[Clang][P1061] Add stuctured binding packs (#121417)

This is an implementation of P1061 Structure Bindings Introduce a Pack
without the ability to use packs outside of templates. There is a couple
o

[Clang][P1061] Add stuctured binding packs (#121417)

This is an implementation of P1061 Structure Bindings Introduce a Pack
without the ability to use packs outside of templates. There is a couple
of ways the AST could have been sliced so let me know what you think.
The only part of this change that I am unsure of is the
serialization/deserialization stuff. I followed the implementation of
other Exprs, but I do not really know how it is tested. Thank you for
your time considering this.

---------

Co-authored-by: Yanzuo Liu <zwuis@outlook.com>

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[Clang] Don't assume unexpanded PackExpansions' size when expanding packs (#120380)

CheckParameterPacksForExpansion() previously assumed that template
arguments don't include PackExpansion types whe

[Clang] Don't assume unexpanded PackExpansions' size when expanding packs (#120380)

CheckParameterPacksForExpansion() previously assumed that template
arguments don't include PackExpansion types when attempting another pack
expansion (i.e. when NumExpansions is present). However, this assumption
doesn't hold for type aliases, whose substitution might involve
unexpanded packs. This can lead to incorrect diagnostics during
substitution because the pack size is not yet determined.

To address this, this patch calculates the minimum pack size (ignoring
unexpanded PackExpansionTypes) and compares it to the previously
expanded size. If the minimum pack size is smaller, then there's still a
chance for future substitution to expand it to a correct size, so we
don't diagnose it too eagerly.

Fixes #61415
Fixes #32252
Fixes #17042

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[Sema] Migrate away from PointerUnion::{is,get} (NFC) (#117498)

Note that PointerUnion::{is,get} have been soft deprecated in
PointerUnion.h:

// FIXME: Replace the uses of is(), get() and dyn_

[Sema] Migrate away from PointerUnion::{is,get} (NFC) (#117498)

Note that PointerUnion::{is,get} have been soft deprecated in
PointerUnion.h:

// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>

I'm not touching PointerUnion::dyn_cast for now because it's a bit
complicated; we could blindly migrate it to dyn_cast_if_present, but
we should probably use dyn_cast when the operand is known to be
non-null.

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[Clang] Preserve partially substituted pack indexing type/expressions (#116782)

Substituting into pack indexing types/expressions can still result in
unexpanded types/expressions, such as `PackInde

[Clang] Preserve partially substituted pack indexing type/expressions (#116782)

Substituting into pack indexing types/expressions can still result in
unexpanded types/expressions, such as `PackIndexingType` or
`PackIndexingExpr`. To handle these cases correctly, we should defer the
pack size checks to the next round of transformation, when the patterns
can be fully expanded.

To that end, the `FullySubstituted` flag is now necessary for computing
the dependencies of `PackIndexingExprs`. Conveniently, this flag can
also represent the prior `ExpandsToEmpty` status with an additional
emptiness check. Therefore, I converted all stored flags to use
`FullySubstituted`.

Fixes https://github.com/llvm/llvm-project/issues/116105

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[Clang] [NFC] Refactor AST visitors in Sema and the static analyser to use DynamicRecursiveASTVisitor (#115144)

This pr refactors all recursive AST visitors in `Sema`, `Analyze`, and
`StaticAnalysi

[Clang] [NFC] Refactor AST visitors in Sema and the static analyser to use DynamicRecursiveASTVisitor (#115144)

This pr refactors all recursive AST visitors in `Sema`, `Analyze`, and
`StaticAnalysis` to inherit from DRAV instead. This is over half of the
visitors that inherit from RAV directly.

See also #115132, #110040, #93462

LLVM Compile-Time Tracker link for this branch:
https://llvm-compile-time-tracker.com/compare.php?from=5adb5c05a2e9f31385fbba8b0436cbc07d91a44d&to=b58e589a86c06ba28d4d90613864d10be29aa5ba&stat=instructions%3Au

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[Clang] Don't assert on substituted-but-yet-expanded packs for nested lambdas (#112896)

Nested lambdas could refer to outer packs that would be expanded by a
larger CXXFoldExpr, in which case that

[Clang] Don't assert on substituted-but-yet-expanded packs for nested lambdas (#112896)

Nested lambdas could refer to outer packs that would be expanded by a
larger CXXFoldExpr, in which case that reference could happen to be a
full expression containing intermediate types/expressions, e.g.
SubstTemplateTypeParmPackType/FunctionParmPackExpr. They are designated
as "UnexpandedPack" dependencies but don't introduce new packs anyway.

