Merge llvm-project main llvmorg-18-init-18359-g93248729cfae

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-18359-g93248729cfae, the
last commit before the upstream release/18.x branch was created.

PR: 276104
MFC after: 1 month

Merge llvm-project main llvmorg-18-init-15088-gd14ee76181fb

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-18-init-15088-gd14ee76181fb.

PR: 276104
MFC after: 1 month

Merge commit 158f4f30adb4 from llvm git (by Corentin Jabot):

[Clang] Do not change the type of captured vars when checking lambda constraints

When checking the constraint of a lambda, we need to respect the constness
of the call operator when establishing the type of capture variables.

In D124351, this was done by adding const to the captured variable...
However, that would change the type of the variable outside of the scope
of the lambda, which is clearly not the desired outcome.

Instead, to ensure const-correctness, we need to populate
a LambdaScopeInfo with the capture variables before checking the
constraints of a generic lambda.

There is no changelog as I'd like to tentatively propose we backport
this change to RC3 as it is a regression introduced in the Clang 17
cycle.

Fixes #61267

Reviewed By: aaron.ballman, #clang-language-wg

Differential Revision: https://reviews.llvm.org/D158433

Merge commit 3ed9e9e3ace6 from llvm git (by Corentin Jabot):

[Clang] Add captures to the instantiation scope of lambda call operators

Like concepts checking, a trailing return type of a lambda
in a dependent context may refer to captures in which case
they may need to be rebuilt, so the map of local decl
should include captures.

This patch reveal a pre-existing issue.
`this` is always recomputed by TreeTransform.

`*this` (like all captures) only become `const`
after the parameter list.

However, if try to recompute the value of `this` (in a parameter)
during template instantiation while determining the type of the call operator,
we will determine it to be const (unless the lambda is mutable).

There is no good way to know at that point that we are in a parameter
or not, the easiest/best solution is to transform the type of this.

Note that doing so break a handful of HLSL tests.
So this is a prototype at this point.

Fixes #65067
Fixes #63675

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D159126

This fixes 'Assertion failed: (isa<LabelDecl>(D) && "declaration not
instantiated in this scope"), function findInstantiationOf' error when
building databases/mongodb44.

PR: 273753
MFC after: 1 month

Merge llvm-project main llvmorg-17-init-19304-gd0b54bb50e51

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvm-project main llvmorg-17-init-19304-gd0b54bb50e51, the
last commit before the upstream release/17.x branch was created.

PR: 273753
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project 13.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13.0.0-0-gd7b669b3a303, aka 13.0.0 release.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR: 255570
MFC after: 6 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Fix clang assertion when compiling the devel/onetbb port

Merge commit 740a164de from llvm git (by Richard Smith):

PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.

Merge commit 9cf98d26e from llvm git (by Richard Smith):

PR46637: Fix handling of placeholder types in trailing-return-types.

Only permit a placeholder type in a trailing-return-type if it would
also have been permitted in the decl-specifier sequence of a
corresponding declaration with no trailing-return-type. The standard
doesn't actually say this, but this is the only thing that makes sense.

Also fix handling of an 'auto' in a trailing-return-type in a parameter
of a generic lambda. We used to crash if we saw such a thing.

Merge commit 234f51a65 from llvm git (by Richard Smith):

Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec483225cbd02ab6c82199e2747ffacb.

PR: 252892
Reported by: thierry
MFC after: 3 days

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/release-10.x up to its last change (upstream
commit llvmorg-10-init-17538-gd11abddb32f).

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/clang/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge commit 158f4f30adb4 from llvm git (by Corentin Jabot):

[Clang] Do not change the type of captured vars when checking lambda constraints

When checking the constraint of a lambda, we need to respect the constness
of the call operator when establishing the type of capture variables.

In D124351, this was done by adding const to the captured variable...
However, that would change the type of the variable outside of the scope
of the lambda, which is clearly not the desired outcome.

Instead, to ensure const-correctness, we need to populate
a LambdaScopeInfo with the capture variables before checking the
constraints of a generic lambda.

There is no changelog as I'd like to tentatively propose we backport
this change to RC3 as it is a regression introduced in the Clang 17
cycle.

Fixes #61267

Reviewed By: aaron.ballman, #clang-language-wg

Differential Revision: https://reviews.llvm.org/D158433

Merge commit 3ed9e9e3ace6 from llvm git (by Corentin Jabot):

[Clang] Add captures to the instantiation scope of lambda call operators

Like concepts checking, a trailing return type of a lambda
in a dependent context may refer to captures in which case
they may need to be rebuilt, so the map of local decl
should include captures.

