Revert r345562: "PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type"

This exposes a (known) CodeGen bug: it can't cope with emitting lvalue
expressions that denote non-odr-used but usable-in-constant-expression
variables. See PR39528 for a testcase.

Reverted for now until that issue can be fixed.

llvm-svn: 346065

3 files changed, 10 insertions, 53 deletions

diff --git a/clang/test/Analysis/nullptr.cpp b/clang/test/Analysis/nullptr.cpp
index e9b975c148a..38e099b7fbd 100644
--- a/clang/test/Analysis/nullptr.cpp
+++ b/clang/test/Analysis/nullptr.cpp
@@ -128,10 +128,18 @@ void shouldNotCrash() {
   decltype(nullptr) p; // expected-note{{'p' declared without an initial value}}
   if (getSymbol()) // expected-note   {{Assuming the condition is false}}
                    // expected-note@-1{{Taking false branch}}
+                   // expected-note@-2{{Assuming the condition is false}}
+                   // expected-note@-3{{Taking false branch}}
+                   // expected-note@-4{{Assuming the condition is true}}
+                   // expected-note@-5{{Taking true branch}}
+    invokeF(p); // expected-warning{{1st function call argument is an uninitialized value}}
+                // expected-note@-1{{1st function call argument is an uninitialized value}}
+  if (getSymbol()) // expected-note   {{Assuming the condition is false}}
+                   // expected-note@-1{{Taking false branch}}
                    // expected-note@-2{{Assuming the condition is true}}
                    // expected-note@-3{{Taking true branch}}
-    invokeF(p);    // expected-note   {{Calling 'invokeF'}}
-                   // expected-note@-1{{Passing null pointer value via 1st parameter 'x'}}
+    invokeF(nullptr); // expected-note   {{Calling 'invokeF'}}
+                      // expected-note@-1{{Passing null pointer value via 1st parameter 'x'}}
   if (getSymbol()) {  // expected-note  {{Assuming the condition is true}}
                       // expected-note@-1{{Taking true branch}}
     X *xx = Type().x; // expected-note   {{Null pointer value stored to field 'x'}}
diff --git a/clang/test/CXX/drs/dr21xx.cpp b/clang/test/CXX/drs/dr21xx.cpp
index b111529b09f..2522ff7dbde 100644
--- a/clang/test/CXX/drs/dr21xx.cpp
+++ b/clang/test/CXX/drs/dr21xx.cpp
@@ -19,16 +19,6 @@ namespace dr2120 { // dr2120: 7
   static_assert(!__is_standard_layout(E), "");
 }
 
-namespace dr2140 { // dr2140: 8
-#if __cplusplus >= 201103L
-  union U { int a; decltype(nullptr) b; };
-  constexpr int *test(U u) {
-    return u.b;
-  }
-  static_assert(!test({123}), "u.b should be valid even when b is inactive");
-#endif
-}
-
 namespace dr2180 { // dr2180: yes
   class A {
     A &operator=(const A &); // expected-note 0-2{{here}}
diff --git a/clang/test/CodeGenCXX/nullptr.cpp b/clang/test/CodeGenCXX/nullptr.cpp
index 222e5e5803c..e93f7061bdd 100644
--- a/clang/test/CodeGenCXX/nullptr.cpp
+++ b/clang/test/CodeGenCXX/nullptr.cpp
@@ -22,44 +22,3 @@ 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;
-}