If the return type is a pointer and the function returns the reference to a
pointer, don't warn since only the value is returned, not the reference.
If a reference function parameter appears in the reference chain, don't warn
since binding happens at the caller scope, so addresses returned are not
to local stack. This includes default arguments as well.
llvm-svn: 277889
For builtin logical operators, there is a well-defined ordering of argument
evaluation. For overloaded operator of the same type, there is no argument
evaluation order, similar to other function calls. When both are present,
uninstantiated templates with an operator&& is treated as an unresolved
function call. Unresolved function calls are treated as normal function calls,
and may result in false positives when the builtin logical operator is used.
Have the unsequenced checker ignore dependent expressions to avoid this
false positive. The check also happens in template instantiations to catch
when the overloaded operator is used.
llvm-svn: 277866
For memset (and others) we can get diagnostics like:
struct stat { int x; };
void foo(struct stat *stamps) {
bzero(stamps, sizeof(stamps));
memset(stamps, 0, sizeof(stamps));
}
t.c:7:28: warning: 'memset' call operates on objects of type 'struct stat' while the size is based on a different type 'struct stat *' [-Wsizeof-pointer-memaccess]
memset(stamps, 0, sizeof(stamps));
~~~~~~ ^~~~~~
t.c:7:28: note: did you mean to dereference the argument to 'sizeof' (and multiply it by the number of elements)?
memset(stamps, 0, sizeof(stamps));
^~~~~~
This patch implements the same class of warnings for bzero.
Differential Revision: https://reviews.llvm.org/D22525
rdar://problem/18963514
llvm-svn: 277787
Fix a crash under -Wthread-safety when finding the destructor for a
lifetime-extending reference.
A patch by Nandor Licker!
Differential Revision: https://reviews.llvm.org/D22419
llvm-svn: 277522
Additionally, for pre-C++1z, instead of forbidding a lambda's closure type from being a literal type through circumlocutorily setting HasNonLiteralTypeFieldsOrBases falsely to true -- handle lambda's more directly in CXXRecordDecl::isLiteral().
One additional small step towards implementing constexpr-lambdas.
Thanks to Richard Smith for his review!
https://reviews.llvm.org/D22662
llvm-svn: 276514
decomposition declarations.
There are a couple of things in the wording that seem strange here:
decomposition declarations are permitted at namespace scope (which we partially
support here) and they are permitted as the declaration in a template (which we
reject).
llvm-svn: 276492
In atomic builtins, we assumed that the LValue conversion on the first
argument would succeed. So, we would crash given code like:
```
void ovl(char);
void ovl(int);
__atomic_store_n(ovl, 0, 0);
```
This patch makes us not assume that said conversion is successful. :)
llvm-svn: 276232
nullabilities of its operands.
This patch defines a function to compute the nullability of conditional
expressions, which enables Sema to precisely detect implicit conversions
of nullable conditional expressions to nonnull pointers.
rdar://problem/25166556
Differential Revision: https://reviews.llvm.org/D22392
llvm-svn: 276076
It's a patch for PR28050. Seems like overloading resolution wipes out
the first standard conversion sequence (before user-defined conversion)
in case of deprecated string literal conversion.
Differential revision: https://reviews.llvm.org/D21228
Patch by Alexander Makarov
llvm-svn: 275970
they're redeclarations. This is necessary in order for name lookup to correctly
find the most recent declaration of the name (which affects default template
argument lookup and cross-module merging, among other things).
llvm-svn: 275612
Extend the __declspec(dll*) attribute to cover ObjC interfaces. This was
requested by Microsoft for their ObjC support. Cover both import and export.
This only adds the semantic analysis portion of the support, code-generation
still remains outstanding. Add some basic initial documentation on the
attributes that were previously empty. Tweak the previous tests to use the
relative expected-warnings to make the tests easier to read.
llvm-svn: 275610
This patch implements PR#22821.
Taking the address of a packed member is dangerous since the reduced
alignment of the pointee is lost. This can lead to memory alignment
faults in some architectures if the pointer value is dereferenced.
This change adds a new warning to clang emitted when taking the address
of a packed member. A packed member is either a field/data member
declared as attribute((packed)) or belonging to a struct/class
declared as such. The associated flag is -Waddress-of-packed-member.
Conversions (either implicit or via a valid casting) to pointer types
with lower or equal alignment requirements (e.g. void* or char*)
silence the warning.
This change also adds a new error diagnostic when the user attempts to
bind a reference to a packed member, regardless of the alignment.
Differential Revision: https://reviews.llvm.org/D20561
llvm-svn: 275417
After thinking about it, we don't really need to forbid
BuiltinTemplateDecls explicitly. The restriction doesn't really buy us
anything.
llvm-svn: 275078
When we have template arguments, we have a function and a pattern, the variable
in init-capture belongs to the pattern decl when checking if the lhs of
"max = current" is modifiable:
auto find = [max = init](auto current) {
max = current;
};
In function isReferenceToNonConstCapture, we handle the case where the decl
context for the variable is not part of the current context.
Instead of crashing, we emit an error message:
cannot assign to a variable captured by copy in a non-mutable lambda
rdar://26997922
llvm-svn: 274392
This patch adds a __nth_element builtin that allows fetching the n-th type of a
parameter pack with very little compile-time overhead. The patch was inspired by
r252036 and r252115 by David Majnemer, which add a similar __make_integer_seq
builtin for efficiently creating a std::integer_sequence.
Reviewed as D15421. http://reviews.llvm.org/D15421
llvm-svn: 274316
function-style cast to a non-dependent type which is then used in an invalid
way. We'd lose the "type dependent" bit here, and downstream Sema processing
would then discard the expression if it was used in a context where its type
rendered it invalid.
llvm-svn: 274267
Original patch by Stefan Bühler http://reviews.llvm.org/D12834
Difference between original and this one:
- fixed all failing tests
- fixed mangling for global variable outside namespace
- emit ABI tags for guards and local names
- clang-format + other stylistic changes
- significantly reworked patch according to Richard's suggestions
Sema part, committed before http://reviews.llvm.org/D17567
Differential revision: http://reviews.llvm.org/D18035
llvm-svn: 274222
constructor would be; this is effectively required by P0136R1. This has the
effect of exposing the validity of the base class initialization steps to
SFINAE checks.
llvm-svn: 274088
We continue accepting "macosx" but canonicalize it to "macos", When emitting
diagnostics, we use "macOS" instead of "OS X".
