Summary:
Clang incorrectly reports empty unions as having a unique object representation. However, this is not correct since `sizeof(EmptyUnion) == 1` AKA it has 8 bits of padding. Therefore it should be treated the same as an empty struct and report `false`.
@erichkeane also suggested this fix should be merged into the 6.0 release branch, so the initial release of `__has_unique_object_representations` is as bug-free as possible.
Reviewers: erichkeane, rsmith, aaron.ballman, majnemer
Reviewed By: erichkeane
Subscribers: cfe-commits, erichkeane
Differential Revision: https://reviews.llvm.org/D42863
llvm-svn: 324134
Summary:
Use corutine function arguments to initialize a promise type, but only
if the promise type defines a constructor that takes those arguments.
Otherwise, fall back to the default constructor.
Test Plan: check-clang
Reviewers: rsmith, GorNishanov, eric_niebler
Reviewed By: GorNishanov
Subscribers: toby-allsopp, lewissbaker, EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D41820
llvm-svn: 323381
Both are related to handling anonymous structures.
* clang didn't handle () around an anonymous struct variable.
* clang also crashed on syntax errors that could lead to other
syntactic constructs following the declaration of an
anonymous struct. While the code is invalid, that's not
a good reason to panic compiler.
Differential Revision: https://reviews.llvm.org/D41788
llvm-svn: 322742
When parsing C++ type construction expressions with list initialization,
forward the locations of the braces to Sema.
Without these locations, the code coverage pass crashes on the given test
case, because the pass relies on getLocEnd() returning a valid location.
Here is what this patch does in more detail:
- Forwards init-list brace locations to Sema (ParseExprCXX),
- Builds an InitializationKind with these locations (SemaExprCXX), and
- Uses these locations for constructor initialization (SemaInit).
The remaining changes fall out of introducing a new overload for
creating direct-list InitializationKinds.
Testing: check-clang, and a stage2 coverage-enabled build of clang with
asserts enabled.
Differential Revision: https://reviews.llvm.org/D41921
llvm-svn: 322729
We were trying to emit a diag::err_bad_multiversion_option diagnostic,
which expects an int as its first argument, with a string argument. As
it happens, the string `Feature` that was causing this was shadowing an
int `Feature` from the surrounding scope. :)
llvm-svn: 322530
While here, fix up the myriad other ways in which Sema's two "can this handler
catch that exception?" implementations get things wrong and unify them.
llvm-svn: 322431
Summary:
The STL types `std::pair` and `std::tuple` can both store reference types. However their constructors cannot adequately check if the initialization of reference types is safe. For example:
```
std::tuple<std::tuple<int> const&> t = 42;
// The stored reference is already dangling.
```
Libc++ has a best effort attempts in tuple to diagnose this, but they're not able to handle all valid cases (If I'm not mistaken). For example initialization of a reference from the result of a class's conversion operator. Libc++ would benefit from having a builtin traits which can provide a much better implementation.
This patch introduce the `__reference_binds_to_temporary(T, U)` trait that determines whether a reference of type `T` bound to an expression of type `U` would bind to a materialized temporary object.
Note that the trait simply returns false if `T` is not a reference type instead of reporting it as an error.
```
static_assert(__is_constructible(int const&, long));
static_assert(__reference_binds_to_temporary(int const&, long));
```
Reviewers: majnemer, rsmith
Reviewed By: rsmith
Subscribers: compnerd, cfe-commits
Differential Revision: https://reviews.llvm.org/D29930
llvm-svn: 322334
In C++17, guaranteed copy elision means that there isn't necessarily a
constructor call when a local variable is initialized by a function call that
returns a scoped_lockable by value. In order to model the effects of
initializing a local variable with a function call returning a scoped_lockable,
pretend that the move constructor was invoked within the caller at the point of
return.
llvm-svn: 322316
GCC's attribute 'target', in addition to being an optimization hint,
also allows function multiversioning. We currently have the former
implemented, this is the latter's implementation.
This works by enabling functions with the same name/signature to coexist,
so that they can all be emitted. Multiversion state is stored in the
FunctionDecl itself, and SemaDecl manages the definitions.
Note that it ends up having to permit redefinition of functions so
that they can all be emitted. Additionally, all versions of the function
must be emitted, so this also manages that.
Note that this includes some additional rules that GCC does not, since
defining something as a MultiVersion function after a usage has been made illegal.
The only 'history rewriting' that happens is if a function is emitted before
it has been converted to a multiversion'ed function, at which point its name
needs to be changed.
Function templates and virtual functions are NOT yet supported (not supported
in GCC either).
