This comes from lengthy discussion between Quuxplusone and ldionne over on D108216.
Right now, libc++ uses a "SCARY metaprogramming" version of _EnableIf that bypasses
all of Clang's clever diagnostic stuff and thus produces bad diagnostics. My recent
benchmarks ( https://quuxplusone.github.io/blog/2021/09/04/enable-if-benchmark/ )
have determined that the SCARYness is not buying us any speedup; therefore we are
happy to drop it and go back to using the standard std::enable_if for all our
SFINAE needs. However, we don't want to type out typename std::enable_if<X>::type
all over the library; we want to use an alias template. And we can't use
std::enable_if_t because we need a solution that works in C++11, and we do not
provide std::enable_if_t in C++11.
Therefore, D109435 switches us from SCARY `_EnableIf` to a normal `__enable_if_t`
(at least in C++11 mode, and possibly everywhere for consistency).
Simultaneously, this Clang patch enables the good diagnostics for `__enable_if_t`.
We don't need to enable good diagnostics for `_EnableIf` because the name
`_EnableIf` has only ever been used for the SCARY version where the good diagnostics
don't trigger anyway.
(Btw, this existing code is all sorts of broken, theoretically speaking.
I filed https://bugs.llvm.org/show_bug.cgi?id=51696 about it last week.
So if someone wants to use this PR as an excuse to go down the rabbit hole
and fix it for real, that would be cool too.)
Differential Revision: https://reviews.llvm.org/D109411
- `this` used in lambda expression parameter declarations needs no capture.
- Set up CXXThisOverride for default template arguments of a lambda.
A similar fix to this is c3d2ebb60f.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D102531
See PR47174.
When canonicalizing nested name specifiers of the type kind,
the prefix for 'DependentTemplateSpecialization' types was being
dropped, leading to malformed types which would cause failures
when rebuilding template names.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D107311
<string> is currently the highest impact header in a clang+llvm build:
https://commondatastorage.googleapis.com/chromium-browser-clang/llvm-include-analysis.html
One of the most common places this is being included is the APInt.h header, which needs it for an old toString() implementation that returns std::string - an inefficient method compared to the SmallString versions that it actually wraps.
This patch replaces these APInt/APSInt methods with a pair of llvm::toString() helpers inside StringExtras.h, adjusts users accordingly and removes the <string> from APInt.h - I was hoping that more of these users could be converted to use the SmallString methods, but it appears that most end up creating a std::string anyhow. I avoided trying to use the raw_ostream << operators as well as I didn't want to lose having the integer radix explicit in the code.
Differential Revision: https://reviews.llvm.org/D103888
This renames the expression value categories from rvalue to prvalue,
keeping nomenclature consistent with C++11 onwards.
C++ has the most complicated taxonomy here, and every other language
only uses a subset of it, so it's less confusing to use the C++ names
consistently, and mentally remap to the C names when working on that
context (prvalue -> rvalue, no xvalues, etc).
Renames:
* VK_RValue -> VK_PRValue
* Expr::isRValue -> Expr::isPRValue
* SK_QualificationConversionRValue -> SK_QualificationConversionPRValue
* JSON AST Dumper Expression nodes value category: "rvalue" -> "prvalue"
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D103720
This is a pre-patch for adding using-enum support. It breaks out
the shadow decl handling of UsingDecl to a new intermediate base
class, BaseUsingDecl, altering the decl hierarchy to
def BaseUsing : DeclNode<Named, "", 1>;
def Using : DeclNode<BaseUsing>;
def UsingPack : DeclNode<Named>;
def UsingShadow : DeclNode<Named>;
def ConstructorUsingShadow : DeclNode<UsingShadow>;
Differential Revision: https://reviews.llvm.org/D101777
For a type-constraint in a lambda signature, this makes the lambda
contain an unexpanded pack; for requirements in a requires-expressions
it makes the requires-expression contain an unexpanded pack; otherwise
it's invalid.
Non-comprehensive list of cases:
* Dumping template arguments;
* Corresponding parameter contains a deduced type;
* Template arguments are for a DeclRefExpr that hadMultipleCandidates()
Type information is added in the form of prefixes (u8, u, U, L),
suffixes (U, L, UL, LL, ULL) or explicit casts to printed integral template
argument, if MSVC codeview mode is disabled.
Differential revision: https://reviews.llvm.org/D77598
Warn when a declaration uses an identifier that doesn't obey the reserved
identifier rule from C and/or C++.