The PlatformName in TargetInfo is changed from "macosx" to "macos" so we can
directly compare the Platform in AvailabilityAttr with the PlatformName
in TargetInfo.
rdar://26795172
rdar://26800775
llvm-svn: 274064
Replace inheriting constructors implementation with new approach, voted into
C++ last year as a DR against C++11.
Instead of synthesizing a set of derived class constructors for each inherited
base class constructor, we make the constructors of the base class visible to
constructor lookup in the derived class, using the normal rules for
using-declarations.
For constructors, UsingShadowDecl now has a ConstructorUsingShadowDecl derived
class that tracks the requisite additional information. We create shadow
constructors (not found by name lookup) in the derived class to model the
actual initialization, and have a new expression node,
CXXInheritedCtorInitExpr, to model the initialization of a base class from such
a constructor. (This initialization is special because it performs real perfect
forwarding of arguments.)
In cases where argument forwarding is not possible (for inalloca calls,
variadic calls, and calls with callee parameter cleanup), the shadow inheriting
constructor is not emitted and instead we directly emit the initialization code
into the caller of the inherited constructor.
Note that this new model is not perfectly compatible with the old model in some
corner cases. In particular:
* if B inherits a private constructor from A, and C uses that constructor to
construct a B, then we previously required that A befriends B and B
befriends C, but the new rules require A to befriend C directly, and
* if a derived class has its own constructors (and so its implicit default
constructor is suppressed), it may still inherit a default constructor from
a base class
llvm-svn: 274049
-Wfor-loop-analysis warnings for a for-loop with a condition variable. In such
a case, the loop condition variable is modified on each iteration of the loop
by definition.
Original commit message:
Rearrange condition handling so that semantic checks on a condition variable
are performed before the other substatements of the construct are parsed,
rather than deferring them until the end. This allows better error recovery
from semantic errors in the condition, improves diagnostic order, and is a
prerequisite for C++17 constexpr if.
llvm-svn: 273600
are performed before the other substatements of the construct are parsed,
rather than deferring them until the end. This allows better error recovery
from semantic errors in the condition, improves diagnostic order, and is a
prerequisite for C++17 constexpr if.
llvm-svn: 273548
This code should be an error:
void foo(int);
void f3() {
int foo(float);
{
float foo(int); // expected-error {{functions that differ only in their return type cannot be overloaded}}
}
}
the foo(float) function declared at function scope should not hide the float(int)
while trying to redeclare functions.
Differential Revision: http://reviews.llvm.org/D19763
llvm-svn: 272961
See https://llvm.org/bugs/show_bug.cgi?id=28100.
In r266561 when I implemented allowing explicit specializations of function templates to override deleted status, I mistakenly assumed (and hence introduced a violable assertion) that when an explicit specialization was being declared, the corresponding specialization of the most specialized function template that it would get linked to would always be the one that was implicitly generated - and so if it was marked as 'deleted' it must have inherited it from the primary template and so should be safe to reset its deleted status, and set it to being an explicit specialization. Obviously during redeclaration of a deleted explicit specialization, in order to avoid a recursive reset, we need to check that the previous specialization is not an explicit specialization (instead of assuming and asserting it) and that it hasn't been referenced, and so only then is it safe to reset its 'deleted' status.
All regression tests pass.
Thanks to Zhendong Su for reporting the bug and David Majnemer for tracking it to my commit r266561, and promptly bringing it to my attention.
llvm-svn: 272631
If definition of default function argument uses itself, clang crashed,
because corresponding function parameter is not associated with the default
argument yet. With this fix clang emits appropriate error message.
This change fixes PR28105.
Differential Revision: http://reviews.llvm.org/D21301
llvm-svn: 272623
This patch implements PR#22821.
Taking the address of a packed member is dangerous since the reduced
alignment of the pointee is lost. This can lead to memory alignment
faults in some architectures if the pointer value is dereferenced.
This change adds a new warning to clang emitted when taking the address
of a packed member. A packed member is either a field/data member
declared as attribute((packed)) or belonging to a struct/class
declared as such. The associated flag is -Waddress-of-packed-member
Differential Revision: http://reviews.llvm.org/D20561
llvm-svn: 272552
The bug report by Gonzalo (https://llvm.org/bugs/show_bug.cgi?id=27507 -- which results in clang crashing when generic lambdas that capture 'this' are instantiated in contexts where the Functionscopeinfo stack is not in a reliable state - yet getCurrentThisType expects it to be) - unearthed some additional bugs in regards to maintaining proper cv qualification through 'this' when performing by value captures of '*this'.
This patch attempts to correct those bugs and makes the following changes:
o) when capturing 'this', we do not need to remember the type of 'this' within the LambdaScopeInfo's Capture - it is never really used for a this capture - so remove it.
o) teach getCurrentThisType to walk the stack of lambdas (even in scenarios where we run out of LambdaScopeInfo's such as when instantiating call operators) looking for by copy captures of '*this' and resetting the type of 'this' based on the constness of that capturing lambda's call operator.
This patch has been baking in review-hell for > 6 weeks - all the comments so far have been addressed and the bug (that it addresses in passing, and I regret not submitting as a separate patch initially) has been reported twice independently, so is frequent and important for us not to just sit on. I merged the cv qualification-fix and the PR-fix initially in one patch, since they resulted from my initial implementation of star-this and so were related. If someone really feels strongly, I can put in the time to revert this - separate the two out - and recommit. I won't claim it's immunized against all bugs, but I feel confident enough about the fix to land it for now.
llvm-svn: 272480
We shouldn't return true from CheckSpecifiedExceptionType if
the record type is incomplete and -fms-extensions is engaged. Otherwise
we will have an incomplete AST.
llvm-svn: 272447
Microsoft headers, comdef.h and comutil.h, assume that this is an OK
thing to do. Downgrade the hard error to a warning if we are in
-fms-extensions mode.
This fixes PR28080.
llvm-svn: 272412
It is possible for a field and a class to have the same name. In such
cases, performing lookup for the field might return a result set with
more than one entry. An overzealous assertion fired, causing us to
crash instead of using the non-class lookup result.
This fixes PR28060.
llvm-svn: 272247
Given the following C++:
```
void foo();
void foo() __attribute__((enable_if(false, "")));
bool bar() {
auto P = foo;
return P == foo;
}
```
We'll currently happily (and correctly) resolve `foo` to the `foo`
overload without `enable_if` when assigning to `P`. However, we'll
complain about an ambiguous overload on the `P == foo` line, because
`Sema::CheckPlaceholderExpr` doesn't recognize that there's only one
`foo` that could possibly work here.
