This PR implement [P3034R1 Module Declarations Shouldn’t be
Macros](https://wg21.link/P3034R1), and refactor the convoluted state
machines in module name lexical analysis.
---------
Signed-off-by: yronglin <yronglin777@gmail.com>
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
The attributes `sized_by`, `counted_by_or_null` and `sized_by_or_null`
have been added as variants on `counted_by`, each with slightly
different semantics. `sized_by` takes a byte size parameter instead of
an element count, allowing pointees with unknown size. The
`counted_by_or_null` and `sized_by_or_null` variants are equivalent to
their base variants, except the pointer can be null regardless of
count/size value. If the pointer is null the size is effectively 0.
rdar://125400354
This fixes#20777. This replaces #94216 which was reverted after being
merged.
Previously the `guarded_by`, `pt_guarded_by`, `acquired_after`, and
`acquired_before` attributes were only supported inside C++ classes or
top level C/C++ declaration.
This patch allows these attributes to be added to struct members in C.
These attributes have also now support experimental late parsing. This
is off by default but can be enabled by passing
`-fexperimental-late-parse-attributes`. This is useful for referring to
a struct member after the annotated member. E.g.
```
struct Example {
int a_value_defined_before __attribute__ ((guarded_by(a_mutex)));
struct Mutex *a_mutex;
};
```
Virtual function pointer entries in v-tables are signed with address
discrimination in addition to declaration-based discrimination, where an
integer discriminator the string hash (see
`ptrauth_string_discriminator`) of the mangled name of the overridden
method. This notably provides diversity based on the full signature of
the overridden method, including the method name and parameter types.
This patch introduces ItaniumVTableContext logic to find the original
declaration of the overridden method.
On AArch64, these pointers are signed using the `IA` key (the
process-independent code key.)
V-table pointers can be signed with either no discrimination, or a
similar scheme using address and decl-based discrimination. In this
case, the integer discriminator is the string hash of the mangled
v-table identifier of the class that originally introduced the vtable
pointer.
On AArch64, these pointers are signed using the `DA` key (the
process-independent data key.)
Not using discrimination allows attackers to simply copy valid v-table
pointers from one object to another. However, using a uniform
discriminator of 0 does have positive performance and code-size
implications on AArch64, and diversity for the most important v-table
access pattern (virtual dispatch) is already better assured by the
signing schemas used on the virtual functions. It is also known that
some code in practice copies objects containing v-tables with `memcpy`,
and while this is not permitted formally, it is something that may be
invasive to eliminate.
This is controlled by:
```
-fptrauth-vtable-pointer-type-discrimination
-fptrauth-vtable-pointer-address-discrimination
```
In addition, this provides fine-grained controls in the
ptrauth_vtable_pointer attribute, which allows overriding the default
ptrauth schema for vtable pointers on a given class hierarchy, e.g.:
```
[[clang::ptrauth_vtable_pointer(no_authentication, no_address_discrimination,
no_extra_discrimination)]]
[[clang::ptrauth_vtable_pointer(default_key, default_address_discrimination,
custom_discrimination, 0xf00d)]]
```
The override is then mangled as a parametrized vendor extension:
```
"__vtptrauth" I
<key>
<addressDiscriminated>
<extraDiscriminator>
E
```
To support this attribute, this patch adds a small extension to the
attribute-emitter tablegen backend.
Note that there are known areas where signing is either missing
altogether or can be strengthened. Some will be addressed in later
changes (e.g., member function pointers, some RTTI).
`dynamic_cast` in particular is handled by emitting an artificial
v-table pointer load (in a way that always authenticates it) before the
runtime call itself, as the runtime doesn't have enough information
today to properly authenticate it. Instead, the runtime is currently
expected to strip the v-table pointer.
---------
Co-authored-by: John McCall <rjmccall@apple.com>
Co-authored-by: Ahmed Bougacha <ahmed@bougacha.org>
This fixes#20777.
Previously the `guarded_by`, `pt_guarded_by`, `acquired_after`, and `acquired_before` attributes were only supported inside C++ classes or top level C/C++ declaration.
