The new builtin `__builtin_dedup_pack` removes duplicates from list of
types.
The added builtin is special in that they produce an unexpanded pack
in the spirit of P3115R0 proposal.
Produced packs can be used directly in template argument lists and get
immediately expanded as soon as results of the computation are
available.
It allows to easily combine them, e.g.:
```cpp
template <class ...T>
struct Normalize {
// Note: sort is not included in this PR, it illustrates the idea.
using result = std::tuple<
__builtin_sort_pack<
__builtin_dedup_pack<int, double, T...>...
>...>;
}
;
```
Limitations:
- only supported in template arguments and bases,
- can only be used inside the templates, even if non-dependent,
- the builtins cannot be assigned to template template parameters.
The actual implementation proceeds as follows:
- When the compiler encounters a `__builtin_dedup_pack` or other
type-producing
builtin with dependent arguments, it creates a dependent
`TemplateSpecializationType`.
- During substitution, if the template arguments are non-dependent, we
will produce: a new type `SubstBuiltinTemplatePackType`, which stores
an argument pack that needs to be substituted. This type is similar to
the existing `SubstTemplateParmPack` in that it carries the argument
pack that needs to be expanded further. The relevant code is shared.
- On top of that, Clang also wraps the resulting type into
`TemplateSpecializationType`, but this time only as a sugar.
- To actually expand those packs, we collect the produced
`SubstBuiltinTemplatePackType` inside `CollectUnexpandedPacks`.
Because we know the size of the produces packs only after the initial
substitution, places that do the actual expansion will need to have a
second run over the substituted type to finalize the expansions (in
this patch we only support this for template arguments, see
`ExpandTemplateArgument`).
If the expansion are requested in the places we do not currently
support, we will produce an error.
More follow-up work will be needed to fully shape this:
- adding the builtin that sorts types,
- remove the restrictions for expansions,
- implementing P3115R0 (scheduled for C++29, see
https://github.com/cplusplus/papers/issues/2300).
The early return for lamda expressions with deduced return types in
Sema::ActOnCapScopeReturnStmt meant that we were not actually perform
the required return type deduction for such lambdas when in a discarded
context.
This PR removes that early return allowing the existing return type
deduction steps to be performed.
Fixes#153884
Fix developed by, and
Co-authored-by: Corentin Jabot <corentinjabot@gmail.com>
This is a major change on how we represent nested name qualifications in
the AST.
* The nested name specifier itself and how it's stored is changed. The
prefixes for types are handled within the type hierarchy, which makes
canonicalization for them super cheap, no memory allocation required.
Also translating a type into nested name specifier form becomes a no-op.
An identifier is stored as a DependentNameType. The nested name
specifier gains a lightweight handle class, to be used instead of
passing around pointers, which is similar to what is implemented for
TemplateName. There is still one free bit available, and this handle can
be used within a PointerUnion and PointerIntPair, which should keep
bit-packing aficionados happy.
* The ElaboratedType node is removed, all type nodes in which it could
previously apply to can now store the elaborated keyword and name
qualifier, tail allocating when present.
* TagTypes can now point to the exact declaration found when producing
these, as opposed to the previous situation of there only existing one
TagType per entity. This increases the amount of type sugar retained,
and can have several applications, for example in tracking module
ownership, and other tools which care about source file origins, such as
IWYU. These TagTypes are lazily allocated, in order to limit the
increase in AST size.
This patch offers a great performance benefit.
It greatly improves compilation time for
[stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for
`test_on2.cpp` in that project, which is the slowest compiling test,
this patch improves `-c` compilation time by about 7.2%, with the
`-fsyntax-only` improvement being at ~12%.
This has great results on compile-time-tracker as well:
This patch also further enables other optimziations in the future, and
will reduce the performance impact of template specialization resugaring
when that lands.
It has some other miscelaneous drive-by fixes.
About the review: Yes the patch is huge, sorry about that. Part of the
reason is that I started by the nested name specifier part, before the
ElaboratedType part, but that had a huge performance downside, as
ElaboratedType is a big performance hog. I didn't have the steam to go
back and change the patch after the fact.
There is also a lot of internal API changes, and it made sense to remove
ElaboratedType in one go, versus removing it from one type at a time, as
that would present much more churn to the users. Also, the nested name
specifier having a different API avoids missing changes related to how
prefixes work now, which could make existing code compile but not work.
