Tested x86_64-pc-linux-gnu, applying to trunk.
-- 8< --
Here during constant evaluation we encounter a VAR_DECL with DECL_VALUE_EXPR
of the RESULT_DECL, where the latter has been adjusted for
pass-by-invisible-reference. We already had the code to deal with this, we
just need to use it in the non-capture case of DECL_VALUE_EXPR as well.
PR c++/118053
gcc/cp/ChangeLog:
* constexpr.cc (cxx_eval_constant_expression): Generalize
DECL_VALUE_EXPR invisiref handling.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1y/constexpr-lambda1.C: New test.
---
gcc/cp/constexpr.cc | 19 +++++++++---------
.../g++.dg/cpp1y/constexpr-lambda1.C | 20 +++++++++++++++++++
2 files changed, 30 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-lambda1.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 299b1345687..59dd0668af3 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -7683,18 +7683,19 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx,
tree t,
definition, so don't try to look at the closure. But if the
captured variable is constant, try to evaluate it directly. */
r = DECL_CAPTURED_VARIABLE (t);
- tree type = TREE_TYPE (t);
- if (TYPE_REF_P (type) != TYPE_REF_P (TREE_TYPE (r)))
- {
- /* Adjust r to match the reference-ness of t. */
- if (TYPE_REF_P (type))
- r = build_address (r);
- else
- r = convert_from_reference (r);
- }
}
else
r = DECL_VALUE_EXPR (t);
+
+ tree type = TREE_TYPE (t);
+ if (TYPE_REF_P (type) != TYPE_REF_P (TREE_TYPE (r)))
+ {
+ /* Adjust r to match the reference-ness of t. */
+ if (TYPE_REF_P (type))
+ r = build_address (r);
+ else
+ r = convert_from_reference (r);
+ }
return cxx_eval_constant_expression (ctx, r, lval, non_constant_p,
overflow_p);
}
diff --git a/gcc/testsuite/g++.dg/cpp1y/constexpr-lambda1.C
b/gcc/testsuite/g++.dg/cpp1y/constexpr-lambda1.C
new file mode 100644
index 00000000000..68152e26b89
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/constexpr-lambda1.C
@@ -0,0 +1,20 @@
+// PR c++/118053
+// { dg-do compile { target c++14 } }
+
+template <typename _Tp> struct vector {
+ _Tp * _M_finish;
+ vector(_Tp);
+ vector(const vector &);
+ constexpr auto back() { return *_M_finish; }
+};
+template <typename Funct> void
+run(Funct funct) { funct(1); }
+
+vector<int>
+runner() try {
+ vector<int> vec{1};
+ run([&](auto) { vec.back(); });
+ return vec;
+} catch (...) {
+ return 1;
+}
base-commit: bf84e5e64662f8f0fdebfc0212e32bfca678f9eb
--
2.48.1
