[Sema] Fix built-in decrement operator overload resolution

C++ [over.built] p4:

"For every pair (T, VQ), where T is an arithmetic type other than bool, and VQ is either volatile or empty, there exist candidate operator functions of the form

  VQ T&      operator--(VQ T&);
  T          operator--(VQ T&, int);
"
The bool type is in position LastPromotedIntegralType in BuiltinOperatorOverloadBuilder::getArithmeticType::ArithmeticTypes, but addPlusPlusMinusMinusArithmeticOverloads() was expecting it at position 0.

Differential Revision: https://reviews.llvm.org/D44988

rdar://problem/34255516

llvm-svn: 329804

2 files changed, 21 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index bae2783bea5..7905f5e6228 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -7796,10 +7796,12 @@ public:
     if (!HasArithmeticOrEnumeralCandidateType)
       return;
 
-    for (unsigned Arith = (Op == OO_PlusPlus? 0 : 1);
-         Arith < NumArithmeticTypes; ++Arith) {
+    for (unsigned Arith = 0; Arith < NumArithmeticTypes; ++Arith) {
+      const auto TypeOfT = ArithmeticTypes[Arith];
+      if (Op == OO_MinusMinus && TypeOfT == S.Context.BoolTy)
+        continue;
       addPlusPlusMinusMinusStyleOverloads(
-        ArithmeticTypes[Arith],
+        TypeOfT,
         VisibleTypeConversionsQuals.hasVolatile(),
         VisibleTypeConversionsQuals.hasRestrict());
     }
diff --git a/clang/test/SemaCXX/overloaded-builtin-operators.cpp b/clang/test/SemaCXX/overloaded-builtin-operators.cpp
index 7a99a898e20..4fa376aed03 100644
--- a/clang/test/SemaCXX/overloaded-builtin-operators.cpp
+++ b/clang/test/SemaCXX/overloaded-builtin-operators.cpp
@@ -62,6 +62,10 @@ void f(Short s, Long l, Enum1 e1, Enum2 e2, Xpmf pmf) {
   // FIXME: should pass (void)static_cast<no&>(islong(e1 % e2));
 }
 
+struct BoolRef {
+  operator bool&();
+};
+
 struct ShortRef { // expected-note{{candidate function (the implicit copy assignment operator) not viable}}
 #if __cplusplus >= 201103L // C++11 or later
 // expected-note@-2 {{candidate function (the implicit move assignment operator) not viable}}
@@ -73,6 +77,10 @@ struct LongRef {
   operator volatile long&();
 };
 
+struct FloatRef {
+  operator float&();
+};
+
 struct XpmfRef { // expected-note{{candidate function (the implicit copy assignment operator) not viable}}
 #if __cplusplus >= 201103L // C++11 or later
 // expected-note@-2 {{candidate function (the implicit move assignment operator) not viable}}
@@ -84,13 +92,19 @@ struct E2Ref {
   operator E2&();
 };
 
-void g(ShortRef sr, LongRef lr, E2Ref e2_ref, XpmfRef pmf_ref) {
+void g(BoolRef br, ShortRef sr, LongRef lr, FloatRef fr, E2Ref e2_ref, XpmfRef pmf_ref) {
   // C++ [over.built]p3
   short s1 = sr++;
 
-  // C++ [over.built]p3
+  // C++ [over.built]p4
   long l1 = lr--;
 
+  // C++ [over.built]p4
+  float f1 = fr--;
+
+  // C++ [over.built]p4
+  bool b2 = br--; // expected-error{{cannot decrement value of type 'BoolRef'}}
+
   // C++ [over.built]p18
   short& sr1 = (sr *= lr);
   volatile long& lr1 = (lr *= sr);