How to review: The important changes are all in
`clang/include/clang/AST` and `clang/lib/AST`, with also important
changes in `clang/lib/Sema/TreeTransform.h`.
The rest and bulk of the changes are mostly consequences of the changes
in API.
PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just
for easier to rebasing. I plan to rename it back after this lands.
Fixes#136624
Fixes https://github.com/llvm/llvm-project/issues/43179
Fixes https://github.com/llvm/llvm-project/issues/68670
Fixes https://github.com/llvm/llvm-project/issues/92757
This is a first pass at implementing
[P2841R7](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2841r7.pdf).
The implementation is far from complete; however, I'm aiming to do that
in chunks, to make our lives easier.
In particular, this does not implement
- Subsumption
- Mangling
- Satisfaction checking is minimal as we should focus on #141776 first
(note that I'm currently very stuck)
FTM, release notes, status page, etc, will be updated once the feature
is more mature. Given the state of the feature, it is not yet allowed in
older language modes.
Of note:
- Mismatches between template template arguments and template template
parameters are a bit wonky. This is addressed by #130603
- We use `UnresolvedLookupExpr` to model template-id. While this is
pre-existing, I have been wondering if we want to introduce a different
OverloadExpr subclass for that. I did not make the change in this patch.
Tracked at https://github.com/llvm/llvm-project/issues/112294
This patch implements from [basic.link]p14 to [basic.link]p18 partially.
The explicitly missing parts are:
- Anything related to specializations.
- Decide if a pointer is associated with a TU-local value at compile
time.
- [basic.link]p15.1.2 to decide if a type is TU-local.
- Diagnose if TU-local functions from other TU are collected to the
overload set. See [basic.link]p19, the call to 'h(N::A{});' in
translation unit #2
There should be other implicitly missing parts as the wording uses
"names" briefly several times. But to implement this precisely, we have
to visit the whole AST, including Decls, Expression and Types, which may
be harder to implement and be more time-consuming for compilation time.
So I choose to implement the common parts.
It won't be too bad to miss some cases since we DIDN'T do any such
checks in the past 3 years. Any new check is an improvement. Given
modules have been basically available since clang15 without such checks,
it will be user unfriendly if we give a hard error now. And there are
a lot of cases which violating the rule actually just fine. So I decide
to emit it as warnings instead of hard errors.
The underlying type of an enumeration is the non-atomic, unqualified
version of the specified type. Clang was rejecting such enumerations,
with a hard error, but now has the ability to downgrade the error into a
warning. Additionally, we diagnose (as a warning) dropping other
qualifiers. _Atomic is special given that an atomic type need not have
the same size as its non-atomic counterpart, and that the C++ version
of <stdatomic.h> defines _Atomic to std::atomic for easing cross-
language atomic use and std::atomic is an invalid enum base in C++.
(Note: we expose _Atomic in C++ even without including
<stdatomic,h>.)
Fixes#147736
443377a9d1a8d4a69a317a1a892184c59dd0aec6 handled simple variable
definitions, but it didn't handle uninitialized variables with a
consteval constructor, and it didn't handle template instantiation.
Fixes#135281 .
We have multiple different attributes in clang representing device
kernels for specific targets/languages. Refactor them into one attribute
with different spellings to make it more easily scalable for new
languages/targets.
---------
Signed-off-by: Sarnie, Nick <nick.sarnie@intel.com>
Reland with debug traces to try to understand a bug that only happens on
one CI configuration
===
This introduces a way detect the libstdc++ version,
use that to enable workarounds.
The version is cached.
This should make it easier in the future to find and remove
these hacks.
I did not find the need for enabling a hack between or after
specific versions, so it's left as a future exercise.
We can extend this fature to other libraries as the need arise.
===
The previous approach broke code generation for the MS ABI due to an
unintended code path during constraint substitution. This time we
address the issue by inspecting the evaluation contexts and thereby
avoiding that code path.
This reapplies 96eced624 (#102857).
This introduces a way detect the libstdc++ version, use that to enable
workarounds.
The version is cached.
This should make it easier in the future to find and remove these hacks.
I did not find the need for enabling a hack between or after specific
versions, so it's left as a future exercise.
We can extend this fature to other libraries as the need arise.
The evaluation context was improperly set up, such that we were trying
to set up cleanups for a global variable at the point of use, which led
to incorrect diagnostics about the variable not being capturable.
