Change prototype merging error into a warning for builtins

As was observed in https://reviews.llvm.org/D123627#3707635, it's
confusing that a user can write:
```
float rintf(void) {}
```
and get a w

Change prototype merging error into a warning for builtins

As was observed in https://reviews.llvm.org/D123627#3707635, it's
confusing that a user can write:
```
float rintf(void) {}
```
and get a warning, but writing:
```
float rintf() {}
```
gives an error. This patch changes the behavior so that both are
warnings, so that users who have functions which conflict with a
builtin identifier can still use that identifier as they wish.

Differential Revision: https://reviews.llvm.org/D131499

(cherry picked from commit 4c02ab8c9742f6c32b17f49a306b3b072486f5c5)

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[C++20] [Modules] Merge same concept decls in global module fragment

According to [basic.def.odr]p14, the same redeclarations in different TU
but not attached to a named module are allowed. But we d

[C++20] [Modules] Merge same concept decls in global module fragment

According to [basic.def.odr]p14, the same redeclarations in different TU
but not attached to a named module are allowed. But we didn't take care
of concept decl for this condition. This patch tries to fix this
problem.

Reviewed By: ilya-biryukov

Differention Revision: https://reviews.llvm.org/D130614

(cherry picked from commit 4d9251bd780d20eebbcb124608b36a69787d5575)

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[Clang] [P2025] Analyze only potential scopes for NRVO

Before the patch we calculated the NRVO candidate looking at the
variable's whole enclosing scope. The research in [P2025] shows that
looking a

[Clang] [P2025] Analyze only potential scopes for NRVO

Before the patch we calculated the NRVO candidate looking at the
variable's whole enclosing scope. The research in [P2025] shows that
looking at the variable's potential scope is better and covers more
cases where NRVO would be safe and desirable.

Many thanks to @Izaron for the original implementation.

Reviewed By: ChuanqiXu

Differential Revision: https://reviews.llvm.org/D119792

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[Clang] Fix how we set the NumPositiveBits on an EnumDecl to cover the case of single enumerator with value zero or an empty enum

Currently in Sema::ActOnEnumBody(...) when calculating NumPositiveBi

[Clang] Fix how we set the NumPositiveBits on an EnumDecl to cover the case of single enumerator with value zero or an empty enum

Currently in Sema::ActOnEnumBody(...) when calculating NumPositiveBits we miss
the case where there is only a single enumerator with value zero and the case of
an empty enum. In both cases we end up with zero positive bits when in fact we
need one bit to store the value zero.

This PR updates the calculation to account for these cases.

Differential Revision: https://reviews.llvm.org/D130301

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[SemaCXX] Set promotion type for enum if its type is promotable to integer type even if it has no definition.

EnumDecl's promotion type is set either to the parsed type or calculated type
after comp

[SemaCXX] Set promotion type for enum if its type is promotable to integer type even if it has no definition.

EnumDecl's promotion type is set either to the parsed type or calculated type
after completing its definition. When it's bool type and has no definition,
its promotion type is bool which is not allowed by clang.

Fixes #56560.

Differential Revision: https://reviews.llvm.org/D130210

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re-land [C++20][Modules] Update handling of implicit inlines [P1779R3]

re-land fixes an unwanted interaction with module-map modules, seen in
Greendragon testing.

This provides updates to
[class.mf

re-land [C++20][Modules] Update handling of implicit inlines [P1779R3]

re-land fixes an unwanted interaction with module-map modules, seen in
Greendragon testing.

This provides updates to
[class.mfct]:
Pre C++20 [class.mfct]p2:
A member function may be defined (8.4) in its class definition, in
which case it is an inline member function (7.1.2)
Post C++20 [class.mfct]p1:
If a member function is attached to the global module and is defined
in its class definition, it is inline.

and
[class.friend]:
Pre-C++20 [class.friend]p5
A function can be defined in a friend declaration of a
class . . . . Such a function is implicitly inline.
Post C++20 [class.friend]p7
Such a function is implicitly an inline function if it is attached
to the global module.

We add the output of implicit-inline to the TextNodeDumper, and amend
a couple of existing tests to account for this, plus add tests for the
cases covered above.

Differential Revision: https://reviews.llvm.org/D129045

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Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit 7c51f02effdbd0d5e12bfd26f9c3b2ab5687c93f because it
stills breaks the LLDB tests. This was re-landed wi

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit 7c51f02effdbd0d5e12bfd26f9c3b2ab5687c93f because it
stills breaks the LLDB tests. This was re-landed without addressing the
issue or even agreement on how to address the issue. More details and
discussion in https://reviews.llvm.org/D112374.