This patch reveal a pre-existing issue.
`this` is always recomputed by TreeTransform.

`*this` (like all captures) only become `const`
after the parameter list.

However, if try to recompute the value of `this` (in a parameter)
during template instantiation while determining the type of the call operator,
we will determine it to be const (unless the lambda is mutable).

There is no good way to know at that point that we are in a parameter
or not, the easiest/best solution is to transform the type of this.

Note that doing so break a handful of HLSL tests.
So this is a prototype at this point.

Fixes #65067
Fixes #63675

Reviewed By: erichkeane

Differential Revision: https://reviews.llvm.org/D159126

This fixes 'Assertion failed: (isa<LabelDecl>(D) && "declaration not
instantiated in this scope"), function findInstantiationOf' error when
building databases/mongodb44.

PR: 273753
MFC after: 1 month

Merge llvm-project main llvmorg-16-init-18548-gb0daacf58f41

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-16-init-18548-gb0daacf58f41.

PR: 271047
MFC after: 1 month

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project 13.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13.0.0-0-gd7b669b3a303, aka 13.0.0 release.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR: 255570
MFC after: 6 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Fix clang assertion when compiling the devel/onetbb port

Merge commit 740a164de from llvm git (by Richard Smith):

PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.

Merge commit 9cf98d26e from llvm git (by Richard Smith):

PR46637: Fix handling of placeholder types in trailing-return-types.

Only permit a placeholder type in a trailing-return-type if it would
also have been permitted in the decl-specifier sequence of a
corresponding declaration with no trailing-return-type. The standard
doesn't actually say this, but this is the only thing that makes sense.

Also fix handling of an 'auto' in a trailing-return-type in a parameter
of a generic lambda. We used to crash if we saw such a thing.

Merge commit 234f51a65 from llvm git (by Richard Smith):

Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec483225cbd02ab6c82199e2747ffacb.

PR: 252892
Reported by: thierry
MFC after: 3 days

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/release-10.x up to its last change (upstream
commit llvmorg-10-init-17538-gd11abddb32f).

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/clang/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-15-init-15358-g53dc0f10787

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-15-init-15358-g53dc0f10787.

PR: 265425
MFC after: 2 weeks

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project 13.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13.0.0-0-gd7b669b3a303, aka 13.0.0 release.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR: 255570
MFC after: 6 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Fix clang assertion when compiling the devel/onetbb port

Merge commit 740a164de from llvm git (by Richard Smith):

PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.

Merge commit 9cf98d26e from llvm git (by Richard Smith):

PR46637: Fix handling of placeholder types in trailing-return-types.

Only permit a placeholder type in a trailing-return-type if it would
also have been permitted in the decl-specifier sequence of a
corresponding declaration with no trailing-return-type. The standard
doesn't actually say this, but this is the only thing that makes sense.

Also fix handling of an 'auto' in a trailing-return-type in a parameter
of a generic lambda. We used to crash if we saw such a thing.

Merge commit 234f51a65 from llvm git (by Richard Smith):

Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec483225cbd02ab6c82199e2747ffacb.

PR: 252892
Reported by: thierry
MFC after: 3 days

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/release-10.x up to its last change (upstream
commit llvmorg-10-init-17538-gd11abddb32f).

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/clang/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project main llvmorg-14-init-10186-gff7f2cfa959b

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-14-init-10186-gff7f2cfa959b.

PR: 261742
MFC after: 2 weeks

Merge llvm-project 13.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13.0.0-0-gd7b669b3a303, aka 13.0.0 release.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR: 255570
MFC after: 6 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Fix clang assertion when compiling the devel/onetbb port

Merge commit 740a164de from llvm git (by Richard Smith):

PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.

Merge commit 9cf98d26e from llvm git (by Richard Smith):

PR46637: Fix handling of placeholder types in trailing-return-types.

Only permit a placeholder type in a trailing-return-type if it would
also have been permitted in the decl-specifier sequence of a
corresponding declaration with no trailing-return-type. The standard
doesn't actually say this, but this is the only thing that makes sense.

Also fix handling of an 'auto' in a trailing-return-type in a parameter
of a generic lambda. We used to crash if we saw such a thing.

Merge commit 234f51a65 from llvm git (by Richard Smith):

Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec483225cbd02ab6c82199e2747ffacb.