This also handles a missed case for VarDecls, where the flag of
ContainsUnexpandedPack was not propagated up to the surrounding lambda.

Fixes #112352

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[Clang] [Sema] Don't crash on unexpanded pack in invalid block literal (#110762)

Consider #109148:
```c++
template <typename ...Ts>
void f() {
[] {
(^Ts);
};
}
```

When we

[Clang] [Sema] Don't crash on unexpanded pack in invalid block literal (#110762)

Consider #109148:
```c++
template <typename ...Ts>
void f() {
[] {
(^Ts);
};
}
```

When we encounter `^Ts`, we try to parse a block and subsequently call
`DiagnoseUnexpandedParameterPack()` (in `ActOnBlockArguments()`), which
sees `Ts` and sets `ContainsUnexpandedParameterPack` to `true` in the
`LambdaScopeInfo` of the enclosing lambda. However, the entire block is
subsequently discarded entirely because it isn’t even syntactically
well-formed. As a result, `ContainsUnexpandedParameterPack` is `true`
despite the lambda’s body no longer containing any unexpanded packs,
which causes an assertion the next time
`DiagnoseUnexpandedParameterPack()` is called.

This pr moves handling of unexpanded parameter packs into
`CapturingScopeInfo` instead so that the same logic is used for both
blocks and lambdas. This fixes this issue since the
`ContainsUnexpandedParameterPack` flag is now part of the block (and
before that, its `CapturingScopeInfo`) and no longer affects the
surrounding lambda directly when the block is parsed. Moreover, this
change makes blocks actually usable with pack expansion.

This fixes #109148.

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[Clang] Don't assert non-empty packs for FunctionParmPackExprs (#107561)

`FunctionParmPackExpr`s are peculiar in that they have to be of
unexpanded dependency while they don't introduce any unexpan

[Clang] Don't assert non-empty packs for FunctionParmPackExprs (#107561)

`FunctionParmPackExpr`s are peculiar in that they have to be of
unexpanded dependency while they don't introduce any unexpanded packs.
So this patch rules them out in the non-empty pack assertion in
`DiagnoseUnexpandedParameterPack()`.

There was a fix #69224, but that turned out to be insufficient.

I also moved the separate tests to a pre-existing file.

Fixes https://github.com/llvm/llvm-project/issues/86361

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[Clang] Fix Handling of Init Capture with Parameter Packs in LambdaScopeForCallOperatorInstantiationRAII (#100766)

This PR addresses issues related to the handling of `init capture` with
parameter

[Clang] Fix Handling of Init Capture with Parameter Packs in LambdaScopeForCallOperatorInstantiationRAII (#100766)

This PR addresses issues related to the handling of `init capture` with
parameter packs in Clang's
`LambdaScopeForCallOperatorInstantiationRAII`.

Previously, `addInstantiatedCapturesToScope` would add `init capture`
containing packs to the scope using the type of the `init capture` to
determine the expanded pack size. However, this approach resulted in a
pack size of 0 because `getType()->containsUnexpandedParameterPack()`
returns `false`. After extensive testing, it appears that the correct
pack size can only be inferred from `getInit`.

But `getInit` may reference parameters and `init capture` from an outer
lambda, as shown in the following example:

```cpp
auto L = [](auto... z) {
return [... w = z](auto... y) {
// ...
};
};
```

To address this, `addInstantiatedCapturesToScope` in
`LambdaScopeForCallOperatorInstantiationRAII` should be called last.
Additionally, `addInstantiatedCapturesToScope` has been modified to only
add `init capture` to the scope. The previous implementation incorrectly
called `MakeInstantiatedLocalArgPack` for other non-init captures
containing packs, resulting in a pack size of 0.