This patch allows these attributes to be added to struct members in C. These attributes have also now support experimental late parsing. This is off by default but can be enabled by passing `-fexperimental-late-parse-attributes`. This is useful for referring to a struct member after the annotated member. E.g.
```
struct Example {
int a_value_defined_before __attribute__ ((guarded_by(a_mutex)));
struct Mutex *a_mutex;
};
```
Patch by Pierre d'Herbemont (@pdherbemont)
Call `DiagnoseUnexpandedParameterPack` when we parse an expression
argument to an attribute and check for implicit code in the
`CollectUnexpandedParameterPacksVisitor` so we can actually find
unexpanded packs in attributes that end up applied to lambda call
operators.
This fixes#93269.
[BoundsSafety] Reland #93121 Allow 'counted_by' attribute on pointers in structs in C (#93121)
Fixes#92687.
Previously the attribute was only allowed on flexible array members.
This patch patch changes this to also allow the attribute on pointer
fields in structs and also allows late parsing of the attribute in some
contexts.
For example this previously wasn't allowed:
```
struct BufferTypeDeclAttributePosition {
size_t count;
char* buffer __counted_by(count); // Now allowed
}
```
Note the attribute is prevented on pointee types where the size isn't
known at compile time. In particular pointee types that are:
* Incomplete (e.g. `void`) and sizeless types
* Function types (e.g. the pointee of a function pointer)
* Struct types with a flexible array member
This patch also introduces late parsing of the attribute when used in
the declaration attribute position. For example
```
struct BufferTypeDeclAttributePosition {
char* buffer __counted_by(count); // Now allowed
size_t count;
}
```
is now allowed but **only** when passing
`-fexperimental-late-parse-attributes`. The motivation for using late
parsing here is to avoid breaking the data layout of structs in existing
code that want to use the `counted_by` attribute. This patch is the
first use of `LateAttrParseExperimentalExt` in `Attr.td` that was
introduced in a previous patch.
Note by allowing the attribute on struct member pointers this now allows
the possiblity of writing the attribute in the type attribute position.
For example:
```
struct BufferTypeAttributePosition {
size_t count;
char *__counted_by(count) buffer; // Now allowed
}
```
However, the attribute in this position is still currently parsed
immediately rather than late parsed. So this will not parse currently:
```
struct BufferTypeAttributePosition {
char *__counted_by(count) buffer; // Fails to parse
size_t count;
}
```
The intention is to lift this restriction in future patches. It has not
been done in this patch to keep this size of this commit small.
There are also several other follow up changes that will need to be
addressed in future patches:
* Make late parsing working with anonymous structs (see
`on_pointer_anon_buf` in `attr-counted-by-late-parsed-struct-ptrs.c`).
* Allow `counted_by` on more subjects (e.g. parameters, returns types)
when `-fbounds-safety` is enabled.
* Make use of the attribute on pointer types in code gen (e.g. for
`_builtin_dynamic_object_size` and UBSan's array-bounds checks).
This work is heavily based on a patch originally written by Yeoul Na.
** Differences between #93121 and this patch **
* The memory leak that caused #93121 to be reverted (see #92687) should
now be fixed. See "The Memory Leak".
* The fix to `pragma-attribute-supported-attributes-list.test`
(originally in cef6387) has been incorporated into this patch.
* A relaxation of counted_by semantics (originally in 112eadd) has been
incorporated into this patch.
* The assert in `Parser::DistributeCLateParsedAttrs` has been removed
because that broke downstream code.
* The switch statement in `Parser::ParseLexedCAttribute` has been
removed in favor of using `Parser::ParseGNUAttributeArgs` which does
the same thing but is more feature complete.
* The `EnterScope` parameter has been plumbed through
`Parser::ParseLexedCAttribute` and `Parser::ParseLexedCAttributeList`.
It currently doesn't do anything but it will be needed in future
commits.
