[cfe-dev] RFC: Nullability qualifiers

Sat Jun 27 05:06:58 PDT 2015

I figured out my issue. I was compiling with -std=c++14 and the nullability
and assume_nonnull features are only enabled for ObjC and GNU mode. Why are
these only supported in GNU mode? I thought GNU mode was only for features
that contradict the standard. How does this feature contradict the standard
given that the names are double and single underscore prefixed? I would
rather not have to compile my code in GNU mode just to enable nullability.
I can check with __has_extension() but at least Apple headers seem to only
use __has_feature so the checks there won't be enabled when not compiling
in GNU mode. If the consensus is that __has_feature(nullability) should
only be enabled for GNU mode, would it make sense to have an f-group flag
like -fnullability to enable it for __has_feature when not compiling in GNU
mode?

Also I found a bug in clang. __has_extension(assume_nonnull) doesn't work
properly. It is missing from the StringCase at the end of the
HasExtension() function in lib/Lex/PPMacroExpansion.cpp. I think it should
be there.

On Sat, Jun 27, 2015 at 12:44 AM, b17 c0de <b17c0de at gmail.com> wrote:

> Apple please implement  __has_feature(nullability) in clang for Xcode 7
> release. :-)
>
>
> On Sat, Jun 27, 2015 at 12:31 AM, Aaron Ballman <aaron at aaronballman.com>
> wrote:
>
>> On Fri, Jun 26, 2015 at 6:29 PM, b17 c0de <b17c0de at gmail.com> wrote:
>> >  It also appears that the current versions of Apple clang (even the
>> newest
>> > beta) don't even support __has_feature(nullability). I take it this has
>> been
>> > fixed in trunk?
>>
>> Correct, trunk is likely also the only place that has _Nonnull and
>> friends, too. If you're developing on OS X and don't need cross
>> compiler support for your code base, I would stick with __nonnull
>> there and you'll be fine. If you need cross compiler support, you'll
>> likely have to piece it together with macros.
>>
>> ~Aaron
>>
>> >
>> > On Fri, Jun 26, 2015 at 11:53 PM, Aaron Ballman <aaron at aaronballman.com
>> >
>> > wrote:
>> >>
>> >> On Fri, Jun 26, 2015 at 5:44 PM, b17 c0de <b17c0de at gmail.com> wrote:
>> >> > OK. What would be the best way to detect if Apple clang supports
>> >> > _Nonnull or
>> >> > only __nonnull though.
>> >>
>> >> I cannot speak for how Apple's Clang works in this regard, but perhaps
>> >> Doug can.
>> >>
>> >> ~Aaron
>> >>
>> >> >
>> >> > On Fri, Jun 26, 2015 at 11:40 PM, Aaron Ballman <
>> aaron at aaronballman.com>
>> >> > wrote:
>> >> >>
>> >> >> On Fri, Jun 26, 2015 at 5:36 PM, b17 c0de <b17c0de at gmail.com>
>> wrote:
>> >> >> > How can one detect if an Apple clang supports the new nullability
>> >> >> > attributes. I tried something like:
>> >> >> >
>> >> >> > #if __has_attribute(_Nonnull)
>> >> >> > #elif __has_attribute(__nonnull)
>> >> >> > #define _Nonnull __nonnull
>> >> >> > #else
>> >> >> > #define _Nonnull
>> >> >> > #endif
>> >> >> >
>> >> >> > But this didn't work. Why doesn't _Nonnull/__nonnull work with
>> >> >> > __has_attribute?
>> >> >>
>> >> >> __has_attribute is used to test for GNU-style attribute support
>> only.
>> >> >> To test for nullability, you should use: __has_feature(nullability)
>> >> >>
>> >> >> ~Aaron
>> >> >>
>> >> >> >
>> >> >> > On Wed, Jun 24, 2015 at 10:39 PM, Douglas Gregor <
>> dgregor at apple.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> Another addendum: due to the conflict with glibc’s __nonnull,
>> we’ll
>> >> >> >> be
>> >> >> >> renaming the __double_underscored keywords to _Big_underscored
>> >> >> >> keywords,
>> >> >> >> e.g.,
>> >> >> >>
>> >> >> >> __nonnull -> _Nonnull
>> >> >> >> __nullable -> _Nullable
>> >> >> >> __null_unspecified -> _Null_unspecified
>> >> >> >>
>> >> >> >> On Darwin, we’ll add predefines
>> >> >> >>
>> >> >> >> #define __nonnull _Nonnull
>> >> >> >> #define __nullable _Nullable
>> >> >> >> #define __null_unspecified _Null_unspecified
>> >> >> >>
>> >> >> >> to keep the existing headers working.
