Implement the lvalue-to-rvalue conversion where needed. The
lvalue-to-rvalue conversion adjusts lvalues of qualified, non-class
type to rvalue expressions of the unqualified variant of that
type. For example, given:

  const int i;
  (void)(i + 17);

the lvalue-to-rvalue conversion for the subexpression "i" will turn it
from an lvalue expression (a DeclRefExpr) with type 'const int' into
an rvalue expression with type 'int'. Both C and C++ mandate this
conversion, and somehow we've slid through without implementing it. 

We now have both DefaultFunctionArrayConversion and
DefaultFunctionArrayLvalueConversion, and which gets used depends on
whether we do the lvalue-to-rvalue conversion or not. Generally, we do
the lvalue-to-rvalue conversion, but there are a few notable
exceptions:
  - the left-hand side of a '.' operator
  - the left-hand side of an assignment
  - a C++ throw expression
  - a subscript expression that's subscripting a vector

Making this change exposed two issues with blocks:
  - we were deducing const-qualified return types of non-class type
  from a block return, which doesn't fit well
  - we weren't always setting the known return type of a block when it
  was provided with the ^return-type syntax

Fixes the current Clang-on-Clang compile failure and PR6076.

llvm-svn: 95167
diff --git a/clang/test/SemaCXX/reinterpret-cast.cpp b/clang/test/SemaCXX/reinterpret-cast.cpp
index da67560..f7ab80e 100644
--- a/clang/test/SemaCXX/reinterpret-cast.cpp
+++ b/clang/test/SemaCXX/reinterpret-cast.cpp
@@ -47,7 +47,7 @@
   // Invalid: T1 const* -> T2*
   (void)reinterpret_cast<int*>(icp); // expected-error {{reinterpret_cast from 'int const *' to 'int *' casts away constness}}
   // Invalid: T1*** -> T2 const* const**
-  int const *const **icpcpp = reinterpret_cast<int const* const**>(ipppc); // expected-error {{reinterpret_cast from 'int ***const' to 'int const *const **' casts away constness}}
+  int const *const **icpcpp = reinterpret_cast<int const* const**>(ipppc); // expected-error {{reinterpret_cast from 'int ***' to 'int const *const **' casts away constness}}
   // Valid: T1* -> T2*
   int *ip = reinterpret_cast<int*>(icpcpp);
   // Valid: T* -> T const*