re PR c++/83806 (Spurious -Wunused-but-set-parameter with nullptr)

/cp
2018-02-08  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/83806
	* typeck.c (decay_conversion): Use mark_rvalue_use for the special
	case of nullptr too.

/testsuite
2018-02-08  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/83806
	* g++.dg/warn/Wunused-parm-11.C: New.

From-SVN: r257502

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 2fc35d2..c68b590 100644 (file)
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2018-02-08  Paolo Carlini  <paolo.carlini@oracle.com>
+
+       PR c++/83806
+       * typeck.c (decay_conversion): Use mark_rvalue_use for the special
+       case of nullptr too.
+
 2018-02-08  Nathan Sidwell  <nathan@acm.org>
 
        * class.c (finish_struct): Fix std:initializer_list diagnostic

diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 83e7678..fe18ea9 100644 (file)
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -2009,7 +2009,10 @@ decay_conversion (tree exp,
     return error_mark_node;
 
   if (NULLPTR_TYPE_P (type) && !TREE_SIDE_EFFECTS (exp))
-    return nullptr_node;
+    {
+      mark_rvalue_use (exp, loc, reject_builtin);
+      return nullptr_node;
+    }
 
   /* build_c_cast puts on a NOP_EXPR to make the result not an lvalue.
      Leave such NOP_EXPRs, since RHS is being used in non-lvalue context.  */

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 92e9e34..c51d2dd 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-02-08  Paolo Carlini  <paolo.carlini@oracle.com>
+
+       PR c++/83806
+       * g++.dg/warn/Wunused-parm-11.C: New.
+
 2018-02-08  Marek Polacek  <polacek@redhat.com>
 
        PR tree-optimization/84238

diff --git a/gcc/testsuite/g++.dg/warn/Wunused-parm-11.C b/gcc/testsuite/g++.dg/warn/Wunused-parm-11.C
new file mode 100644 (file)
index 0000000..35896df
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-parm-11.C
@@ -0,0 +1,13 @@
+// PR c++/83806
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wunused-but-set-parameter" }
+
+template <class X, class Y>
+bool equals(X x, Y y) {
+    return (x == y); 
+}
+
+int main() {
+    const char* p = nullptr;
+    equals(p, nullptr);
+}