From: Jason Merrill <jason@redhat.com>
To: gcc-patches List <gcc-patches@gcc.gnu.org>
Subject: C++ PATCH for c++/80840, ICE with constexpr and reference template parm
Date: Wed, 31 May 2017 17:16:00 -0000 [thread overview]
Message-ID: <CADzB+2nPNqi2uCRQrAUcRKwz4=6PEqG1Jy9vObLOJj3b9pzMew@mail.gmail.com> (raw)
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In convert_nontype_argument to reference type we were inappropriately
checking value_dependent_expression_p on an expression that might be a
VAR_DECL and might be a TEMPLATE_PARM_INDEX of reference type. It's
inappropriate in the former case because we don't care about the value
of the object, only its address; we only want to test for the latter
case.
Tested x86_64-pc-linux-gnu, applying to trunk.
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commit 388ec8de844dda6785d55daef0fffc90eb49118c
Author: Jason Merrill <jason@redhat.com>
Date: Tue May 30 21:38:17 2017 -0400
PR c++/80840 - ICE with constexpr and reference
* pt.c (convert_nontype_argument): Don't test whether a decl is
value-dependent when binding to a reference.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c1a8885..8239a3e 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -6749,7 +6749,11 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
}
}
- if (!value_dependent_expression_p (expr))
+ if (TREE_CODE (TREE_TYPE (expr)) == REFERENCE_TYPE
+ && value_dependent_expression_p (expr))
+ /* OK, dependent reference. We don't want to ask whether a DECL is
+ itself value-dependent, since what we want here is its address. */;
+ else
{
if (!DECL_P (expr))
{
@@ -6771,8 +6775,11 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
return NULL_TREE;
}
- expr = build_nop (type, build_address (expr));
+ expr = build_address (expr);
}
+
+ if (!same_type_p (type, TREE_TYPE (expr)))
+ expr = build_nop (type, expr);
}
/* [temp.arg.nontype]/5, bullet 4
diff --git a/gcc/testsuite/g++.dg/template/ref10.C b/gcc/testsuite/g++.dg/template/ref10.C
new file mode 100644
index 0000000..60e91d0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/ref10.C
@@ -0,0 +1,13 @@
+// PR c++/80840
+// { dg-do compile { target c++11 } }
+
+template <class T, T X>
+struct Just;
+
+template <const double& X>
+struct Number {
+ static constexpr double value = X;
+ using result = Just<const double&, value>;
+};
+
+int main() {}
reply other threads:[~2017-05-31 17:11 UTC|newest]
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