Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/14?
-- >8 --
We've had a wrong-code problem since r14-4140, due to which we
forget to initialize a variable.
In consteval39.C, we evaluate
struct QQQ q;
<<cleanup_point <<< Unknown tree: expr_stmt
QQQ::QQQ (&q, TARGET_EXPR <D.2687, <<< Unknown tree: aggr_init_expr
5
__ct_comp
D.2687
(struct basic_string_view *) <<< Unknown tree: void_cst >>>
(const char *) "" >>>>) >>>>>;
into
struct QQQ q;
<<cleanup_point <<< Unknown tree: expr_stmt
{.data={._M_len=42, ._M_str=0}} >>>>>;
and then the useless expr_stmt is dropped on the floor, so q isn't
initialized. As pre-r14-4140, we need to handle constructors specially.
With this patch, we generate:
struct QQQ q;
<<cleanup_point <<< Unknown tree: expr_stmt
q = {.data={._M_len=42, ._M_str=0}} >>>>>;
initializing q properly.
PR c++/117501
gcc/cp/ChangeLog:
* cp-gimplify.cc (cp_fold_immediate_r): If DECL is a constructor,
build up an INIT_EXPR to initialize its object.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/consteval39.C: New test.
* g++.dg/cpp2a/consteval40.C: New test.
---
gcc/cp/cp-gimplify.cc | 13 ++++++++++--
gcc/testsuite/g++.dg/cpp2a/consteval39.C | 27 ++++++++++++++++++++++++
gcc/testsuite/g++.dg/cpp2a/consteval40.C | 25 ++++++++++++++++++++++
3 files changed, 63 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval39.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/consteval40.C
diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index 4ec3de13008..65b486ab943 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1259,7 +1259,16 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees,
void *data_)
not need to produce a constant expression. */
if (DECL_IMMEDIATE_FUNCTION_P (decl))
{
- tree e = cxx_constant_value (stmt, tf_none);
+ tree obj_arg = NULL_TREE;
+ if (call_p && DECL_CONSTRUCTOR_P (decl))
+ if (tree o = get_nth_callarg (stmt, 0))
+ if (!is_dummy_object (o))
+ {
+ obj_arg = o;
+ if (TREE_CODE (obj_arg) == ADDR_EXPR)
+ obj_arg = TREE_OPERAND (obj_arg, 0);
+ }
+ tree e = cxx_constant_value (stmt, obj_arg, tf_none);
if (e == error_mark_node)
{
/* This takes care of, e.g.,
@@ -1297,7 +1306,7 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees,
void *data_)
}
/* We've evaluated the consteval function call. */
if (call_p)
- *stmt_p = e;
+ *stmt_p = obj_arg ? cp_build_init_expr (obj_arg, e) : e;
}
/* We've encountered a function call that may turn out to be consteval
later. Store its caller so that we can ensure that the call is
diff --git a/gcc/testsuite/g++.dg/cpp2a/consteval39.C
b/gcc/testsuite/g++.dg/cpp2a/consteval39.C
new file mode 100644
index 00000000000..523e8260eab
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/consteval39.C
@@ -0,0 +1,27 @@
+// PR c++/117501
+// { dg-do run { target c++20 } }
+
+constexpr unsigned
+length ()
+{
+ bool __trans_tmp_1 = __builtin_is_constant_evaluated();
+ if (__trans_tmp_1)
+ return 42;
+ return 1;
+}
+struct basic_string_view {
+ constexpr basic_string_view(const char *) : _M_len{length()}, _M_str{} {}
+ long _M_len;
+ char _M_str;
+};
+struct QQQ {
+ consteval QQQ(basic_string_view d) : data(d) {}
+ basic_string_view data;
+};
+int
+main ()
+{
+ QQQ q("");
+ if (q.data._M_len != 42)
+ __builtin_abort ();
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/consteval40.C
b/gcc/testsuite/g++.dg/cpp2a/consteval40.C
new file mode 100644
index 00000000000..4d3ba20092b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/consteval40.C
@@ -0,0 +1,25 @@
+// PR c++/117501
+// { dg-do run { target c++20 } }
+
+constexpr int
+twiddle (int i)
+{
+ if (__builtin_is_constant_evaluated ())
+ return 3;
+ return i;
+}
+struct S {
+ constexpr S(int i) : i{twiddle (i)} {}
+ int i;
+};
+struct Q {
+ consteval Q(S s_) : s{s_, s_} {}
+ S s[2];
+};
+int
+main ()
+{
+ Q q(twiddle (42));
+ if (q.s[0].i != 3 || q.s[1].i != 3)
+ __builtin_abort ();
+}
base-commit: ceabea405ffdc851736e240111be9b297ad86c53
--
2.48.1
