[C++20] [Modules] Disable preferred_name when writing a C++20 Module interface

Currently, the use of preferred_name would block implementing std
modules in libcxx. See https://github.com/llvm/llvm-p

[C++20] [Modules] Disable preferred_name when writing a C++20 Module interface

Currently, the use of preferred_name would block implementing std
modules in libcxx. See https://github.com/llvm/llvm-project/issues/56490
for example.
The problem is pretty hard and it looks like we couldn't solve it in a
short time. So we sent this patch as a workaround to avoid blocking us
to modularize STL. This is intended to be fixed properly in the future.

Reviewed By: erichkeane, aaron.ballman, tahonermann

Differential Revision: https://reviews.llvm.org/D130331

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[NFC] Start saving InstantiatedFromDecl in non-template functions

In cases where a non-template function is defined inside a function
template, we don't have information about the original uninstant

[NFC] Start saving InstantiatedFromDecl in non-template functions

In cases where a non-template function is defined inside a function
template, we don't have information about the original uninstantiated
version. In the case of concepts instantiation, we will need the
ability to get back to the original template. This patch splits a piece
of the deferred concepts instantaition patch off to accomplish the
storage of this, with minor runtime overhead, and zero additional
storage.

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Revert "Re-apply "Deferred Concept Instantiation Implementation"""

This reverts commit befa8cf087dbb8159a4d9dc8fa4d6748d6d5049a.

Apparently this breaks some libc++ builds with an apparent assertion

Revert "Re-apply "Deferred Concept Instantiation Implementation"""

This reverts commit befa8cf087dbb8159a4d9dc8fa4d6748d6d5049a.

Apparently this breaks some libc++ builds with an apparent assertion,
so I'm looking into that .

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Re-apply "Deferred Concept Instantiation Implementation""

This reverts commit d4d47e574ecae562ab32f8ac7fa3f4d424bb6574.

This fixes the lldb crash that was observed by ensuring that our
friend-'temp

Re-apply "Deferred Concept Instantiation Implementation""

This reverts commit d4d47e574ecae562ab32f8ac7fa3f4d424bb6574.

This fixes the lldb crash that was observed by ensuring that our
friend-'template contains reference to' TreeTransform properly handles a
TemplateDecl.

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Revert "Deferred Concept Instantiation Implementation"

This reverts commit 2f207439521d62d9551b2884158368e8b34084e5 because it
triggers an assertion when building an LLDB test program:

Assertion

Revert "Deferred Concept Instantiation Implementation"

This reverts commit 2f207439521d62d9551b2884158368e8b34084e5 because it
triggers an assertion when building an LLDB test program:

Assertion failed: (InstantiatingSpecializations.empty() && "failed to
clean up an InstantiatingTemplate?"), function ~Sema, file
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/clang/lib/Sema/Sema.cpp,
line 458.

More details in https://reviews.llvm.org/D126907.

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Deferred Concept Instantiation Implementation

This is a continuation of D119544. Based on @rsmith 's feed back
showing me https://eel.is/c++draft/temp#friend-9, We should properly
handle friend fun

Deferred Concept Instantiation Implementation

This is a continuation of D119544. Based on @rsmith 's feed back
showing me https://eel.is/c++draft/temp#friend-9, We should properly
handle friend functions now.

Differential Revision: https://reviews.llvm.org/D126907

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[C++20] [Module] Support reachable definition initially/partially

This patch introduces a new kind of ModuleOwnershipKind as
ReachableWhenImported. This intended the status for reachable described
a

[C++20] [Module] Support reachable definition initially/partially

This patch introduces a new kind of ModuleOwnershipKind as
ReachableWhenImported. This intended the status for reachable described
at: https://eel.is/c++draft/module.reach#3.

Note that this patch is not intended to support all semantics about
reachable semantics. For example, this patch didn't implement discarded
declarations in GMF. (https://eel.is/c++draft/module.global.frag#3).

This fixes: https://bugs.llvm.org/show_bug.cgi?id=52281 and
https://godbolt.org/z/81f3ocjfW.

Reviewed By: rsmith, iains

Differential Revision: https://reviews.llvm.org/D113545

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Revert "[C++20] [Modules] Implement Reachable initiallly"

This reverts commit a223ba0a697c1598b434cf2495c9cd9ec5640fc7.

The previous commit don't contain additional information, which is bad.

[C++20] [Modules] Implement Reachable initiallly

[Clang][Modules] Merge availability attributes on imported decls

Currently we do not in general merge attributes when importing decls from modules. This patch handles availability, but long term we

[Clang][Modules] Merge availability attributes on imported decls

Currently we do not in general merge attributes when importing decls from modules. This patch handles availability, but long term we need to properly handle all attributes.

I tried to use Sema::mergeDeclAttributes, but it caused test crashes as I don't think it expects to be called in this context. We really shouldn't have duplicate code for merging attributes long term, but for now this fixes availability. There's already a TODO for this in the declaration of ASTDeclReader::mergeInheritableAttributes.