Differential Revision: https://reviews.llvm.org/D93095
We used to trigger assertion when transforming c-tor with unparsed
default argument. Now we ignore such constructors for this purpose.
Differential Revision: https://reviews.llvm.org/D97965
Combined with 'da98651 - Revert "DR2064:
decltype(E) is only a dependent', this change (5a391d3) caused verifier
errors when building Chromium. See https://crbug.com/1168494#c1 for a
reproducer.
Additionally it reverts changes that were dependent on this one, see
below.
> Following up on PR48517, fix handling of template arguments that refer
> to dependent declarations.
>
> Treat an id-expression that names a local variable in a templated
> function as being instantiation-dependent.
>
> This addresses a language defect whereby a reference to a dependent
> declaration can be formed without any construct being value-dependent.
> Fixing that through value-dependence turns out to be problematic, so
> instead this patch takes the approach (proposed on the core reflector)
> of allowing the use of pointers or references to (but not values of)
> dependent declarations inside value-dependent expressions, and instead
> treating template arguments as dependent if they evaluate to a constant
> involving such dependent declarations.
>
> This ends up affecting a bunch of OpenMP tests, due to OpenMP
> imprecisely handling instantiation-dependent constructs, bailing out
> early instead of processing dependent constructs to the extent possible
> when handling the template.
>
> Previously committed as 8c1f2d15b8, and
> reverted because a dependency commit was reverted.
This reverts commit 5a391d38ac.
It also restores clang/test/SemaCXX/coroutines.cpp to its state before
da986511fb.
Revert "[c++20] P1907R1: Support for generalized non-type template arguments of scalar type."
> Previously committed as 9e08e51a20, and
> reverted because a dependency commit was reverted. This incorporates the
> following follow-on commits that were also reverted:
>
> 7e84aa1b81 by Simon Pilgrim
> ed13d8c667 by me
> 95c7b6cadb by Sam McCall
> 430d5d8429 by Dave Zarzycki
This reverts commit 4b574008ae.
Revert "[msabi] Mangle a template argument referring to array-to-pointer decay"
> [msabi] Mangle a template argument referring to array-to-pointer decay
> applied to an array the same as the array itself.
>
> This follows MS ABI, and corrects a regression from the implementation
> of generalized non-type template parameters, where we "forgot" how to
> mangle this case.
This reverts commit 18e093faf7.
Previously committed as 9e08e51a20, and
reverted because a dependency commit was reverted. This incorporates the
following follow-on commits that were also reverted:
7e84aa1b81 by Simon Pilgrim
ed13d8c667 by me
95c7b6cadb by Sam McCall
430d5d8429 by Dave Zarzycki
to dependent declarations.
Treat an id-expression that names a local variable in a templated
function as being instantiation-dependent.
This addresses a language defect whereby a reference to a dependent
declaration can be formed without any construct being value-dependent.
Fixing that through value-dependence turns out to be problematic, so
instead this patch takes the approach (proposed on the core reflector)
of allowing the use of pointers or references to (but not values of)
dependent declarations inside value-dependent expressions, and instead
treating template arguments as dependent if they evaluate to a constant
involving such dependent declarations.
This ends up affecting a bunch of OpenMP tests, due to OpenMP
imprecisely handling instantiation-dependent constructs, bailing out
early instead of processing dependent constructs to the extent possible
when handling the template.
Previously committed as 8c1f2d15b8, and
reverted because a dependency commit was reverted.
to dependent declarations.
Treat an id-expression that names a local variable in a templated
function as being instantiation-dependent.
This addresses a language defect whereby a reference to a dependent
declaration can be formed without any construct being value-dependent.
Fixing that through value-dependence turns out to be problematic, so
instead this patch takes the approach (proposed on the core reflector)
of allowing the use of pointers or references to (but not values of)
dependent declarations inside value-dependent expressions, and instead
treating template arguments as dependent if they evaluate to a constant
involving such dependent declarations.
This ends up affecting a bunch of OpenMP tests, due to OpenMP
imprecisely handling instantiation-dependent constructs, bailing out
early instead of processing dependent constructs to the extent possible
when handling the template.
dependent until it's been converted to match its parameter.
The type of a non-type template parameter can in general affect whether
the template argument is dependent.
Note that this is not always possible. For template arguments that name
static local variables in templates, the type of the template parameter
affects whether the argument is dependent, so the query is imprecise
until we know the parameter type. For example, in:
template<typename T> void f() {
static const int n = 5;
typename T::template X<n> x;
}
... we don't know whether 'n' is dependent until we know whether the
corresponding template parameter is of type 'int' or 'const int&'.