This patch teaches `Sema::CheckPlaceholderExpr` how to properly deal
with such cases.
Grepping for other callers of things like
`Sema::ResolveAndFixSingleFunctionTemplateSpecialization`, it *looks*
like this is the last place that needed to be fixed up. If I'm wrong,
I'll see if there's something we can do that beats what amounts to
whack-a-mole with bugs.
llvm-svn: 272080
We would attempt to evaluate the sizeof a dependent type to check for an
integral overflow. However, because the dependent type is not yet resolved, we
cannot determine if the expression would overflow. Report a failure to perform
a symbolic evaluation of a constant involving the dependent type.
llvm-svn: 271762
It is only a crash if the compiler optimize for this!=nullptr because
LocalInstantiationScope::getPartiallySubstitutedPack checks if 'this' is null
(This is crashing when clang is compiled with GCC6)
Differential Revision: http://reviews.llvm.org/D20511
llvm-svn: 270845
This implements support for MS-specific __unaligned qualifier in functions and
makes the following test case both compile and mangle correctly:
struct S {
void f() __unaligned;
};
void S::f() __unaligned {
}
Differential Revision: http://reviews.llvm.org/D20437
llvm-svn: 270834
Currently, the constexpr evaluator is very conservative about unmodeled
side-effects when we're evaluating an expression in a mode that allows
such side-effects.
This patch makes us note when we might have actually encountered an
unmodeled side-effect, which allows us to be more accurate when we know
an unmodeled side-effect couldn't have occurred.
This patch has been split into two commits; this one primarily
introduces the bits necessary to track whether we might have potentially
hit such a side-effect. The one that actually does the tracking (which
boils down to more or less a rename of keepEvaluatingAfterFailure to
noteFailure) is coming soon.
Differential Revision: http://reviews.llvm.org/D18540
llvm-svn: 270781
const' variable. That variable might be defined as 'constexpr', so we cannot
prove that a use of it could never be a constant expression.
llvm-svn: 270774
If we have some function with dllimport attribute and then we have the function
definition in the same module but without dllimport attribute we should add
dllexport attribute to this function definition.
The same should be done for variables.
Example:
struct __declspec(dllimport) C3 {
~C3();
};
C3::~C3() {;} // we should export this definition.
Patch by Andrew V. Tischenko
Differential revision: http://reviews.llvm.org/D18953
llvm-svn: 270686
Add two tests which show our error handling behavior for invalid
parameters in the layout_version and empty_bases attributes.
Amend our documentation to make it more clear that
__declspec(empty_bases) and __declspec(layout_version) can only apply to
classes, structs, and unions.
llvm-svn: 270461
MSVC now supports the __is_assignable type trait intrinsic,
to enable easier and more efficient implementation of the
Standard Library's is_assignable trait.
As of Visual Studio 2015 Update 3, the VC Standard Library
implementation uses the new intrinsic unconditionally.
The implementation is pretty straightforward due to the previously
existing is_nothrow_assignable and is_trivially_assignable.
We handle __is_assignable via the same code as the other two except
that we skip the extra checks for nothrow or triviality.
Patch by Dave Bartolomeo!
Differential Revision: http://reviews.llvm.org/D20492
llvm-svn: 270458
The layout_version attribute is pretty straightforward: use the layout
rules from version XYZ of MSVC when used like
struct __declspec(layout_version(XYZ)) S {};
The empty_bases attribute is more interesting. It tries to get the C++
empty base optimization to fire more often by tweaking the MSVC ABI
rules in subtle ways:
1. Disable the leading and trailing zero-sized object flags if a class
is marked __declspec(empty_bases) and is empty.
This means that given:
struct __declspec(empty_bases) A {};
struct __declspec(empty_bases) B {};
struct C : A, B {};
'C' will have size 1 and nvsize 0 despite not being annotated
__declspec(empty_bases).
2. When laying out virtual or non-virtual bases, disable the injection
of padding between classes if the most derived class is marked
__declspec(empty_bases).
This means that given:
struct A {};
struct B {};
struct __declspec(empty_bases) C : A, B {};
'C' will have size 1 and nvsize 0.
3. When calculating the offset of a non-virtual base, choose offset zero
if the most derived class is marked __declspec(empty_bases) and the
base is empty _and_ has an nvsize of 0.
Because of the ABI rules, this does not mean that empty bases
reliably get placed at offset 0!
For example:
struct A {};
struct B {};
struct __declspec(empty_bases) C : A, B { virtual ~C(); };
'C' will be pointer sized to account for the vfptr at offset 0.
'A' and 'B' will _not_ be at offset 0 despite being empty!
Instead, they will be located right after the vfptr.
This occurs due to the interaction betweeen non-virtual base layout
and virtual function pointer injection: injection occurs after the
nv-bases and shifts them down by the size of a pointer.
llvm-svn: 270457
an identifier table lookup, *and* copy the LangOptions (including various
std::vector<std::string>s). Twice. We call this function once each time we start
parsing a declaration specifier sequence, and once for each call to Sema::Diag.
This reduces the compile time for a sample .c file from the linux kernel by 20%.
llvm-svn: 270009
a base class via a using-declaration. If a class has a using-declaration
declaring either a constructor or an assignment operator, eagerly declare its
special members in case they need to displace a shadow declaration from a
using-declaration.
llvm-svn: 269398
This patch implements __unaligned (MS extension) as a proper type qualifier
(before that, it was implemented as an ignored attribute).
It also fixes PR27367 and PR27666.
Differential Revision: http://reviews.llvm.org/D20103
llvm-svn: 269220
This patch fixes a bug where we would assume all value-dependent
enable_if conditions give successful results.
Instead, we consider value-dependent enable_if conditions to always
fail. While this isn't ideal, this is the best we can realistically do
without changing both enable_if's semantics and large parts of Sema
(specifically, all of the parts that don't expect type dependence to
come out of nowhere, and that may interact with overload resolution).
Differential Revision: http://reviews.llvm.org/D20130
llvm-svn: 269154
This patch corresponds to reviews:
http://reviews.llvm.org/D15120http://reviews.llvm.org/D19125
It adds support for the __float128 keyword, literals and target feature to
enable it. Based on the latter of the two aforementioned reviews, this feature
is enabled on Linux on i386/X86 as well as SystemZ.