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[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which go

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

---

Troubleshooting list to deal with any breakage seen with this patch:

1) The most likely effect one would see by this patch is a change in how
a type is printed. The type printer will, by design and default,
print types as written. There are customization options there, but
not that many, and they mainly apply to how to print a type that we
somehow failed to track how it was written. This patch fixes a
problem where we failed to distinguish between a type
that was written without any elaborated-type qualifiers,
such as a 'struct'/'class' tags and name spacifiers such as 'std::',
and one that has been stripped of any 'metadata' that identifies such,
the so called canonical types.
Example:
```
namespace foo {
struct A {};
A a;
};
```
If one were to print the type of `foo::a`, prior to this patch, this
would result in `foo::A`. This is how the type printer would have,
by default, printed the canonical type of A as well.
As soon as you add any name qualifiers to A, the type printer would
suddenly start accurately printing the type as written. This patch
will make it print it accurately even when written without
qualifiers, so we will just print `A` for the initial example, as
the user did not really write that `foo::` namespace qualifier.

2) This patch could expose a bug in some AST matcher. Matching types
is harder to get right when there is sugar involved. For example,
if you want to match a type against being a pointer to some type A,
then you have to account for getting a type that is sugar for a
pointer to A, or being a pointer to sugar to A, or both! Usually
you would get the second part wrong, and this would work for a
very simple test where you don't use any name qualifiers, but
you would discover is broken when you do. The usual fix is to
either use the matcher which strips sugar, which is annoying
to use as for example if you match an N level pointer, you have
to put N+1 such matchers in there, beginning to end and between
all those levels. But in a lot of cases, if the property you want
to match is present in the canonical type, it's easier and faster
to just match on that... This goes with what is said in 1), if
you want to match against the name of a type, and you want
the name string to be something stable, perhaps matching on
the name of the canonical type is the better choice.

3) This patch could exposed a bug in how you get the source range of some
TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
which only looks at the given TypeLoc node. This patch introduces a new,
and more common TypeLoc node which contains no source locations on itself.
This is not an inovation here, and some other, more rare TypeLoc nodes could
also have this property, but if you use getLocalSourceRange on them, it's not
going to return any valid locations, because it doesn't have any. The right fix
here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
into the inner TypeLoc to get the source range if it doesn't find it on the
top level one. You can use getLocalSourceRange if you are really into
micro-optimizations and you have some outside knowledge that the TypeLocs you are
dealing with will always include some source location.

4) Exposed a bug somewhere in the use of the normal clang type class API, where you
have some type, you want to see if that type is some particular kind, you try a
`dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
Again, like 2), this would usually have been tested poorly with some simple tests with
no qualifications, and would have been broken had there been any other kind of type sugar,
be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.

5) It could be a bug in this patch perhaps.

Let me know if you need any help!

Signed-off-by: Matheus Izvekov <[email protected]>

Differential Revision: https://reviews.llvm.org/D112374

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[clang] Use value instead of getValue (NFC)

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit bdc6974f92304f4ed542241b9b89ba58ba6b20aa because it
breaks all the LLDB tests that import the std module

Revert "[clang] Implement ElaboratedType sugaring for types written bare"

This reverts commit bdc6974f92304f4ed542241b9b89ba58ba6b20aa because it
breaks all the LLDB tests that import the std module.

import-std-module/array.TestArrayFromStdModule.py
import-std-module/deque-basic.TestDequeFromStdModule.py
import-std-module/deque-dbg-info-content.TestDbgInfoContentDequeFromStdModule.py
import-std-module/forward_list.TestForwardListFromStdModule.py
import-std-module/forward_list-dbg-info-content.TestDbgInfoContentForwardListFromStdModule.py
import-std-module/list.TestListFromStdModule.py
import-std-module/list-dbg-info-content.TestDbgInfoContentListFromStdModule.py
import-std-module/queue.TestQueueFromStdModule.py
import-std-module/stack.TestStackFromStdModule.py
import-std-module/vector.TestVectorFromStdModule.py
import-std-module/vector-bool.TestVectorBoolFromStdModule.py
import-std-module/vector-dbg-info-content.TestDbgInfoContentVectorFromStdModule.py
import-std-module/vector-of-vectors.TestVectorOfVectorsFromStdModule.py

https://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/45301/

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[clang] Ignore DependentSizeArray in -Warray-parameter

Acknowledge we don't know how to handle those yet.

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which go

[clang] Implement ElaboratedType sugaring for types written bare

Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.

The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.

An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.