** The Memory Leak **
The problem was that these lines parsed the attributes but then did nothing to free the memory
```
assert(!getLangOpts().CPlusPlus);
for (auto *LateAttr : LateFieldAttrs)
ParseLexedCAttribute(*LateAttr);
```
To fix this this a new `Parser::ParseLexedCAttributeList` method has been
added (based on `Parser::ParseLexedAttributeList`) which does the
necessary memory management. The intention is to merge these two
methods together so there is just one implementation in a future patch
(#93263).
A more principled fixed here would be to fix the ownership of the
`LateParsedAttribute` objects. In principle `LateParsedAttrList` should own
its pointers exclusively and be responsible for deallocating them.
Unfortunately this is complicated by `LateParsedAttribute` objects also
being stored in another data structure (`LateParsedDeclarations`) as
can be seen below (`LA` gets stored in two places).
```
// Handle attributes with arguments that require late parsing.
LateParsedAttribute *LA =
new LateParsedAttribute(this, *AttrName, AttrNameLoc);
LateAttrs->push_back(LA);
// Attributes in a class are parsed at the end of the class, along
// with other late-parsed declarations.
if (!ClassStack.empty() && !LateAttrs->parseSoon())
getCurrentClass().LateParsedDeclarations.push_back(LA);
```
this means the ownership of LateParsedAttribute objects isn't very
clear.
rdar://125400257
This is a followup to #81014 and #84582: Before this patch, Clang
would accept `__attribute__((assume))` and `[[clang::assume]]` as
nonstandard spellings for the `[[omp::assume]]` attribute; this
resulted in a potentially very confusing name clash with C++23’s
`[[assume]]` attribute (and GCC’s `assume` attribute with the same
semantics).
This pr replaces every usage of `__attribute__((assume))` with
`[[omp::assume]]` and makes `__attribute__((assume))` and
`[[clang::assume]]` alternative spellings for C++23’s `[[assume]]`;
this shouldn’t cause any problems due to differences in appertainment
and because almost no-one was using this variant spelling to begin
with (a use in libclc has already been changed to use a different
attribute).
Add `environment` parameter to Clang availability attribute. The allowed
values for this parameter are a subset of values allowed in the
`llvm::Triple` environment component. If the `environment` parameters is
present, the declared availability attribute applies only to targets
with the same platform and environment.
This new parameter will be initially used for annotating HLSL functions
for the `shadermodel` platform because in HLSL built-in function
availability can depend not just on the shader model version (mapped to
`llvm::Triple::OSType`) but also on the target shader stage (mapped to
`llvm::Triple::EnvironmentType`). See example in #89802 and
microsoft/hlsl-specs#204 for more details.
The environment parameter is currently supported only for HLSL.
Fixes#89802
Previously the attribute was only allowed on flexible array members.
This patch patch changes this to also allow the attribute on pointer
fields in structs and also allows late parsing of the attribute in some
contexts.
For example this previously wasn't allowed:
```
struct BufferTypeDeclAttributePosition {
size_t count;
char* buffer __counted_by(count); // Now allowed
}
```
Note the attribute is prevented on pointee types where the size isn't
known at compile time. In particular pointee types that are:
* Incomplete (e.g. `void`) and sizeless types
* Function types (e.g. the pointee of a function pointer)
* Struct types with a flexible array member
This patch also introduces late parsing of the attribute when used in
the declaration attribute position. For example
```
struct BufferTypeDeclAttributePosition {
char* buffer __counted_by(count); // Now allowed
size_t count;
}
```
is now allowed but **only** when passing
`-fexperimental-late-parse-attributes`. The motivation for using late
parsing here is to avoid breaking the data layout of structs in existing
code that want to use the `counted_by` attribute. This patch is the
first use of `LateAttrParseExperimentalExt` in `Attr.td` that was
introduced in a previous patch.
Note by allowing the attribute on struct member pointers this now allows
the possiblity of writing the attribute in the type attribute position.
For example:
```
struct BufferTypeAttributePosition {
size_t count;
char *__counted_by(count) buffer; // Now allowed
}
```
However, the attribute in this position is still currently parsed
immediately rather than late parsed. So this will not parse currently:
```
struct BufferTypeAttributePosition {
char *__counted_by(count) buffer; // Fails to parse
size_t count;
}
```
The intention is to lift this restriction in future patches. It has not
been done in this patch to keep this size of this commit small.