### Impact

This patch affects scenarios where
`LambdaScopeForCallOperatorInstantiationRAII` is passed with
`ShouldAddDeclsFromParentScope = false`, preventing the correct addition
of the current lambda's `init capture` to the scope. There are two main
scenarios for `ShouldAddDeclsFromParentScope = false`:

1. **Constraints**: Sometimes constraints are instantiated in place
rather than delayed. In this case,
`LambdaScopeForCallOperatorInstantiationRAII` does not need to add `init
capture` to the scope.
2. **`noexcept` Expressions**: The expressions inside `noexcept` have
already been transformed, and the packs referenced within have been
expanded. Only `RebuildLambdaInfo` needs to add the expanded captures to
the scope, without requiring `addInstantiatedCapturesToScope` from
`LambdaScopeForCallOperatorInstantiationRAII`.

### Considerations

An alternative approach could involve adding a data structure within the
lambda to record the expanded size of the `init capture` pack. However,
this would increase the lambda's size and require extensive
modifications.

This PR is a prerequisite for implmenting
https://github.com/llvm/llvm-project/issues/61426

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[HLSL] Implement intangible AST type (#97362)

HLSL has a set of intangible types which are described in in the
[draft HLSL Specification
(**[Basic.types]**)](https://microsoft.github.io/hlsl-specs

[HLSL] Implement intangible AST type (#97362)

HLSL has a set of intangible types which are described in in the
[draft HLSL Specification
(**[Basic.types]**)](https://microsoft.github.io/hlsl-specs/specs/hlsl.pdf):
There are special implementation-defined types such as handle types,
which fall into a category of standard intangible types. Intangible
types are types that have no defined object representation or value
representation, as such the size is unknown at compile time.

A class type T is an intangible class type if it contains an base
classes or members of intangible class type, standard intangible type,
or arrays of such types. Standard intangible types and intangible class
types are collectively called intangible
types([9](https://microsoft.github.io/hlsl-specs/specs/hlsl.html#Intangible)).

This PR implements one standard intangible type `__hlsl_resource_t`
and sets up the infrastructure that will make it easier to add more
in the future, such as samplers or raytracing payload handles. The
HLSL intangible types are declared in
`clang/include/clang/Basic/HLSLIntangibleTypes.def` and this file is
included with related macro definition in most places that require edits
when a new type is added.

The new types are added as keywords and not typedefs to make sure they
cannot be redeclared, and they can only be declared in builtin implicit
headers. The `__hlsl_resource_t` type represents a handle to a memory
resource and it is going to be used in builtin HLSL buffer types like this:

template <typename T>
class RWBuffer {
[[hlsl::contained_type(T)]]
[[hlsl::is_rov(false)]]
[[hlsl::resource_class(uav)]]
__hlsl_resource_t Handle;
};

Part 1/3 of llvm/llvm-project#90631.

---------

Co-authored-by: Justin Bogner <mail@justinbogner.com>

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Reapply [Clang][C++26] Implement "Ordering of constraints involving fold expressions (#99022)

Implement https://isocpp.org/files/papers/P2963R3.pdf

Revert "[Clang][C++26] Implement "Ordering of constraints involving fold expressions" (#99007)

Reverts llvm/llvm-project#98160

Breaks CI on some architectures

[Clang][C++26] Implement "Ordering of constraints involving fold expressions (#98160)

Implement https://isocpp.org/files/papers/P2963R3.pdf

[clang][NFC] Move documentation of `Sema` functions into `Sema.h`

This patch moves documentation of `Sema` functions from `.cpp` files to `Sema.h` when there was no documentation in the latter, or i

[clang][NFC] Move documentation of `Sema` functions into `Sema.h`

This patch moves documentation of `Sema` functions from `.cpp` files to `Sema.h` when there was no documentation in the latter, or it can be trivially subsumed. More complicated cases when there's less trivial divergence between documentation attached to declaration and the one attached to implementation are left for a later PR that would require review.

It appears that doxygen can find the documentation for a function defined out-of-line even if it's attached to an implementation, and not declaration. But other tools, e.g. clangd, are not as powerful. So this patch significantly improves autocompletion experience for (at least) clangd-based IDEs.

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[Clang] [Sema] Diagnose unexpanded parameter packs in attributes (#93482)

Call `DiagnoseUnexpandedParameterPack` when we parse an expression
argument to an attribute and check for implicit code in

[Clang] [Sema] Diagnose unexpanded parameter packs in attributes (#93482)

Call `DiagnoseUnexpandedParameterPack` when we parse an expression
argument to an attribute and check for implicit code in the
`CollectUnexpandedParameterPacksVisitor` so we can actually find
unexpanded packs in attributes that end up applied to lambda call
operators.