PR: 252892
Reported by: thierry
MFC after: 3 days

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/release-10.x up to its last change (upstream
commit llvmorg-10-init-17538-gd11abddb32f).

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/clang/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Merge llvm-project 13.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13.0.0-0-gd7b669b3a303, aka 13.0.0 release.

PR: 258209
MFC after: 2 weeks

Merge llvm-project main llvmorg-13-init-16847-g88e66fa60ae5

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-13-init-16847-g88e66fa60ae5, the last commit before
the upstream release/13.x branch was created.

PR: 258209
MFC after: 2 weeks

Merge llvm-project 12.0.0 release

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12.0.0-0-gd28af7c654d8, a.k.a. 12.0.0 release.

PR: 255570
MFC after: 6 weeks

Merge llvm-project main llvmorg-12-init-17869-g8e464dd76bef

This updates llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and
openmp to llvmorg-12-init-17869-g8e464dd76bef, the last commit before the
upstream release/12.x branch was created.

PR: 255570
MFC after: 6 weeks

Fix clang assertion when compiling the devel/onetbb port

Merge commit 740a164de from llvm git (by Richard Smith):

PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.

Merge commit 9cf98d26e from llvm git (by Richard Smith):

PR46637: Fix handling of placeholder types in trailing-return-types.

Only permit a placeholder type in a trailing-return-type if it would
also have been permitted in the decl-specifier sequence of a
corresponding declaration with no trailing-return-type. The standard
doesn't actually say this, but this is the only thing that makes sense.

Also fix handling of an 'auto' in a trailing-return-type in a parameter
of a generic lambda. We used to crash if we saw such a thing.

Merge commit 234f51a65 from llvm git (by Richard Smith):

Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec483225cbd02ab6c82199e2747ffacb.

PR: 252892
Reported by: thierry
MFC after: 3 days

Merge llvm, clang, compiler-rt, libc++, libunwind, lld, lldb and openmp
master 2e10b7a39b9, the last commit before the llvmorg-12-init tag, from
which release/11.x was branched.

Note that for now, I rolled back all our local changes to make merging
easier, and I will reapply the still-relevant ones after updating to
11.0.0-rc1.

Merge ^/vendor/lvm-project/release-10.x up to its last change (upstream
commit llvmorg-10-init-17538-gd11abddb32f).

Merge ^/vendor/lvm-project/master up to its last change (upstream commit
e26a78e70), and resolve conflicts.

Merge ^/vendor/clang/dist up to its last change, and resolve conflicts.

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.

Fix clang assertion when compiling the devel/onetbb port

Merge commit 740a164de from llvm git (by Richard Smith):

PR46377: Fix dependence calculation for function types and typedef
types.

We previously did not treat a function type as dependent if it had a
parameter pack with a non-dependent type -- such a function type depends
on the arity of the pack so is dependent even though none of the
parameter types is dependent. In order to properly handle this, we now
treat pack expansion types as always being dependent types (depending on
at least the pack arity), and always canonically being pack expansion
types, even in the unusual case when the pattern is not a dependent
type. This does mean that we can have canonical types that are pack
expansions that contain no unexpanded packs, which is unfortunate but
not inaccurate.

We also previously did not treat a typedef type as
instantiation-dependent if its canonical type was not
instantiation-dependent. That's wrong because instantiation-dependence
is a property of the type sugar, not of the type; an
instantiation-dependent type can have a non-instantiation-dependent
canonical type.

Merge commit 9cf98d26e from llvm git (by Richard Smith):

PR46637: Fix handling of placeholder types in trailing-return-types.

Only permit a placeholder type in a trailing-return-type if it would
also have been permitted in the decl-specifier sequence of a
corresponding declaration with no trailing-return-type. The standard
doesn't actually say this, but this is the only thing that makes sense.

Also fix handling of an 'auto' in a trailing-return-type in a parameter
of a generic lambda. We used to crash if we saw such a thing.

Merge commit 234f51a65 from llvm git (by Richard Smith):

Don't crash if we deserialize a pack expansion type whose pattern
contains no packs.

Fixes a regression from 740a164dec483225cbd02ab6c82199e2747ffacb.

PR: 252892
Reported by: thierry
MFC after: 3 days

Move all sources from the llvm project into contrib/llvm-project.

This uses the new layout of the upstream repository, which was recently
migrated to GitHub, and converted into a "monorepo". That is, most of
the earlier separate sub-projects with their own branches and tags were
consolidated into one top-level directory, and are now branched and
tagged together.

Updating the vendor area to match this layout is next.