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C++ PATCH for c++/64603 (wrong error with sizeof and constexpr)
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 21 Jan 2015 16:53:56 -0500
- Subject: C++ PATCH for c++/64603 (wrong error with sizeof and constexpr)
- Authentication-results: sourceware.org; auth=none
For some reason, when converting sizeof("Main")-1 to int, we end up with
(unsigned)5UL + -1U, which fold fails to fold to 4U, but
initializer_constant_valid_p is happy to accept. I'm dealing with this
by always reprocessing expressions in the constexpr code.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit e8254e33cb727aebc874d1508b13386a6cbd093b
Author: Jason Merrill <jason@redhat.com>
Date: Wed Jan 21 07:45:02 2015 -0500
PR c++/64603
* constexpr.c (cxx_eval_constant_expression): Only shortcut
constant CONSTRUCTORs.
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index decc84d..7853d37 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -2943,9 +2943,6 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
*overflow_p = true;
return t;
}
- if (TREE_CODE (t) != NOP_EXPR
- && reduced_constant_expression_p (t))
- return fold (t);
switch (TREE_CODE (t))
{
@@ -3315,6 +3312,10 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
break;
case CONSTRUCTOR:
+ if (TREE_CONSTANT (t))
+ /* Don't re-process a constant CONSTRUCTOR, but do fold it to
+ VECTOR_CST if applicable. */
+ return fold (t);
r = cxx_eval_bare_aggregate (ctx, t, lval,
non_constant_p, overflow_p);
break;
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-sizeof1.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-sizeof1.C
new file mode 100644
index 0000000..d9a032b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-sizeof1.C
@@ -0,0 +1,15 @@
+// PR c++/64603
+// { dg-do compile { target c++11 } }
+
+template <int i> constexpr int find_longest_name()
+{
+ return sizeof("Main") - 1;
+}
+
+template <int i, int l = find_longest_name<i>()> void create_all_loggers()
+{}
+
+int main()
+{
+ create_all_loggers<1>();
+}