diff mbox series

[C,6/6] c23: construct composite type for tagged types

Message ID 748ad71f62bb0e306d2fc050763b2e69ca81190f.camel@tugraz.at
State New
Headers show
Series [C,1/6] c: reorganize recursive type checking | expand

Commit Message

Martin Uecker Aug. 26, 2023, 4:26 p.m. UTC
Support for constructing composite type for structs and unions
in C23.

gcc/c:
	* c-typeck.cc (composite_type_internal): Adapted from
	composite_type to support structs and unions.
	(composite_type): New wrapper function.
	(build_conditional_operator): Return composite type.

gcc/testsuite:
	* gcc.dg/c2x-tag-composite-1.c: New test.
	* gcc.dg/c2x-tag-composite-2.c: New test.
	* gcc.dg/c2x-tag-composite-3.c: New test.
	* gcc.dg/c2x-tag-composite-4.c: New test.
---
 gcc/c/c-typeck.cc                          | 114 +++++++++++++++++----
 gcc/testsuite/gcc.dg/c2x-tag-composite-1.c |  26 +++++
 gcc/testsuite/gcc.dg/c2x-tag-composite-2.c |  16 +++
 gcc/testsuite/gcc.dg/c2x-tag-composite-3.c |  17 +++
 gcc/testsuite/gcc.dg/c2x-tag-composite-4.c |  21 ++++
 5 files changed, 176 insertions(+), 18 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/c2x-tag-composite-1.c
 create mode 100644 gcc/testsuite/gcc.dg/c2x-tag-composite-2.c
 create mode 100644 gcc/testsuite/gcc.dg/c2x-tag-composite-3.c
 create mode 100644 gcc/testsuite/gcc.dg/c2x-tag-composite-4.c

Comments

Joseph Myers Nov. 7, 2023, 11:45 p.m. UTC | #1
On Sat, 26 Aug 2023, Martin Uecker via Gcc-patches wrote:

> @@ -501,9 +510,61 @@ composite_type (tree t1, tree t2)
>  	return build_type_attribute_variant (t1, attributes);
>        }
>  
> -    case ENUMERAL_TYPE:
>      case RECORD_TYPE:
>      case UNION_TYPE:
> +      if (flag_isoc2x && !comptypes_same_p (t1, t2))
> +	{
> +	  gcc_checking_assert (COMPLETE_TYPE_P (t1) && COMPLETE_TYPE_P (t2));
> +	  gcc_checking_assert (comptypes (t1, t2));
> +
> +	  /* If a composite type for these two types is already under
> +	     construction, return it.  */
> +
> +	  for (struct composite_cache *c = cache; c != NULL; c = c->next)
> +	    if (c->t1 == t1 && c->t2 == t2)
> +	       return c->composite;
> +
> +	  /* Otherwise, create a new type node and link it into the cache.  */
> +
> +	  tree n = make_node (code1);
> +	  struct composite_cache cache2 = { t1, t2, n, cache };
> +	  cache = &cache2;
> +
> +	  tree f1 = TYPE_FIELDS (t1);
> +	  tree f2 = TYPE_FIELDS (t2);
> +	  tree fields = NULL_TREE;
> +
> +	  for (tree a = f1, b = f2; a && b;
> +	       a = DECL_CHAIN (a), b = DECL_CHAIN (b))
> +	    {
> +	      tree ta = TREE_TYPE (a);
> +	      tree tb = TREE_TYPE (b);
> +
> +	      gcc_assert (DECL_NAME (a) == DECL_NAME (b));
> +	      gcc_assert (comptypes (ta, tb));
> +
> +	      tree f = build_decl (input_location, FIELD_DECL, DECL_NAME (a),
> +				   composite_type_internal (ta, tb, cache));
> +
> +	      DECL_FIELD_CONTEXT (f) = n;
> +	      DECL_CHAIN (f) = fields;

There is a lot more per-field setup done in grokdeclarator, grokfield and 
finish_struct when a struct or union is defined.  I'm concerned that just 
calling build_decl here and then missing most of the per-field setup done 
elsewhere will not get the composite type set up correctly, especially in 
cases such as bit-fields and packed structures.

