c23: tag compatibility rules for struct and unions

Implement redeclaration and compatibility rules for
structures and unions in C23.

gcc/c/:
	* c-decl.cc (previous_tag): New function.
	(parser_xref_tag): Find earlier definition.
	(get_parm_info): Turn off warning for C23.
	(start_struct): Allow redefinitons.
	(finish_struct): Diagnose conflicts.
	* c-tree.h (comptypes_same_p): Add prototype.
	* c-typeck.cc (comptypes_same_p): New function.
	(comptypes_internal): Activate comparison of tagged types.
	(convert_for_assignment): Ignore qualifiers.
	(digest_init): Add error.
	(initialized_elementwise_p): Allow compatible types.

gcc/testsuite/:
	* gcc.dg/c23-enum-7.c: Remove warning.
	* gcc.dg/c23-tag-1.c: New test.
	* gcc.dg/c23-tag-2.c: New deactivated test.
	* gcc.dg/c23-tag-3.c: New test.
	* gcc.dg/c23-tag-4.c: New test.
	* gcc.dg/c23-tag-5.c: New deactivated test.
	* gcc.dg/c23-tag-6.c: New test.
	* gcc.dg/c23-tag-7.c: New test.
	* gcc.dg/c23-tag-8.c: New test.
	* gcc.dg/gnu23-tag-1.c: New test.
	* gcc.dg/gnu23-tag-2.c: New test.
	* gcc.dg/gnu23-tag-3.c: New test.
	* gcc.dg/gnu23-tag-4.c: New test.
	* gcc.dg/pr112488-2.c: Remove warning.
This commit is contained in:
Martin Uecker 2023-08-15 14:58:32 +02:00
parent 514ea1df44
commit 23fee88f84
17 changed files with 454 additions and 17 deletions

View file

@ -2037,6 +2037,28 @@ locate_old_decl (tree decl)
decl, TREE_TYPE (decl));
}
/* Helper function. For a tagged type, it finds the declaration
for a visible tag declared in the the same scope if such a
declaration exists. */
static tree
previous_tag (tree type)
{
struct c_binding *b = NULL;
tree name = TYPE_NAME (type);
if (name)
b = I_TAG_BINDING (name);
if (b)
b = b->shadowed;
if (b && B_IN_CURRENT_SCOPE (b))
return b->decl;
return NULL_TREE;
}
/* Subroutine of duplicate_decls. Compare NEWDECL to OLDDECL.
Returns true if the caller should proceed to merge the two, false
if OLDDECL should simply be discarded. As a side effect, issues
@ -8573,11 +8595,14 @@ get_parm_info (bool ellipsis, tree expr)
if (TREE_CODE (decl) != UNION_TYPE || b->id != NULL_TREE)
{
if (b->id)
{
/* The %s will be one of 'struct', 'union', or 'enum'. */
if (!flag_isoc23)
warning_at (b->locus, 0,
"%<%s %E%> declared inside parameter list"
" will not be visible outside of this definition or"
" declaration", keyword, b->id);
}
else
/* The %s will be one of 'struct', 'union', or 'enum'. */
warning_at (b->locus, 0,
@ -8668,6 +8693,16 @@ parser_xref_tag (location_t loc, enum tree_code code, tree name,
present, only a definition in the current scope is relevant. */
ref = lookup_tag (code, name, has_enum_type_specifier, &refloc);
/* If the visble type is still being defined, see if there is
an earlier definition (which may be complete). */
if (flag_isoc23 && ref && C_TYPE_BEING_DEFINED (ref))
{
tree vis = previous_tag (ref);
if (vis)
ref = vis;
}
/* If this is the right type of tag, return what we found.
(This reference will be shadowed by shadow_tag later if appropriate.)
If this is the wrong type of tag, do not return it. If it was the
@ -8782,6 +8817,14 @@ start_struct (location_t loc, enum tree_code code, tree name,
if (name != NULL_TREE)
ref = lookup_tag (code, name, true, &refloc);
/* For C23, even if we already have a completed definition,
we do not use it. We will check for consistency later.
If we are in a nested redefinition the type is not
complete. We will then detect this below. */
if (flag_isoc23 && ref && TYPE_SIZE (ref))
ref = NULL_TREE;
if (ref && TREE_CODE (ref) == code)
{
if (TYPE_STUB_DECL (ref))
@ -9581,6 +9624,25 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes,
warning_at (loc, 0, "union cannot be made transparent");
}
/* Check for consistency with previous definition. */
if (flag_isoc23)
{
tree vistype = previous_tag (t);
if (vistype
&& TREE_CODE (vistype) == TREE_CODE (t)
&& !C_TYPE_BEING_DEFINED (vistype))
{
TYPE_STUB_DECL (vistype) = TYPE_STUB_DECL (t);
if (c_type_variably_modified_p (t))
error ("redefinition of struct or union %qT with variably "
"modified type", t);
else if (!comptypes_same_p (t, vistype))
error ("redefinition of struct or union %qT", t);
}
}
C_TYPE_BEING_DEFINED (t) = 0;
tree incomplete_vars = C_TYPE_INCOMPLETE_VARS (TYPE_MAIN_VARIANT (t));
for (x = TYPE_MAIN_VARIANT (t); x; x = TYPE_NEXT_VARIANT (x))
{

