Force a load when creating a reference to a temporary copied from a bitfield.

For this source:
  const int &ref = someStruct.bitfield;

We used to generate this AST:

  DeclStmt [...]
  `-VarDecl [...] ref 'const int &'
    `-MaterializeTemporaryExpr [...] 'const int' lvalue
      `-ImplicitCastExpr [...] 'const int' lvalue <NoOp>
        `-MemberExpr [...] 'int' lvalue bitfield .bitfield [...]
          `-DeclRefExpr [...] 'struct X' lvalue ParmVar [...] 'someStruct' 'struct X'

Notice the lvalue inside the MaterializeTemporaryExpr, which is very
confusing (and caused an assertion to fire in the analyzer - PR15694).

We now generate this:

  DeclStmt [...]
  `-VarDecl [...] ref 'const int &'
    `-MaterializeTemporaryExpr [...] 'const int' lvalue
      `-ImplicitCastExpr [...] 'int' <LValueToRValue>
        `-MemberExpr [...] 'int' lvalue bitfield .bitfield [...]
          `-DeclRefExpr [...] 'struct X' lvalue ParmVar [...] 'someStruct' 'struct X'

Which makes a lot more sense. This allows us to remove code in both
CodeGen and AST that hacked around this special case.

The commit also makes Clang accept this (legal) C++11 code:

  int &&ref = std::move(someStruct).bitfield

PR15694 / <rdar://problem/13600396>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179250 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/test/Analysis/reference.cpp b/test/Analysis/reference.cpp
index 8dd0baf8c3..bcab80b04b 100644
--- a/test/Analysis/reference.cpp
+++ b/test/Analysis/reference.cpp
@@ -224,3 +224,13 @@ namespace rdar11212286 {
     return *x; // no-warning
   }
 }
+
+namespace PR15694 {
+  class C {
+    bool bit : 1;
+    template <class T> void bar(const T &obj) {}
+    void foo() {
+      bar(bit); // don't crash
+    }
+  };
+}