Fixes#140632Fixes#140622
Fixes https://github.com/llvm/llvm-project/issues/135032
Due to nested templates, when instantiating the outer layer (the
template class), the inner layer (the template variable) uses delayed
instantiation.
This causes the declaration (VarDecl) of the template variable to retain
the type from the original template declaration (i.e., auto), and it
loses the initializer.
Later, when instantiating the template variable, its
VarTemplateSpecializationDecl type depends on the VarDecl type.
Thus, the VarTemplateSpecializationDecl also has no initializer, and its
type remains auto.
Ultimately, when building the reference expression in
Sema::BuildDeclarationNameExpr, the expression's type is auto and stays
as auto until code generation, triggering llvm_unreachable in
CodeGenTypes::ConvertType.
Since I noticed that the deduction of auto type is caused by the
initializer
I plan to do special processing for template variables of type auto,
that is, to prevent their delayed instantiation
so that their initializers will not be lost when the outer template
class is instantiated
Since 346077aa, we began using the primary template's lexical
DeclContext for template arguments in order to properly instantiate a
friend definition.
There is a missed peculiar case, as in a friend template is specialized
within a dependent context. In this scenario, the primary template is
not a definition, whereas the specialization is. So the primary
template's DeclContext doesn't provide anything meaningful
for instantiation.
Fixes https://github.com/llvm/llvm-project/issues/139052
- Defines a new declaration node `HLSLRootSignature` in `DeclNodes.td`
that will consist of a `TrailingObjects` of the in-memory construction
of the root signature, namely an array of `hlsl::rootsig::RootElement`s
- Defines a new clang attr `RootSignature` which simply holds an
identifier to a corresponding root signature declaration as above
- Integrate the `HLSLRootSignatureParser` to construct the decl node in
`ParseMicrosoftAttributes` and then attach the parsed attr with an
identifier to the entry point function declaration.
- Defines the various required declaration methods
- Add testing that the declaration and reference attr are created
correctly, and some syntactical error tests.
It was previously proposed that we could have the root elements
reference be stored directly as an additional member of the attribute
and to not have a separate root signature decl. In contrast, by defining
them separately as this change proposes, we will allow a unique root
signature to have its own declaration in the AST tree. This allows us to
only construct a single root signature for all duplicate root signature
attributes. Having it located directly as a declaration might also prove
advantageous when we consider root signature libraries.
Resolves https://github.com/llvm/llvm-project/issues/119011
This patch adds templated `operator<<` for diagnostics that pass scoped
enums, saving people from `llvm::to_underlying()` clutter on the side of
emitting the diagnostic. This eliminates 80 out of 220 usages of
`llvm::to_underlying()` in Clang.
I also backported `std::is_scoped_enum_v` from C++23.
This reapplies #134038
Since the last patch, this fixes a null pointer dereference where the
TSI of the destructor wasn't properly propagated into the
DeclarationNameInfo. We now construct a LocInfoType for dependent cases,
as done elsewhere in getDestructorName, such that GetTypeFromParser can
correctly obtain the TSI.
---
This patch fixes two long-standing bugs that prevent Clang from
instantiating local class members inside a dependent context. These bugs
were introduced in commits
21eb1af469
and
919df9d75a.
21eb1af469
introduced a concept called eligible methods such that it did an attempt
to skip past ineligible method instantiation when instantiating class
members. Unfortunately, this broke the instantiation chain for local
classes - getTemplateInstantiationPattern() would fail to find the
correct definition pattern if the class was defined within a partially
transformed dependent context.
919df9d75a
introduced a separate issue by incorrectly copying the
DeclarationNameInfo during function definition instantiation from the
template pattern, even though that DNI might contain a transformed
TypeSourceInfo. Since that TSI was already updated when the declaration
was instantiated, this led to inconsistencies. As a result, the final
instantiated function could lose track of the transformed declarations,
hence we crash: https://compiler-explorer.com/z/vjvoG76Tf.
This PR corrects them by
1. Removing the bypass logic for method instantiation. The eligible flag
is independent of instantiation and can be updated properly afterward,
so skipping instantiation is unnecessary.
2. Carefully handling TypeSourceInfo by creating a new instance that
preserves the pattern's source location while using the already
transformed type.
This patch fixes two long-standing bugs that prevent Clang from
instantiating local class members inside a dependent context. These bugs
were introduced in commits 21eb1af469c3 and 919df9d75a.