>> >> >> >>
>> >> >> >> - Doug
>> >> >> >>
>> >> >> >> On Mar 2, 2015, at 1:22 PM, Douglas Gregor <dgregor at apple.com>
>> >> >> >> wrote:
>> >> >> >>
>> >> >> >> Hello all,
>> >> >> >>
>> >> >> >> Null pointers are a significant source of problems in
>> applications.
>> >> >> >> Whether it’s SIGSEGV taking down a process or a foolhardy
>> attempt to
>> >> >> >> recover
>> >> >> >> from NullPointerException breaking invariants everywhere, it’s a
>> >> >> >> problem
>> >> >> >> that’s bad enough for Tony Hoare to call the invention of the
>> null
>> >> >> >> reference
>> >> >> >> his billion dollar mistake [1]. It’s not the ability to create a
>> >> >> >> null
>> >> >> >> pointer that is a problem—having a common sentinel value meaning
>> “no
>> >> >> >> value”
>> >> >> >> is extremely useful—but that it’s very hard to determine whether,
>> >> >> >> for a
>> >> >> >> particular pointer, one is expected to be able to use null. C
>> >> >> >> doesn’t
>> >> >> >> distinguish between “nullable” and “nonnull” pointers, so we
>> turn to
>> >> >> >> documentation and experimentation. Consider strchr from the C
>> >> >> >> standard
>> >> >> >> library:
>> >> >> >>
>> >> >> >> char *strchr(const char *s, int c);
>> >> >> >>
>> >> >> >> It is “obvious” to a programmer who knows the semantics of strchr
>> >> >> >> that
>> >> >> >> it’s important to check for a returned null, because null is
>> used as
>> >> >> >> the
>> >> >> >> sentinel for “not found”. Of course, your tools don’t know that,
>> so
>> >> >> >> they
>> >> >> >> cannot help when you completely forget to check for the null
>> case.
>> >> >> >> Bugs
>> >> >> >> ensue.
>> >> >> >>
>> >> >> >> Can I pass a null string to strchr? The standard is unclear [2],
>> and
>> >> >> >> my
>> >> >> >> platform’s implementation happily accepts a null parameter and
>> >> >> >> returns
>> >> >> >> null,
>> >> >> >> so obviously I shouldn’t worry about it… until I port my code, or
>> >> >> >> the
>> >> >> >> underlying implementation changes because my expectations and the
>> >> >> >> library
>> >> >> >> implementor’s expectations differ. Given the age of strchr, I
>> >> >> >> suspect
>> >> >> >> that
>> >> >> >> every implementation out there has an explicit, defensive check
>> for
>> >> >> >> a
>> >> >> >> null
>> >> >> >> string, because it’s easier to add yet more defensive (and
>> generally
>> >> >> >> useless) null checks than it is to ask your clients to fix their
>> >> >> >> code.
>> >> >> >> Scale
>> >> >> >> this up, and code bloat ensues, as well as wasted programmer
>> effort
>> >> >> >> that
>> >> >> >> obscures the places where checking for null really does matter.
>> >> >> >>
>> >> >> >> In a recent version of Xcode, Apple introduced an extension to
>> >> >> >> C/C++/Objective-C that expresses the nullability of pointers in
>> the
>> >> >> >> type
>> >> >> >> system via new nullability qualifiers . Nullability qualifiers
>> >> >> >> express
>> >> >> >> nullability as part of the declaration of strchr  [2]:
>> >> >> >>
>> >> >> >> __nullable char *strchr(__nonnull const char *s, int c);
>> >> >> >>
>> >> >> >> With this, programmers and tools alike can better reason about
>> the
>> >> >> >> use
>> >> >> >> of
>> >> >> >> strchr with null pointers.
>> >> >> >>
>> >> >> >> We’d like to contribute the implementation (and there is a patch
>> >> >> >> attached
>> >> >> >> at the end [3]), but since this is a nontrivial extension to all
>> of
>> >> >> >> the
>> >> >> >> C
>> >> >> >> family of languages that Clang supports, we believe that it
>> needs to
>> >> >> >> be
>> >> >> >> discussed here first.