View file

@ -757,6 +757,7 @@ extern tree c_objc_common_truthvalue_conversion (location_t, tree);
extern tree require_complete_type (location_t, tree);
extern bool same_translation_unit_p (const_tree, const_tree);
extern int comptypes (tree, tree);
extern bool comptypes_same_p (tree, tree);
extern int comptypes_check_different_types (tree, tree, bool *);
extern int comptypes_check_enum_int (tree, tree, bool *);
extern bool c_mark_addressable (tree, bool = false);

View file

@ -1080,6 +1080,23 @@ comptypes (tree type1, tree type2)
return ret ? (data.warning_needed ? 2 : 1) : 0;
}
/* Like comptypes, but it returns non-zero only for identical
types. */
bool
comptypes_same_p (tree type1, tree type2)
{
struct comptypes_data data = { };
bool ret = comptypes_internal (type1, type2, &data);
if (data.different_types_p)
return false;
return ret;
}
/* Like comptypes, but if it returns non-zero because enum and int are
compatible, it sets *ENUM_AND_INT_P to true. */
@ -1266,12 +1283,12 @@ comptypes_internal (const_tree type1, const_tree type2,
case ENUMERAL_TYPE:
case RECORD_TYPE:
case UNION_TYPE:
if (false)
{
return tagged_types_tu_compatible_p (t1, t2, data);
}
if (!flag_isoc23)
return false;
return tagged_types_tu_compatible_p (t1, t2, data);
case VECTOR_TYPE:
return known_eq (TYPE_VECTOR_SUBPARTS (t1), TYPE_VECTOR_SUBPARTS (t2))
&& comptypes_internal (TREE_TYPE (t1), TREE_TYPE (t2), data);
@ -7102,7 +7119,7 @@ convert_for_assignment (location_t location, location_t expr_loc, tree type,
/* Aggregates in different TUs might need conversion. */
if ((codel == RECORD_TYPE || codel == UNION_TYPE)
&& codel == coder
&& comptypes (type, rhstype))
&& comptypes (TYPE_MAIN_VARIANT (type), TYPE_MAIN_VARIANT (rhstype)))
return convert_and_check (expr_loc != UNKNOWN_LOCATION
? expr_loc : location, type, rhs);
@ -8457,6 +8474,13 @@ digest_init (location_t init_loc, tree type, tree init, tree origtype,
conversion. */
inside_init = convert (type, inside_init);
if ((code == RECORD_TYPE || code == UNION_TYPE)
&& !comptypes (TYPE_MAIN_VARIANT (type), TYPE_MAIN_VARIANT (TREE_TYPE (inside_init))))
{
error_init (init_loc, "invalid initializer");
return error_mark_node;
}
if (require_constant
&& TREE_CODE (inside_init) == COMPOUND_LITERAL_EXPR)
{
@ -10542,7 +10566,7 @@ initialize_elementwise_p (tree type, tree value)
return !VECTOR_TYPE_P (value_type);
if (AGGREGATE_TYPE_P (type))
return type != TYPE_MAIN_VARIANT (value_type);
return !comptypes (type, TYPE_MAIN_VARIANT (value_type));
return false;
}