This fixes #93269.

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[Clang][Sema] Avoid pack expansion for expanded empty PackIndexingExprs (#92385)

We previously doubled the id-expression expansion, even when the pack
was expanded to empty. The previous condition

[Clang][Sema] Avoid pack expansion for expanded empty PackIndexingExprs (#92385)

We previously doubled the id-expression expansion, even when the pack
was expanded to empty. The previous condition for determining whether we
should expand couldn't distinguish between cases where 'the expansion
was previously postponed' and 'the expansion occurred but resulted in
emptiness.'

In the latter scenario, we crash because we have not been examining the
current lambda's parent local instantiation scope since
[D98068](https://reviews.llvm.org/D98068): Any Decls instantiated in the
parent scope are not visible to the generic lambda, and thus any attempt
of looking for instantiated Decls in the lambda is capped to the current
Lambda's LIS.

Fixes https://github.com/llvm/llvm-project/issues/92230

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[Clang] Do not try to diagnose parameter packs in invalid pack expressions (#89257)

In a pack expression, if the id-expression is not valid, do no try to
detect whether it is a pack as that would l

[Clang] Do not try to diagnose parameter packs in invalid pack expressions (#89257)

In a pack expression, if the id-expression is not valid, do no try to
detect whether it is a pack as that would lead to a crash trying to
print a recovery expression.

Fixes #88929

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[clang][Sema] Avoid guessing unexpanded packs' size in getFullyPackExpandedSize (#87768)

There has been an optimization for `SizeOfPackExprs` since c5452ed9, in
which
we overlooked a case where th

[clang][Sema] Avoid guessing unexpanded packs' size in getFullyPackExpandedSize (#87768)

There has been an optimization for `SizeOfPackExprs` since c5452ed9, in
which
we overlooked a case where the template arguments were not yet
formed into a `PackExpansionType` at the token annotation stage. This
led to a problem in that a template involving such expressions may
lose its nature of being dependent, causing some false-positive
diagnostics.

Fixes https://github.com/llvm/llvm-project/issues/84220

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[Clang][C++26] Implement Pack Indexing (P2662R3). (#72644)

Implements https://isocpp.org/files/papers/P2662R3.pdf

The feature is exposed as an extension in older language modes.
Mangling is not

[Clang][C++26] Implement Pack Indexing (P2662R3). (#72644)

Implements https://isocpp.org/files/papers/P2662R3.pdf

The feature is exposed as an extension in older language modes.
Mangling is not yet supported and that is something we will have to do before release.

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[c++20] P1907R1: Support for generalized non-type template arguments of scalar type. (#78041)

Previously committed as 9e08e51a20d0d2b1c5724bb17e969d036fced4cd, and
reverted because a dependency comm

[c++20] P1907R1: Support for generalized non-type template arguments of scalar type. (#78041)

Previously committed as 9e08e51a20d0d2b1c5724bb17e969d036fced4cd, and
reverted because a dependency commit was reverted, then committed again
as 4b574008aef5a7235c1f894ab065fe300d26e786 and reverted again because
"dependency commit" 5a391d38ac6c561ba908334d427f26124ed9132e was
reverted. But it doesn't seem that 5a391d38ac6c was a real dependency
for this.

This commit incorporates 4b574008aef5a7235c1f894ab065fe300d26e786 and
18e093faf726d15f210ab4917142beec51848258 by Richard Smith (@zygoloid),
with some minor fixes, most notably:

- `UncommonValue` renamed to `StructuralValue`

- `VK_PRValue` instead of `VK_RValue` as default kind in lvalue and
member pointer handling branch in
`BuildExpressionFromNonTypeTemplateArgumentValue`;

- handling of `StructuralValue` in `IsTypeDeclaredInsideVisitor`;

- filling in `SugaredConverted` along with `CanonicalConverted`
parameter in `Sema::CheckTemplateArgument`;

- minor cleanup in
`TemplateInstantiator::transformNonTypeTemplateParmRef`;

- `TemplateArgument` constructors refactored;

- `ODRHash` calculation for `UncommonValue`;

- USR generation for `UncommonValue`;