>> >> >> >>
>> >> >> >> Goals
>> >> >> >> We have several specific goals that informed the design of this
>> >> >> >> feature.
>> >> >> >>
>> >> >> >> Allow the intended nullability to be expressed on all pointers:
>> >> >> >> Pointers
>> >> >> >> are used throughout library interfaces, and the nullability of
>> those
>> >> >> >> pointers is an important part of the API contract with users.
>> It’s
>> >> >> >> too
>> >> >> >> simplistic to only allow function parameters to have nullability,
>> >> >> >> for
>> >> >> >> example, because it’s also important information for data
>> members,
>> >> >> >> pointers-to-pointers (e.g., "a nonnull pointer to a nullable
>> pointer
>> >> >> >> to
>> >> >> >> an
>> >> >> >> integer”), arrays of pointers, etc.
>> >> >> >> Enable better tools support for detecting nullability problems:
>> The
>> >> >> >> nullability annotations should be useful for tools (especially
>> the
>> >> >> >> static
>> >> >> >> analyzer) that can reason about the use of null, to give warnings
>> >> >> >> about
>> >> >> >> both
>> >> >> >> missed null checks (the result of strchr could be null…) as well
>> as
>> >> >> >> for
>> >> >> >> unnecessarily-defensive code.
>> >> >> >> Support workflows where all interfaces provide nullability
>> >> >> >> annotations:
>> >> >> >> In
>> >> >> >> moving from a world where there are no nullability annotations to
>> >> >> >> one
>> >> >> >> where
>> >> >> >> we hope to see many such annotations, we’ve found it helpful to
>> move
>> >> >> >> header-by-header, auditing a complete header to give it
>> nullability
>> >> >> >> qualifiers. Once one has done that, additions to the header need
>> to
>> >> >> >> be
>> >> >> >> held
>> >> >> >> to the same standard, so we need a design that allows us to warn
>> >> >> >> about
>> >> >> >> pointers that don’t provide nullability annotations for some
>> >> >> >> declarations in
>> >> >> >> a header that already has some nullability annotations.
>> >> >> >>
>> >> >> >> Zero effect on ABI or code generation: There are a huge number of
>> >> >> >> interfaces that could benefit from the use of nullability
>> >> >> >> qualifiers,
>> >> >> >> but we
>> >> >> >> won’t get widespread adoption if introducing the nullability
>> >> >> >> qualifiers
>> >> >> >> means breaking existing code, either in the ABI (say, because
>> >> >> >> nullability
>> >> >> >> qualifiers are mangled into the type) or at execution time (e.g.,
>> >> >> >> because a
>> >> >> >> non-null pointer ends up being null along some error path and
>> causes
>> >> >> >> undefined behavior).
>> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >> >> Why not __attribute__((nonnull))?
>> >> >> >> Clang already has an attribute to express nullability, “nonnull”,
>> >> >> >> which
>> >> >> >> we
>> >> >> >> inherited from GCC [4]. The “nonnull” attribute can be placed on
>> >> >> >> functions
>> >> >> >> to indicate which parameters cannot be null: one either specifies
>> >> >> >> the
>> >> >> >> indices of the arguments that cannot be null, e.g.,
>> >> >> >>
>> >> >> >> extern void *my_memcpy (void *dest, const void *src, size_t len)
>> >> >> >> __attribute__((nonnull (1, 2)));
>> >> >> >>
>> >> >> >> or omits the list of indices to state that all pointer arguments
>> >> >> >> cannot
>> >> >> >> be
>> >> >> >> null, e.g.,
>> >> >> >>
>> >> >> >> extern void *my_memcpy (void *dest, const void *src, size_t len)
>> >> >> >> __attribute__((nonnull));
>> >> >> >>
>> >> >> >> More recently, “nonnull”  has grown the ability to be applied to
>> >> >> >> parameters, and one can use the companion attribute
>> returns_nonnull
>> >> >> >> to
>> >> >> >> state
>> >> >> >> that a function returns a non-null pointer:
>> >> >> >>
>> >> >> >> extern void *my_memcpy (__attribute__((nonnull)) void *dest,
>> >> >> >> __attribute__((nonnull)) const void *src, size_t len)
>> >> >> >> __attribute__((returns_nonnull));
>> >> >> >>
>> >> >> >> There are a number of problems here. First, there are different
>> >> >> >> attributes
>> >> >> >> to express the same idea at different places in the grammar, and
>> the
>> >> >> >> use of
>> >> >> >> the “nonnull” attribute on the function actually has an effect on
>> >> >> >> the
>> >> >> >> function parameters can get very, very confusing. Quick, which
>> >> >> >> pointers
>> >> >> >> are
>> >> >> >> nullable vs. non-null in this example?