View file

@ -26,17 +26,15 @@ enum e13 : short x13; /* { dg-error "'enum' underlying type may not be specified
enum e14 : short f14 (); /* { dg-error "'enum' underlying type may not be specified here" } */
typeof (enum e15 : long) x15; /* { dg-error "'enum' underlying type may not be specified here" } */
int f16 (enum e16 : char p); /* { dg-error "'enum' underlying type may not be specified here" } */
/* { dg-warning "will not be visible outside of this definition or declaration" "warning" { target *-*-* } .-1 } */
int f17 (enum e17 : char); /* { dg-error "'enum' underlying type may not be specified here" } */
/* { dg-warning "will not be visible outside of this definition or declaration" "warning" { target *-*-* } .-1 } */
struct s18 { enum e18 : int x; }; /* { dg-error "'enum' underlying type may not be specified here" } */
/* But those are OK if the enum content is defined. */
enum e19 : short { E19 } x19;
enum e20 : long { E20 } f20 ();
typeof (enum e21 : long { E21 }) x21;
int f22 (enum e22 : long long { E22 } p); /* { dg-warning "will not be visible outside of this definition or declaration" } */
int f23 (enum e23 : long long { E23 } p); /* { dg-warning "will not be visible outside of this definition or declaration" } */
int f22 (enum e22 : long long { E22 } p);
int f23 (enum e23 : long long { E23 } p);
struct s24 { enum e24 : int { E24 } x; };
/* Incompatible kinds of tags in the same scope are errors. */

View file

@ -0,0 +1,67 @@
/*
* { dg-do compile }
* { dg-options "-std=c23" }
*/
// allowed and forbidden redefinitions of the same struct/union in the same scope
typedef struct p { int a; } pd_t;
typedef struct p { int a; } pd_t;
typedef struct bar { int x; } X;
typedef struct bar { float x; } Y; /* { dg-error "redefinition of struct or union" } */
void test(void)
{
struct foo { int x; };
struct foo { float x; }; /* { dg-error "redefinition of struct or union" } */
}
struct aa { int a; };
void f(void)
{
typedef struct aa A;
struct bb { struct aa a; } x;
struct aa { int a; };
typedef struct aa A; /* { dg-error "redefinition" } */
struct bb { struct aa a; } y; /* { dg-error "redefinition of struct or union" } */
(void)x; (void)y;
}
void h(void)
{
struct a2 { int a; };
{
typedef struct a2 A;
struct b2 { struct a2 a; } x;
struct a2 { int a; };
typedef struct a2 A; /* { dg-error "redefinition" } */
struct b2 { struct a2 a; } y; /* { dg-error "redefinition of struct or union" } */
(void)x; (void)y;
}
}
union cc { int x; float y; } z;
union cc { int x; float y; } z1;
union cc { float y; int x; } z2; /* { dg-error "redefinition of struct or union" } */
void g(void)
{
struct s { int a; };
struct s { int a; } x0;
struct p { struct s c; } y1 = { x0 };
struct p { struct s { int a; } c; } y = { x0 };
}
struct q { struct { int a; }; };
struct q { struct { int a; }; };
struct q { int a; }; /* { dg-error "redefinition of struct or union" } */
struct r { int a; char b[]; };
struct r { int a; char b[]; };
struct r { int a; char b[1]; }; /* { dg-error "redefinition of struct or union" } */

View file

@ -0,0 +1,43 @@
/* { dg-do compile { target { ! "*-*-*" } } }
* { dg-options "-std=c23" }
*/
// compatibility of structs in assignment
typedef struct p { int a; } pd_t;
void test1(void)
{
pd_t y0;
struct p { int a; } x;
y0 = x;
}
void test2(void)
{
struct p { int a; } x;
struct p y0 = x;
}
void test3(void)
{
struct p { int a; } x;
pd_t y0 = x;
}
typedef struct p { int a; } p2_t;
void test4(void)
{
p2_t x;
pd_t y0 = x;
}
void test5(void)
{
struct q { int a; } a;
struct q { int a; } b;
a = b;
}