Note that the test you have of bit-fields (c2x-tag-composite-3.c) probably 
doesn't exercise this code, because the two types are the same (defined in 
the same scope, so it would be an error if they weren't the same) and so 
the comptypes_same_p check should short-circuit this code.  You need to 
test such issues in cases where the types are genuinely not the same - and 
for bit-fields, that includes ensuring you cover code paths that depend on 
each of DECL_BIT_FIELD, DECL_C_BIT_FIELD, DECL_BIT_FIELD_TYPE, to make 
sure that all of those are correct.
diff mbox series

Patch

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 2489fa1e3d1..357367eab09 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -381,8 +381,15 @@  build_functype_attribute_variant (tree ntype, tree otype, tree attrs)
    nonzero; if that isn't so, this may crash.  In particular, we
    assume that qualifiers match.  */
 
+struct composite_cache {
+  tree t1;
+  tree t2;
+  tree composite;
+  struct composite_cache* next;
+};
+
 tree
-composite_type (tree t1, tree t2)
+composite_type_internal (tree t1, tree t2, struct composite_cache* cache)
 {
   enum tree_code code1;
   enum tree_code code2;
@@ -425,7 +432,8 @@  composite_type (tree t1, tree t2)
       {
 	tree pointed_to_1 = TREE_TYPE (t1);
 	tree pointed_to_2 = TREE_TYPE (t2);
-	tree target = composite_type (pointed_to_1, pointed_to_2);
+	tree target = composite_type_internal (pointed_to_1,
+					       pointed_to_2, cache);
         t1 = build_pointer_type_for_mode (target, TYPE_MODE (t1), false);
 	t1 = build_type_attribute_variant (t1, attributes);
 	return qualify_type (t1, t2);
@@ -433,7 +441,8 @@  composite_type (tree t1, tree t2)
 
     case ARRAY_TYPE:
       {
-	tree elt = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
+	tree elt = composite_type_internal (TREE_TYPE (t1), TREE_TYPE (t2),
+					    cache);
 	int quals;
 	tree unqual_elt;
 	tree d1 = TYPE_DOMAIN (t1);
@@ -501,9 +510,61 @@  composite_type (tree t1, tree t2)
 	return build_type_attribute_variant (t1, attributes);
       }
 
