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*)
will silence the warning.
Differential Revision: https://reviews.llvm.org/D20561
llvm-svn: 278483
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
These ExprWithCleanups are added for holding a RunCleanupsScope not
for destructor calls; rather, they are for lifetime marks. This requires
ExprWithCleanups to keep a bit to indicate whether it have cleanups with
side effects (e.g. dtor calls).
Differential Revision: http://reviews.llvm.org/D20498
llvm-svn: 272296
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
Summary:
This only warns on casts of the address of a function defined in the
current TU. In this case, the fix is likely to be local and the warning
useful.
Here are some things we could experiment with in the future:
- Fire on declarations as well as definitions
- Limit the warning to non-void function prototypes
- Limit the warning to mismatches of caller and callee cleanup CCs
This warning is currently off by default while we study its usefulness.
Reviewers: thakis, rtrieu
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D17348
llvm-svn: 269116
While we correctly assigned an inheritance model for the source of a
member pointer upcast, we did not do so for the destination.
This fixes PR27030.
llvm-svn: 264065
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
In {CG,}ExprConstant.cpp, we weren't treating vector splats properly.
This patch makes us treat splats more properly.
Additionally, this patch adds a new cast kind which allows a bool->int
cast to result in -1 or 0, instead of 1 or 0 (for true and false,
respectively), so we can sanely model OpenCL bool->int casts in the AST.
Differential Revision: http://reviews.llvm.org/D14877
llvm-svn: 257559
is complete (with an error produced if not) and a function that merely queries
whether the type is complete. Either way we'll trigger instantiation if
necessary, but only the former will diagnose and recover from missing module
imports.
The intent of this change is to prevent a class of bugs where code would call
RequireCompleteType(..., 0) and then ignore the result. With modules, we must
check the return value and use it to determine whether the definition of the
type is visible.
This also fixes a debug info quality issue: calls to isCompleteType do not
trigger the emission of debug information for a type in limited-debug-info
mode. This allows us to avoid emitting debug information for type definitions
in more cases where we believe it is safe to do so.
llvm-svn: 256049
for the derived class into it. This is mostly just a cleanup, but could in
principle be a bugfix if there is some codepath that reaches here and didn't
previously require a complete type (I couldn't find any such codepath, though).
llvm-svn: 256037
Previously, __weak was silently accepted and ignored in MRC mode.
That makes this a potentially source-breaking change that we have to
roll out cautiously. Accordingly, for the time being, actual support
for __weak references in MRC is experimental, and the compiler will
reject attempts to actually form such references. The intent is to
eventually enable the feature by default in all non-GC modes.
(It is, of course, incompatible with ObjC GC's interpretation of
__weak.)
If you like, you can enable this feature with
-Xclang -fobjc-weak
but like any -Xclang option, this option may be removed at any point,
e.g. if/when it is eventually enabled by default.
This patch also enables the use of the ARC __unsafe_unretained qualifier
in MRC. Unlike __weak, this is being enabled immediately. Since
variables are essentially __unsafe_unretained by default in MRC,
the only practical uses are (1) communication and (2) changing the
default behavior of by-value block capture.
As an implementation matter, this means that the ObjC ownership
qualifiers may appear in any ObjC language mode, and so this patch
removes a number of checks for getLangOpts().ObjCAutoRefCount
that were guarding the processing of these qualifiers. I don't
expect this to be a significant drain on performance; it may even
be faster to just check for these qualifiers directly on a type
(since it's probably in a register anyway) than to do N dependent
loads to grab the LangOptions.
rdar://9674298
llvm-svn: 251041
This fixes a bug where one can take the address of a conditionally
enabled function to drop its enable_if guards. For example:
int foo(int a) __attribute__((enable_if(a > 0, "")));
int (*p)(int) = &foo;
int result = p(-1); // compilation succeeds; calls foo(-1)
Overloading logic has been updated to reflect this change, as well.
Functions with enable_if attributes that are always true are still
allowed to have their address taken.
Differential Revision: http://reviews.llvm.org/D13607
llvm-svn: 250090
I cannot come up with a testcase which would rely on this call to
RequireCompleteType, I believe that it is superfluous given the current
state of clang.
llvm-svn: 247367
Original class was not marked with inheritance attribute and it causes a crash on codegen.
Differential Revision: http://reviews.llvm.org/D11828
llvm-svn: 244428
to consider the storage size of the vector instead of its
sizeof. In other words, ban <3 x int> to <4 x int> casts,
which produced invalid IR anyway.
Also, attempt to be a little more rigorous, or at least
explicit, about when enums are allowed in these casts.
rdar://21901132
llvm-svn: 243069
In the test, y1 is not reference compatible to y2 and we currently assume
the cast is ill-formed so we emit a diagnostic. Instead, in order to honour
the standard, if y1 it's not reference-compatible to y2 then it can't be
converted using a static_cast, and a reinterpret_cast should be tried instead.
Richard Smith provided the correct interpretation of the standard and
explanation about the subtle difference between "can't be cast" and "the cast
is ill-formed". The former applies in this case.
PR: 23802
llvm-svn: 241998
The patch is generated using this command:
$ tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
-checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
work/llvm/tools/clang
To reduce churn, not touching namespaces spanning less than 10 lines.
llvm-svn: 240270
The machinery added to permit a static_cast from void-ptr to fn-ptr
unintentionally gets triggered for c-style casts and function-style
casts. The observable effect was a diagnostic issued inappropriately.
llvm-svn: 239382
The MSVC 2013 and 2015 implementation of std::atomic is specialized for
pointer types. The member functions are implemented using a static_cast
from void-ptr to function-ptr which is not allowed in the standard.