View file

@ -0,0 +1,16 @@
/*
* { dg-do compile }
* { dg-options "-std=c23" }
*/
// conflicting types via linkage
extern struct foo { int x; } x;
extern struct bar { float x; } y;
void test(void)
{
extern struct foo { int x; } x;
extern struct bar { int x; } y; /* { dg-error "conflicting types" } */
}

View file

@ -0,0 +1,26 @@
/*
* { dg-do compile }
* { dg-options "-std=c23" }
*/
// conflicting types for anonymous structs / unions
extern struct { int x; } a;
extern struct { int x; } a; /* { dg-error "conflicting types" } */
extern union { int x; } b;
extern union { int x; } b; /* { dg-error "conflicting types" } */
typedef struct { int x; } u;
typedef struct { int x; } v;
u c;
v c; /* { dg-error "conflicting types" } */
typedef union { int x; } q;
typedef union { int x; } r;
q d;
r d; /* { dg-error "conflicting types" } */

View file

@ -0,0 +1,33 @@
/* { dg-do run { target { ! "*-*-*" } } }
* { dg-options "-std=c23 -fpermissive" }
*/
// nesting and parameters
#define product_type(T, A, B) \
struct product_ ## T { A a ; B b ; }
#define sum_type(T, A, B) \
struct sum_ ## T { _Bool flag ; union { A a ; B b ; }; }
float foo1(product_type(iSfd_, int, sum_type(fd, float, double)) x)
{
return x.b.a;
}
static void test1(void)
{
product_type(iSfd_, int, sum_type(fd, float, double)) y = { 3, { 1, { .a = 1. } } };
product_type(iSfd_, int, sum_type(fd, float, double)) z = y;
product_type(iSfd_, int, sum_type(fd, float, double)) *zp = &y;
float a = foo1(y);
product_type(iSid_, int, sum_type(id, int, double)) *wp = &y; /* { dg-warning "incompatible pointer type" } */
float b = foo1(y);
product_type(iSid_, int, sum_type(id, int, double)) w = *wp;
(void)a; (void)b; (void)z; (void)zp; (void)w; (void)wp;
}
int main()
{
test1();
}

View file

@ -0,0 +1,58 @@
/*
* { dg-do compile }
* { dg-options "-std=c23" }
*/
// (in-)completeness
struct foo {
char x[10];
} x;
// complete, same type
struct foo {
_Static_assert(_Generic(&x, struct foo*: 1, default: 0));
char x[_Generic(&x, struct foo*: 10, default: 1)];
_Static_assert(_Generic(0, struct foo: 0, default: 1));
};
// incomplete, same type
struct bar* p;
struct bar {
_Static_assert(_Generic(p, struct bar*: 1, default: 0));
char x[_Generic(p, struct bar*: 10, default: 1)];
_Static_assert(_Generic(0, struct bar: 0, default: 1)); /* { dg-error "incomplete type" } */
};
struct bar {
char x[10];
};
struct h *hp;
void f(void)
{
// again incomplete, different type
struct foo {
char x[_Generic(&x, struct foo*: 1, default: 10)];
_Static_assert(_Generic(0, struct foo: 0, default: 1)); /* { dg-error "incomplete type" } */
};
struct foo z;
_Static_assert(10 == sizeof(z.x), "");
// still incomplete, different type
struct h {
char x[_Generic(hp, struct h*: 1, default: 10)];
_Static_assert(_Generic(0, struct h: 0, default: 1)); /* { dg-error "incomplete type" } */
};
struct h y;
_Static_assert(10 == sizeof(y.x), "");
}

View file

@ -0,0 +1,12 @@
/*
* { dg-do compile }
* { dg-options "-std=c23" }
*/
// recursive declarations
extern struct bar { struct bar* p; int x; } b;
extern struct bar { struct bar* p; int x; } b;
struct foo { struct foo { struct foo* p; int x; }* p; int x; } a; /* { dg-error "nested" } */