This is also the second attempt in commiting this feature. The first attempt
did not enable it on required platforms which caused failures when compiling
type_traits with -std=gnu++11.
If you see failures with compiling this header on your platform after this
commit, it is likely that your platform needs to have this feature enabled.
llvm-svn: 268898
If the address of a field is taken as a pointer to member, we should
not warn that the field is not used.
Normaly, yse of fields are done from MemberExpr, but in case of pointer to
member, it is in a DeclRefExpr
Differential Revision: http://reviews.llvm.org/D20054
llvm-svn: 268895
This patch implements __unaligned (MS extension) as a proper type qualifier
(before that, it was implemented as an ignored attribute).
It also fixes PR27367.
Differential Revision: http://reviews.llvm.org/D19654
llvm-svn: 268727
* an unscoped enumerator whose enumeration is a class member is itself a class
member, so can only be the subject of a class-scope using-declaration.
* a scoped enumerator cannot be the subject of a class-scope using-declaration.
llvm-svn: 268594
Fix crash in BuildCXXDefaultInitExpr when member of template class has
same name as the class itself.
Based on patch by Raphael "Teemperor" Isemann!
Differential Revision: http://reviews.llvm.org/D19721
llvm-svn: 268082
Slightly updated version, double-checked build and tests.
Improve implementation of MS pragmas that use stack + compatibility fixes.
This patch:
1. Changes implementation of #pragma vtordisp to use PragmaStack class
that other stack pragmas use;
2. Fixes "#pragma vtordisp()" behavior - it shouldn't affect the stack;
3. Supports "save-restore" of pragma stacks on enter / exit a C++ method
body, as MSVC does.
TODO:
1. Change implementation of #pragma pack to use the same approach;
2. Introduce diagnostics on popping named stack slots, as MSVC does.
Reviewers:
rnk, thakis
Differential revision: http://reviews.llvm.org/D19361
llvm-svn: 268029
if we are parsing a template specialization.
This commit makes changes to clear the TemplateParamScope bit and set
the TemplateParamParent field of the current scope to null if a template
specialization is being parsed.
Before this commit, Sema::ActOnStartOfLambdaDefinition would check
whether the parent template scope had any decls to determine whether
or not a template specialization was being parsed. This wasn't correct
since it couldn't distinguish between a real template specialization and
a template defintion with an unnamed template parameter (only template
parameters with names are added to the scope's decl list). To fix the
bug, this commit changes the code to check the pointer to the parent
template scope rather than the decl list.
rdar://problem/23440346
Differential Revision: http://reviews.llvm.org/D19175
llvm-svn: 267975
Usually these parameters are used solely to initialize the field in the
initializer list, and there is no real shadowing confusion.
There is a new warning under -Wshadow called
-Wshadow-field-in-constructor-modified. It attempts to find
modifications of such constructor parameters that probably intended to
modify the field.
It has some false negatives, though, so there is another warning group,
-Wshadow-field-in-constructor, which always warns on this special case.
For users who just want the old behavior and don't care about these fine
grained groups, we have a new warning group called -Wshadow-all that
activates everything.
Fixes PR16088.
Reviewers: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D18271
llvm-svn: 267957
with a generic lambda.
This patch fixes Sema::InstantiateVariableInitializer to switch to the
context of the variable before instantiating its initializer, which is
necessary to set the correct type for VarTemplateSpecializationDecl.
This is the first part of the patch that was reviewed here:
http://reviews.llvm.org/D19175
rdar://problem/23440346
llvm-svn: 267956
It makes compiler-rt tests fail if the gold plugin is enabled.
Revert "Rework interface for bitset-using features to use a notion of LTO visibility."
Revert "Driver: only produce CFI -fvisibility= error when compiling."
Revert "clang/test/CodeGenCXX/cfi-blacklist.cpp: Exclude ms targets. They would be non-cfi."
llvm-svn: 267871
Rework implementation of several MS pragmas that use internal stack:
vtordisp, {bss|code|const|data}_seg.
This patch:
1. Makes #pragma vtordisp use PragmaStack class as *_seg pragmas do;
2. Fixes "#pragma vtordisp()" behavior: it shouldn't affect stack;
3. Saves/restores the stacks on enter/exit a C++ method body.
llvm-svn: 267866
Bitsets, and the compiler features they rely on (vtable opt, CFI),
only have visibility within the LTO'd part of the linkage unit. Therefore,
only enable these features for classes with hidden LTO visibility. This
notion is based on object file visibility or (on Windows)
dllimport/dllexport attributes.
We provide the [[clang::lto_visibility_public]] attribute to override the
compiler's LTO visibility inference in cases where the class is defined
in the non-LTO'd part of the linkage unit, or where the ABI supports
calling classes derived from abstract base classes with hidden visibility
in other linkage units (e.g. COM on Windows).
If the cross-DSO CFI mode is enabled, bitset checks are emitted even for
classes with public LTO visibility, as that mode uses a separate mechanism
to cause bitsets to be exported.
This mechanism replaces the whole-program-vtables blacklist, so remove the
-fwhole-program-vtables-blacklist flag.
Because __declspec(uuid()) now implies [[clang::lto_visibility_public]], the
support for the special attr:uuid blacklist entry is removed.
Differential Revision: http://reviews.llvm.org/D18635
llvm-svn: 267784
Remove the floating point to bool conversion warnings. Some of these
conversions will be caught by -Wliteral-conversion and -Wfloat-conversion
llvm-svn: 267234
Restructure the implict floating point to integer conversions so that
interesting sub-groups are under different flags. Breakdown of warnings:
No warning:
Exact conversions from floating point to integer:
int x = 10.0;
int x = 1e10;
-Wliteral-conversion - Floating point literal to integer with rounding:
int x = 5.5;
int x = -3.4;
-Wfloat-conversion - All conversions not covered by the above two:
int x = GetFloat();
int x = 5.5 + 3.5;
-Wfloat-zero-conversion - The expression converted has a non-zero floating
point value that gets converted to a zero integer value, excluded the cases
falling under -Wliteral-conversion. Subset of -Wfloat-conversion.
int x = 1.0 / 2.0;
-Wfloat-overflow-conversion - The floating point value is outside the range
of the integer type, exluding cases from -Wliteral conversion. Subset of
-Wfloat-conversion.
char x = 500;
char x = -1000;
-Wfloat-bool-conversion - Any conversion of a floating point type to bool.