For the Itanium ABI, this implements the mangling rule suggested in
https://github.com/itanium-cxx-abi/cxx-abi/issues/47, namely mangling
such template arguments as being cast to the parameter type in the case
where the template name is overloadable. This can cause a mangling
change for rare cases, where
* the template argument declaration is converted from its declared type
to the type of the template parameter, and
* the template parameter either has a deduced type or is a parameter of
a function template.
However, such changes are necessary to avoid mangling collisions. The
ABI changes can be reversed with -fclang-abi-compat=11 or earlier.
Re-commit with a fix for a couple of regressions.
Differential Revision: https://reviews.llvm.org/D91488
This attribute permits a typedef to be associated with a class template
specialization as a preferred way of naming that class template
specialization. This permits us to specify that (for example) the
preferred way to express 'std::basic_string<char>' is as 'std::string'.
The attribute is applied to the various class templates in libc++ that have
corresponding well-known typedef names.
This is a re-commit. The previous commit was reverted because it exposed
a pre-existing bug that has since been fixed / worked around; see
PR48434.
Differential Revision: https://reviews.llvm.org/D91311
This change exposed a pre-existing issue with deserialization cycles
caused by a combination of attributes and template instantiations
violating the deserialization ordering restrictions; see PR48434 for
details.
A previous commit attempted to work around PR48434, but appears to have
only been a partial fix, and fixing this properly seems non-trivial.
Backing out for now to unblock things.
This reverts commit 98f76adf4e and
commit a64c26a47a.
This attribute permits a typedef to be associated with a class template
specialization as a preferred way of naming that class template
specialization. This permits us to specify that (for example) the
preferred way to express 'std::basic_string<char>' is as 'std::string'.
The attribute is applied to the various class templates in libc++ that have
corresponding well-known typedef names.
Differential Revision: https://reviews.llvm.org/D91311
As reported in PR48177, the type-deduction extraction ends up going into
an infinite loop when the type referred to has a recursive definition.
This stops recursing and just substitutes the type-source-info the
TypeLocBuilder identified when transforming the base.
Similar to Windows Itanium, PS4 is also an Itanium C++ ABI variant
which shares the goal of semantic compatibility with Microsoft C++
code that uses dllimport/export.
This change introduces a new function to determine from the triple
if an environment aims for compatibility with MS C++ code w.r.t to
these attributes and guards the relevant code paths using that
function.
Differential Revision: https://reviews.llvm.org/D90299
non-type template parameters.
Create a unique TemplateParamObjectDecl instance for each such value,
representing the globally unique template parameter object to which the
template parameter refers.
No IR generation support yet; that will follow in a separate patch.
folding to not constant folding.
Constant folding of ICEs is done as a GCC compatibility measure, but new
code was picking it up, presumably by accident, due to the bad default.
While here, also switch the flag from a bool to an enum to make it more
obvious what it means at call sites. This highlighted a couple of places
where our behavior is different between C++11 and C++14 due to switching
from checking for an ICE to checking for a converted constant
expression (where there is no 'fold' codepath).
They can get stale at use time because of updates from other recursive
specializations. Instead, rely on the existence of previous declarations to add
the specialization.
Differential Revision: https://reviews.llvm.org/D87853
template parameters.
No support for the new kinds of non-type template argument yet.
This is not entirely NFC for prior language modes: we have historically
incorrectly accepted rvalue references as the types of non-type template
parameters. Such invalid code is now rejected.
This is recommit of 6c8041aa0f, reverted in de044f7562 because of some
fails. Original commit message is below.
This change allow a CastExpr to have optional FPOptionsOverride object,
stored in trailing storage. Of all cast nodes only ImplicitCastExpr,
CStyleCastExpr, CXXFunctionalCastExpr and CXXStaticCastExpr are allowed
to have FPOptions.
Differential Revision: https://reviews.llvm.org/D85960
This change allow a CastExpr to have optional FPOptionsOverride object,
stored in trailing storage. Of all cast nodes only ImplicitCastExpr,
CStyleCastExpr, CXXFunctionalCastExpr and CXXStaticCastExpr are allowed
to have FPOptions.
Differential Revision: https://reviews.llvm.org/D85960
arguments.
Don't build a variable template specialization declaration until its
scope and template arguments are non-dependent.
No functionality change intended, but the AST representation is now more
consistent with how we model other templates.
Nico Weber