- more correct MS compatibility mangling algorithm (tested on MSVC ver.
19.35; toolset ver. 143);

- IR emitting fixed on using a subobject as a template argument when the
corresponding template parameter is used in an lvalue context;

- `noundef` attribute and opaque pointers in `template-arguments` test;

- analysis for C++17 mode is turned off for templates in
`warn-bool-conversion` test; in C++17 and C++20 mode, array reference
used as a template argument of pointer type produces template argument
of UncommonValue type, and
`BuildExpressionFromNonTypeTemplateArgumentValue` makes
`OpaqueValueExpr` for it, and `DiagnoseAlwaysNonNullPointer` cannot see
through it; despite of "These cases should not warn" comment, I'm not
sure about correct behavior; I'd expect a suggestion to replace `if` by
`if constexpr`;

- `temp.arg.nontype/p1.cpp` and `dr18xx.cpp` tests fixed.

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[clang][Sema] Avoid non-empty unexpanded pack assertion for FunctionParmPackExpr (#69224)

Closes https://github.com/llvm/llvm-project/issues/61460.

We have FunctionParmPackExpr that serves as the

[clang][Sema] Avoid non-empty unexpanded pack assertion for FunctionParmPackExpr (#69224)

Closes https://github.com/llvm/llvm-project/issues/61460.

We have FunctionParmPackExpr that serves as the unexpanded expression
but from which the visitor collects none, which may lead to assertion
failure during the template instantiation.

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[SemaCXX]use CorrectDelayedTyposInExpr in ActOnCXXFoldExpr only when Diag

PR #61326

- fix clang crash when fold expression contains a delayed typos correction.

code snippet in `ActOnCXXFoldExpr`
`

[SemaCXX]use CorrectDelayedTyposInExpr in ActOnCXXFoldExpr only when Diag

PR #61326

- fix clang crash when fold expression contains a delayed typos correction.

code snippet in `ActOnCXXFoldExpr`
``` if (!LHS || !RHS) {
Expr *Pack = LHS ? LHS : RHS;
assert(Pack && "fold expression with neither LHS nor RHS");
DiscardOperands();
if (!Pack->containsUnexpandedParameterPack())
return Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
<< Pack->getSourceRange();
}
```
`DiscardOperands` will be triggered when LHS/RHS is delayed typo correction expression.
It will output and clean all diagnose but still return a valid expression. (in else branch)
valid expression will be handled in caller function. When caller wants to output the diagnose, the diagnose in delayed typo correction expression has been consumed in `ActOnCXXFoldExpr`. It causes clang crash.

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D145892

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Revert two patches to fix GH58452 regression

GH58452 is a regression in the 16.0 release branch caused by both:
b8a1b698afb2fc84819c7596090aabf4d826b436 and
3a0309c53674be56b5cfce038d78a0c2c6e2a98c

Revert two patches to fix GH58452 regression

GH58452 is a regression in the 16.0 release branch caused by both:
b8a1b698afb2fc84819c7596090aabf4d826b436 and
3a0309c53674be56b5cfce038d78a0c2c6e2a98c

This patch reverts both of those to make the 'valid' code stop
diagnosing
at the expense of crashes on invalid + unclear diagnostics.

This patch also adds the tests from GH58452 to prevent any
re-application from breaking this again.

Revert "[clang] Improve diagnostics for expansion length mismatch"
This reverts commit 3a0309c53674be56b5cfce038d78a0c2c6e2a98c.
Revert "[clang] fix missing initialization of original number of expansions"
This reverts commit b8a1b698afb2fc84819c7596090aabf4d826b436.

Differential Revision: https://reviews.llvm.org/D145605

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[clang] Use std::optional instead of llvm::Optional (NFC)

This patch replaces (llvm::|)Optional< with std::optional<. I'll post
a separate patch to remove #include "llvm/ADT/Optional.h".

This is p

[clang] Use std::optional instead of llvm::Optional (NFC)

This patch replaces (llvm::|)Optional< with std::optional<. I'll post
a separate patch to remove #include "llvm/ADT/Optional.h".

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

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[clang] Add #include <optional> (NFC)

This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Option

[clang] Add #include <optional> (NFC)

This patch adds #include <optional> to those files containing
llvm::Optional<...> or Optional<...>.

I'll post a separate patch to actually replace llvm::Optional with
std::optional.

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

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