There are also several other follow up changes that will need to be
addressed in future patches:
* Make late parsing working with anonymous structs (see
`on_pointer_anon_buf` in `attr-counted-by-late-parsed-struct-ptrs.c`).
* Allow `counted_by` on more subjects (e.g. parameters, returns types)
when `-fbounds-safety` is enabled.
* Make use of the attribute on pointer types in code gen (e.g. for
`_builtin_dynamic_object_size` and UBSan's array-bounds checks).
This work is heavily based on a patch originally written by Yeoul Na.
rdar://125400257
Co-authored-by: Dan Liew <dan@su-root.co.uk>
This patch continues previous efforts to split `Sema` up, this time
covering code completion.
Context can be found in #84184.
Dropping `Code` prefix from function names in `SemaCodeCompletion` would
make sense, but I think this PR has enough changes already.
As usual, formatting changes are done as a separate commit. Hopefully
this helps with the review.
I'm planning to remove StringRef::equals in favor of
StringRef::operator==.
- StringRef::operator==/!= outnumber StringRef::equals by a factor of
24 under clang/ in terms of their usage.
- The elimination of StringRef::equals brings StringRef closer to
std::string_view, which has operator== but not equals.
- S == "foo" is more readable than S.equals("foo"), especially for
!Long.Expression.equals("str") vs Long.Expression != "str".
attempt to fix https://github.com/llvm/llvm-project/issues/12361
Consider this example:
```cpp
class D {
class E{
class F{};
friend void foo(D::E::F& q);
};
friend void foo(D::E::F& q);
};
void foo(D::E::F& q) {}
```
The first friend declaration of foo is correct. After that, the second
friend declaration delayed access checking and set its previous
declaration to be the first one. When doing access checking of `F`(which
is private filed of `E`), we put its canonical declaration(the first
friend declaration) into `EffectiveContext.Functions`. Actually, we are
still checking the first one. This is incorrect due to the delayed
checking.
Creating a new scope to indicate we are parsing a friend declaration and
doing access checking in time.
The following program produces a diagnostic in Clang and EDG, but
compiles correctly in GCC and MSVC:
```cpp
#include <vector>
consteval std::vector<int> fn() { return {1,2,3}; }
constexpr int a = fn()[1];
```
Clang's diagnostic is as follows:
```cpp
<source>:6:19: error: call to consteval function 'fn' is not a constant expression
6 | constexpr int a = fn()[1];
| ^
<source>:6:19: note: pointer to subobject of heap-allocated object is not a constant expression
/opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/14.0.1/../../../../include/c++/14.0.1/bits/allocator.h:193:31: note: heap allocation performed here
193 | return static_cast<_Tp*>(::operator new(__n));
| ^
1 error generated.
Compiler returned: 1
```
Based on my understanding of
[`[dcl.constexpr]/6`](https://eel.is/c++draft/dcl.constexpr#6):
> In any constexpr variable declaration, the full-expression of the
initialization shall be a constant expression
It seems to me that GCC and MSVC are correct: the initializer `fn()[1]`
does not evaluate to an lvalue referencing a heap-allocated value within
the `vector` returned by `fn()`; it evaluates to an lvalue-to-rvalue
conversion _from_ that heap-allocated value.
This PR turns out to be a bug fix on the implementation of
[P2564R3](https://wg21.link/p2564r3); as such, it only applies to C++23
and later. The core problem is that the definition of a
constant-initialized variable
([`[expr.const/2]`](https://eel.is/c++draft/expr.const#2)) is contingent
on whether the initializer can be evaluated as a constant expression:
> A variable or temporary object o is _constant-initialized_ if [...]
the full-expression of its initialization is a constant expression when
interpreted as a _constant-expression_, [...]
