From: Marek Polacek <polacek@redhat.com>
Date: Mon, 17 Jun 2024 21:53:12 +0000 (-0400)
Subject: c++: ICE with __has_unique_object_representations [PR115476]
X-Git-Tag: basepoints/gcc-16~7928
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fc382a373e6824bb998007d1dcb0805b0cf4b8e8;p=thirdparty%2Fgcc.git

c++: ICE with __has_unique_object_representations [PR115476]

Here we started to ICE with r13-25: in check_trait_type, for "X[]" we
return true here:

  if (kind == 1 && TREE_CODE (type) == ARRAY_TYPE && !TYPE_DOMAIN (type))
    return true; // Array of unknown bound. Don't care about completeness.

and then end up crashing in record_has_unique_obj_representations:

4836	  if (cur != wi::to_offset (sz))

because sz is null.

https://eel.is/c++draft/type.traits#tab:meta.unary.prop-row-47-column-3-sentence-1
says that the preconditions for __has_unique_object_representations are:
"T shall be a complete type, cv void, or an array of unknown bound" and
that "For an array type T, the same result as
has_unique_object_representations_v<remove_all_extents_t<T>>" so T[]
should be treated as T.  So we should use kind==2 for the trait.

	PR c++/115476

gcc/cp/ChangeLog:

	* semantics.cc (finish_trait_expr)
	<case CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS>: Move below to call
	check_trait_type with kind==2.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/has-unique-obj-representations4.C: New test.
---

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 6c1813d37c6..8e3e4e23b72 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12959,7 +12959,6 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_HAS_NOTHROW_COPY:
     case CPTK_HAS_TRIVIAL_COPY:
     case CPTK_HAS_TRIVIAL_DESTRUCTOR:
-    case CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS:
       if (!check_trait_type (type1))
 	return error_mark_node;
       break;
@@ -12969,6 +12968,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_STD_LAYOUT:
     case CPTK_IS_TRIVIAL:
     case CPTK_IS_TRIVIALLY_COPYABLE:
+    case CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS:
       if (!check_trait_type (type1, /* kind = */ 2))
 	return error_mark_node;
       break;
diff --git a/gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations4.C b/gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations4.C
new file mode 100644
index 00000000000..d6949dc7005
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/has-unique-obj-representations4.C
@@ -0,0 +1,16 @@
+// PR c++/115476
+// { dg-do compile { target c++11 } }
+
+struct X;
+static_assert(__has_unique_object_representations(X), "");	  // { dg-error "invalid use of incomplete type" }
+static_assert(__has_unique_object_representations(X[]), "");  // { dg-error "invalid use of incomplete type" }
+static_assert(__has_unique_object_representations(X[1]), "");  // { dg-error "invalid use of incomplete type" }
+static_assert(__has_unique_object_representations(X[][1]), "");  // { dg-error "invalid use of incomplete type" }
+
+struct X {
+  int x;
+};
+static_assert(__has_unique_object_representations(X), "");
+static_assert(__has_unique_object_representations(X[]), "");
+static_assert(__has_unique_object_representations(X[1]), "");
+static_assert(__has_unique_object_representations(X[][1]), "");