Additionally, constructors/destructors are disallowed, but the former is
planned.
llvm-svn: 322028
Check whether we are comparing the same entity, not merely the same
declaration, and don't assume that weak declarations resolve to distinct
entities.
llvm-svn: 321976
during template argument deduction.
We already did this when the injected-class-name was in P, but missed the case
where it was in A. This (probably) can't happen except in implicit deduction
guides.
llvm-svn: 321779
Summary:
The diagnostic was mostly introduced in D38101 by me, as a reaction to wasting a lot of time, see [[ https://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20171009/206427.html | mail ]].
However, the diagnostic is pretty dumb. While it works with no false-positives,
there are some questionable cases that are diagnosed when one would argue that they should not be.
The common complaint is that it diagnoses the comparisons between an `int` and
`long` when compiling for a 32-bit target as tautological, but not when
compiling for 64-bit targets. The underlying problem is obvious: data model.
In most cases, 64-bit target is `LP64` (`int` is 32-bit, `long` and pointer are
64-bit), and the 32-bit target is `ILP32` (`int`, `long`, and pointer are 32-bit).
I.e. the common pattern is: (pseudocode)
```
#include <limits>
#include <cstdint>
int main() {
using T1 = long;
using T2 = int;
T1 r;
if (r < std::numeric_limits<T2>::min()) {}
if (r > std::numeric_limits<T2>::max()) {}
}
```
As an example, D39149 was trying to fix this diagnostic in libc++, and it was not well-received.
This *could* be "fixed", by changing the diagnostics logic to something like
`if the types of the values being compared are different, but are of the same size, then do diagnose`,
and i even attempted to do so in D39462, but as @rjmccall rightfully commented,
that implementation is incomplete to say the least.
So to stop causing trouble, and avoid contaminating upcoming release, lets do this workaround:
* move these three diags (`warn_unsigned_always_true_comparison`, `warn_unsigned_enum_always_true_comparison`, `warn_tautological_constant_compare`) into it's own `-Wtautological-constant-in-range-compare`
* Disable them by default
* Make them part of `-Wextra`
* Additionally, give `warn_tautological_constant_compare` it's own flag `-Wtautological-type-limit-compare`.
I'm not happy about that name, but i can't come up with anything better.
This way all three of them can be enabled/disabled either altogether, or one-by-one.
Reviewers: aaron.ballman, rsmith, smeenai, rjmccall, rnk, mclow.lists, dim
Reviewed By: aaron.ballman, rsmith, dim
Subscribers: thakis, compnerd, mehdi_amini, dim, hans, cfe-commits, rjmccall
Tags: #clang
Differential Revision: https://reviews.llvm.org/D41512
llvm-svn: 321691
Previously, we would:
* compute the type of the conversion function and static invoker as a
side-effect of template argument deduction for a conversion
* re-compute the type as part of deduced return type deduction when building
the conversion function itself
Neither of these turns out to be quite correct. There are other ways to reach a
declaration of the conversion function than in a conversion (such as an
explicit call or friend declaration), and performing auto deduction causes the
function type to be rebuilt in the context of the lambda closure type (which is
different from the context in which it originally appeared, resulting in
spurious substitution failures for constructs that are valid in one context but
not the other, such as the use of an enclosing class's "this" pointer).
This patch switches us to use a different strategy: as before, we use the
declared type of the operator() to form the type of the conversion function and
invoker, but we now populate that type as part of return type deduction for the
conversion function. And the invoker is now treated as simply being an
implementation detail of building the conversion function, and isn't given
special treatment by template argument deduction for the conversion function
any more.
llvm-svn: 321683
(Re-submission of D39937 with fixed tests.)
Adjust wording for const-qualification mismatch to be a little more clear.
Also add another diagnostic for a ref qualifier mismatch, which previously produced a useless error (this error path is simply very old; see rL119336):
Before:
error: cannot initialize object parameter of type 'X0' with an expression of type 'X0'
After:
error: 'this' argument to member function 'rvalue' is an lvalue, but function has rvalue ref-qualifier
Reviewers: aaron.ballman
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, cfe-commits
Differential Revision: https://reviews.llvm.org/D41646
llvm-svn: 321609
Summary:
Adjust wording for const-qualification mismatch to be a little more clear.
Also add another diagnostic for a ref qualifier mismatch, which previously produced a useless error (this error path is simply very old; see rL119336):
Before:
error: cannot initialize object parameter of type 'X0' with an expression of type 'X0'
After:
error: 'this' argument to member function 'rvalue' is an lvalue, but function has rvalue ref-qualifier
Reviewers: rsmith, aaron.ballman
Reviewed By: aaron.ballman
Subscribers: lebedev.ri, aaron.ballman, cfe-commits
Differential Revision: https://reviews.llvm.org/D39937
llvm-svn: 321592
This is a slightly odd construct (it's more common to see "A (::B)()") but can
happen in friend declarations, and the parens are not redundant as they prevent
the :: binding to the left.
llvm-svn: 321318
An unscoped enumeration used as template argument, should not have any
qualified information about its enclosing scope, as its visibility is
global.
