From d1d8fd2884b44598d80de1038b086eec41519d4b Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Thu, 22 Feb 2024 18:49:08 -0500
Subject: [PATCH] c++: direct-init of an array of class type [PR59465]
...from another array in a mem-initializer should not be accepted.
We already reject
struct string {} a[1];
string x[1](a);
but
struct pair {
string s[1];
pair() : s(a) {}
};
is wrongly accepted.
It started to be accepted with r0-110915-ga034826198b771:
<https://gcc.gnu.org/pipermail/gcc-patches/2011-August/320236.html>
which was supposed to be a cleanup, not a deliberate change to start
accepting the code. The build_vec_init_expr code was added in r165976:
<https://gcc.gnu.org/pipermail/gcc-patches/2010-October/297582.html>.
It appears that we do the magic copy array when we have a defaulted
constructor and we generate code for its mem-initializer which
initializes an array. I also see that we go that path for compound
literals. So when initializing an array member, we can limit building
up a VEC_INIT_EXPR to those special cases.
PR c++/59465
gcc/cp/ChangeLog:
* init.cc (can_init_array_with_p): New.
(perform_member_init): Check it.
gcc/testsuite/ChangeLog:
* g++.dg/init/array62.C: New test.
* g++.dg/init/array63.C: New test.
* g++.dg/init/array64.C: New test.
---
gcc/cp/init.cc | 31 ++++++++++++++++++++++++++---
gcc/testsuite/g++.dg/init/array62.C | 19 ++++++++++++++++++
gcc/testsuite/g++.dg/init/array63.C | 13 ++++++++++++
gcc/testsuite/g++.dg/init/array64.C | 22 ++++++++++++++++++++
4 files changed, 82 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/init/array62.C
create mode 100644 gcc/testsuite/g++.dg/init/array63.C
create mode 100644 gcc/testsuite/g++.dg/init/array64.C
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index d2586fad86b1..dbd37d47cbf5 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -934,6 +934,33 @@ find_uninit_fields (tree *t, hash_set<tree> *uninitialized, tree member)
}
}
+/* Return true if it's OK to initialize an array TYPE from INIT. Mere mortals
+ can't copy arrays, but the compiler can do so with a VEC_INIT_EXPR in
+ certain cases. */
+
+static bool
+can_init_array_with_p (tree type, tree init)
+{
+ if (!init)
+ /* Value-init, OK. */
+ return true;
+ if (!same_type_ignoring_top_level_qualifiers_p (type, TREE_TYPE (init)))
+ return false;
+ /* We're called from synthesize_method, and we're processing the
+ mem-initializers of a constructor. */
+ if (DECL_DEFAULTED_FN (current_function_decl))
+ return true;
+ /* As an extension, we allow copying from a compound literal. */
+ if (TREE_CODE (init) == TARGET_EXPR)
+ {
+ init = TARGET_EXPR_INITIAL (init);
+ if (TREE_CODE (init) == CONSTRUCTOR)
+ return CONSTRUCTOR_C99_COMPOUND_LITERAL (init);
+ }
+
+ return false;
+}
+
/* Initialize MEMBER, a FIELD_DECL, with INIT, a TREE_LIST of
arguments. If TREE_LIST is void_type_node, an empty initializer
list was given; if NULL_TREE no initializer was given. UNINITIALIZED
@@ -1087,9 +1114,7 @@ perform_member_init (tree member, tree init, hash_set<tree> &uninitialized)
{
if (TREE_CODE (type) == ARRAY_TYPE)
{
- if (init == NULL_TREE
- || same_type_ignoring_top_level_qualifiers_p (type,
- TREE_TYPE (init)))
+ if (can_init_array_with_p (type, init))
{
if (TYPE_DOMAIN (type) && TYPE_MAX_VALUE (TYPE_DOMAIN (type)))
{
diff --git a/gcc/testsuite/g++.dg/init/array62.C b/gcc/testsuite/g++.dg/init/array62.C
new file mode 100644
index 000000000000..2a786a36e4e8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/array62.C
@@ -0,0 +1,19 @@
+// PR c++/59465
+// { dg-do compile }
+
+struct string {} a[1];
+struct pair {
+ string s[1];
+ pair() : s(a) {} // { dg-error "invalid initializer for array member" }
+};
+
+struct S {
+ char s[10];
+ S() : s("aaa") {}
+};
+
+void
+g ()
+{
+ string x[1](a); // { dg-error "array must be initialized" }
+}
diff --git a/gcc/testsuite/g++.dg/init/array63.C b/gcc/testsuite/g++.dg/init/array63.C
new file mode 100644
index 000000000000..57e980561680
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/array63.C
@@ -0,0 +1,13 @@
+// PR c++/59465
+// { dg-do compile }
+
+struct I {
+ const bool b;
+};
+struct O {
+ I a[2];
+ static I const data[2];
+ O() : a(data){} // { dg-error "invalid initializer for array member" }
+};
+
+I const O::data[2] = {true, false};
diff --git a/gcc/testsuite/g++.dg/init/array64.C b/gcc/testsuite/g++.dg/init/array64.C
new file mode 100644
index 000000000000..e0afdfab39a5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/init/array64.C
@@ -0,0 +1,22 @@
+// PR c++/59465
+// { dg-do compile }
+
+static const int my_size = 10;
+
+class UserType
+{
+public:
+ UserType(): f_(){}
+private:
+int f_;
+};
+
+typedef UserType Array[my_size];
+
+class Foo
+{
+public:
+ Foo(Array& m) : m_(m) {}; // { dg-error "invalid initializer for array member" }
+private:
+ Array m_;
+};
--
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