user interface and documentation, and update __cplusplus for C++20.
WG21 considers the C++20 standard to be finished (even though it still
has some more steps to pass through in the ISO process).
The old flag names are accepted for compatibility, as usual, and we
still have lots of references to C++2a in comments and identifiers;
those can be cleaned up separately.
explicit functions that are not candidates.
It's not always obvious that the reason a conversion was not possible is
because the function you wanted to call is 'explicit', so explicitly say
if that's the case.
It would be nice to rank the explicit candidates higher in the
diagnostic if an implicit conversion sequence exists for their
arguments, but unfortunately we can't determine that without potentially
triggering non-immediate-context errors that we're not permitted to
produce.
Summary:
When a variable is named in a context where we can't directly emit a
reference to it (because we don't know for sure that it's going to be
defined, or it's from an enclosing function and not captured, or the
reference might not "work" for some reason), we emit a copy of the
variable as a global and use that for the known-to-be-read-only access.
This reinstates r363295, reverted in r363352, with a fix for PR42276:
we now produce a proper name for a non-odr-use reference to a static
constexpr data member. The name <mangled-name>.const is used in that
case; such names are reserved to the implementation for cases such as
this and should demangle nicely.
Reviewers: rjmccall
Subscribers: jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D63157
llvm-svn: 363428
Revert 363340 "Remove unused SK_LValueToRValue initialization step."
Revert 363337 "PR23833, DR2140: an lvalue-to-rvalue conversion on a glvalue of type"
Revert 363295 "C++ DR712 and others: handle non-odr-use resulting from an lvalue-to-rvalue conversion applied to a member access or similar not-quite-trivial lvalue expression."
llvm-svn: 363352
Summary:
When a variable is named in a context where we can't directly emit a
reference to it (because we don't know for sure that it's going to be
defined, or it's from an enclosing function and not captured, or the
reference might not "work" for some reason), we emit a copy of the
variable as a global and use that for the known-to-be-read-only access.
Reviewers: rjmccall
Subscribers: jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D63157
llvm-svn: 363295
template name is not visible to unqualified lookup.
In order to support this without a severe degradation in our ability to
diagnose typos in template names, this change significantly restructures
the way we handle template-id-shaped syntax for which lookup of the
template name finds nothing.
Instead of eagerly diagnosing an undeclared template name, we now form a
placeholder template-name representing a name that is known to not find
any templates. When the parser sees such a name, it attempts to
disambiguate whether we have a less-than comparison or a template-id.
Any diagnostics or typo-correction for the name are delayed until its
point of use.
The upshot should be a small improvement of our diagostic quality
overall: we now take more syntactic context into account when trying to
resolve an undeclared identifier on the left hand side of a '<'. In
fact, this works well enough that the backwards-compatible portion (for
an undeclared identifier rather than a lookup that finds functions but
no function templates) is enabled in all language modes.
llvm-svn: 360308
CWG 1691 changed the definition of the namespaces associated with a class
type or enumeration type.
For a class type, the associated namespaces are the innermost enclosing
namespaces of the associated classes. For an enumeration type, the associated
namespace is the innermost enclosing namespace of its declaration.
This also fixes CWG 1690 and CWG 1692.
Differential Revision: https://reviews.llvm.org/D60573
Reviewed By: rjmccall, rsmith
llvm-svn: 358882
The goal here is to exercise each rule in [basic.lookup.argdep] at least once.
These new tests expose what I believe are 2 issues:
1. CWG 1691 needs to be implemented (p2: [...] Its associated namespaces are
the innermost enclosing namespaces of its associated classes [...]) The
corresponding tests are adl_class_type::X2 and adl_class_type::X5.
2. The end of paragraph 2 ([...] Additionally, if the aforementioned set of
overloaded functions is named with a template-id, its associated classes
and namespaces also include those of its type template-arguments and its
template template-arguments.) is not implemented. Closely related, the
restriction on non-dependent parameter types in this same paragraph needs
to be removed. The corresponding tests are in adl_overload_set (both issues
are from CWG 997).
Differential Revision: https://reviews.llvm.org/D60570
Reviewed By: riccibruno, Quuxplusone
llvm-svn: 358881
global module fragment.
We know that the declaration in question should have been introduced by
a '#include', so try to figure out which one and suggest it. Don't
suggest importing the global module fragment itself!
llvm-svn: 358631
and the global and private module fragment.
For now, the private module fragment introducer is ignored, but use of
the global module fragment introducer should be properly enforced.
llvm-svn: 358353
members of dependent contexts.
This permits cases where the names before and after the '::' in a
dependent inherited constructor using-declaration do not match, but
where we can nonetheless tell when parsing the template that a
constructor is being named. Under (open) core language DR 2070, such
cases will probably be ill-formed, but r335182 does not quite give
that result and didn't intend to change this, so restore the old
behavior for now.
llvm-svn: 335381
function-style cast.
This fires for cases such as
T(x);
... where 'x' was previously declared and T is a type. This construct declares
a variable named 'x' rather than the (probably expected) interpretation of a
function-style cast of 'x' to T.
llvm-svn: 314570
This doesn't affect our code generation in any material way -- we already give
such declarations internal linkage from a codegen perspective -- but it has
some subtle effects on code validity.
We suppress the 'L' (internal linkage) marker for mangled names in anonymous
namespaces, because it is redundant (the information is already carried by the
namespace); this deviates from GCC's behavior if a variable or function in an
anonymous namespace is redundantly declared 'static' (where GCC does include
the 'L'), but GCC's behavior is incoherent because such a declaration can be
validly declared with or without the 'static'.