Subset of -Wfloat-conversion.
if (GetFloat()) {}
bool x = 5.0;
-Wfloat-bool-constant-conversion - Conversion of a compile time evaluatable
floating point value to bool. Subset of -Wfloat-bool-conversion.
bool x = 1.0;
bool x = 4.0 / 20.0;
Also add EvaluateAsFloat to Sema, which is similar to EvaluateAsInt, but for
floating point values.
llvm-svn: 267054
With this patch compiler emits warning if it tries to make implicit instantiation
of a template but cannot find the template definition. The warning can be suppressed
by explicit instantiation declaration or by command line options
-Wundefined-var-template and -Wundefined-func-template. The implementation follows
the discussion of http://reviews.llvm.org/D12326.
Differential Revision: http://reviews.llvm.org/D16396
llvm-svn: 266719
template<class T> void f(T) = delete;
template<> void f(int); // OK.
f(3); // OK
Implementation strategy:
When an explicit specialization of a function template, a member function template or a member function of a class template is declared, clang first implicitly instantiates the declaration of a specialization from the templated-entity being explicitly specialized (since their signatures must be the same) and then links the explicit specialization being declared as a redeclaration of the aforementioned specialization.
The problem was that when clang 'implicitly instantiates' the initial specialization, it marks the corresponding FunctionDecl as deleted if the corresponding templated-entity was deleted, rather than waiting to see whether the explicit specialization being declared provides a non-deleted body. (The eager marking of delete has advantages during overload resolution I suppose, where we don't have to try and instantiate a definition of the function to see if it is deleted).
The present fix entails recognizing that when clang knows that an explicit specialization is being declared (for whichever templated-entity), the prior implicit instantiation should not inherit the 'deleted' status, and so we reset it to false.
I suppose an alternative fix (amongst others) could consider creating a new context (ExplicitSpecializationDeclarationSubstitution or some such) that is checked during template-argument-deduction and final substitution, and avoid inheriting the deleted status during declaration substitution. But while conceptually cleaner, that would be a slightly more involved change (as could be some of the other alternatives: such as avoid tagging implicit specializations as deleted, and check their primary templates for the deleted status where needed), and so I chose a different path. Hopefully it'll prove to not be a bad choice.
llvm-svn: 266561
Since this patch provided support for the __float128 type but disabled it
on all platforms by default, some platforms can't compile type_traits with
-std=gnu++11 since there is a specialization with __float128.
This reverts the patch until D19125 is approved (i.e. we know which platforms
need this support enabled).
llvm-svn: 266460
This patch implements __unaligned as a type qualifier; before that, it was
modeled as an attribute. Proper mangling of __unaligned is implemented as well.
Some OpenCL code/tests are tangenially affected, as they relied on existing
number and sizes of type qualifiers.
Differential Revision: http://reviews.llvm.org/D18596
llvm-svn: 266415
The example below should work identically with and without compiler native
wchar_t support.
void foo(wchar_t * t = L"");
Differential Revision: http://reviews.llvm.org/D19056
llvm-svn: 266287
This patch corresponds to review:
http://reviews.llvm.org/D15120
It adds support for the __float128 keyword, literals and a target feature to
enable it. This support is disabled by default on all targets and any target
that has support for this type is free to add it.
Based on feedback that I've received from target maintainers, this appears to
be the right thing for most targets. I have not heard from the maintainers of
X86 which I believe supports this type. I will subsequently investigate the
impact of enabling this on X86.
llvm-svn: 266186
Add a triple to the run lines so that integers will the same sizes across runs.
Also add a compile time check to ensure the assumptions about sizes are met.
llvm-svn: 265991
This is a fix for https://llvm.org/bugs/show_bug.cgi?id=25561 which was a
crash on invalid. Change the handling of invalid decls to have a catch-all
case to prevent unexpecting decls from triggering an assertion.
llvm-svn: 265467
This warning sometimes will infinitely recurse on CXXRecordDecl's from
ill-formed recursive classes that have fields of themselves. Skip processing
these classes to prevent this from happening.
Fixes https://llvm.org/bugs/show_bug.cgi?id=27142
llvm-svn: 264991
In some cases, when we encounter a direct function call with an
incorrect number of arguments, we'll emit a diagnostic, and pretend that
the call to the function was valid. For example, in C:
int foo();
int a = foo(1);
Prior to this patch, we'd get an ICE if foo had an enable_if attribute,
because CheckEnableIf assumes that the number of arguments it gets
passed is valid for the function it's passed. Now, we check that the
number of args looks valid prior to checking enable_if conditions.
This fix was not done inside of CheckEnableIf because the problem
presently can only occur in one caller of CheckEnableIf (ActOnCallExpr).
Additionally, checking inside of CheckEnableIf would make us emit
multiple diagnostics for the same error (one "enable_if failed", one
"you gave this function the wrong number of arguments"), which seems
worse than just complaining about the latter.
llvm-svn: 264975
Support the constexpr specifier on lambda expressions - and support its inference from the lambda call operator's body.
i.e.
auto L = [] () constexpr { return 5; };
static_assert(L() == 5); // OK
auto Implicit = [] (auto a) { return a; };
static_assert(Implicit(5) == 5);
We do not support evaluation of lambda's within constant expressions just yet.
Implementation Strategy:
- teach ParseLambdaExpressionAfterIntroducer to expect a constexpr specifier and mark the invented function call operator's declarator's decl-specifier with it; Have it emit fixits for multiple decl-specifiers (mutable or constexpr) in this location.
- for cases where constexpr is not explicitly specified, have buildLambdaExpr check whether the invented function call operator satisfies the requirements of a constexpr function, by calling CheckConstexprFunctionDecl/Body.
Much obliged to Richard Smith for his patience and his care, in ensuring the code is clang-worthy.
llvm-svn: 264513
use. In order for this to fire, the function needed to be a templated function
marked 'constexpr' and declared but not defined. This weird pattern appears in
libstdc++'s alloc_traits.h.
llvm-svn: 264471
non-deterministic diagnostics (and non-deterministic PCH files). Check these
when building a module rather than serializing it; it's not reasonable for a
module's use to be satisfied by a definition in the user of the module.
llvm-svn: 264466
lambda-expression. We don't actually instantiate the closure type / operator()
in the template in order to produce the closure type / operator() in the
instantiation, so this isn't caught by the normal path.
llvm-svn: 264184
This commit adds a named argument to AvailabilityAttr, while r263652 adds an
optional string argument to __attribute__((deprecated)).
