From 1439f35553a8aaa034deda26b4072bdec4af8f79 Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Fri, 11 Jan 2019 23:21:40 +0000
Subject: [PATCH] PR c++/88692, c++/87882 - -Wredundant-move false positive
 with *this.

	* typeck.c (maybe_warn_pessimizing_move): Return if ARG isn't
	ADDR_EXPR.

	* g++.dg/cpp0x/Wredundant-move5.C: New test.
	* g++.dg/cpp0x/Wredundant-move6.C: New test.

From-SVN: r267862
---
 gcc/cp/ChangeLog                              |  6 +++
 gcc/cp/typeck.c                               |  5 +-
 gcc/testsuite/ChangeLog                       |  6 +++
 gcc/testsuite/g++.dg/cpp0x/Wredundant-move5.C | 53 +++++++++++++++++++
 gcc/testsuite/g++.dg/cpp0x/Wredundant-move6.C | 43 +++++++++++++++
 5 files changed, 111 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/Wredundant-move5.C
 create mode 100644 gcc/testsuite/g++.dg/cpp0x/Wredundant-move6.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 0eb669b3eac..9c661a5ced2 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-11  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/88692, c++/87882 - -Wredundant-move false positive with *this.
+	* typeck.c (maybe_warn_pessimizing_move): Return if ARG isn't
+	ADDR_EXPR.
+
 2019-01-11  Jason Merrill  <jason@redhat.com>
 
 	PR c++/88312 - pack expansion of decltype.
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index e399cd3fe45..43d2899a3c4 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -9412,8 +9412,9 @@ maybe_warn_pessimizing_move (tree retval, tree functype)
 	{
 	  tree arg = CALL_EXPR_ARG (fn, 0);
 	  STRIP_NOPS (arg);
-	  if (TREE_CODE (arg) == ADDR_EXPR)
-	    arg = TREE_OPERAND (arg, 0);
+	  if (TREE_CODE (arg) != ADDR_EXPR)
+	    return;
+	  arg = TREE_OPERAND (arg, 0);
 	  arg = convert_from_reference (arg);
 	  /* Warn if we could do copy elision were it not for the move.  */
 	  if (can_do_nrvo_p (arg, functype))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f991df8673c..11845e3d0cc 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-11  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/88692, c++/87882 - -Wredundant-move false positive with *this.
+	* g++.dg/cpp0x/Wredundant-move5.C: New test.
+	* g++.dg/cpp0x/Wredundant-move6.C: New test.
+
 2019-01-11  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/85956
diff --git a/gcc/testsuite/g++.dg/cpp0x/Wredundant-move5.C b/gcc/testsuite/g++.dg/cpp0x/Wredundant-move5.C
new file mode 100644
index 00000000000..0e2ec46d11e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/Wredundant-move5.C
@@ -0,0 +1,53 @@
+// PR c++/88692
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wredundant-move" }
+
+// Define std::move.
+namespace std {
+  template<typename _Tp>
+    struct remove_reference
+    { typedef _Tp   type; };
+
+  template<typename _Tp>
+    struct remove_reference<_Tp&>
+    { typedef _Tp   type; };
+
+  template<typename _Tp>
+    struct remove_reference<_Tp&&>
+    { typedef _Tp   type; };
+
+  template<typename _Tp>
+    constexpr typename std::remove_reference<_Tp>::type&&
+    move(_Tp&& __t) noexcept
+    { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
+}
+
+struct X {
+    X f() && {
+        return std::move(*this); // { dg-bogus "redundant move in return statement" }
+    }
+
+    X f2() & {
+        return std::move(*this); // { dg-bogus "redundant move in return statement" }
+    }
+
+    X f3() {
+        return std::move(*this); // { dg-bogus "redundant move in return statement" }
+    }
+};
+
+struct S { int i; int j; };
+
+struct Y {
+  S f1 (S s) {
+    return std::move (s); // { dg-warning "redundant move in return statement" }
+  }
+
+  S f2 (S* s) {
+    return std::move (*s); // { dg-bogus "redundant move in return statement" }
+  }
+
+  S f3 (S** s) {
+    return std::move (**s); // { dg-bogus "redundant move in return statement" }
+  }
+};
diff --git a/gcc/testsuite/g++.dg/cpp0x/Wredundant-move6.C b/gcc/testsuite/g++.dg/cpp0x/Wredundant-move6.C
new file mode 100644
index 00000000000..5808a78638e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/Wredundant-move6.C
@@ -0,0 +1,43 @@
+// PR c++/87882
+// { dg-do compile { target c++11 } }
+// { dg-options "-Wredundant-move" }
+
+// Define std::move.
+namespace std {
+  template<typename _Tp>
+    struct remove_reference
+    { typedef _Tp   type; };
+
+  template<typename _Tp>
+    struct remove_reference<_Tp&>
+    { typedef _Tp   type; };
+
+  template<typename _Tp>
+    struct remove_reference<_Tp&&>
+    { typedef _Tp   type; };
+
+  template<typename _Tp>
+    constexpr typename std::remove_reference<_Tp>::type&&
+    move(_Tp&& __t) noexcept
+    { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
+}
+
+struct Foo {
+   Foo Bar() {
+     return std::move(*this); // { dg-bogus "redundant move in return statement" }
+   }
+   Foo Baz() {
+     return *this;
+   }
+  int i;
+};
+
+void Move(Foo & f)
+{
+  f = Foo{}.Bar();
+}
+
+void NoMove(Foo & f)
+{
+  f = Foo{}.Baz();
+}
-- 
2.30.2