21eb1af469c3 introduced a concept called eligible methods such that it
did an attempt to skip past ineligible method instantiation when
instantiating class members. Unfortunately, this broke the instantiation
chain for local classes - getTemplateInstantiationPattern() would fail
to find the correct definition pattern if the class was defined within a
partially transformed dependent context.
919df9d75a introduced a separate issue by incorrectly copying the
DeclarationNameInfo during function definition instantiation from the
template pattern, even though that DNI might contain a transformed
TypeSourceInfo. Since that TSI was already updated when the declaration
was instantiated, this led to inconsistencies. As a result, the final
instantiated function could lose track of the transformed declarations,
hence we crash: https://compiler-explorer.com/z/vjvoG76Tf.
This PR corrects them by
1. Removing the bypass logic for method instantiation. The eligible flag
is independent of instantiation and can be updated properly afterward,
so skipping instantiation is unnecessary.
2. Carefully handling TypeSourceInfo by creating a new instance that
preserves the pattern's source location while using the already
transformed type.
Fixes https://github.com/llvm/llvm-project/issues/59734
Fixes https://github.com/llvm/llvm-project/issues/132208
This relands https://github.com/llvm/llvm-project/pull/135119, after
fixing crashes seen in LLDB CI reported here:
https://github.com/llvm/llvm-project/pull/135119#issuecomment-2794910840
Fixes https://github.com/llvm/llvm-project/pull/135119
This changes the TemplateArgument representation to hold a flag
indicating whether a tempalte argument of expression type is supposed to
be canonical or not.
This gets one step closer to solving
https://github.com/llvm/llvm-project/issues/92292
This still doesn't try to unique as-written TSTs. While this would
increase the amount of memory savings and make code dealing with the AST
more well-behaved, profiling template argument lists is still too
expensive for this to be worthwhile, at least for now.
This also fixes the context creation of TSTs, so that they don't in some
cases get incorrectly flagged as sugar over their own canonical form.
This is captured in the test expectation change of some AST dumps.
This fixes some places which were unnecessarily canonicalizing these
TSTs.
This is a basic implementation of P2719: "Type-aware allocation and
deallocation functions" described at http://wg21.link/P2719
The proposal includes some more details but the basic change in
functionality is the addition of support for an additional implicit
parameter in operators `new` and `delete` to act as a type tag. Tag is
of type `std::type_identity<T>` where T is the concrete type being
allocated. So for example, a custom type specific allocator for `int`
say can be provided by the declaration of
void *operator new(std::type_identity<int>, size_t, std::align_val_t);
void operator delete(std::type_identity<int>, void*, size_t, std::align_val_t);
However this becomes more powerful by specifying templated declarations,
for example
template <typename T> void *operator new(std::type_identity<T>, size_t, std::align_val_t);
template <typename T> void operator delete(std::type_identity<T>, void*, size_t, std::align_val_t););
Where the operators being resolved will be the concrete type being
operated over (NB. A completely unconstrained global definition as above
is not recommended as it triggers many problems similar to a general
override of the global operators).
These type aware operators can be declared as either free functions or
in class, and can be specified with or without the other implicit
parameters, with overload resolution performed according to the existing
standard parameter prioritisation, only with type parameterised
operators having higher precedence than non-type aware operators. The
only exception is destroying_delete which for reasons discussed in the
paper we do not support type-aware variants by default.
This changes the TemplateArgument representation to hold a flag
indicating whether a template argument of expression type is supposed to
be canonical or not.
This gets one step closer to solving
https://github.com/llvm/llvm-project/issues/92292
This still doesn't try to unique as-written TSTs. While this would
increase the amount of memory savings and make code dealing with the AST
more well-behaved, profiling template argument lists is still too
expensive for this to be worthwhile, at least for now. Without this
uniquing, this patch stands neutral in terms of performance impact.
This also fixes the context creation of TSTs, so that they don't in some
cases get incorrectly flagged as sugar over their own canonical form.
This is captured in the test expectation change of some AST dumps.
This fixes some places which were unnecessarily canonicalizing these
TSTs.
OpenACC 3.3-NEXT has changed the way tags for copy, copyin, copyout, and
create clauses are specified, and end up adding a few extras, and
permits them as a list. This patch encodes these as bitmask enum so
they can be stored succinctly, but still diagnose reasonably.