Permit this conversion if -fms-compatibility is present.
This fixes PR23733.
llvm-svn: 238877
clang currently calls MarkVTableUsed() for classes that get their virtual
methods called or that participate in a dynamic_cast. This is unnecessary,
since CodeGen only emits vtables when it generates constructor, destructor, and
vtt code. (*)
Note that Sema::MarkVTableUsed() doesn't cause the emission of a vtable.
Its main user-visible effect is that it instantiates virtual member functions
of template classes, to make sure that if codegen decides to write a vtable
all the entries in the vtable are defined.
While this shouldn't change the behavior of codegen (other than being faster),
it does make clang more permissive: virtual methods of templates (in particular
destructors) end up being instantiated less often. In particular, classes that
have members that are smart pointers to incomplete types will now get their
implicit virtual destructor instantiated less frequently. For example, this
used to not compile but does now compile:
template <typename T> struct OwnPtr {
~OwnPtr() { static_assert((sizeof(T) > 0), "TypeMustBeComplete"); }
};
class ScriptLoader;
struct Base { virtual ~Base(); };
struct Sub : public Base {
virtual void someFun() const {}
OwnPtr<ScriptLoader> m_loader;
};
void f(Sub *s) { s->someFun(); }
The more permissive behavior matches both gcc (where this is not often
observable, since in practice most things with virtual methods have a key
function, and Sema::DefineUsedVTables() skips vtables for classes with key
functions) and cl (which is my motivation for this change) – this fixes
PR20337. See this issue and the review thread for some discussions about
optimizations.
This is similar to r213109 in spirit. r225761 was a prerequisite for this
change.
Various tests relied on "a->f()" marking a's vtable as used (in the sema
sense), switch these to just construct a on the stack. This forces
instantiation of the implicit constructor, which will mark the vtable as used.
(*) The exception is -fapple-kext mode: In this mode, qualified calls to
virtual functions (`a->Base::f()`) still go through the vtable, and since the
vtable pointer off this doesn't point to Base's vtable, this needs to reference
Base's vtable directly. To keep this working, keep referencing the vtable for
virtual calls in apple kext mode.
llvm-svn: 227073
We know that const_cast<char *>((void)Something) is ill-formed, even if
'Something' is dependent because you can't cast from void to a pointer
type.
This fixes PR21845.
llvm-svn: 224299
OpenCL v2.0 s6.5.5 restricts conversion of pointers to different address spaces:
- the named address spaces (__global, __local, and __private) => __generic - implicitly converted;
- __generic => named - with an explicit cast;
- named <=> named - disallowed;
- __constant <=> any other - disallowed.
llvm-svn: 222834
The compilation pipeline doesn't actually need to know about the high-level
concept of diagnostic mappings, and hiding the final computed level presents
several simplifications and other potential benefits.
The only exceptions are opportunistic checks to see whether expensive code
paths can be avoided for diagnostics that are guaranteed to be ignored at a
certain SourceLocation.
This commit formalizes that invariant by introducing and using
DiagnosticsEngine::isIgnored() in place of individual level checks throughout
lex, parse and sema.
llvm-svn: 211005
Summary:
Previously, we would generate a single name for all reference
temporaries and allow LLVM to rename them for us. Instead, number the
reference temporaries as we build them in Sema.
Reviewers: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D3554
llvm-svn: 207776
If the C-style type cast is applied to the overloaded
function and the destination type is function type,
then Clang will crash with assertion failure. For example,
void foo(int);
void foo(int, int);
void bar() {
typedef void (ft)(int);
ft p = (ft)foo;
}
In this case, the overloaded function foo will be cast to
a function type, which should be considered as an error.
But, unfortunately, since the function resolution is using
canonical type, the matched function will be returned, and
result in SEGV.
This patch fixes this issue by removing the assertion and
add some error diagnostics as the one in static_cast.
llvm-svn: 206133
Properly determine the inheritance model when dealing with nullptr:
- If a nullptr template argument is being checked against
pointer-to-member parameter, nail down an inheritance model.
N.B. We will chose an inheritance model even if we won't ultimately
choose the template to instantiate! Cooky, right?
- Null pointer-to-datamembers have a virtual base table offset of -1,
not zero. Previously, we chose an offset of 0.
llvm-svn: 200920
This reverts commit r199475 (which reverted r199416) with fixes for the
breakages.
We wouldn't lock an inheritance model if we saw a pointer-to-member
formed as a result of the address-of operator.
llvm-svn: 199482
The MSVC ABI is rather finicky about the exact representation of it's
pointer-to-member representation. The exact position of when and where
it will go with one representation versus another appears to be when it
desires the pointer-to-member to be complete.
To properly implement this in clang, do several things:
- Give up on tracking the polymorphic nature of the class. It isn't
useful to Sema and is only pertinent when choosing CodeGen-time
details like whether the field-offset can be 0 instead of -1.
- Insist on locking-in the inheritance model when we ask our
pointer-to-member type to be complete. From there, grab the
underlying CXXRecordDecl and try to make *that* complete. Once we've
done this, we can calculate it's inheritance model and apply it using
an attribute.
N.B. My first bullet point is a lie. We will eventually care about the
specifics of whether or not a CXXRecordDecl is or is not polymorphic
because MSVC compatible mangling of such things depends on it. However,
I believe we will handle this in a rather different way.
llvm-svn: 199416
Richard Smith