Differential Revision: https://reviews.llvm.org/D127182

rdar://85820301

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Revert ""Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation"""""

This reverts commit a425cac31e2e4cee8e14b7b9a99c8ba17c1ebb52.

There is another libc++ test, that this time causes us

Revert ""Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation"""""

This reverts commit a425cac31e2e4cee8e14b7b9a99c8ba17c1ebb52.

There is another libc++ test, that this time causes us to hit an
assertion. Reverting, likely for a while this time.

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"Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation""""

This includes a fix for the libc++ issue I ran across with friend
declarations not properly being identified as overloads.

Th

"Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation""""

This includes a fix for the libc++ issue I ran across with friend
declarations not properly being identified as overloads.

This reverts commit 45c07db31cc76802a1a2e41bed1ce9c1b8198181.

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Revert "Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation"""

This reverts commit a97899108e495147985e5e9492e742d51d5cc97a.

The patch caused some problems with the libc++ `__range_a

Revert "Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation"""

This reverts commit a97899108e495147985e5e9492e742d51d5cc97a.

The patch caused some problems with the libc++ `__range_adaptor_closure`
that I haven't been able to figure out the cause of, so I am reverting
while I figure out whether this is a solvable problem/issue with the
CFE, or libc++ depending on an older 'incorrect' behavior.

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Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation""

This reverts commit 0c31da48389754822dc3eecc4723160c295b9ab2.

I've solved the issue with the PointerUnion by making the
`Functio

Re-apply 4b6c2cd642 "Deferred Concept Instantiation Implementation""

This reverts commit 0c31da48389754822dc3eecc4723160c295b9ab2.

I've solved the issue with the PointerUnion by making the
`FunctionTemplateDecl` pointer be a NamedDecl, that could be a
`FunctionDecl` or `FunctionTemplateDecl` depending. This is enforced
with an assert.

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Revert "Deferred Concept Instantiation Implementation"

This reverts commit 4b6c2cd647e9e5a147954886338f97ffb6a1bcfb.

The patch caused numerous ARM 32 bit build failures, since we added a
5th item t

Revert "Deferred Concept Instantiation Implementation"

This reverts commit 4b6c2cd647e9e5a147954886338f97ffb6a1bcfb.

The patch caused numerous ARM 32 bit build failures, since we added a
5th item to the PointerUnion, and went over the 2-bits available in the
32 bit pointers.

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Deferred Concept Instantiation Implementation

As reported here: https://github.com/llvm/llvm-project/issues/44178

Concepts are not supposed to be instantiated until they are checked, so
this patch

Deferred Concept Instantiation Implementation

As reported here: https://github.com/llvm/llvm-project/issues/44178

Concepts are not supposed to be instantiated until they are checked, so
this patch implements that and goes through significant amounts of work
to make sure we properly re-instantiate the concepts correctly.

Differential Revision: https://reviews.llvm.org/D119544

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[modules] Merge equivalent extensions and diagnose ivar redeclarations for extensions loaded from different modules.

Emitting metadata for the same ivar multiple times can lead to
miscompilations. O

[modules] Merge equivalent extensions and diagnose ivar redeclarations for extensions loaded from different modules.

Emitting metadata for the same ivar multiple times can lead to
miscompilations. Objective-C runtime adds offsets to calculate ivar
position in memory and presence of duplicate offsets causes wrong final
position thus overwriting unrelated memory.

Such a situation is impossible with modules disabled as clang diagnoses
ivar redeclarations during sema checks after parsing
(`Sema::ActOnFields`). Fix the case with modules enabled by checking
during deserialization if ivar is already declared. We also support
a use case where the same category ends up in multiple modules. We
don't want to treat this case as ivar redeclaration and instead merge
corresponding ivars.

rdar://83468070

Differential Revision: https://reviews.llvm.org/D121177

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[modules] Merge variable template specializations.

[modules] Merge ObjC interface ivars with anonymous types.

Without the fix ivars with anonymous types can trigger errors like

> error: 'TestClass::structIvar' from module 'Target' is not present in

[modules] Merge ObjC interface ivars with anonymous types.

Without the fix ivars with anonymous types can trigger errors like

> error: 'TestClass::structIvar' from module 'Target' is not present in definition of 'TestClass' provided earlier
> [...]
> note: declaration of 'structIvar' does not match

It happens because types of ivars from different modules are considered
to be different. And it is caused by not merging anonymous `TagDecl`
from different modules.

To fix that I've changed `serialization::needsAnonymousDeclarationNumber`
to handle anonymous `TagDecl` inside `ObjCInterfaceDecl`. But that's not
sufficient as C code inside `ObjCInterfaceDecl` doesn't use interface
decl as a decl context but switches to its parent (TranslationUnit in
most cases). I'm changing that to make `ObjCContainerDecl` the lexical
decl context but keeping the semantic decl context intact.