>> >> >> >>
>> >> >> >> __attribute__((nonnull)) void *my_realloc (void *ptr, size_t
>> size);
>> >> >> >>
>> >> >> >> According to that declaration, ptr is nonnull and the function
>> >> >> >> returns
>> >> >> >> a
>> >> >> >> nullable pointer… but that’s the opposite of how it reads (and
>> >> >> >> behaves,
>> >> >> >> if
>> >> >> >> this is anything like a realloc that cannot fail). Moreover,
>> because
>> >> >> >> these
>> >> >> >> two attributes are declaration attributes, not type attributes,
>> you
>> >> >> >> cannot
>> >> >> >> express that nullability of the inner pointer in a multi-level
>> >> >> >> pointer
>> >> >> >> or an
>> >> >> >> array of pointers, which makes these attributes verbose,
>> confusing,
>> >> >> >> and
>> >> >> >> not
>> >> >> >> sufficiently generally. These attributes fail the first of our
>> >> >> >> goals.
>> >> >> >>
>> >> >> >> These attributes aren’t as useful as they could be for tools
>> support
>> >> >> >> (the
>> >> >> >> second and third goals), because they only express the nonnull
>> case,
>> >> >> >> leaving
>> >> >> >> no way to distinguish between the unannotated case (nobody has
>> >> >> >> documented
>> >> >> >> the nullability of some parameter) and the nullable case (we know
>> >> >> >> the
>> >> >> >> pointer can be null). From a tooling perspective, this is a
>> killer:
>> >> >> >> the
>> >> >> >> static analyzer absolutely cannot warn that one has forgotten to
>> >> >> >> check
>> >> >> >> for
>> >> >> >> null for every unannotated pointer, because the false-positive
>> rate
>> >> >> >> would be
>> >> >> >> astronomical.
>> >> >> >>
>> >> >> >> Finally, we’ve recently started considering violations of the
>> >> >> >> __attribute__((nonnull)) contract to be undefined behavior, which
>> >> >> >> fails
>> >> >> >> the
>> >> >> >> last of our goals. This is something we could debate further if
>> it
>> >> >> >> were
>> >> >> >> the
>> >> >> >> only problem, but these declaration attributes fall all of our
>> >> >> >> criteria, so
>> >> >> >> it’s not worth discussing.
>> >> >> >>
>> >> >> >> Nullability Qualifiers
>> >> >> >> We propose the addition of a new set of type qualifiers,  spelled
>> >> >> >> __nullable, __nonnull, and __null_unspecified, to Clang. These
>> are
>> >> >> >> collectively known as nullability qualifiers and may be written
>> >> >> >> anywhere any
>> >> >> >> other type qualifier may be written (such as const) on any type
>> >> >> >> subject
>> >> >> >> to
>> >> >> >> the following restrictions:
>> >> >> >>
>> >> >> >> Two nullability qualifiers shall not appear in the same set of
>> >> >> >> qualifiers.
>> >> >> >> A nullability qualifier shall qualify any pointer type, including
>> >> >> >> pointers
>> >> >> >> to objects, pointers to functions, C++ pointers to members, block
>> >> >> >> pointers,
>> >> >> >> and Objective-C object pointers.
>> >> >> >> A nullability qualifier in the declaration-specifiers applies to
>> the
>> >> >> >> innermost pointer type of each declarator (e.g., __nonnull int *
>> is
>> >> >> >> equivalent to int * __nonnull).
>> >> >> >> A nullability qualifier applied to a typedef of a
>> >> >> >> nullability-qualified
>> >> >> >> pointer type shall specify the same nullability as the underlying
>> >> >> >> type
>> >> >> >> of
>> >> >> >> the typedef.
