On Wed, Jan 10, 2018 at 11:59 AM, Jason Merrill <ja...@redhat.com> wrote:
> On Wed, Jan 10, 2018 at 11:56 AM, Jakub Jelinek <ja...@redhat.com> wrote:
>> On Wed, Jan 10, 2018 at 11:52:16AM -0500, Jason Merrill wrote:
>>> On Fri, Jan 5, 2018 at 5:14 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>>> > Jason's recent change removed a mark_rvalue_use call from
>>> > constant_value_1,
>>> > which unfortunately regressed quite a few cases where
>>> > -Wunused-but-set-variable now has false positives.
>>>
>>> > The easiest fix seems to be just deal with the -Wunused-but-set-variable
>>> > issue at that point.
>>>
>>> Hmm, we ought to have called mark_rvalue_use before we get here. I'm
>>> concerned that these issues indicate that lambda captures won't work
>>> in the situations in the testcase, since we rely on mark_rvalue_use to
>>> look through them.
>>
>> Unless you have ideas where to put those mark_rvalue_use calls, I'll defer
>> these PRs to you then, this was just an attempt for an easy way out of it
>> for the warning. At least the testcases should be usable for future patch.
>
> Makes sense, thanks.
Fixed thus:
commit b84a080faaf81b956ae930ba092dd0caf5669fc0
Author: Jason Merrill <ja...@redhat.com>
Date: Wed Jan 10 17:36:01 2018 -0500
PR c++/82728 - wrong -Wunused-but-set-variable
PR c++/82799
PR c++/83690
* call.c (perform_implicit_conversion_flags): Call mark_rvalue_use.
* decl.c (case_conversion): Likewise.
* semantics.c (finish_static_assert): Call
perform_implicit_conversion_flags.
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index c822a70a017..5f2c6becb35 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -10514,6 +10514,11 @@ perform_implicit_conversion_flags (tree type, tree
expr,
void *p;
location_t loc = EXPR_LOC_OR_LOC (expr, input_location);
+ if (TREE_CODE (type) == REFERENCE_TYPE)
+ expr = mark_lvalue_use (expr);
+ else
+ expr = mark_rvalue_use (expr);
+
if (error_operand_p (expr))
return error_mark_node;
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 6ba657801d9..ee469d35137 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -3541,6 +3541,8 @@ case_conversion (tree type, tree value)
if (value == NULL_TREE)
return value;
+ value = mark_rvalue_use (value);
+
if (cxx_dialect >= cxx11
&& (SCOPED_ENUM_P (type)
|| !INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P (TREE_TYPE (value))))
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 60608c797f2..f9c5285f724 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -8608,6 +8608,8 @@ void
finish_static_assert (tree condition, tree message, location_t location,
bool member_p)
{
+ tsubst_flags_t complain = tf_warning_or_error;
+
if (message == NULL_TREE
|| message == error_mark_node
|| condition == NULL_TREE
@@ -8640,9 +8642,9 @@ finish_static_assert (tree condition, tree message,
location_t location,
}
/* Fold the expression and convert it to a boolean value. */
- condition = instantiate_non_dependent_expr (condition);
- condition = cp_convert (boolean_type_node, condition, tf_warning_or_error);
- condition = maybe_constant_value (condition);
+ condition = perform_implicit_conversion_flags (boolean_type_node, condition,
+ complain, LOOKUP_NORMAL);
+ condition = fold_non_dependent_expr (condition);
if (TREE_CODE (condition) == INTEGER_CST && !integer_zerop (condition))
/* Do nothing; the condition is satisfied. */
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch2.C
b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch2.C
new file mode 100644
index 00000000000..677f3056bf8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-switch2.C
@@ -0,0 +1,18 @@
+// PR c++/82728
+// { dg-do compile { target c++11 } }
+
+void
+foo ()
+{
+ const int i = 1;
+
+ [=]()
+ {
+ switch (0)
+ {
+ case i:
+ break;
+ }
+ static_assert (i, "i");
+ };
+}
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-27.C
b/gcc/testsuite/g++.dg/warn/Wunused-var-27.C
new file mode 100644
index 00000000000..0ef71531284
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-27.C
@@ -0,0 +1,14 @@
+// PR c++/82728
+// { dg-do compile }
+// { dg-options "-Wunused-but-set-variable" }
+
+void
+foo ()
+{
+ const int i = 1; // { dg-bogus "set but not used" }
+ switch (0)
+ {
+ case i:
+ break;
+ }
+}
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-28.C
b/gcc/testsuite/g++.dg/warn/Wunused-var-28.C
new file mode 100644
index 00000000000..69601671535
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-28.C
@@ -0,0 +1,15 @@
+// PR c++/82799
+// { dg-do compile }
+// { dg-options "-Wunused-but-set-variable" }
+
+enum E { b };
+struct C {
+ template <E>
+ int foo ()
+ {
+ const bool i = 0; // { dg-bogus "set but not used" }
+ const int r = i ? 7 : 9;
+ return r;
+ }
+ void bar () { foo <b> (); }
+};
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-29.C
b/gcc/testsuite/g++.dg/warn/Wunused-var-29.C
new file mode 100644
index 00000000000..24eeb958f4a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-29.C
@@ -0,0 +1,10 @@
+// PR c++/83690
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused-but-set-variable" }
+
+void
+foo ()
+{
+ constexpr bool foo = true; // { dg-bogus "set but not used" }
+ static_assert (foo, "foo");
+}
