On Tue, Mar 12, 2024 at 09:57:14AM -0400, Jason Merrill wrote:
> On 3/11/24 19:27, Marek Polacek wrote:
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/13?
> >
> > -- >8 --
> > This ICE started with the fairly complicated r13-765. We crash in
> > gimplify_var_or_parm_decl because a stray VAR_DECL leaked there.
> > The problem is ultimately that potential_prvalue_result_of wasn't
> > correctly handling arrays and replace_placeholders_for_class_temp_r
> > replaced a PLACEHOLDER_EXPR in a TARGET_EXPR which is used in the
> > context of copy elision. If I have
> >
> > M m[2] = { M{""}, M{""} };
> >
> > then we don't invoke the M(const M&) copy-ctor. I think the fix is
> > to detect such a case in potential_prvalue_result_of.
> >
> > PR c++/109966
> >
> > gcc/cp/ChangeLog:
> >
> > * typeck2.cc (potential_prvalue_result_of): Add walk_subtrees
> > parameter. Handle initializing an array from a
> > brace-enclosed-initializer.
> > (replace_placeholders_for_class_temp_r): Pass walk_subtrees down to
> > potential_prvalue_result_of.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * g++.dg/cpp1y/nsdmi-aggr20.C: New test.
> > * g++.dg/cpp1y/nsdmi-aggr21.C: New test.
> > ---
> > gcc/cp/typeck2.cc | 27 ++++++++---
> > gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C | 17 +++++++
> > gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C | 59 +++++++++++++++++++++++
> > 3 files changed, 96 insertions(+), 7 deletions(-)
> > create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C
> > create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C
> >
> > diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
> > index 31198b2f9f5..8b99ce78e9a 100644
> > --- a/gcc/cp/typeck2.cc
> > +++ b/gcc/cp/typeck2.cc
> > @@ -1406,46 +1406,59 @@ digest_init_flags (tree type, tree init, int flags,
> > tsubst_flags_t complain)
> > A a = (A{}); // initializer
> > A a = (1, A{}); // initializer
> > A a = true ? A{} : A{}; // initializer
> > + A arr[1] = { A{} }; // initializer
> > auto x = A{}.x; // temporary materialization
> > auto x = foo(A{}); // temporary materialization
> > FULL_EXPR is the whole expression, SUBOB is its TARGET_EXPR subobject.
> > */
> > static bool
> > -potential_prvalue_result_of (tree subob, tree full_expr)
> > +potential_prvalue_result_of (tree subob, tree full_expr, int
> > *walk_subtrees)
> > {
> > +#define RECUR(t) potential_prvalue_result_of (subob, t, walk_subtrees)
> > if (subob == full_expr)
> > return true;
> > else if (TREE_CODE (full_expr) == TARGET_EXPR)
> > {
> > tree init = TARGET_EXPR_INITIAL (full_expr);
> > if (TREE_CODE (init) == COND_EXPR)
> > - return (potential_prvalue_result_of (subob, TREE_OPERAND (init, 1))
> > - || potential_prvalue_result_of (subob, TREE_OPERAND (init, 2)));
> > + return (RECUR (TREE_OPERAND (init, 1))
> > + || RECUR (TREE_OPERAND (init, 2)));
> > else if (TREE_CODE (init) == COMPOUND_EXPR)
> > - return potential_prvalue_result_of (subob, TREE_OPERAND (init, 1));
> > + return RECUR (TREE_OPERAND (init, 1));
> > /* ??? I don't know if this can be hit. */
> > else if (TREE_CODE (init) == PAREN_EXPR)
> > {
> > gcc_checking_assert (false);
> > - return potential_prvalue_result_of (subob, TREE_OPERAND (init, 0));
> > + return RECUR (TREE_OPERAND (init, 0));
> > }
> > }
> > + /* The array case listed above. */
> > + else if (TREE_CODE (full_expr) == CONSTRUCTOR
> > + && TREE_CODE (TREE_TYPE (full_expr)) == ARRAY_TYPE)
> > + for (constructor_elt &e: CONSTRUCTOR_ELTS (full_expr))
> > + if (e.value == subob)
> > + {
> > + *walk_subtrees = 0;
>
> Why clear walk_subtrees? Won't that mean we fail to replace any
> placeholders nested within an array element initializer?
Right. I couldn't find a testcase where that would cause a problem
but I think I just wasn't inventive enough.
Originally, I was checking same_type_ignoring_top_level_qualifiers_p
but that's not going to work for code like
struct N { N(M); };
N arr[2] = { M{""}, M{""} };
or with operator M(). But I suppose I could just use can_convert
like below. What do you think about that?
dg.exp passed, full regtest running.
-- >8 --
This ICE started with the fairly complicated r13-765. We crash in
gimplify_var_or_parm_decl because a stray VAR_DECL leaked there.
The problem is ultimately that potential_prvalue_result_of wasn't
correctly handling arrays and replace_placeholders_for_class_temp_r
replaced a PLACEHOLDER_EXPR in a TARGET_EXPR which is used in the
context of copy elision. If I have
M m[2] = { M{""}, M{""} };
then we don't invoke the M(const M&) copy-ctor. I think the fix is
to detect such a case in potential_prvalue_result_of.
