From 46ab17dbae559b0823d43f6f8ffb12f9dc0d10d5 Mon Sep 17 00:00:00 2001
From: Patrick Palka <ppalka@gcc.gnu.org>
Date: Fri, 18 Dec 2015 23:16:33 +0000
Subject: Fix PR c++/68978 (bogus error: lvalue required as left operand of
 assignment)

gcc/cp/ChangeLog:

	PR c++/68978
	* tree.c (lvalue_kind) [MODOP_EXPR]: New case.

gcc/testsuite/ChangeLog:

	PR c++/68978
	* g++.dg/template/pr68978.C: New test.

From-SVN: r231841
---
 gcc/cp/ChangeLog                        |  5 +++++
 gcc/cp/tree.c                           |  6 +++++
 gcc/testsuite/ChangeLog                 |  5 +++++
 gcc/testsuite/g++.dg/template/pr68978.C | 39 +++++++++++++++++++++++++++++++++
 4 files changed, 55 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/template/pr68978.C

(limited to 'gcc')

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index d471721..9b8c2ff 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2015-12-18  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/68978
+	* tree.c (lvalue_kind) [MODOP_EXPR]: New case.
+
 2015-12-18  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/67592
diff --git a/gcc/cp/tree.c b/gcc/cp/tree.c
index ae176d0..250fe27 100644
--- a/gcc/cp/tree.c
+++ b/gcc/cp/tree.c
@@ -185,6 +185,12 @@ lvalue_kind (const_tree ref)
       op2_lvalue_kind = lvalue_kind (TREE_OPERAND (ref, 2));
       break;
 
+    case MODOP_EXPR:
+      /* We expect to see unlowered MODOP_EXPRs only during
+	 template processing.  */
+      gcc_assert (processing_template_decl);
+      return clk_ordinary;
+
     case MODIFY_EXPR:
     case TYPEID_EXPR:
       return clk_ordinary;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ceba598..20ac322 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-12-18  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/68978
+	* g++.dg/template/pr68978.C: New test.
+
 2015-12-18  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/68860
diff --git a/gcc/testsuite/g++.dg/template/pr68978.C b/gcc/testsuite/g++.dg/template/pr68978.C
new file mode 100644
index 0000000..1904532
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/pr68978.C
@@ -0,0 +1,39 @@
+// PR c++/68978
+
+int i = 0, c = 0, radix = 10, max = 0x7fffffff;
+
+template <typename T> int toi_1() {
+  if (max < ((i *= radix) += c))
+    return 0;
+  return i;
+}
+
+template <typename T> int toi_2() {
+  if (max < ((i = radix) = c))
+    return 0;
+  return i;
+}
+
+template <typename T> int toi_3() {
+  if (max < ((i = radix) += c))
+    return 0;
+  return i;
+}
+
+template <typename T> int toi_4() {
+  if (max < ((i += radix) = c))
+    return 0;
+  return i;
+}
+
+template <typename T> int toi_5() {
+  if (max < (((i = radix) += (c += 5)) *= 30))
+    return 0;
+  return i;
+}
+
+int x = toi_1<int> ();
+int y = toi_2<int> ();
+int z = toi_3<int> ();
+int w = toi_4<int> ();
+int r = toi_5<int> ();
-- 
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