This was commited in r263687 and reverted in 263752 due to misaligned
access.
rdar://20588929
llvm-svn: 263958
Implement lambda capture of *this by copy.
For e.g.:
struct A {
int d = 10;
auto foo() { return [*this] (auto a) mutable { d+=a; return d; }; }
};
auto L = A{}.foo(); // A{}'s lifetime is gone.
// Below is still ok, because *this was captured by value.
assert(L(10) == 20);
assert(L(100) == 120);
If the capture was implicit, or [this] (i.e. *this was captured by reference), this code would be otherwise undefined.
Implementation Strategy:
- amend the parser to accept *this in the lambda introducer
- add a new king of capture LCK_StarThis
- teach Sema::CheckCXXThisCapture to handle by copy captures of the
enclosing object (i.e. *this)
- when CheckCXXThisCapture does capture by copy, the corresponding
initializer expression for the closure's data member
direct-initializes it thus making a copy of '*this'.
- in codegen, when assigning to CXXThisValue, if *this was captured by
copy, make sure it points to the corresponding field member, and
not, unlike when captured by reference, what the field member points
to.
- mark feature as implemented in svn
Much gratitude to Richard Smith for his carefully illuminating reviews!
llvm-svn: 263921
Some functions can't have their address taken. If we encounter an
overload set where only one of the candidates can have its address
taken, we should automatically select that candidate's type in type
deduction.
Differential Revision: http://reviews.llvm.org/D15591
llvm-svn: 263888
Some functions can't have their address taken. If we encounter an
overload set where only one of the candidates can have its address
taken, we should automatically select that candidate in cast
expressions.
Differential Revision: http://reviews.llvm.org/D17701
llvm-svn: 263887
This commit adds a named argument to AvailabilityAttr, while r263652 adds an
optional string argument to __attribute__((deprecated)). This enables the
compiler to provide Fix-Its for deprecated declarations.
rdar://20588929
llvm-svn: 263687
The declaration of the destructor of an invalid class was not properly marked
as noexcept. As a result, the definition of the same destructor, which was
properly implicitly marked as noexcept, would not match the definition.
This would cause the definition CXXDestructorDecl to be matked as invalid
and omited from the AST.
Differential Revision: http://reviews.llvm.org/D17988
llvm-svn: 263639
r263299 added a fixit for the -Wformat-security warning, but that runs
into complications with our guideline that error recovery should be done
as-if the fixit had been applied. Putting the fixit on a note avoids that.
llvm-svn: 263584
Original patch by Stefan Bühler http://reviews.llvm.org/D12834
Difference between original and this one:
- fixed all comments in original code review
- added more tests, all new diagnostics now covered by tests
- moved abi_tag on re-declaration checks to Sema::mergeDeclAttributes
where they actually may work as designed
- clang-format + other stylistic changes
Mangle part will be sent for review as a separate patch.
Differential Revision: http://reviews.llvm.org/D17567
llvm-svn: 263015
Similar to the template cases in r262050, when a C++ method in an
unavailable struct/class calls unavailable API, don't diagnose an error.
I.e., this case was failing:
void foo() __attribute__((unavailable));
struct __attribute__((unavailable)) A {
void bar() { foo(); }
};
Since A is unavailable, A::bar is allowed to call foo. However, we were
emitting a diagnostic here. This commit checks up the context chain
from A::bar, in a manner inspired by SemaDeclAttr.cpp:isDeclUnavailable.
I expected to find other related issues but failed to trigger them:
- I wondered if DeclBase::getAvailability should check for
`TemplateDecl` instead of `FunctionTemplateDecl`, but I couldn't find
a way to trigger this. I left behind a few extra tests to make sure
we don't regress.
- I wondered if Sema::isFunctionConsideredUnavailable should be
symmetric, checking up the context chain of the callee (this commit
only checks up the context chain of the caller). However, I couldn't
think of a testcase that didn't require first referencing the
unavailable type; this, we already diagnose.
rdar://problem/25030656
llvm-svn: 262921
exactly the same as clang's existing [[clang::fallthrough]] attribute, which
has been updated to have the same semantics. The one significant difference
is that [[fallthrough]] is ill-formed if it's not used immediately before a
switch label (even when -Wimplicit-fallthrough is disabled). To support that,
we now build a CFG of any function that uses a '[[fallthrough]];' statement
to check.
In passing, fix some bugs with our support for statement attributes -- in
particular, diagnose their use on declarations, rather than asserting.
llvm-svn: 262881
Previously, the failed capture of a variable in nested lambdas may crash when
the lambda pointer is null. Only give the note if a location can be retreived
from the lambda pointer.
llvm-svn: 262765
with a prior UsingDecl -- those should not even really be found by the lookup
here, except that we use the same lookup results for two different checks, and
the other check needs them.
This happens to work in *almost all* cases, because either the lookup results
list the UsingDecl first (and the NonTag result gets replaced by something
else) or because the problematic declaration is a function (which causes us to
use different logic to detect conflicts). This can also be triggered from a
state only reachable through modules (where the name lookup results can contain
multiple UsingDecls in the same scope).
llvm-svn: 262105
If the availability context is `FunctionTemplateDecl`, we should look
through it to the `FunctionDecl`. This prevents a diagnostic in the
following case:
class C __attribute__((unavailable));
template <class T> void foo(C&) __attribute__((unavailable));
This adds tests for availability in templates in many other cases, but
that was the only case that failed before this patch.
I added a feature `__has_feature(attribute_availability_in_templates)`
so users can test for this.
rdar://problem/24561029
llvm-svn: 262050
A member expression's base doesn't always have an impact on what the
member decl would evaluate to. In such a case, the base is used as a
poor man's scope qualifier.
This fixes PR26738.
Differential Revision: http://reviews.llvm.org/D17619
llvm-svn: 261975
r261297 called hasUserProvidedDefaultConstructor() to check if defining a
const object is ok. This is incorrect for this example:
struct X { template<typename ...T> X(T...); int n; };
const X x; // formerly OK, now bogus error
Instead, track if a class has a defaulted default constructor, and disallow
a const object for classes that either have defaulted default constructors or
if they need an implicit constructor.
