[clang][Sema] Fix a clang crash with btf_type_tag

For the following program,
$ cat t.c
struct t {
int (__attribute__((btf_type_tag("rcu"))) *f)();
int a;
};
int foo(struct t *arg) {

[clang][Sema] Fix a clang crash with btf_type_tag

For the following program,
$ cat t.c
struct t {
int (__attribute__((btf_type_tag("rcu"))) *f)();
int a;
};
int foo(struct t *arg) {
return arg->a;
}
Compiling with 'clang -g -O2 -S t.c' will cause a failure like below:
clang: /home/yhs/work/llvm-project/clang/lib/Sema/SemaType.cpp:6391: void {anonymous}::DeclaratorLocFiller::VisitParenTypeLoc(clang::ParenTypeLoc):
Assertion `Chunk.Kind == DeclaratorChunk::Paren' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
......
#5 0x00007f89e4280ea5 abort (/lib64/libc.so.6+0x21ea5)
#6 0x00007f89e4280d79 _nl_load_domain.cold.0 (/lib64/libc.so.6+0x21d79)
#7 0x00007f89e42a6456 (/lib64/libc.so.6+0x47456)
#8 0x00000000045c2596 GetTypeSourceInfoForDeclarator((anonymous namespace)::TypeProcessingState&, clang::QualType, clang::TypeSourceInfo*) SemaType.cpp:0:0
#9 0x00000000045ccfa5 GetFullTypeForDeclarator((anonymous namespace)::TypeProcessingState&, clang::QualType, clang::TypeSourceInfo*) SemaType.cpp:0:0
......

The reason of the failure is due to the mismatch of TypeLoc and D.getTypeObject().Kind. For example,
the TypeLoc is
BTFTagAttributedType 0x88614e0 'int btf_type_tag(rcu)()' sugar
|-ParenType 0x8861480 'int ()' sugar
| `-FunctionNoProtoType 0x8861450 'int ()' cdecl
| `-BuiltinType 0x87fd500 'int'
while corresponding D.getTypeObject().Kind points to DeclaratorChunk::Paren, and
this will cause later assertion.

To fix the issue, similar to AttributedTypeLoc, let us skip BTFTagAttributedTypeLoc in
GetTypeSourceInfoForDeclarator().

Differential Revision: https://reviews.llvm.org/D136807

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[C++20] [Modules] Handle reachability for enum class

In previous reachability patch, we missed the case for enum class.
Trying to handle it in this patch and add the corresponding tests.

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.

show more ...

[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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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] 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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[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

[Sema] Remove unused function after 8c7b64b5ae2a

[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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[Clang] Add the `annotate_type` attribute

This is an analog to the `annotate` attribute but for types. The intent is to allow adding arbitrary annotations to types for use in static analysis tools.

[Clang] Add the `annotate_type` attribute

This is an analog to the `annotate` attribute but for types. The intent is to allow adding arbitrary annotations to types for use in static analysis tools.

For details, see this RFC:

https://discourse.llvm.org/t/rfc-new-attribute-annotate-type-iteration-2/61378

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D111548

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Allow use of an elaborated type specifier in a _Generic association in C++

Currently, Clang accepts this code in C mode (where the tag is required
to be used) but rejects it in C++ mode thinking tha

Allow use of an elaborated type specifier in a _Generic association in C++

Currently, Clang accepts this code in C mode (where the tag is required
to be used) but rejects it in C++ mode thinking that the association is
defining a new type.

void foo(void) {
struct S { int a; };
_Generic(something, struct S : 1);
}
Clang thinks this in C++ because it sees struct S : when parsing the
class specifier and decides that must be a type definition (because the
colon signifies the presence of a base class type). This patch adds a
new declarator context to represent a _Generic association so that we
can distinguish these situations properly.

Fixes #55562

Differential Revision: https://reviews.llvm.org/D126969

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Revert "Drop qualifiers from return types in C (DR423)"

This reverts commit d374b65f2da1bdd3d9a7e9ac8ed4ad5467c882f9.

The changes lose AST fidelity (reported in #55778), but also may be
improperly

Revert "Drop qualifiers from return types in C (DR423)"

This reverts commit d374b65f2da1bdd3d9a7e9ac8ed4ad5467c882f9.

The changes lose AST fidelity (reported in #55778), but also may be
improperly dropping _Atomic qualifiers. I am rolling the changes back
until I've finished discussions in WG14 about the proper resolution to
DR423.

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[amdgpu] Add amdgpu_kernel calling conv attribute to clang

Allows emitting define amdgpu_kernel void @func() IR from C or C++.

This replaces the current workflow which is to write a stub in opencl

[amdgpu] Add amdgpu_kernel calling conv attribute to clang

Allows emitting define amdgpu_kernel void @func() IR from C or C++.

This replaces the current workflow which is to write a stub in opencl that
calls an external C function implemented in C++ combined through llvm-link.

Calling the resulting function still requires a manual implementation of the
ABI from the host side. The primary application is for more rapid debugging
of the amdgpu backend by permuting a C or C++ test file instead of manually
updating an IR file.

Implementation closely follows D54425. Non-amd reviewers from there.

Reviewed By: yaxunl

Differential Revision: https://reviews.llvm.org/D125970

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Drop qualifiers from return types in C (DR423)

WG14 DR423 (https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2148.htm#dr_423),
resolved during the C11 time frame, changed the way qualifiers are
hand

Drop qualifiers from return types in C (DR423)

WG14 DR423 (https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2148.htm#dr_423),
resolved during the C11 time frame, changed the way qualifiers are
handled on function return types and in cast expressions after it was
noted that these types are now directly observable via generic
selection expressions. In C, the function declarator is adjusted to
ignore all qualifiers (including _Atomic qualifiers).

