Hi!
The following testcase is rejected in 8.3, but was accepted in 8.2 and
is in 9.x. This started with my PR87934
* constexpr.c (cxx_eval_constant_expression) <case CONSTRUCTOR>: Do
re-process TREE_CONSTANT CONSTRUCTORs if they aren't reduced constant
expressions.
backport, where the NSDMI CONSTRUCTOR that contains CONST_DECLs is now
constexpr evaluated so that it doesn't contain them. The difference from
9.x is that 9.x doesn't call get_target_expr if we got a CONSTRUCTOR for a
class type for something that has been originally a CONSTRUCTOR too.
This patch cherry-picks just that hunk of the r9-3835 change.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for 8.4?
Is the testcase alone ok for trunk/9.3?
2020-02-25 Jakub Jelinek <ja...@redhat.com>
PR c++/93905
Backported from mainline
2018-11-04 Jason Merrill <ja...@redhat.com>
* constexpr.c (cxx_eval_outermost_constant_expr): Don't wrap a
CONSTRUCTOR if one was passed in.
* g++.dg/cpp0x/pr93905.C: New test.
--- gcc/cp/constexpr.c.jj 2020-02-25 14:04:47.912615737 +0100
+++ gcc/cp/constexpr.c 2020-02-25 21:05:02.537781661 +0100
@@ -4977,15 +4977,13 @@ cxx_eval_outermost_constant_expr (tree t
if (TREE_CODE (t) == TARGET_EXPR
&& TARGET_EXPR_INITIAL (t) == r)
return t;
- else
+ else if (TREE_CODE (t) != CONSTRUCTOR)
{
r = get_target_expr (r);
TREE_CONSTANT (r) = true;
- return r;
}
}
- else
- return r;
+ return r;
}
/* Returns true if T is a valid subexpression of a constant expression,
--- gcc/testsuite/g++.dg/cpp0x/pr93905.C.jj 2020-02-25 21:03:51.976820018
+0100
+++ gcc/testsuite/g++.dg/cpp0x/pr93905.C 2020-02-25 21:03:28.281168717
+0100
@@ -0,0 +1,18 @@
+// PR c++/93905
+// { dg-do compile { target c++11 } }
+
+enum class E { VALUE };
+
+struct B {
+ E e{E::VALUE};
+protected:
+ ~B () = default;
+};
+
+struct D : B {};
+
+int
+main ()
+{
+ D d{};
+}
Jakub