Signed-off-by: Matheus Izvekov <[email protected]>

Differential Revision: https://reviews.llvm.org/D112374

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Revert "[C++20][Modules] Update handling of implicit inlines [P1779R3]"

This reverts commit ef0fa9f0ef3e as a follow up to b19d3ee7120b which
reverted commit ac507102d258. See https://reviews.llvm.o

Revert "[C++20][Modules] Update handling of implicit inlines [P1779R3]"

This reverts commit ef0fa9f0ef3e as a follow up to b19d3ee7120b which
reverted commit ac507102d258. See https://reviews.llvm.org/D126189 for
more details.

show more ...

[C++20][Modules] Update handling of implicit inlines [P1779R3]

This provides updates to
[class.mfct]:
Pre C++20 [class.mfct]p2:
A member function may be defined (8.4) in its class definition, in

[C++20][Modules] Update handling of implicit inlines [P1779R3]

This provides updates to
[class.mfct]:
Pre C++20 [class.mfct]p2:
A member function may be defined (8.4) in its class definition, in
which case it is an inline member function (7.1.2)
Post C++20 [class.mfct]p1:
If a member function is attached to the global module and is defined
in its class definition, it is inline.

and
[class.friend]:
Pre-C++20 [class.friend]p5
A function can be defined in a friend declaration of a
class . . . . Such a function is implicitly inline.
Post C++20 [class.friend]p7
Such a function is implicitly an inline function if it is attached
to the global module.

We add the output of implicit-inline to the TextNodeDumper, and amend
a couple of existing tests to account for this, plus add tests for the
cases covered above.

Differential Revision: https://reviews.llvm.org/D129045

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[clang] Introduce -Warray-parameter

This warning exist in GCC[0] and warns about re-declarations of functions
involving arguments of array or pointer types of inconsistent kinds or forms.

This is n

[clang] Introduce -Warray-parameter

This warning exist in GCC[0] and warns about re-declarations of functions
involving arguments of array or pointer types of inconsistent kinds or forms.

This is not the exact same implementation as GCC's : there's no warning level
and that flag has no effect on -Warray-bounds.

[0] https://gcc.gnu.org/onlinedocs/gcc-12.1.0/gcc/Warning-Options.html#index-Wno-array-parameter

Differential Revision: https://reviews.llvm.org/D128449

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[C++20][Modules] Allow for redeclarations in partitions.

The existing provision is not sufficient, it did not allow for the cases
where an implementation partition includes the primary module interf

[C++20][Modules] Allow for redeclarations in partitions.

The existing provision is not sufficient, it did not allow for the cases
where an implementation partition includes the primary module interface,
or for the case that an exported interface partition is contains a decl
that is then implemented in a regular implementation unit.

It is somewhat unfortunate that we have to compare top level module names
to achieve this, since built modules are not necessarily available.

TODO: It might be useful to cache a hash of the primary module name if
this test proves to be a significant load.

Differential Revision: https://reviews.llvm.org/D127624

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[OpenMP] Add variant extension that applies to declarations

This patch adds a new extension to the `omp begin / end declare variant`
support that causes it to apply to function declarations as well.

[OpenMP] Add variant extension that applies to declarations

This patch adds a new extension to the `omp begin / end declare variant`
support that causes it to apply to function declarations as well. This
is explicitly not done in the standard, but can be useful in some
situations so we should provide it as an extension. This will allow us
to uniquely bind and overload existing definitions with a simple
declaration using variants.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D124624

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[Clang] Fix: Restore warning inadvertently removed by D126061.

Before D126061, Clang would warn about this code

```
struct X {
[[deprecated]] struct Y {};
};
```

with the warning

attribut

[Clang] Fix: Restore warning inadvertently removed by D126061.

Before D126061, Clang would warn about this code

```
struct X {
[[deprecated]] struct Y {};
};
```

with the warning

attribute 'deprecated' is ignored, place it after "struct" to apply attribute to type declaration

D126061 inadvertently caused this warning to no longer be emitted. This patch
restores the previous behavior.

The reason for the bug is that after D126061, C++11 attributes applied to a
member declaration are no longer placed in `DS.getAttributes()` but are instead
tracked in a separate list (`DeclAttrs`). In the case of a free-standing
decl-specifier-seq, we would simply ignore the contents of this list. Instead,
we now pass the list on to `Sema::ParsedFreeStandingDeclSpec()` so that it can
issue the appropriate warning.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D128499

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[clang] Don't use Optional::hasValue (NFC)

This patch replaces Optional::hasValue with the implicit cast to bool
in conditionals only.

Revert "Don't use Optional::hasValue (NFC)"

This reverts commit aa8feeefd3ac6c78ee8f67bf033976fc7d68bc6d.