That can't be known until we've finished parsing the initializer, by
which time we've already added immediate invocations and consteval
references to the current expression evaluation context. This will have
the effect of evaluating said invocations as full expressions when the
context is popped, even if they're subexpressions of a larger constant
expression initializer. If, however, the variable _is_
constant-initialized, then its initializer is [manifestly
constant-evaluated](https://eel.is/c++draft/expr.const#20):
> An expression or conversion is _manifestly constant-evaluated_ if it
is [...] **the initializer of a variable that is usable in constant
expressions or has constant initialization** [...]
which in turn means that any subexpressions naming an immediate function
are in an [immediate function
context](https://eel.is/c++draft/expr.const#16):
> An expression or conversion is in an immediate function context if it
is potentially evaluated and either [...] it is a **subexpression of a
manifestly constant-evaluated expression** or conversion
and therefore _are not to be considered [immediate
invocations](https://eel.is/c++draft/expr.const#16) or
[immediate-escalating
expressions](https://eel.is/c++draft/expr.const#17) in the first place_:
> An invocation is an _immediate invocation_ if it is a
potentially-evaluated explicit or implicit invocation of an immediate
function and **is not in an immediate function context**.
> An expression or conversion is _immediate-escalating_ if **it is not
initially in an immediate function context** and [...]
The approach that I'm therefore proposing is:
1. Create a new expression evaluation context for _every_ variable
initializer (rather than only nonlocal ones).
2. Attach initializers to `VarDecl`s _prior_ to popping the expression
evaluation context / scope / etc. This sequences the determination of
whether the initializer is in an immediate function context _before_ any
contained immediate invocations are evaluated.
3. When popping an expression evaluation context, elide all evaluations
of constant invocations, and all checks for consteval references, if the
context is an immediate function context. Note that if it could be
ascertained that this was an immediate function context at parse-time,
we [would never have
registered](760910ddb9/clang/lib/Sema/SemaExpr.cpp (L17799))
these immediate invocations or consteval references in the first place.
Most of the test changes previously made for this PR are now reverted
and passing as-is. The only test updates needed are now as follows:
- A few diagnostics in `consteval-cxx2a.cpp` are updated to reflect that
it is the `consteval tester::tester` constructor, not the more narrow
`make_name` function call, which fails to be evaluated as a constant
expression.
- The reclassification of `warn_impcast_integer_precision_constant` as a
compile-time diagnostic adds a (somewhat duplicative) warning when
attempting to define an enum constant using a narrowing conversion. It
also, however, retains the existing diagnostics which @erichkeane
(rightly) objected to being lost from an earlier revision of this PR.
---------
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Reapplies #84050, addressing a bug which cases a crash when an
expression with the type of the current instantiation is used as the
_postfix-expression_ in a class member access expression (arrow form).
According to [class.mem.general] p8:
> A complete-class context of a class (template) is a
> - function body,
> - default argument,
> - default template argument,
> - _noexcept-specifier_, or
> - default member initializer
>
> within the member-specification of the class or class template.
When testing #90152, it came to my attention that we do _not_ consider
the _noexcept-specifier_ of a friend function declaration to be a
complete-class context (something which the Microsoft standard library
depends on). Although a comment states that this is "consistent with
what other implementations do", the only other implementation that
exhibits this behavior is GCC (MSVC and EDG both late-parse the
_noexcept-specifier_).
This patch changes _noexcept-specifiers_ of friend function declarations
to be late parsed, which is in agreement with the standard & majority of
implementations. Pre-#90152, our existing implementation falls "in
between" the implementation consensus: within non-template classes, we
would not find latter declared members (qualified and unqualified),
while within class templates we would not find latter declared member
when named with a unqualified name, we would find members named with a
qualified name (even when lookup context is the current instantiation).
Therefore, this _shouldn't_ be a breaking change -- any code that didn't
compile will continue to not compile (since a _noexcept-specifier_ is
not part of the deduction substitution
loci (see [temp.deduct.general] p7), and any code which
did compile should continue to do so.