View file

@ -0,0 +1,10 @@
/* { dg-do compile }
{ dg-options "-std=c23" } */
void foo(void)
{
struct bar { struct bar* next; };
struct bar { struct bar* next; };
struct bar { struct bar { struct bar* next; }* next; }; /* { dg-error "nested" } */
}

View file

@ -0,0 +1,10 @@
/*
* { dg-do compile }
* { dg-options "-std=gnu23" }
*/
struct r { int a; char b[]; };
struct r { int a; char b[0]; }; /* allowed GNU extension */
struct r { int a; char b[1]; }; /* { dg-error "redefinition of struct or union" } */

View file

@ -0,0 +1,18 @@
/*
* { dg-do compile }
* { dg-options "-std=gnu23" }
*/
// conflicting attributes
extern struct [[gnu::transaction_safe]] foo { int x; } x;
extern struct [[gnu::unused]] foo2 { int x; } x2;
extern struct [[gnu::may_alias]] foo3 { int x; } x3;
void test()
{
extern struct foo { int x; } x; /* { dg-error "conflicting types" } */
extern struct foo2 { int x; } x2;
extern struct foo3 { int x; } x3;
}

View file

@ -0,0 +1,28 @@
/*
* { dg-do compile }
* { dg-options "-Wno-vla -std=gnu23" }
*/
// arrays in structs
void foo(int n, int m)
{
struct f { int b; int a[n]; };
struct f { int b; int a[n]; }; /* { dg-error "redefinition of struct or union" } */
struct f { int b; int a[m]; }; /* { dg-error "redefinition of struct or union" } */
struct f { int b; int a[5]; }; /* { dg-error "redefinition of struct or union" } */
struct f { int b; int a[]; }; /* { dg-error "redefinition of struct or union" } */
struct g { int a[n]; int b; };
struct g { int a[n]; int b; }; /* { dg-error "redefinition of struct or union" } */
struct g { int a[m]; int b; }; /* { dg-error "redefinition of struct or union" } */
struct g { int a[4]; int b; }; /* { dg-error "redefinition of struct or union" } */
struct h { int (*a)[n]; int b; };
struct h { int (*a)[n]; int b; }; /* { dg-error "redefinition of struct or union" } */
struct h { int (*a)[m]; int b; }; /* { dg-error "redefinition of struct or union" } */
struct h { int (*a)[4]; int b; }; /* { dg-error "redefinition of struct or union" } */
struct h { int (*a)[]; int b; }; /* { dg-error "redefinition of struct or union" } */
}

View file

@ -0,0 +1,31 @@
/* { dg-do compile }
* { dg-options "-std=gnu23" } */
// structs with variably modified types
void bar(int n, int m)
{
struct f { int b; int a[n]; } *x;
{ struct f { int b; int a[n]; } *x2 = x; }
{ struct f { int b; int a[m]; } *x2 = x; }
{ struct f { int b; int a[5]; } *x2 = x; }
{ struct f { int b; int a[0]; } *x2 = x; }
{ struct f { int b; int a[]; } *x2 = x; }
struct g { int a[n]; int b; } *y;
{ struct g { int a[n]; int b; } *y2 = y; }
{ struct g { int a[m]; int b; } *y2 = y; }
{ struct g { int a[4]; int b; } *y2 = y; }
struct h { int b; int a[5]; } *w;
{ struct h { int b; int a[5]; } *w2 = w; }
{ struct h { int b; int a[n]; } *w2 = w; }
{ struct h { int b; int a[m]; } *w2 = w; }
struct i { int b; int (*a)(int c[n]); } *u;
{ struct i { int b; int (*a)(int c[4]); } *u2 = u; }
{ struct i { int b; int (*a)(int c[]); } *u2 = u; }
{ struct i { int b; int (*a)(int c[*]); } *u2 = u; }
}

View file

@ -3,7 +3,7 @@
extern void abort(void);
int test(int *n, struct T { char a[*n], b[*n]; }*) { /* { dg-warning "declared inside parameter list" } */
int test(int *n, struct T { char a[*n], b[*n]; }*) {
return sizeof(struct T) - sizeof(struct T);
}