Don't use Optional::hasValue (NFC)

[MSVC] Add initial support for MSVC pragma optimize

MSVC's pragma optimize turns optimizations on or off based on the list
passed. At the moment, we only support an empty optimization list.

i.e. `#

[MSVC] Add initial support for MSVC pragma optimize

MSVC's pragma optimize turns optimizations on or off based on the list
passed. At the moment, we only support an empty optimization list.

i.e. `#pragma optimize("", on | off)`

From MSVC's docs:

| Parameter | Type of optimization |
|-----------|--------------------------------------------------|
| g | Enable global optimizations. Deprecated |
| s or t | Specify short or fast sequences of machine code |
| y | Generate frame pointers on the program stack |

https://docs.microsoft.com/en-us/cpp/preprocessor/optimize?view=msvc-170

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D125723

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[clang] Don't use Optional::hasValue (NFC)

[Concepts] Implement overload resolution for destructors (P0848)

This patch implements a necessary part of P0848, the overload resolution for destructors.
It is now possible to overload destructors

[Concepts] Implement overload resolution for destructors (P0848)

This patch implements a necessary part of P0848, the overload resolution for destructors.
It is now possible to overload destructors based on constraints, and the eligible destructor
will be selected at the end of the class.

The approach this patch takes is to perform the overload resolution in Sema::ActOnFields
and to mark the selected destructor using a new property in FunctionDeclBitfields.

CXXRecordDecl::getDestructor is then modified to use this property to return the correct
destructor.

This closes https://github.com/llvm/llvm-project/issues/45614.

Reviewed By: #clang-language-wg, erichkeane

Differential Revision: https://reviews.llvm.org/D126194

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[clang] Reject non-declaration C++11 attributes on declarations

For backwards compatiblity, we emit only a warning instead of an error if the
attribute is one of the existing type attributes that we

[clang] Reject non-declaration C++11 attributes on declarations

For backwards compatiblity, we emit only a warning instead of an error if the
attribute is one of the existing type attributes that we have historically
allowed to "slide" to the `DeclSpec` just as if it had been specified in GNU
syntax. (We will call these "legacy type attributes" below.)

The high-level changes that achieve this are:

- We introduce a new field `Declarator::DeclarationAttrs` (with appropriate
accessors) to store C++11 attributes occurring in the attribute-specifier-seq
at the beginning of a simple-declaration (and other similar declarations).
Previously, these attributes were placed on the `DeclSpec`, which made it
impossible to reconstruct later on whether the attributes had in fact been
placed on the decl-specifier-seq or ahead of the declaration.

- In the parser, we propgate declaration attributes and decl-specifier-seq
attributes separately until we can place them in
`Declarator::DeclarationAttrs` or `DeclSpec::Attrs`, respectively.

- In `ProcessDeclAttributes()`, in addition to processing declarator attributes,
we now also process the attributes from `Declarator::DeclarationAttrs` (except
if they are legacy type attributes).

- In `ConvertDeclSpecToType()`, in addition to processing `DeclSpec` attributes,
we also process any legacy type attributes that occur in
`Declarator::DeclarationAttrs` (and emit a warning).

- We make `ProcessDeclAttribute` emit an error if it sees any non-declaration
attributes in C++11 syntax, except in the following cases:
- If it is being called for attributes on a `DeclSpec` or `DeclaratorChunk`
- If the attribute is a legacy type attribute (in which case we only emit
a warning)

The standard justifies treating attributes at the beginning of a
simple-declaration and attributes after a declarator-id the same. Here are some
relevant parts of the standard:

- The attribute-specifier-seq at the beginning of a simple-declaration
"appertains to each of the entities declared by the declarators of the
init-declarator-list" (https://eel.is/c++draft/dcl.dcl#dcl.pre-3)

- "In the declaration for an entity, attributes appertaining to that entity can
appear at the start of the declaration and after the declarator-id for that
declaration." (https://eel.is/c++draft/dcl.dcl#dcl.pre-note-2)

- "The optional attribute-specifier-seq following a declarator-id appertains to
the entity that is declared."
(https://eel.is/c++draft/dcl.dcl#dcl.meaning.general-1)

The standard contains similar wording to that for a simple-declaration in other
similar types of declarations, for example:

- "The optional attribute-specifier-seq in a parameter-declaration appertains to
the parameter." (https://eel.is/c++draft/dcl.fct#3)

- "The optional attribute-specifier-seq in an exception-declaration appertains
to the parameter of the catch clause" (https://eel.is/c++draft/except.pre#1)

The new behavior is tested both on the newly added type attribute
`annotate_type`, for which we emit errors, and for the legacy type attribute
`address_space` (chosen somewhat randomly from the various legacy type
attributes), for which we emit warnings.

Depends On D111548

Reviewed By: aaron.ballman, rsmith

Differential Revision: https://reviews.llvm.org/D126061

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