The problem here is that first check_initializer calls
build_aggr_init_full_exprs, which does overload resolution, but then in the
case of failed constexpr throws away the result and does it again in
build_functional_cast. But in the first overload resolution,
reshape_init_array_1 decided to reuse the inner CONSTRUCTORs because
tf_error is set, so we know we're committed. But the second pass gets
confused by the CONSTRUCTORs with non-init-list types.
Fixed by avoiding a second pass: instead, pass the call from build_aggr_init
to build_cplus_new, which will turn it into a TARGET_EXPR. I don't bother
to change the object argument because it will be replaced later in
simplify_aggr_init_expr.
Tested x86_64-pc-linux-gnu, applying to trunk.
PR c++/102307
gcc/cp/ChangeLog:
* decl.cc (check_initializer): Use build_cplus_new in case of
constexpr failure.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/constexpr-array2.C: New test.
---
gcc/cp/decl.cc | 17 ++++++++++++-----
gcc/testsuite/g++.dg/cpp1z/constexpr-array2.C | 12 ++++++++++++
2 files changed, 24 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/constexpr-array2.C
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 5654bc754e6..381259cb9cf 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -7413,12 +7413,19 @@ check_initializer (tree decl, tree init, int flags,
vec<tree, va_gc> **cleanups)
/* Declared constexpr or constinit, but no suitable initializer;
massage init appropriately so we can pass it into
store_init_value for the error. */
- if (CLASS_TYPE_P (type)
- && (!init || TREE_CODE (init) == TREE_LIST))
+ tree new_init = NULL_TREE;
+ if (!processing_template_decl
+ && TREE_CODE (init_code) == CALL_EXPR)
+ new_init = build_cplus_new (type, init_code, tf_none);
+ else if (CLASS_TYPE_P (type)
+ && (!init || TREE_CODE (init) == TREE_LIST))
+ new_init = build_functional_cast (input_location, type,
+ init, tf_none);
+ if (new_init)
{
- init = build_functional_cast (input_location, type,
- init, tf_none);
- if (TREE_CODE (init) == TARGET_EXPR)
+ init = new_init;
+ if (TREE_CODE (init) == TARGET_EXPR
+ && !(flags & LOOKUP_ONLYCONVERTING))
TARGET_EXPR_DIRECT_INIT_P (init) = true;
}
init_code = NULL_TREE;
diff --git a/gcc/testsuite/g++.dg/cpp1z/constexpr-array2.C
b/gcc/testsuite/g++.dg/cpp1z/constexpr-array2.C
new file mode 100644
index 00000000000..c30e3f2361d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/constexpr-array2.C
@@ -0,0 +1,12 @@
+// PR c++/102307
+// { dg-do compile { target c++11 } }
+
+#include <array>
+template <unsigned N, unsigned M> struct Matrix {
+ constexpr Matrix(double const (&arr)[N][M]); // { dg-warning "never defined"
}
+ constexpr Matrix(std::array<std::array<double, M>, N> const &arr);
+};
+int main() {
+ constexpr Matrix<2, 3>
+ mat {{ {1.0, 2.0, 3.0}, {4.0, 5.0, 6.0} }}; // { dg-error "before its
definition" }
+}
base-commit: ed12749a3c9d9569a2c23df2e0db2136dcd3512d
--
2.27.0