-    case ENUMERAL_TYPE:
     case RECORD_TYPE:
     case UNION_TYPE:
+      if (flag_isoc2x && !comptypes_same_p (t1, t2))
+	{
+	  gcc_checking_assert (COMPLETE_TYPE_P (t1) && COMPLETE_TYPE_P (t2));
+	  gcc_checking_assert (comptypes (t1, t2));
+
+	  /* If a composite type for these two types is already under
+	     construction, return it.  */
+
+	  for (struct composite_cache *c = cache; c != NULL; c = c->next)
+	    if (c->t1 == t1 && c->t2 == t2)
+	       return c->composite;
+
+	  /* Otherwise, create a new type node and link it into the cache.  */
+
+	  tree n = make_node (code1);
+	  struct composite_cache cache2 = { t1, t2, n, cache };
+	  cache = &cache2;
+
+	  tree f1 = TYPE_FIELDS (t1);
+	  tree f2 = TYPE_FIELDS (t2);
+	  tree fields = NULL_TREE;
+
+	  for (tree a = f1, b = f2; a && b;
+	       a = DECL_CHAIN (a), b = DECL_CHAIN (b))
+	    {
+	      tree ta = TREE_TYPE (a);
+	      tree tb = TREE_TYPE (b);
+
+	      gcc_assert (DECL_NAME (a) == DECL_NAME (b));
+	      gcc_assert (comptypes (ta, tb));
+
+	      tree f = build_decl (input_location, FIELD_DECL, DECL_NAME (a),
+				   composite_type_internal (ta, tb, cache));
+
+	      DECL_FIELD_CONTEXT (f) = n;
+	      DECL_CHAIN (f) = fields;
+	      fields = f;
+	    }
+
+	  TYPE_NAME (n) = TYPE_NAME (t1);
+	  TYPE_FIELDS (n) = nreverse (fields);
+	  TYPE_ATTRIBUTES (n) = attributes;
+	  layout_type (n);
+	  n = build_type_attribute_variant (n, attributes);
+	  n = qualify_type (n, t1);
+
+	  gcc_checking_assert (comptypes (n, t1));
+	  gcc_checking_assert (comptypes (n, t2));
+
+	  return n;
+	}
+      /* FALLTHRU */
+    case ENUMERAL_TYPE:
       if (attributes != NULL)
 	{
 	  /* Try harder not to create a new aggregate type.  */
@@ -518,7 +579,8 @@  composite_type (tree t1, tree t2)
       /* Function types: prefer the one that specified arg types.
 	 If both do, merge the arg types.  Also merge the return types.  */
       {
-	tree valtype = composite_type (TREE_TYPE (t1), TREE_TYPE (t2));
+	tree valtype = composite_type_internal (TREE_TYPE (t1),
+						TREE_TYPE (t2), cache);
 	tree p1 = TYPE_ARG_TYPES (t1);
 	tree p2 = TYPE_ARG_TYPES (t2);
 	int len;
@@ -563,6 +625,16 @@  composite_type (tree t1, tree t2)
 	for (; p1 && p1 != void_list_node;
 	     p1 = TREE_CHAIN (p1), p2 = TREE_CHAIN (p2), n = TREE_CHAIN (n))
 	  {
+	     tree mv1 = TREE_VALUE (p1);
+	     if (mv1 && mv1 != error_mark_node
+		 && TREE_CODE (mv1) != ARRAY_TYPE)
+	       mv1 = TYPE_MAIN_VARIANT (mv1);
+
+	     tree mv2 = TREE_VALUE (p2);
+	     if (mv2 && mv2 != error_mark_node
+		 && TREE_CODE (mv2) != ARRAY_TYPE)
+	       mv2 = TYPE_MAIN_VARIANT (mv2);
+
 	    /* A null type means arg type is not specified.
 	       Take whatever the other function type has.  */
 	    if (TREE_VALUE (p1) == NULL_TREE)
@@ -583,10 +655,6 @@  composite_type (tree t1, tree t2)
 		&& TREE_VALUE (p1) != TREE_VALUE (p2))
 	      {
 		tree memb;
-		tree mv2 = TREE_VALUE (p2);
-		if (mv2 && mv2 != error_mark_node
-		    && TREE_CODE (mv2) != ARRAY_TYPE)
-		  mv2 = TYPE_MAIN_VARIANT (mv2);
 		for (memb = TYPE_FIELDS (TREE_VALUE (p1));
 		     memb; memb = DECL_CHAIN (memb))
 		  {
@@ -596,8 +664,9 @@  composite_type (tree t1, tree t2)
 		      mv3 = TYPE_MAIN_VARIANT (mv3);
 		    if (comptypes (mv3, mv2))
 		      {
-			TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
-							 TREE_VALUE (p2));
+			TREE_VALUE (n) = composite_type_internal (TREE_TYPE (memb),
+								  TREE_VALUE (p2),
+								  cache);
 			pedwarn (input_location, OPT_Wpedantic,
 				 "function types not truly compatible in ISO C");
 			goto parm_done;
@@ -608,10 +677,6 @@  composite_type (tree t1, tree t2)
 		&& TREE_VALUE (p2) != TREE_VALUE (p1))
 	      {
 		tree memb;
-		tree mv1 = TREE_VALUE (p1);
-		if (mv1 && mv1 != error_mark_node
-		    && TREE_CODE (mv1) != ARRAY_TYPE)
-		  mv1 = TYPE_MAIN_VARIANT (mv1);
 		for (memb = TYPE_FIELDS (TREE_VALUE (p2));
 		     memb; memb = DECL_CHAIN (memb))
 		  {
@@ -621,15 +686,17 @@  composite_type (tree t1, tree t2)
 		      mv3 = TYPE_MAIN_VARIANT (mv3);
 		    if (comptypes (mv3, mv1))
 		      {
-			TREE_VALUE (n) = composite_type (TREE_TYPE (memb),
-							 TREE_VALUE (p1));
+			TREE_VALUE (n)
+				= composite_type_internal (TREE_TYPE (memb),
+							   TREE_VALUE (p1),
+							   cache);
 			pedwarn (input_location, OPT_Wpedantic,
 				 "function types not truly compatible in ISO C");
 			goto parm_done;
 		      }
 		  }
 	      }
-	    TREE_VALUE (n) = composite_type (TREE_VALUE (p1), TREE_VALUE (p2));
+	    TREE_VALUE (n) = composite_type_internal (mv1, mv2, cache);
 	  parm_done: ;
 	  }
 
@@ -641,7 +708,13 @@  composite_type (tree t1, tree t2)
     default:
       return build_type_attribute_variant (t1, attributes);
     }
+}
 
+tree
+composite_type (tree t1, tree t2)
+{
+  struct composite_cache cache = { };
+  return composite_type_internal (t1, t2, &cache);
 }
 