Bug report and fix approach by Richard Smith, thanks!
llvm-svn: 261770
C++11 requires const objects to have a user-provided constructor, even for
classes without any fields. DR 253 relaxes this to say "If the implicit default
constructor initializes all subobjects, no initializer should be required."
clang is currently the only compiler that implements this C++11 rule, and e.g.
libstdc++ relies on something like DR 253 to compile in newer versions. This
change makes it possible to build code that says `const vector<int> v;' again
when using libstdc++5.2 and _GLIBCXX_DEBUG
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60284).
Fixes PR23381.
http://reviews.llvm.org/D16552
llvm-svn: 261297
Fixes crash referenced in PR25181 where dyn_cast is called on a null
instance of LM.Method.
Reviewers: majnemer, rnk
Patch by Don Hinton
Differential Revision: http://reviews.llvm.org/D17072
llvm-svn: 261292
-Wcomma will detect and warn on most uses of the builtin comma operator. It
currently whitelists the first and third statements of the for-loop. For other
cases, the warning can be silenced by casting the first operand of the comma
operator to void.
Differential Revision: http://reviews.llvm.org/D3976
llvm-svn: 261278
Previously we would leave behind the old name specifier prefix, which
creates an invalid AST. Other callers of CorrectTypo update their
CXXScopeSpec objects with the correction specifier if one is present.
llvm-svn: 260993
In my previous commit (rL260881) I forget to svn add tests. This commit adds
them.
Differential Revision: http://reviews.llvm.org/D16846
llvm-svn: 260882
In the case that the array indexing itself is within a type dependent context,
bail out of the evaluation. We would previously try to symbolically evaluate
the expression which would then try to evaluate a non-address expression as an
address, triggering an assertion in Asserts builds.
We only need to consider the array subscript expression itself as in the case
that the base itself being type dependent is handled appropriately in EvalAddr.
Resolves PR26599.
llvm-svn: 260867
When a null constant is used in a macro, walk through the macro stack to
determine where the null constant is written and where the context is located.
Only warn if both locations are within the same macro expansion. This helps
function-like macros which involve pointers be treated as if they were
functions.
llvm-svn: 260776
Fix a crash while parsing this code:
struct X {
friend constexpr int foo(X*) { return 12; }
static constexpr int j = foo(static_cast<X*>(nullptr));
};
Differential Revision: http://reviews.llvm.org/D16973
llvm-svn: 260675
If the typo happens after a successful deduction for an earlier
return statement, we should check if the deduced type is null
before using it.
The typo correction happens after we try to deduce the return
type and we ignore the deduction from the typo and continue
to typo correction.
rdar://24342247
llvm-svn: 259820
When performing a cast from an __unknown_anytype function call to a
non-void type, we need to make sure that type is complete. Fixes
rdar://problem/23959960.
llvm-svn: 259681
C++14 generic lambdas. It conflicts with the C++14 return type deduction
mechanism, and results in us failing to actually deduce the lambda's return
type in some cases.
llvm-svn: 259609
Allow "mode" attribute for enum types, except for vector modes, for compatibility with GCC.
Support "mode" attribute with dependent types.
Differential Revision: http://reviews.llvm.org/D16219
llvm-svn: 259497
Move the function to get a macro name from DiagnosticRenderer.cpp to Lexer.cpp
so that other files can use it. Lexer now has two functions to get the
immediate macro name, the newly added one is better for diagnostic purposes.
Make -Wnull-conversion use this function for better NULL macro detection.
llvm-svn: 258778
Per C++14 [class.virtual]p8, it is OK for the return type's class type
to be incomplete so long as the return type is the same between the base
and complete classes.
This fixes PR26297.
llvm-svn: 258768
-Wdelete-non-virtual-dtor warns if A is a type with virtual functions but
without virtual dtor has its constructor called via `delete a`. This makes the
warning also fire if the dtor is called via `a->~A()`. This would've found a
security bug in Chromium at compile time. Fixes PR26137.
To fix the warning, add a virtual destructor, make the class final, or remove
its other virtual methods. If you want to silence the warning, there's also
a fixit that shows how:
test.cc:12:3: warning: destructor called on 'B' ... [-Wdelete-non-virtual-dtor]
b->~B();
^
test.cc:12:6: note: qualify call to silence this warning
b->~B();
^
B::
http://reviews.llvm.org/D16206
llvm-svn: 257939
This attribute may be attached to a function definition and instructs the backend to generate appropriate function entry/exit code so that
it can be used directly as an interrupt handler.
The IRET instruction, instead of the RET instruction, is used to return from interrupt or exception handlers. All registers, except for the EFLAGS register which is restored by the IRET instruction, are preserved by the compiler.
Any interruptible-without-stack-switch code must be compiled with -mno-red-zone since interrupt handlers can and will, because of the hardware design, touch
the red zone.
interrupt handler must be declared with a mandatory pointer argument:
struct interrupt_frame;
__attribute__ ((interrupt))
void f (struct interrupt_frame *frame) {
...
}
and user must properly define the structure the pointer pointing to.
exception handler:
The exception handler is very similar to the interrupt handler with a different mandatory function signature:
#ifdef __x86_64__
typedef unsigned long long int uword_t;
#else
typedef unsigned int uword_t;
#endif
struct interrupt_frame;
__attribute__ ((interrupt))
void f (struct interrupt_frame *frame, uword_t error_code) {
...
}
and compiler pops the error code off stack before the IRET instruction.
The exception handler should only be used for exceptions which push an error code and all other exceptions must use the interrupt handler.
The system will crash if the wrong handler is used.
Differential Revision: http://reviews.llvm.org/D15709
llvm-svn: 257867
-Wnull-conversion warning.
These functions are basically equivalent to other pointer returning fuctions
which are already excluded by -Wnull-conversion.
llvm-svn: 257231
Given an expression like `(&Foo)();`, we perform overload resolution as
if we are calling `Foo` directly. This causes problems if `Foo` is a
function that can't have its address taken. This patch teaches overload
resolution to ignore functions that can't have their address taken in
such cases.
Differential Revision: http://reviews.llvm.org/D15590
llvm-svn: 257016
By storing the instantiated expression back in the ParmVarDecl,
we remove the last need for separately storing the sub-expression
of a CXXDefaultArgExpr. This makes PCH/Modules merging quite
simple: CXXDefaultArgExpr records are serialized as references
to the ParmVarDecl, and we ignore redundant attempts to overwrite
the instantiated expression.
This has some extremely marginal impact on user-facing semantics.
However, the major effect is that it avoids IRGen errors about
conflicting definitions due to lambdas in the argument being
instantiated multiple times while sharing the same mangling.
