Implement a rudimentary form of generic lambdas.

Specifically, the following features are not included in this commit:
  - any sort of capturing within generic lambdas 
  - generic lambdas within template functions and nested 
    within other generic lambdas
  - conversion operator for captureless lambdas
  - ensuring all visitors are generic lambda aware
  (Although I have gotten some useful feedback on my patches of the above and will be incorporating that as I submit those patches for commit)

As an example of what compiles through this commit:

template <class F1, class F2>
struct overload : F1, F2 {
    using F1::operator();
    using F2::operator();
    overload(F1 f1, F2 f2) : F1(f1), F2(f2) { }
  };

  auto Recursive = [](auto Self, auto h, auto ... rest) {
    return 1 + Self(Self, rest...);
  };
  auto Base = [](auto Self, auto h) {
      return 1;
  };
  overload<decltype(Base), decltype(Recursive)> O(Base, Recursive);
  int num_params =  O(O, 5, 3, "abc", 3.14, 'a');

Please see attached tests for more examples.

This patch has been reviewed by Doug and Richard.  Minor changes (non-functionality affecting) have been made since both of them formally looked at it, but the changes involve removal of supernumerary return type deduction changes (since they are now redundant, with richard having committed a recent patch to address return type deduction for C++11 lambdas using C++14 semantics). 



Some implementation notes:

  - Add a new Declarator context => LambdaExprParameterContext to 
    clang::Declarator to allow the use of 'auto' in declaring generic
    lambda parameters
      
  - Add various helpers to CXXRecordDecl to facilitate identifying
    and querying a closure class
  
  - LambdaScopeInfo (which maintains the current lambda's Sema state)
    was augmented to house the current depth of the template being
    parsed (id est the Parser calls Sema::RecordParsingTemplateParameterDepth)
    so that SemaType.cpp::ConvertDeclSpecToType may use it to immediately 
    generate a template-parameter-type when 'auto' is parsed in a generic
    lambda parameter context.  (i.e we do NOT use AutoType deduced to 
    a template parameter type - Richard seemed ok with this approach).  
    We encode that this template type was generated from an auto by simply
    adding $auto to the name which can be used for better diagnostics if needed.

  - SemaLambda.h was added to hold some common lambda utility
    functions (this file is likely to grow ...)
    
  - Teach Sema::ActOnStartOfFunctionDef to check whether it
    is being called to instantiate a generic lambda's call
    operator, and if so, push an appropriately prepared
    LambdaScopeInfo object on the stack.
    
  - various tests were added - but much more will be needed.

There is obviously more work to be done, and both Richard (weakly) and Doug (strongly) 
have requested that LambdaExpr be removed form the CXXRecordDecl LambdaDefinitionaData
in a future patch which is forthcoming.

A greatful thanks to all reviewers including Eli Friedman, James Dennett, 
and especially the two gracious wizards (Richard Smith and Doug Gregor) 
who spent hours providing feedback (in person in Chicago and on the mailing lists).  
And yet I am certain that I have allowed unidentified bugs to creep in; bugs, that I will do my best to slay, once identified!

Thanks!


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191453 91177308-0d34-0410-b5e6-96231b3b80d8
Fix up fallout from r187156.

The previous change caused the driver to translate -Wa,-L to the
-msave-temp-labels option for cc1as, but cc1as did not accept that option.
This patch follows the same approach used for similar options (-relax-all,
-noexecstack) in the previous patch.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191458 91177308-0d34-0410-b5e6-96231b3b80d8
Fix error recovery when a return type correction includes a new name specifier.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191459 91177308-0d34-0410-b5e6-96231b3b80d8
Remove an unused variable - thanks to Nick Lewycky for pointing this out!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191462 91177308-0d34-0410-b5e6-96231b3b80d8
Debug info: Fix a crash when trying to construct a type with redundant
ownership qualifiers.
Fixes rdar://problem/14990656.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191463 91177308-0d34-0410-b5e6-96231b3b80d8
ObjectiveC migrator: function pointer is not an
inner pointer for annotation to
objc_returns_inner_pointer purposes.
// rdar://15044991


