130:25: warning: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:131:25: warning: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:131:27: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:131:30: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:139:33: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:139:36: warning: in initializer for s2: positional init of field in struct s2, declared with attribute designated_init
+designated-init.c:146:25: warning: positional init of field in struct nest2, declared with attribute designated_init
+designated-init.c:147:25: warning: positional init of field in struct nest2, declared with attribute designated_init
+ * check-error-end
+ */