This introduces a new class 'UnsignedOrNone', which models a lite
version of `std::optional<unsigned>`, but has the same size as
'unsigned'.
This replaces most uses of `std::optional<unsigned>`, and similar
schemes utilizing 'int' and '-1' as sentinel.
Besides the smaller size advantage, this is simpler to serialize, as its
internal representation is a single unsigned int as well.
Fix for regression #130917, changes in #111992 were too broad. This change reduces scope of previous fix. Added `ExternalASTSource::wasThisDeclarationADefinition` to detect cases when FunctionDecl lost body due to declaration merges.
This is the last item of the OpenACC 3.3 spec. It includes the
implicit-name version of 'routine', plus significant refactorings to
make the two work together. The implicit name version is represented as
an attribute on the function call. This patch also implements the
clauses for the implicit-name version, as well as the A.3.4 warning.
See discussion in https://github.com/llvm/llvm-project/issues/125071.
Makes the note clearer for the unreachable case:
Before:
```
./hoge.h:5:12: warning: instantiation of function 'x<int>' required here, but no definition is available [-Wundefined-func-template]
5 | void f() { x<int>(); }
| ^
./shared_ptr2.h:4:6: note: forward declaration of template entity is here
4 | void x() { T t; (void)t; }
| ^
./hoge.h:5:12: note: add an explicit instantiation declaration to suppress this warning if 'x<int>' is explicitly instantiated in another translation unit
5 | void f() { x<int>(); }
|
```
After:
```
./hoge.h:5:12: warning: instantiation of function 'x<int>' required here, but no definition is available [-Wundefined-func-template]
5 | void f() { x<int>(); }
| ^
./shared_ptr2.h:4:6: note: declaration of template entity is unreachable here
4 | void x() { T t; (void)t; }
| ^
1 warning generated.
```
The 'bind' clause allows the renaming of a function during code
generation. There are a few rules about when this can/cannot happen,
and it takes either a string or identifier (previously mis-implemetned
as ID-expression) argument.
Note there are additional rules to this in the implicit-function routine
case, but that isn't implemented in this patch, as implicit-function
routine is not yet implemented either.
When checking the template template parameters of template template
parameters, the PartialOrdering context was not correctly propagated.
This also has a few drive-by fixes, such as checking the template
parameter lists of template template parameters, which was previously
missing and would have been it's own bug, but we need to fix it in order
to prevent crashes in error recovery in a simple way.
Fixes#130362
There is a slightly different list for routine on which clauses are
permitted after it (like the rest of the constructs), but this
implements and tests them to make sure we get them right.
'nohost' is only valid on routine, and states that the compiler
shouldn't compile this routine for the host. It has no arguments, so no
checking is required besides putting it in the AST.
These 4 clauses are mutually exclusive, AND require at least one of
them. Additionally, gang has some additional restrictions in that only
the 'dim' specifier is permitted. This patch implements all of this, and
ends up refactoring the handling of each of these clauses for
readabililty.
The 'routine' construct has two forms, one which takes the name of a
function that it applies to, and another where it implicitly figures it
out based on the next declaration. This patch implements the former with
the required restrictions on the name and the function-static-variables
as specified.
What has not been implemented is any clauses for this, any of the A.3.4
warnings, or the other form.
For constexpr function templates, we immediately instantiate them upon
reference. However, if the function isn't defined at the time of
instantiation, even though it might be defined later, the instantiation
would forever fail.
This patch corrects the behavior by popping up failed instantiations
through PendingInstantiations, so that we are able to instantiate them
again in the future (e.g. at the end of TU.)
Fixes https://github.com/llvm/llvm-project/issues/125747
The 'declare' construct is the first of two 'declaration' level
constructs, so it is legal in any place a declaration is, including as a
statement, which this accomplishes by wrapping it in a DeclStmt. All
clauses on this have a 'same scope' requirement, which this enforces as
declaration context instead, which makes it possible to implement these
as a template.
The 'link' and 'device_resident' clauses are also added, which have some
similar/small restrictions, but are otherwise pretty rote.
This patch implements all of the above.
This merges the functionality of ResolvedUnexpandedPackExpr into
FunctionParmPackExpr. I also added a test to show that
https://github.com/llvm/llvm-project/issues/125103 should be fixed with
this. I put the removal of ResolvedUnexpandedPackExpr in its own commit.
Let me know what you think.
Fixes#125103