In the case of scoped enumerations, they must include information
about their enclosing scope.
Patch by Carlos Alberto Enciso!
Differential Revision: https://reviews.llvm.org/D39239
llvm-svn: 321312
This allows you to dump C++ code that spells bool instead of _Bool, leaves off the elaborated type specifiers when printing struct or class names, and other C-isms.
Fixes the -Wreorder issue and fixes the ast-dump-color.cpp test.
llvm-svn: 321310
This allows you to dump C++ code that spells bool instead of _Bool, leaves off the elaborated type specifiers when printing struct or class names, and other C-isms.
llvm-svn: 321223
The initializeLocal function of UnaryTransformTypeLoc missed
the UnderlyingTInfo member. This caused a null-dereference
issue, as reported in PR23421. This patch correctly initializss
the UnderlyingTInfo.
llvm-svn: 320765
Summary:
In D41064, I proposed adding `#pragma clang diagnostic ignored
"-Wuser-defined-literals"` to some of libc++'s headers, since these
warnings are now triggered by clang's new `-std=gnu++14` default:
```
$ cat test.cpp
#include <string>
$ clang -std=c++14 -Wsystem-headers -Wall -Wextra -c test.cpp
In file included from test.cpp:1:
In file included from /usr/include/c++/v1/string:470:
/usr/include/c++/v1/string_view:763:29: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string_view<char> operator "" sv(const char *__str, size_t __len)
^
/usr/include/c++/v1/string_view:769:32: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string_view<wchar_t> operator "" sv(const wchar_t *__str, size_t __len)
^
/usr/include/c++/v1/string_view:775:33: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string_view<char16_t> operator "" sv(const char16_t *__str, size_t __len)
^
/usr/include/c++/v1/string_view:781:33: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string_view<char32_t> operator "" sv(const char32_t *__str, size_t __len)
^
In file included from test.cpp:1:
/usr/include/c++/v1/string:4012:24: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string<char> operator "" s( const char *__str, size_t __len )
^
/usr/include/c++/v1/string:4018:27: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string<wchar_t> operator "" s( const wchar_t *__str, size_t __len )
^
/usr/include/c++/v1/string:4024:28: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string<char16_t> operator "" s( const char16_t *__str, size_t __len )
^
/usr/include/c++/v1/string:4030:28: warning: user-defined literal suffixes not starting with '_' are reserved [-Wuser-defined-literals]
basic_string<char32_t> operator "" s( const char32_t *__str, size_t __len )
^
8 warnings generated.
```
Both @aaron.ballman and @mclow.lists felt that adding this workaround to
the libc++ headers was the wrong way, and it should be fixed in clang
instead.
Here is a proposal to do just that. I verified that this suppresses the
warning, even when -Wsystem-headers is used, and that the warning is
still emitted for a declaration outside of system headers.
Reviewers: aaron.ballman, mclow.lists, rsmith
Reviewed By: aaron.ballman
Subscribers: mclow.lists, aaron.ballman, andrew, emaste, cfe-commits
Differential Revision: https://reviews.llvm.org/D41080
llvm-svn: 320755
There are many more expr types that can be a capability expr, like
CXXThisExpr, CallExpr, MemberExpr. Instead of enumerating all of them,
just check typeHasCapability for any type given.
Also add & and * operators to allowed unary operators.
Differential Revision: https://reviews.llvm.org/D41224
llvm-svn: 320753
Adding the new enumerator forced a bunch more changes into this patch than I
would have liked. The -Wtautological-compare warning was extended to properly
check the new comparison operator, clang-format needed updating because it uses
precedence levels as weights for determining where to break lines (and several
operators increased their precedence levels with this change), thread-safety
analysis needed changes to build its own IL properly for the new operator.
All "real" semantic checking for this operator has been deferred to a future
patch. For now, we use the relational comparison rules and arbitrarily give
the builtin form of the operator a return type of 'void'.
llvm-svn: 320707
The two asserts are too aggressive. In C++ mode, an
enum is NOT considered an integral type, but an enum value
is allowed to be an enum. This patch relaxes the two asserts
to allow the enum value as well (as typechecking does).
llvm-svn: 320411
Summary:
This is a side-effect brought in by p0620r0, which allows other placeholder types (derived from `auto` and `decltype(auto)`) to be usable in a `new` expression with a single-clause //braced-init-list// as its initializer (8.3.4 [expr.new]/2). N3922 defined its semantics.
