on cxx-abi-dev (thread starting 2016-10-11). This is currently hidden behind a
cc1-only -m flag, pending discussion of how best to deal with language changes
that require use of new symbols from the ABI library.
llvm-svn: 285664
mismatched dynamic exception specifications in expressions from an error to a
warning, since this is no longer ill-formed in C++1z.
Allow reference binding of a reference-to-non-noexcept function to a noexcept
function lvalue. As defect resolutions, also allow a conditional between
noexcept and non-noexcept function lvalues to produce a non-noexcept function
lvalue (rather than decaying to a function pointer), and allow function
template argument deduction to deduce a reference to non-noexcept function when
binding to a noexcept function type.
llvm-svn: 284905
This has two significant effects:
1) Direct relational comparisons between null pointer constants (0 and nullopt)
and pointers are now ill-formed. This was always the case for C, and it
appears that C++ only ever permitted by accident. For instance, cases like
nullptr < &a
are now rejected.
2) Comparisons and conditional operators between differently-cv-qualified
pointer types now work, and produce a composite type that both source
pointer types can convert to (when possible). For instance, comparison
between 'int **' and 'const int **' is now valid, and uses an intermediate
type of 'const int *const *'.
Clang previously supported #2 as an extension.
We do not accept the cases in #1 as an extension. I've tested a fair amount of
code to check that this doesn't break it, but if it turns out that someone is
relying on this, we can easily add it back as an extension.
This is a re-commit of r284800.
llvm-svn: 284890
This has two significant effects:
1) Direct relational comparisons between null pointer constants (0 and nullopt)
and pointers are now ill-formed. This was always the case for C, and it
appears that C++ only ever permitted by accident. For instance, cases like
nullptr < &a
are now rejected.
2) Comparisons and conditional operators between differently-cv-qualified
pointer types now work, and produce a composite type that both source
pointer types can convert to (when possible). For instance, comparison
between 'int **' and 'const int **' is now valid, and uses an intermediate
type of 'const int *const *'.
Clang previously supported #2 as an extension.
We do not accept the cases in #1 as an extension. I've tested a fair amount of
code to check that this doesn't break it, but if it turns out that someone is
relying on this, we can easily add it back as an extension.
llvm-svn: 284800
not instantiate exception specifications of functions if they were only used in
unevaluated contexts (other than 'noexcept' expressions).
In C++17 onwards, this becomes essential since the exception specification is
now part of the function's type.
Note that this means that constructs like the following no longer work:
struct A {
static T f() noexcept(...);
decltype(f()) *p;
};
... because the decltype expression now needs the exception specification of
'f', which has not yet been parsed.
llvm-svn: 284549
Summary:
Move alpha.valist from potential to alpha since it was implemented in D15227
Cleanup some HTML comments, add a missing link
Reviewers: jordan_rose, zaks.anna
Subscribers: cfe-commits, xazax.hun
Differential Revision: https://reviews.llvm.org/D25663
llvm-svn: 284445
Instead of ignoring the evaluation order rule, ignore the "destroy parameters
in reverse construction order" rule for the small number of problematic cases.
This only causes incorrect behavior in the rare case where both parameters to
an overloaded operator <<, >>, ->*, &&, ||, or comma are of class type with
non-trivial destructor, and the program is depending on those parameters being
destroyed in reverse construction order.
We could do a little better here by reversing the order of parameter
destruction for those functions (and reversing the argument evaluation order
for all direct calls, not just those with operator syntax), but that is not a
complete solution to the problem, as the same situation can be reached by an
indirect function call.
Approach reviewed off-line by rnk.
llvm-svn: 282777
function correctly when targeting MS ABIs (this appears to have never mattered
prior to this change).
Update test case to always cover both 32-bit and 64-bit Windows ABIs, since
they behave somewhat differently from each other here.
Update test case to also cover operators , && and ||, which it appears are also
affected by P0145R3 (they're not explicitly called out by the design document,
but this is the emergent behavior of the existing wording).
Original commit message:
P0145R3 (C++17 evaluation order tweaks): evaluate the right-hand side of
assignment and compound-assignment operators before the left-hand side. (Even
if it's an overloaded operator.)
This completes the implementation of P0145R3 + P0400R0 for all targets except
Windows, where the evaluation order guarantees for <<, >>, and ->* are
unimplementable as the ABI requires the function arguments are evaluated from
right to left (because parameter destructors are run from left to right in the
callee).
llvm-svn: 282619
assignment and compound-assignment operators before the left-hand side. (Even
if it's an overloaded operator.)
This completes the implementation of P0145R3 + P0400R0 for all targets except
Windows, where the evaluation order guarantees for <<, >>, and ->* are
unimplementable as the ABI requires the function arguments are evaluated from
right to left (because parameter destructors are run from left to right in the
callee).
llvm-svn: 282556
explicit specialization to a warning for C++98 mode (this is a defect report
resolution, so per our informal policy it should apply in C++98), and turn
the warning on by default for C++11 and later. In all cases where it fires, the
right thing to do is to remove the pointless explicit instantiation.
llvm-svn: 280308
Fix the explanation of how to run tests after migration
from autotools to cmake.
Significantly expand the "debugging" section
with more interesting stuff.
Update the table of contents accordingly.
Fix paragraphs in the overview section.
Differential Revision: https://reviews.llvm.org/D22874
llvm-svn: 277029
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
compiler-rt is optional. We often get email from users with compiler-rt
build errors who don't actually need compiler-rt. Marking it optional
should help them avoid those potential problems.
While I'm here, update a reference to the build directory and remove an
obsolete reference to llvm-gcc. Nobody today is under the impression
that Clang depends on GCC.
llvm-svn: 265963
This is the clang equivalent to llvm commit 264601. When using Visual Studio 2015, cmake now puts the native visualizers in llvm.sln, so the developer automatically sees custom visualizations.
Much thanks to ariccio who provided extensive help on this change. (manual installation still needed on VS2013).
llvm-svn: 264603
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
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
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
to force debug build and hopefully enable more precise warnings.
Static Analyzer is much more efficient when built in debug mode
(-UNDEBUG) so we advice users to enable it manually. This may be
inconvenient in case of large complex projects (think about Linux
distros e.g. Android or Tizen). This patch adds a flag to scan-build
which inserts -UNDEBUG automatically.
Differential Revision: http://reviews.llvm.org/D16200
llvm-svn: 261204
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
DR407, the C++ standard doesn't really say how this should work. Here's what we
do (which is consistent with DR407 as far as I can tell):
* When performing name lookup for an elaborated-type-specifier, a tag
declaration hides a typedef declaration that names the same type.
* When performing any other kind of lookup, a typedef declaration hides
a tag declaration that names the same type.
In any other case where lookup finds both a typedef and a tag (that is, when
they name different types), the lookup will be ambiguous. If lookup finds a
tag and a typedef that name the same type, and finds anything else, the lookup
will always be ambiguous (even if the other entity would hide the tag, it does
not also hide the typedef).
llvm-svn: 252959
std::initializer_list<T> type. Instead, the list must contain a single element
and the type is deduced from that.
In Clang 3.7, we warned by default on all the cases that would change meaning
due to this change. In Clang 3.8, we will support only the new rules -- per
the request in N3922, this change is applied as a Defect Report against earlier
versions of the C++ standard.
This change is not entirely trivial, because for lambda init-captures we
previously did not track the difference between direct-list-initialization and
copy-list-initialization. The difference was not previously observable, because
the two forms of initialization always did the same thing (the elements of the
initializer list were always copy-initialized regardless of the initialization
style used for the init-capture).
llvm-svn: 252688
Devin Coughlin