Test "check-dup-decls-inside-objc.m" doesn't reflect a change in
functionality but captures the existing behavior to prevent regressions.

rdar://85563013

Differential Revision: https://reviews.llvm.org/D118525

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[Clang] Implement __builtin_source_location.

This builtin returns the address of a global instance of the
`std::source_location::__impl` type, which must be defined (with an
appropriate shape) befor

[Clang] Implement __builtin_source_location.

This builtin returns the address of a global instance of the
`std::source_location::__impl` type, which must be defined (with an
appropriate shape) before calling the builtin.

It will be used to implement std::source_location in libc++ in a
future change. The builtin is compatible with GCC's implementation,
and libstdc++'s usage. An intentional divergence is that GCC declares
the builtin's return type to be `const void*` (for
ease-of-implementation reasons), while Clang uses the actual type,
`const std::source_location::__impl*`.

In order to support this new functionality, I've also added a new
'UnnamedGlobalConstantDecl'. This artificial Decl is modeled after
MSGuidDecl, and is used to represent a generic concept of an lvalue
constant with global scope, deduplicated by its value. It's possible
that MSGuidDecl itself, or some of the other similar sorts of things
in Clang might be able to be refactored onto this more-generic
concept, but there's enough special-case weirdness in MSGuidDecl that
I gave up attempting to share code there, at least for now.

Finally, for compatibility with libstdc++'s <source_location> header,
I've added a second exception to the "cannot cast from void* to T* in
constant evaluation" rule. This seems a bit distasteful, but feels
like the best available option.

Reviewers: aaron.ballman, erichkeane

Differential Revision: https://reviews.llvm.org/D120159

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[Clang] Fix Unevaluated Lambdas

Unlike other types, when lambdas are instanciated,
they are recreated from scratch.
When an unevaluated lambdas appear in the type of a function,
parameter it is inst

[Clang] Fix Unevaluated Lambdas

Unlike other types, when lambdas are instanciated,
they are recreated from scratch.
When an unevaluated lambdas appear in the type of a function,
parameter it is instanciated in the wrong declaration context,
as parameters are transformed before the function.

To support lambda in function parameters, we try to
compute whether they are dependant without looking at the
declaration context.

This is a short term stopgap solution to avoid clang
iceing. A better fix might be to inject some kind of
transparent declaration with correctly computed dependency
for function parameters, variable templates, etc.

Fixes https://github.com/llvm/llvm-project/issues/50376
Fixes https://github.com/llvm/llvm-project/issues/51414
Fixes https://github.com/llvm/llvm-project/issues/51416
Fixes https://github.com/llvm/llvm-project/issues/51641
Fixes https://github.com/llvm/llvm-project/issues/54296

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D121532

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[clang][ASTReader] Fix memory leak while reading FriendTemplateDecls

Allocate on ASTContext, rather than just on heap, so that template
parameter lists are freed up.

Differential Revision: https://

[clang][ASTReader] Fix memory leak while reading FriendTemplateDecls

Allocate on ASTContext, rather than just on heap, so that template
parameter lists are freed up.

Differential Revision: https://reviews.llvm.org/D120081

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[modules] Add a flag for TagDecl if it was a definition demoted to a declaration.

For redeclaration chains we maintain an invariant of having only a
single definition in the chain. In a single trans

[modules] Add a flag for TagDecl if it was a definition demoted to a declaration.

For redeclaration chains we maintain an invariant of having only a
single definition in the chain. In a single translation unit we make
sure not to create duplicates. But modules are separate translation
units and they can contain definitions for the same symbol
independently. When we load such modules together, we need to demote
duplicate definitions to keep the AST invariants.

Some AST clients are interested in distinguishing
declaration-that-was-demoted-from-definition and
declaration-that-was-never-a-definition. For that purpose introducing
`IsThisDeclarationADemotedDefinition`. No functional change intended.

rdar://84677782

Differential Revision: https://reviews.llvm.org/D118855

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[NFC] [AST] Move isSameEntity into ASTContext

Currently we are trying to implement the semantics of C++ Modules. A big
challenge would be the ODR checking. Previously we did this in
ASTReader, it wo

[NFC] [AST] Move isSameEntity into ASTContext

Currently we are trying to implement the semantics of C++ Modules. A big
challenge would be the ODR checking. Previously we did this in
ASTReader, it would handle the cases like:
```
module;
export module a_module;
import another_module; // check the ODR consistency here
```
or
```
export module m;
import a_module;
import another_module; // check the ODR consistency here
```

However, it wouldn't handle the case:
```
import another_module; // When we check ODR here, everything looks fine.
```

In the case, the read process is ended. But we need to check the ODR
still. To reuse the facility we do in ASTReader, this patch moves the
corresponding codes into ASTContext. This should be good since there
were facilities like `hasSameTemplateName` and `hasSameType`.

Although the patch is a little bit big, all of the change should be
trivial.

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D118223

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[clang][OpenMP5.1] Initial parsing/sema for 'indirect' clause

Differential Revision: https://reviews.llvm.org/D116764