>> >> >> >>
>> >> >> >>
>> >> >> >> The meanings of the three nullability qualifiers are as follows:
>> >> >> >>
>> >> >> >> __nullable: the pointer may store a null value at runtime (as
>> part
>> >> >> >> of
>> >> >> >> the
>> >> >> >> API contract)
>> >> >> >> __nonnull: the pointer should not store a null value at runtime
>> (as
>> >> >> >> part
>> >> >> >> of the API contract). it is possible that the value can be null,
>> >> >> >> e.g.,
>> >> >> >> in
>> >> >> >> erroneous historic uses of an API, and it is up to the library
>> >> >> >> implementor
>> >> >> >> to decide to what degree she will accommodate such clients.
>> >> >> >> __null_unspecified: it is unclear whether the pointer can be
>> null or
>> >> >> >> not.
>> >> >> >> Use of this type qualifier is extremely rare in practice, but it
>> >> >> >> fills
>> >> >> >> a
>> >> >> >> small but important niche when auditing a particular header to
>> add
>> >> >> >> nullability qualifiers: sometimes the nullability contract for a
>> few
>> >> >> >> APIs in
>> >> >> >> the header is unclear even when looking at the implementation for
>> >> >> >> historical
>> >> >> >> reasons, and establishing the contract requires more extensive
>> >> >> >> study.
>> >> >> >> In
>> >> >> >> such cases, it’s often best to mark that pointer as
>> >> >> >> __null_unspecified
>> >> >> >> (which will help silence the warning about unannotated pointers
>> in a
>> >> >> >> header)
>> >> >> >> and move on, coming back to __null_unspecified pointers when the
>> >> >> >> appropriate
>> >> >> >> graybeard has been summoned out of retirement [5].
>> >> >> >>
>> >> >> >> Assumes-nonnull Regions
>> >> >> >> We’ve found that it's fairly common for the majority of pointers
>> >> >> >> within
>> >> >> >> a
>> >> >> >> particular header to be __nonnull. Therefore, we’ve introduced
>> >> >> >> assumes-nonnull regions that assume that certain unannotated
>> >> >> >> pointers
>> >> >> >> implicitly get the __nonnull nullability qualifiers.
>> Assumes-nonnull
>> >> >> >> regions
>> >> >> >> are marked by pragmas:
>> >> >> >>
>> >> >> >> #pragma clang assume_nonnull begin
>> >> >> >>         __nullable char *strchr(const char *s, int c); // s is
>> >> >> >> inferred
>> >> >> >> to
>> >> >> >> be __nonnull
>> >> >> >> void *my_realloc (__nullable void *ptr, size_t size); //
>> my_realloc
>> >> >> >> is
>> >> >> >> inferred to return __nonnull
>> >> >> >> #pragma clang assume_nonnull end
>> >> >> >>
>> >> >> >> We infer __nonnull within an assumes_nonnull region when:
>> >> >> >>
>> >> >> >> The pointer is a non-typedef declaration, such as a function
>> >> >> >> parameter,
>> >> >> >> variable, or data member, or the result type of a function. It’s
>> >> >> >> very
>> >> >> >> rare
>> >> >> >> for one to warn typedefs to specify nullability information;
>> rather,
>> >> >> >> it’s
>> >> >> >> usually the user of the typedef that needs to specify
>> nullability.
>> >> >> >> The pointer is a single-level pointer, e.g., int* but not int**,
>> >> >> >> because
>> >> >> >> we’ve found that programmers can get confused about the
>> nullability
>> >> >> >> of
>> >> >> >> multi-level pointers (is it a __nullable pointer to __nonnull
>> >> >> >> pointers,
>> >> >> >> or
>> >> >> >> the other way around?) and inferring nullability for any of the
>> >> >> >> pointers in
>> >> >> >> a multi-level pointer compounds the situation.
>> >> >> >>
>> >> >> >>
>> >> >> >> Note that no #include may occur within an assumes_nonnull region,
>> >> >> >> and
>> >> >> >> assumes_nonnull regions cannot cross header boundaries.
>> >> >> >>
>> >> >> >> Type System Impact
>> >> >> >> Nullability qualifiers are mapped to type attributes within the
>> >> >> >> Clang
>> >> >> >> type
>> >> >> >> system, but a nullability-qualified pointer type is not
>> semantically
>> >> >> >> distinct from its unqualified pointer type. Therefore, one may
>> >> >> >> freely
>> >> >> >> convert between nullability-qualified and
>> non-nullability-qualified
>> >> >> >> pointers, or between nullability-qualified pointers with
>> different
>> >> >> >> nullability qualifiers. One cannot overload on nullability
>> >> >> >> qualifiers,
>> >> >> >> write
>> >> >> >> C++ class template partial specializations that identify
>> nullability
>> >> >> >> qualifiers, or inspect nullability via type traits in any way.