Clang already handles the cast expression case correctly (by performing
the lvalue conversion, which drops the qualifiers as well), but with
these changes it will now also handle function declarations
appropriately.

Fixes #39595

Differential Revision: https://reviews.llvm.org/D125919

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Silence some false positive -Wstrict-prototype warnings

Before issuing the warning about use of a strict prototype, check if
the declarator is required to have a prototype through some other means
d

Silence some false positive -Wstrict-prototype warnings

Before issuing the warning about use of a strict prototype, check if
the declarator is required to have a prototype through some other means
determined at parse time.

This silences false positives in OpenCL code (where the functions are
forced to have a prototype) and block literal expressions.

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[AArch64][SVE] Add aarch64_sve_pcs attribute to Clang

Enable function attribute aarch64_sve_pcs at the C level, which correspondes to
aarch64_sve_vector_pcs at the LLVM IR level.

This requirement w

[AArch64][SVE] Add aarch64_sve_pcs attribute to Clang

Enable function attribute aarch64_sve_pcs at the C level, which correspondes to
aarch64_sve_vector_pcs at the LLVM IR level.

This requirement was created by this addition to the ARM C Language Extension:
https://github.com/ARM-software/acle/pull/194

Differential Revision: https://reviews.llvm.org/D124998

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Fix a crash on targets where __bf16 isn't supported

We'd nondeterministically assert (and later crash) when calculating the size or
alignment of a __bf16 type when the type isn't supported on a targ

Fix a crash on targets where __bf16 isn't supported

We'd nondeterministically assert (and later crash) when calculating the size or
alignment of a __bf16 type when the type isn't supported on a target because of
reading uninitialized values. Now we check whether the type is supported first.

Fixes #50171

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Change the behavior of implicit int diagnostics

C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 w

Change the behavior of implicit int diagnostics

C89 allowed a type specifier to be elided with the resulting type being
int, aka implicit int behavior. This feature was subsequently removed
in C99 without a deprecation period, so implementations continued to
support the feature. Now, as with implicit function declarations, is a
good time to reevaluate the need for this support.

This patch allows -Wimplicit-int to issue warnings in C89 mode (off by
default), defaults the warning to an error in C99 through C17, and
disables support for the feature entirely in C2x. It also removes a
warning about missing declaration specifiers that really was just an
implicit int warning in disguise and other minor related cleanups.

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Silence -Wstrict-prototype diagnostics in C2x mode

This also disables the diagnostic when the user passes -fno-knr-functions.

[clang] Eliminate TypeProcessingState::trivial.

This flag is redundant -- it's true iff `savedAttrs` is empty.

Querying `savedAttrs.empty()` should not take any more time than querying the
`trivial

[clang] Eliminate TypeProcessingState::trivial.

This flag is redundant -- it's true iff `savedAttrs` is empty.

Querying `savedAttrs.empty()` should not take any more time than querying the
`trivial` flag, so this should not have a performance impact either.

I noticed this while working on https://reviews.llvm.org/D111548.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D123783

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[C2x] Disallow functions without prototypes/functions with identifier lists

WG14 has elected to remove support for K&R C functions in C2x. The
feature was introduced into C89 already deprecated, so

[C2x] Disallow functions without prototypes/functions with identifier lists

WG14 has elected to remove support for K&R C functions in C2x. The
feature was introduced into C89 already deprecated, so after this long
of a deprecation period, the committee has made an empty parameter list
mean the same thing in C as it means in C++: the function accepts no
arguments exactly as if the function were written with (void) as the
parameter list.

This patch implements WG14 N2841 No function declarators without
prototypes (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2841.htm)
and WG14 N2432 Remove support for function definitions with identifier
lists (http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2432.pdf).

It also adds The -fno-knr-functions command line option to opt into
this behavior in other language modes.

Differential Revision: https://reviews.llvm.org/D123955

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[HLSL] Pointers are unsupported in HLSL

HLSL does not support pointers or references. This change generates
errors in sema for generating pointer, and reference types as well as
common operators (ad

[HLSL] Pointers are unsupported in HLSL

HLSL does not support pointers or references. This change generates
errors in sema for generating pointer, and reference types as well as
common operators (address-of, dereference, arrow), which are used with
pointers and are unsupported in HLSL.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D123167

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[C89/C2x] Improve diagnostics around strict prototypes in C

Functions without prototypes in C (also known as K&R C functions) were
introduced into C89 as a deprecated feature and C2x is now reclaimi

[C89/C2x] Improve diagnostics around strict prototypes in C

Functions without prototypes in C (also known as K&R C functions) were
introduced into C89 as a deprecated feature and C2x is now reclaiming
that syntax space with different semantics. However, Clang's
-Wstrict-prototypes diagnostic is off-by-default (even in pedantic
mode) and does not suffice to warn users about issues in their code.

This patch changes the behavior of -Wstrict-prototypes to only diagnose
declarations and definitions which are not going to change behavior in
C2x mode, and enables the diagnostic in -pedantic mode. The diagnostic
is now specifically about the fact that the feature is deprecated.

It also adds -Wdeprecated-non-prototype, which is grouped under
-Wstrict-prototypes and diagnoses declarations or definitions which
will change behavior in C2x mode. This diagnostic is enabled by default
because the risk is higher for the user to continue to use the
deprecated feature.

Differential Revision: https://reviews.llvm.org/D122895

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