 /* Return the type of a conditional expression between pointers to
@@ -5480,6 +5553,11 @@  build_conditional_expr (location_t colon_loc, tree ifexp, bool ifexp_bcp,
     result_type = type2;
   else if (code1 == POINTER_TYPE && code2 == NULLPTR_TYPE)
     result_type = type1;
+  else if (RECORD_OR_UNION_TYPE_P (type1) && RECORD_OR_UNION_TYPE_P (type2)
+	   && comptypes (TYPE_MAIN_VARIANT (type1),
+			 TYPE_MAIN_VARIANT (type2)))
+    result_type = composite_type (TYPE_MAIN_VARIANT (type1),
+				  TYPE_MAIN_VARIANT (type2));
 
   if (!result_type)
     {
diff --git a/gcc/testsuite/gcc.dg/c2x-tag-composite-1.c b/gcc/testsuite/gcc.dg/c2x-tag-composite-1.c
new file mode 100644
index 00000000000..aae11f6cee2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-tag-composite-1.c
@@ -0,0 +1,26 @@ 
+/* { dg-do compile } */
+/* { dg-options "-std=c2x" } */
+
+void b(void)
+{
+	int n = 3;
+
+	  extern struct f { char (*x)[3]; char (*y)[]; } q;
+	{ extern struct f { char (*x)[]; char (*y)[4]; } q; 
+	  _Static_assert(3 == sizeof(*q.x), "");
+	  _Static_assert(4 == sizeof(*q.y), "");
+	}
+	{ extern struct f { char (*x)[2]; char (*y)[]; } q; (void)q; }	/* { dg-error "conflicting" } */
+
+	{ struct f { char (*x)[n]; char (*y)[3]; }* qp = &q; (void)*qp; }
+	(void)q;
+
+	  static struct g { int a; char buf[n]; } *p; (void)p;
+	{ static struct g { int a; char buf[3]; } *p; (void)p; }
+
+	  static struct h { int a; void (*s)(char buf[n]); } *t; (void)t;
+	{ static struct h { int a; void (*s)(char buf[3]); } *t; (void)t; }
+}
+
+
+
diff --git a/gcc/testsuite/gcc.dg/c2x-tag-composite-2.c b/gcc/testsuite/gcc.dg/c2x-tag-composite-2.c
new file mode 100644
index 00000000000..dfc4336751a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-tag-composite-2.c
@@ -0,0 +1,16 @@ 
+/* { dg-do compile } */
+/* { dg-options "-std=c2x" } */
+
+
+struct foo { int (*(*i)(void))[]; } x;
+
+
+void f(void)
+{ 
+	const struct foo { int (*(*i)())[3]; } y;
+	_Static_assert(3 * sizeof(int) == sizeof(*((1 ? &x : &y)->i())), "");
+}
+
+void g(struct foo { int x; } a);
+void g(const struct foo { int x; } a);
+
diff --git a/gcc/testsuite/gcc.dg/c2x-tag-composite-3.c b/gcc/testsuite/gcc.dg/c2x-tag-composite-3.c
new file mode 100644
index 00000000000..02159f3c44d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-tag-composite-3.c
@@ -0,0 +1,17 @@ 
+/* { dg-do compile }
+ * { dg-options "-std=c2x" }
+ */
+
+// bit-fields
+
+extern struct foo { int x:3; } x;
+struct foo { int x:3; } y;
+
+void f(void)
+{
+	extern typeof(*(1 ? &x : &y)) x;
+	&x.x;					/* { dg-error "bit-field" } */
+}
+
+struct foo { int x:2; };			/* { dg-error "redefinition" } */
+
diff --git a/gcc/testsuite/gcc.dg/c2x-tag-composite-4.c b/gcc/testsuite/gcc.dg/c2x-tag-composite-4.c
new file mode 100644
index 00000000000..1bd98cc1a44
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/c2x-tag-composite-4.c
@@ -0,0 +1,21 @@ 
+/* { dg-do compile }
+ * { dg-options "-std=c2x" } 
+ */
+
+// conditional operator
+
+void f(void)
+{
+	struct foo { int x; } a;
+	struct foo { int x; } b;
+	1 ? a : b;
+}
+
+struct bar { int x; } a;
+
+void g(void)
+{
+	struct bar { int x; } b;
+	1 ? a : b;
+}
+