It should also slightly improve memory usage and module file size.
rdar://23810407
llvm-svn: 256983
When the condition in an if statement, while statement, or for loop is created
during template instantiation, it calls MakeFullExpr with only the condition
expression. However, when these conditions are created for non-templated
code in the Parser, an additional SourceLocation is passed to MakeFullExpr.
The impact of this was that non-dependent templated code could produce
diagnostics that the same code outside templates would not. Adding the missing
SourceLocation makes diagnostics consistent between templated and non-templated
code.
llvm-svn: 256976
Summary:
There are a number of files in the tree which have been accidentally checked in with DOS line endings. Convert these to native line endings.
There are also a few files which have DOS line endings on purpose, and I have set the svn:eol-style property to 'CRLF' on those.
Reviewers: joerg, aaron.ballman
Subscribers: aaron.ballman, cfe-commits
Differential Revision: http://reviews.llvm.org/D15849
llvm-svn: 256704
The MS ABI emits a special default constructor closure thunk if a
default constructor has a weird calling convention or default arguments.
The MS ABI has a quirk: there can be only one such thunk because the
mangling scheme does not have room for distinct manglings. We must
raise a diagnostic in this eventuality.
N.B. MSVC sorta gets this right. Multiple default constructors result
in the default constructor closure getting emitted but they seem to
get confused by which default constructors are reasonable to reference
from the closure. We try to be a little more careful which results in
mild differences in behavior.
llvm-svn: 256661
declaration. This fixes an issue where we would reject (due to a claimed
ambiguity) a case where lookup finds multiple NamespaceAliasDecls from
different scopes that nominate the same namespace.
The C++ standard doesn't make it clear that such a case is in fact valid (which
I'm working on fixing), but there are no relevant rules that distinguish using
declarations and namespace alias declarations here, so it makes sense to treat
them the same way.
llvm-svn: 256601
underlying decls. Preserve the found declaration throughout, and only map to
the underlying declaration when we want to check whether it's the right kind.
This allows us to provide the right source location for the found declaration,
and prepares for the possibility of underlying decls with a different name
from the found decl.
llvm-svn: 256575
This patch fixes PR16677. The latter represents the case when due to
misprinted character class definition occurs in the scope of template
arguments. Base class of this class depends on the template parameter in the
same scope and cannot be resolved, it causes crash. Right behavior is to
make semantic processing even if the definition is wrong, as the code
that emits appropriate message is called after the processing.
llvm-svn: 256511
Given the following code:
int *_Nullable ptr;
int *_Nonnull nn = ptr;
...In C, clang will warn you about `nn = ptr`, because you're assigning
a nonnull pointer to a nullable pointer. In C++, clang issues no such
warning. This patch helps ensure that clang doesn't ever miss an
opportunity to complain about C++ code.
N.B. Though this patch has a differential revision link, the actual
review took place over email.
Differential Revision: http://reviews.llvm.org/D14938
llvm-svn: 255556
All problems described in http://llvm.org/PR25636 are implemented except for return value of the 'put' property. This patch fixes this problem with the indexed properties
Differential Revision: http://reviews.llvm.org/D15174
llvm-svn: 255218
This is the 5th Lit test patch.
Expanded expected diagnostics to vary by C++ dialect.
Expanded RUN line to: default, C++98/03 and C++11.
llvm-svn: 255196
variables in C, in the cases where we can constant-fold it to a value
regardless (such as floating-point division by zero and signed integer
overflow). Strictly enforcing this rule breaks too much code.
llvm-svn: 254992
https://llvm.org/bugs/show_bug.cgi?id=20334
Unfortunately, clang currently checks for a certain brokenness of implementations of std::initializer_list in CodeGen (void
AggExprEmitter::VisitCXXStdInitializerListExpr), not in SemaInit. Until that is fixed, make sure we don't let broken attempts that are aggregates leak through into sema, which allows maintenance of expected invariants, and avoids triggering an assertion.
llvm-svn: 254889
to treat as an ICE results in undefined behavior. Instead, return the "natural"
result of the operation (signed wraparound / inf / nan).
llvm-svn: 254699
do scope-based lookup when looking for redeclarations of them. Add some related
missing checks for the scope-based redeclaration lookup: properly filter the
list of found declarations to match the scope, and diagnose shadowing of a
template parameter name.
llvm-svn: 254663
The tests were failing because the types of some member functions, when
printed, unexpectedly had "__attribute__((thiscall))" at the end. The
types in question were relatively unimportant to begin with, so they
were removed/replaced with regexes.
llvm-svn: 254650
The introduction of pass_object_size fixed a few bugs related to taking
the address of a function with enable_if attributes. This patch adds
tests for the cases that were fixed.
llvm-svn: 254646
These additions were meant to go in as a part of r254554; while it's
certainly nice to have new functionality, it's nicer if we have tests to
go with it. :)
llvm-svn: 254632
side-effect, so that we don't allow speculative evaluation of such expressions
during code generation.
This caused a diagnostic quality regression, so fix constant expression
diagnostics to prefer either the first "can't be constant folded" diagnostic or
the first "not a constant expression" diagnostic depending on the kind of
evaluation we're doing. This was always the intent, but didn't quite work
correctly before.
This results in certain initializers that used to be constant initializers to
no longer be; in particular, things like:
float f = 1e100;
are no longer accepted in C. This seems appropriate, as such constructs would
lead to code being executed if sanitizers are enabled.
llvm-svn: 254574
`pass_object_size` is our way of enabling `__builtin_object_size` to
produce high quality results without requiring inlining to happen
everywhere.
A link to the design doc for this attribute is available at the
Differential review link below.
Differential Revision: http://reviews.llvm.org/D13263
llvm-svn: 254554
Function types can be extracted from member pointer types.
However, the type is not appropriate without first adjusting the calling
convention.
This fixes PR25661.
llvm-svn: 254323
We will still allow it in system headers, in macros from system headers, when
combined with an 'asm' label, and under the flag -Wno-register.
llvm-svn: 254097
MSVC supports 'property' attribute and allows to apply it to the declaration of an empty array in a class or structure definition.
For example:
```
__declspec(property(get=GetX, put=PutX)) int x[];
```
The above statement indicates that x[] can be used with one or more array indices. In this case, i=p->x[a][b] will be turned into i=p->GetX(a, b), and p->x[a][b] = i will be turned into p->PutX(a, b, i);
Differential Revision: http://reviews.llvm.org/D13336
llvm-svn: 254067
Richard Trieu