We still deviate from the standard in one regard here: extern "C" declarations
in anonymous namespaces are still granted external linkage. Changing those does
not appear to have been an intentional consequence of the standard change in
DR1113.
llvm-svn: 314037
If a function or variable has a type with no linkage (and is not extern "C"),
any use of it requires a definition within the same translation unit; the idea
is that it is not possible to define the entity elsewhere, so any such use is
necessarily an error.
There is an exception, though: some types formally have no linkage but
nonetheless can be referenced from other translation units (for example, this
happens to anonymous structures defined within inline functions). For entities
with those types, we suppress the diagnostic except under -pedantic.
llvm-svn: 313729
Printing typedefs or type aliases using clang_getTypeSpelling() is missing the
namespace they are defined in. This is in contrast to other types that always
yield the full typename including namespaces.
Patch by Michael Reiher!
Differential Revision: https://reviews.llvm.org/D29944
llvm-svn: 297465
name. If the dependent name happened to end in a template-id (X<T>::Y<U>), we
would fail to notice that the 'typename' keyword is missing when resolving it
to a type.
It turns out that GCC has a similar bug. If this shows up in much real code, we
can easily downgrade this to an ExtWarn.
llvm-svn: 293815
Under this defect resolution, the injected-class-name of a class or class
template cannot be used except in very limited circumstances (when declaring a
constructor, in a nested-name-specifier, in a base-specifier, or in an
elaborated-type-specifier). This is apparently done to make parsing easier, but
it's a pain for us since we don't know whether a template-id using the
injected-class-name is valid at the point when we annotate it (we don't yet
know whether the template-id will become part of an elaborated-type-specifier).
As a tentative resolution to a perceived language defect, mem-initializer-ids
are added to the list of exceptions here (they generally follow the same rules
as base-specifiers).
When the reference to the injected-class-name uses the 'typename' or 'template'
keywords, we permit it to be used to name a type or template as an extension;
other compilers also accept some cases in this area. There are also a couple of
corner cases with dependent template names that we do not yet diagnose, but
which will also get this treatment.
llvm-svn: 292518
Summary:
Per https://wg21.link/CWG1677, the C++11 standard did not clarify that constant
initialization of an object allowed constexpr brace-or-equal initialization of
subobjects:
struct foo_t { union { int i; volatile int j; } u; };
__attribute__((__require_constant_initialization__))
static const foo_t x = {{0}};
Because foo_t::u has a volatile member, the initializer for x fails. However,
there is really no good reason, because this:
union foo_u { int i; volatile int j; };
__attribute__((__require_constant_initialization__))
static const foo_u x = {0};
does have a constant initializer.
(This was triggered by musl's pthread_mutex_t type when building under C++11.)
Reviewers: rsmith
Subscribers: EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D28427
llvm-svn: 291480
Other compilers accept invalid code here that we reject, and we need a
better error message to try to convince users that the code is really
incorrect. Consider:
class Foo {
typedef MyIterHelper<Foo> iterator;
friend class iterator;
};
Previously our wording was "elaborated type refers to a typedef".
"elaborated type" isn't widely known terminology, so the new diagnostic
says "typedef 'iterator' cannot be referenced with class specifier".
Reviewers: rsmith
Differential Revision: https://reviews.llvm.org/D25216
llvm-svn: 289259
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
So, we now reject that. We also warn for any external-linkage global
variable named main in C, because it results in undefined behavior.
PR: 24309
Differential Revision: http://reviews.llvm.org/D11658
Reviewed by: rsmith
llvm-svn: 245051
We didn't correctly expect a QualifiedTypeLoc when faced with fixing a
variable array type into a constant array type.
Differential Revision: http://reviews.llvm.org/D8958
llvm-svn: 235251
Previously if an enumeration was used in a nested name specifier in pre-C++11
language dialect, error message was 'XXX is not a class, namespace, or scoped
enumeration'. This patch removes the word 'scoped' as in C++11 any enumeration
may be used in this context.
llvm-svn: 226410
We've decided to make the core rewriter class and PP rewriters mandatory.
They're only a few hundred lines of code in total and not worth supporting as a
distinct build configuration, especially since doing so disables key compiler
features.
This reverts commit r213150.
Revert "clang/test: Introduce the feature "rewriter" for --enable-clang-rewriter."
This reverts commit r213148.
Revert "Move clang/test/Frontend/rewrite-*.c to clang/test/Frontend/Rewriter/"
This reverts commit r213146.
llvm-svn: 213159
C++ [basic.start.main]p1: "It shall have a return type of type int"
ISO C is also clear about this, so only accept 'int' with qualifiers in GNUMode
C.
llvm-svn: 212171
Summary:
Naming the destructor using a typedef-name for the class-name is
well-formed.
This fixes PR19620.
Reviewers: rsmith, doug.gregor
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D3583
llvm-svn: 209319
Rather than simply saying "X is not a class or namespace", clarify what
X is by providing the aka type in the case where X is a type, or
pointing to the named declaration if there's an unambiguous one to refer
to. In the ambiguous case, the ambiguities are already enumerated
(though could be clarified by describing what kind of entities they are)
Included a few FIXMEs in tests where some further improvements could be
made.
llvm-svn: 201038
redeclaration, not just when looking them up for a use -- we need the implicit
declaration to appropriately check various properties of them (notably, whether
they're deleted).
llvm-svn: 200729
bit fields of zero size. Warnings are generated in C++ mode and if
only such type is defined inside extern "C" block.
The patch fixed PR5065.
Differential Revision: http://llvm-reviews.chandlerc.com/D2151
llvm-svn: 194653
Richard Smith