From 0476d069e394fec587858985ddee870360aec1ee Mon Sep 17 00:00:00 2001
From: Richard Smith <richard-llvm@metafoo.co.uk>
Date: Thu, 13 Jun 2019 23:31:04 +0000
Subject: PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type
 nullptr_t does not access memory.

We now reuse CK_NullToPointer to represent a conversion from a glvalue
of type nullptr_t to a prvalue of nullptr_t where necessary.

This reinstates r345562, reverted in r346065, now that CodeGen's
handling of non-odr-used variables has been fixed.

llvm-svn: 363337
---
 clang/test/CodeGenCXX/nullptr.cpp | 47 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

(limited to 'clang/test/CodeGenCXX/nullptr.cpp')

diff --git a/clang/test/CodeGenCXX/nullptr.cpp b/clang/test/CodeGenCXX/nullptr.cpp
index e93f7061bdd..823c0d7d18a 100644
--- a/clang/test/CodeGenCXX/nullptr.cpp
+++ b/clang/test/CodeGenCXX/nullptr.cpp
@@ -22,3 +22,50 @@ void g() {
 const std::type_info& f2() {
   return typeid(nullptr_t);
 }
+
+union U {
+  int n;
+  nullptr_t b;
+};
+// CHECK-LABEL: define {{.*}}pr23833_a
+// CHECK: store
+// CHECK: load
+// CHECK-NOT: load
+// CHECK: ret i1 false
+bool pr23833_a(U &u) { return u.b; }
+
+// CHECK-LABEL: define {{.*}}pr23833_b
+// CHECK: store
+// CHECK: load
+// CHECK-NOT: load
+// CHECK: ret i8* null
+nullptr_t pr23833_b(nullptr_t &n) { return n; }
+
+struct X1 { operator int*(); };
+struct X2 { operator const nullptr_t&(); };
+
+// CHECK-LABEL: define {{.*}}pr23833_c
+// CHECK: call {{.*}}X1
+// CHECK: call {{.*}}X2
+// CHECK-NOT: load
+// CHECK: ret i32
+int pr23833_c() {
+  return X1() != X2();
+}
+
+// CHECK-LABEL: define {{.*}}pr23833_d
+// CHECK: call {{.*}}X2
+// CHECK-NOT: load
+// CHECK: store
+// CHECK: load
+// CHECK: ret i32*
+int *pr23833_d() {
+  int *p = X2();
+  return p;
+}
+
+namespace PR39528 {
+  constexpr nullptr_t null = nullptr;
+  void f(nullptr_t);
+  void g() { f(null); }
+}
-- 
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