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
We would attempt to determine the inheritance relationship between
classes 'A' and 'B' during static_cast if we tried to convert from 'int
A::*' to 'int B::*'. However, the question "does A derive from B" is
not meaningful when 'A' isn't defined.
Handle this case by requiring that 'A' be defined.
This fixes PR18506.
llvm-svn: 199374
We don't really need to perform semantic analysis on the dependent expression
anyway, so just call the cast dependent.
<rdar://problem/15012610>
llvm-svn: 190981
In addition to storing more useful information in the AST, this
fixes a semantic check in template instantiation which checks whether
the l-paren location is valid.
Fixes PR16903.
llvm-svn: 188495
This matches how we normally perform semantic analysis for other sorts
of invalid expressions: it means we don't have to reason about invalid
sub-expressions.
Fixes PR16680.
llvm-svn: 187276
This became allowed by accident in r131201, but triggers an assert.
That patch added an exception to allow conversion from pointers to
narrow integral types for MSVC compatibility. However, a pointer can
already be converted to bool in a civilized manner; allowing conversion
via reinterpret_cast is a bad idea.
Fixes PR16222.
llvm-svn: 183394
This change is motivated from user feedback that some APIs use
void* as an opaque "context" object that may not really be a pointer.
Such users want an ability to turn off the warning for casts
to void* while preserving the warning for other cases.
Implements <rdar://problem/14016721>.
llvm-svn: 182884
- References to ObjC bit-field ivars are bit-field lvalues;
fixes rdar://13794269, which got me started down this.
- Introduce Expr::refersToBitField, switch a couple users to
it where semantically important, and comment the difference
between this and the existing API.
- Discourage Expr::getBitField by making it a bit longer and
less general-sounding.
- Lock down on const_casts of bit-field gl-values until we
hear back from the committee as to whether they're allowed.
llvm-svn: 181252
The suggestion was already in the text of the note; this just adds the
actual fixit and the appropriate test cases.
Patch by Alexander Zinenko!
llvm-svn: 178274
uncovered.
This required manually correcting all of the incorrect main-module
headers I could find, and running the new llvm/utils/sort_includes.py
script over the files.
I also manually added quite a few missing headers that were uncovered by
shuffling the order or moving headers up to be main-module-headers.
llvm-svn: 169237
This implementation doesn't warn on anything that GCC doesn't warn on with the
exception of templates specializations (GCC doesn't warn, Clang does). The
specific skipped cases (boolean, constant expressions, enums) are open for
debate/adjustment if anyone wants to demonstrate that GCC is being overly
conservative here. The only really obvious false positive I found was in the
Clang regression suite's MPI test - apparently MPI uses specific flag values in
pointer constants. (eg: #define FOO (void*)~0)
llvm-svn: 166039
Nathan Sidwell