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191465 91177308-0d34-0410-b5e6-96231b3b80d8
ObjectiveC migrator: Donlt annotate NS_RETURNS_INNER_POINTER
on class methods, as it makes no sense. // rdar://15069200


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191468 91177308-0d34-0410-b5e6-96231b3b80d8
Remove some stray underscores from copyright block. Fix first line length to match length of the one after the copyright block.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191483 91177308-0d34-0410-b5e6-96231b3b80d8
Sema: Respect -fdelayed-template-parsing when parsing constexpr functions

Functions declared as constexpr must have their parsing delayed in
-fdelayed-template-parsing mode so as not to upset later template
instantiation.

N.B. My reading of the standard makes it seem like delayed template
parsing is at odds with constexpr.  We may want to make refinements in
other places in clang to make constexpr play nicer with this feature.

This fixes PR17334.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191484 91177308-0d34-0410-b5e6-96231b3b80d8
NumericLiteralParser::ParseNumberStartingWithZero(): Try to appease MSC16's miscompilation.

Investigating yet. It seems msc16 miscompiles s[1] to be folded.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191485 91177308-0d34-0410-b5e6-96231b3b80d8
Add -fno-unsigned-char and ignore it. We already support -fno-signed-char, add
both flags to the driver test.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191486 91177308-0d34-0410-b5e6-96231b3b80d8
AST: Handle qualified array types in typeid() expressions

The intent of getTypeOperand() was to yield an unqualified type.
However QualType::getUnqualifiedType() does not strip away qualifiers on
arrays.

N.B.  This worked fine when typeid() was applied to an expression
because we would inject as implicit cast to the unqualified array type
in the AST.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191487 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format: Fix formatting bug with comment in weird place.

Before:
  template <typename T>
  // T should be one of {A, B}.
      void f() {}

After:
  template <typename T>
  // T should be one of {A, B}.
  void f() {}

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191492 91177308-0d34-0410-b5e6-96231b3b80d8
AST: Handle multidimensional arrays inside of __uuidof()

We previously handled one-dimensional arrays but didn't consider the
general case.  The fix is simple: keep going through subsequent
dimensions until we get to the base element.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191493 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format: Improve formatting of functions with multiple trailing tokens.

Before:
  void SomeFunction(aaaaaaaaaaaaaaaaaaaaaaaaaa,
                    aaaaaaaaaaaaaaaaaaaaaaaaaa) override
  final;

After:
  void SomeFunction(aaaaaaaaaaaaaaaaaaaaaaaaaa,
                    aaaaaaaaaaaaaaaaaaaaaaaaaa) override final;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191494 91177308-0d34-0410-b5e6-96231b3b80d8
Correctly indent with tabs when whitespace starts from the column not divisible by TabWidth.

Summary:
The width of the first inserted tab character depends on the initial
column, so we need to handle the first tab in a special manner.

Reviewers: klimek, djasper

Reviewed By: klimek

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1763

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191497 91177308-0d34-0410-b5e6-96231b3b80d8
Abstract out the emission of vtables, add basic support for vtable emission when using -cxx-abi microsoft

Reviewed at http://llvm-reviews.chandlerc.com/D1532

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191523 91177308-0d34-0410-b5e6-96231b3b80d8
Implemented tab usage only for indentation (http://llvm.org/PR17363)

Summary:
Changed UseTab to be a enum with three options: Never, Always,
ForIndentation (true/false are still supported when reading .clang-format).
IndentLevel should currently be propagated correctly for all tokens, except for
block comments. Please take a look at the general idea before I start dealing
with block comments.

Reviewers: klimek, djasper

Reviewed By: klimek

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1770

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191527 91177308-0d34-0410-b5e6-96231b3b80d8
Updated clang-format style options doc.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191528 91177308-0d34-0410-b5e6-96231b3b80d8
Updated examples of UseTab option

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@191529 91177308-0d34-0410-b5e6-96231b3b80d8