>> >> >> >>
>> >> >> >> Said more strongly, removing nullability qualifiers from a
>> >> >> >> well-formed
>> >> >> >> program will not change its behavior in any way, nor will the
>> >> >> >> semantics
>> >> >> >> of a
>> >> >> >> program change when any set of (well-formed) nullability
>> qualifiers
>> >> >> >> are
>> >> >> >> added to it. Operationally, this means that nullability
>> qualifiers
>> >> >> >> are
>> >> >> >> not
>> >> >> >> part of the canonical type in Clang’s type system, and that any
>> >> >> >> warnings we
>> >> >> >> produce based on nullability information will necessarily be
>> >> >> >> dependent
>> >> >> >> on
>> >> >> >> Clang’s ability to retain type sugar during semantic analysis.
>> >> >> >>
>> >> >> >> While it’s somewhat exceptional for us to introduce new type
>> >> >> >> qualifiers
>> >> >> >> that don’t produce semantically distinct types, we feel that
>> this is
>> >> >> >> the
>> >> >> >> only plausible design and implementation strategy for this
>> feature:
>> >> >> >> pushing
>> >> >> >> nullability qualifiers into the type system semantically would
>> cause
>> >> >> >> significant changes to the language (e.g., overloading, partial
>> >> >> >> specialization) and break ABI (due to name mangling) that would
>> >> >> >> drastically
>> >> >> >> reduce the number of potential users, and we feel that Clang’s
>> >> >> >> support
>> >> >> >> for
>> >> >> >> maintaining type sugar throughout semantic analysis is generally
>> >> >> >> good
>> >> >> >> enough
>> >> >> >> [6] to get the benefits of nullability annotations in our tools.
>> >> >> >>
>> >> >> >> Looking forward to our discussion.
>> >> >> >>
>> >> >> >> - Doug (with Jordan Rose and Anna Zaks)
>> >> >> >>
>> >> >> >> [1]
>> >> >> >>
>> http://en.wikipedia.org/wiki/Tony_Hoare#Apologies_and_retractions
>> >> >> >> [2] The standard description of strchr seems to imply that the
>> >> >> >> parameter
>> >> >> >> cannot be null
>> >> >> >> [3] The patch is complete, but should be reviewed on cfe-commits
>> >> >> >> rather
>> >> >> >> than here. There are also several logic parts to this monolithic
>> >> >> >> patch:
>> >> >> >> (a) __nonnull/__nullable/__null_unspecified type specifiers
>> >> >> >> (b) nonnull/nullable/null_unspecified syntactic sugar for
>> >> >> >> Objective-C
>> >> >> >> (c) Warning about inconsistent application of nullability
>> specifiers
>> >> >> >> within a given header
>> >> >> >> (d) assume_nonnnull begin/end pragmas
>> >> >> >> (e) Objective-C null_resettable property attribute
>> >> >> >> [4] https://gcc.gnu.org/onlinedocs/gcc/Function-Attributes.html
>> >> >> >> (search
>> >> >> >> for “nonnull”)
>> >> >> >> [5] No graybeards were harmed in the making of this feature.
>> >> >> >> [6] Template instantiation is the notable exception here,
>> because it
>> >> >> >> always canonicalizes types.
>> >> >> >>
>> >> >> >> <nullability.patch>
>> >> >> >> _______________________________________________
>> >> >> >> cfe-dev mailing list
>> >> >> >> cfe-dev at cs.uiuc.edu
>> >> >> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>> >> >> >>
>> >> >> >>
>> >> >> >>
>> >> >> >> _______________________________________________
>> >> >> >> cfe-dev mailing list
>> >> >> >> cfe-dev at cs.uiuc.edu
>> >> >> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>> >> >> >>
>> >> >> >
>> >> >> >
>> >> >> > _______________________________________________
>> >> >> > cfe-dev mailing list
>> >> >> > cfe-dev at cs.uiuc.edu
>> >> >> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>> >> >> >
>> >> >
>> >> >
>> >
>> >
>>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20150627/a9938a2a/attachment.html>