PR c++/109966
gcc/cp/ChangeLog:
* typeck2.cc (potential_prvalue_result_of): Handle initializing an
array from a brace-enclosed-initializer.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/nsdmi-aggr20.C: New test.
* g++.dg/cpp1y/nsdmi-aggr21.C: New test.
---
gcc/cp/typeck2.cc | 18 +++++--
gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C | 17 +++++++
gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C | 59 +++++++++++++++++++++++
3 files changed, 90 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C
diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
index 31198b2f9f5..21d4f42ae20 100644
--- a/gcc/cp/typeck2.cc
+++ b/gcc/cp/typeck2.cc
@@ -1406,6 +1406,7 @@ digest_init_flags (tree type, tree init, int flags,
tsubst_flags_t complain)
A a = (A{}); // initializer
A a = (1, A{}); // initializer
A a = true ? A{} : A{}; // initializer
+ A arr[1] = { A{} }; // initializer
auto x = A{}.x; // temporary materialization
auto x = foo(A{}); // temporary materialization
@@ -1414,24 +1415,33 @@ digest_init_flags (tree type, tree init, int flags,
tsubst_flags_t complain)
static bool
potential_prvalue_result_of (tree subob, tree full_expr)
{
+#define RECUR(t) potential_prvalue_result_of (subob, t)
if (subob == full_expr)
return true;
else if (TREE_CODE (full_expr) == TARGET_EXPR)
{
tree init = TARGET_EXPR_INITIAL (full_expr);
if (TREE_CODE (init) == COND_EXPR)
- return (potential_prvalue_result_of (subob, TREE_OPERAND (init, 1))
- || potential_prvalue_result_of (subob, TREE_OPERAND (init, 2)));
+ return (RECUR (TREE_OPERAND (init, 1))
+ || RECUR (TREE_OPERAND (init, 2)));
else if (TREE_CODE (init) == COMPOUND_EXPR)
- return potential_prvalue_result_of (subob, TREE_OPERAND (init, 1));
+ return RECUR (TREE_OPERAND (init, 1));
/* ??? I don't know if this can be hit. */
else if (TREE_CODE (init) == PAREN_EXPR)
{
gcc_checking_assert (false);
- return potential_prvalue_result_of (subob, TREE_OPERAND (init, 0));
+ return RECUR (TREE_OPERAND (init, 0));
}
}
+ /* The array case listed above. */
+ else if (TREE_CODE (full_expr) == CONSTRUCTOR
+ && TREE_CODE (TREE_TYPE (full_expr)) == ARRAY_TYPE
+ && can_convert (strip_array_types (TREE_TYPE (full_expr)),
+ TREE_TYPE (subob), tf_none))
+ return true;
+
return false;
+#undef RECUR
}
/* Callback to replace PLACEHOLDER_EXPRs in a TARGET_EXPR (which isn't used
diff --git a/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C
b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C
new file mode 100644
index 00000000000..4796d861e83
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr20.C
@@ -0,0 +1,17 @@
+// PR c++/109966
+// { dg-do compile { target c++14 } }
+
+#define SA(X) static_assert ((X),#X)
+
+struct A {
+ int a;
+ int b = a;
+};
+
+struct B {
+ int x = 0;
+ int y[1]{A{x}.b};
+};
+
+constexpr B b = { };
+SA(b.y[0] == 0);
diff --git a/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C
b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C
new file mode 100644
index 00000000000..efec45bc1a8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/nsdmi-aggr21.C
@@ -0,0 +1,59 @@
+// PR c++/109966
+// { dg-do compile { target c++14 } }
+
+struct k {
+ k(const char *);
+};
+struct M {
+ k name;
+ int j = 42;
+ int i = j;
+};
+
+M m = M{""};
+
+struct S {
+ M arr1[1]{M{""}};
+ M a1[1] = { (M{""}) };
+ M a2[1] = { (true, M{""}) };
+ M a3[1] = { true ? M{""} : M{""} };
+ M arr2[2]{M{""}, M{""}};
+ M arr3[3]{M{""}, M{""}, M{""}};
+
+ M arr1e[1] = {M{""}};
+ M arr2e[2] = {M{""}, M{""}};
+ M arr3e[3] = {M{""}, M{""}, M{""}};
+
+ M arr1l[1] = { m };
+ M arr2l[2] = { m, m };
+ M arr3l[3] = { m, m, m };
+
+ M m1 = M{""};
+ M m2 = m;
+ M m3{M{""}};
+ M m4 = {M{""}};
+} o;
+
+struct N {
+ N(M);
+};
+
+struct Z {
+ N arr1[1]{ M{""} };
+ N arr2[2]{ M{""}, M{""} };
+ N arr1e[1] = { M{""} };
+ N arr2e[2] = { M{""}, M{""} };
+} z;
+
+struct Y {
+ k name;
+ int j = 42;
+ int i = j;
+ operator M();
+};
+
+struct W {
+ M arr1[1]{ Y{""} };
+ M arr2[2]{ Y{""}, Y{""} };
+ M arr3[3]{ Y{""}, Y{""}, Y{""} };
+} w;
base-commit: ef79c64cb5762c86ee04ddfcedb7fe31eaa3bac8
--
2.44.0