References:
http://wg21.link/p0620r0http://wg21.link/n3922
Reviewers: rsmith, aaron.ballman
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D39451
llvm-svn: 320401
Summary:
Clang was crashing when diagnosing an unused-lambda-capture for a VLA because
From.getVariable() is null for the capture of a VLA bound.
Warning about the VLA bound capture is not helpful, so only warn for the VLA
itself.
Fixes: PR35555
Reviewers: aaron.ballman, dim, rsmith
Reviewed By: aaron.ballman, dim
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D41016
llvm-svn: 320396
and fold together into a single function.
In so doing, fix a handful of remaining bugs where we would report false
positives or false negatives if we promote a signed value to an unsigned type
for the comparison.
This re-commits r320122 and r320124, minus two changes:
* Comparisons between a constant and a non-constant expression of enumeration
type never warn, not even if the constant is out of range. We should be
warning about the creation of such a constant, not about its use.
* We do not use more precise bit-widths for comparisons against bit-fields.
The more precise diagnostics probably are the right thing, but we should
consider moving them under their own warning flag.
Other than the refactoring, this patch should only change the behavior for the
buggy cases (where the warnings didn't take into account that promotion from
signed to unsigned can leave a range of inaccessible values in the middle of
the promoted type).
llvm-svn: 320211
> Unify implementation of our two different flavours of -Wtautological-compare.
>
> In so doing, fix a handful of remaining bugs where we would report false
> positives or false negatives if we promote a signed value to an unsigned type
> for the comparison.
This caused a new warning in Chromium:
../../base/trace_event/trace_log.cc:1545:29: error: comparison of constant 64
with expression of type 'unsigned int' is always true
[-Werror,-Wtautological-constant-out-of-range-compare]
DCHECK(handle.event_index < TraceBufferChunk::kTraceBufferChunkSize);
~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The 'unsigned int' is really a 6-bit bitfield, which is why it's always
less than 64.
I thought we didn't use to warn (with out-of-range-compare) when comparing
against the boundaries of a type?
llvm-svn: 320162
In so doing, fix a handful of remaining bugs where we would report false
positives or false negatives if we promote a signed value to an unsigned type
for the comparison.
llvm-svn: 320122
This is a fix for PR35509 in which we crash because we attempt to compute the
alignment of an incomplete type.
Differential Revision: https://reviews.llvm.org/D40895
llvm-svn: 320017
Summary:
This feature was discussed but not yet proposed. It allows a structured binding to appear as a //condition//
if (auto [ok, val] = f(...))
So the user can save an extra //condition// if the statement can test the value to-be-decomposed instead. Formally, it makes the value of the underlying object of the structured binding declaration also the value of a //condition// that is an initialized declaration.
Considering its logicality which is entirely evident from its trivial implementation, I think it might be acceptable to land it as an extension for now before I write the paper.
Reviewers: rsmith, faisalv, aaron.ballman
Reviewed By: rsmith
Subscribers: aaron.ballman, cfe-commits
Differential Revision: https://reviews.llvm.org/D39284
llvm-svn: 320011
As rsmith pointed out, the original implementation of this intrinsic
missed a number of important situations. This patch fixe a bunch of
shortcomings and implementation details to make it work correctly.
Differential Revision: https://reviews.llvm.org/D39347
llvm-svn: 319446
Sometimes we check the validity of some construct between producing a
diagnostic and producing its notes. Ideally, we wouldn't do that, but in
practice running code that "cannot possibly produce a diagnostic" in such a
situation should be safe, and reasonable factoring of some code requires it
with our current diagnostics infrastruture. If this does happen, a diagnostic
that's suppressed due to SFINAE should not cause notes connected to the prior
diagnostic to be suppressed.
llvm-svn: 319408
This also clarifies some terminology used by the diagnostic (methods -> Objective-C methods, fields -> non-static data members, etc).
Many of the tests needed to be updated in multiple places for the diagnostic wording tweaks. The first instance of the diagnostic for that attribute is fully specified and subsequent instances cut off the complete list (to make it easier if additional subjects are added in the future for the attribute).
llvm-svn: 319002
This implements [dcl.modules.export] from the C++ Modules TS, which lets a module re-export another module with the "export import" syntax.
Differential Revision: https://reviews.llvm.org/D40270
llvm-svn: 318744
This caused warnings also when the if or else comes from macros. There was an
attempt to fix this in r318556, but that introduced new problems and was
reverted. Reverting this too until the whole issue is sorted.
> This looks like it was just an oversight.
>
> Fixes http://llvm.org/pr35319
>
> git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@318456 91177308-0d34-0410-b5e6-96231b3b80d8
llvm-svn: 318667
Richard Trieu