This patch changes the `LateParsed` field of `Attr` in `Attr.td` to be
an instantiation of the new `LateAttrParseKind` class. The instation can be one of the following:
* `LateAttrParsingNever` - Corresponds with the false value of `LateParsed` prior to this patch (the default for an attribute).
* `LateAttrParseStandard` - Corresponds with the true value of `LateParsed` prior to this patch.
* `LateAttrParseExperimentalExt` - A new mode described below.
`LateAttrParseExperimentalExt` is an experimental extension to
`LateAttrParseStandard`. Essentially this allows
`Parser::ParseGNUAttributes(...)` to distinguish between these cases:
1. Only `LateAttrParseExperimentalExt` attributes should be late parsed.
2. Both `LateAttrParseExperimentalExt` and `LateAttrParseStandard`
attributes should be late parsed.
Callers (and indirect callers) of `Parser::ParseGNUAttributes(...)`
indicate the desired behavior by setting a flag in the
`LateParsedAttrList` object that is passed to the function.
In addition to the above, a new driver and frontend flag
(`-fexperimental-late-parse-attributes`) with a corresponding LangOpt
(`ExperimentalLateParseAttributes`) is added that changes how
`LateAttrParseExperimentalExt` attributes are parsed.
* When the flag is disabled (default), in cases where only
`LateAttrParsingExperimentalOnly` late parsing is requested, the
attribute will be parsed immediately (i.e. **NOT** late parsed). This
allows the attribute to act just like a `LateAttrParseStandard`
attribute when the flag is disabled.
* When the flag is enabled, in cases where only
`LateAttrParsingExperimentalOnly` late parsing is requested, the
attribute will be late parsed.
The motivation behind this change is to allow the new `counted_by`
attribute (part of `-fbounds-safety`) to support late parsing but
**only** when `-fexperimental-late-parse-attributes` is enabled. This
attribute needs to support late parsing to allow it to refer to fields
later in a struct definition (or function parameters declared later).
However, there isn't a precedent for supporting late attribute parsing
in C so this flag allows the new behavior to exist in Clang but not be
on by default. This behavior was requested as part of the
`-fbounds-safety` RFC process
(https://discourse.llvm.org/t/rfc-enforcing-bounds-safety-in-c-fbounds-safety/70854/68).
This patch doesn't introduce any uses of `LateAttrParseExperimentalExt`.
This will be added for the `counted_by` attribute in a future patch
(https://github.com/llvm/llvm-project/pull/87596). A consequence is the
new behavior added in this patch is not yet testable. Hence, the lack of
tests covering the new behavior.
rdar://125400257
Consider the following:
```cpp
template<typename T>
struct A
{
auto f()
{
return this->x;
}
};
```
Although `A` has no dependent base classes and the lookup context for
`x` is the current instantiation, we currently do not diagnose the
absence of a member `x` until `A<T>::f` is instantiated. This patch
moves the point of diagnosis for such expressions to occur at the point
of definition (i.e. prior to instantiation).
The attribute name "HLSLSemantics" is confusing, because semantics
aren't always the annotation that are applied to specific variables. The
name for this attribute needs to be less specific. This PR changes the
attribute name from HLSLSemantic to HLSLAnnotation, and changes the
associated function and variable names to support this conceptual
change.
The HLSLAnnotation attribute will never be output in ast-dump due to it
being parsed for the attribute that it represents. There is no
functional change, so there are no accompanying tests.
This PR remove `InMaterializeTemporaryObjectContext` , because it's
redundant, materialize non-cv void prvalue temporaries in discarded
expressions can only appear under lifetime-extension context.
Signed-off-by: yronglin <yronglin777@gmail.com>
In `-fbounds-safety`, bounds annotations are considered type attributes
rather than declaration attributes. Constructing them as type attributes
allows us to extend the attribute to apply nested pointers, which is
essential to annotate functions that involve out parameters: `void
foo(int *__counted_by(*out_count) *out_buf, int *out_count)`.
We introduce a new sugar type to support bounds annotated types,
`CountAttributedType`. In order to maintain extra data (the bounds
expression and the dependent declaration information) that is not
trackable in `AttributedType` we create a new type dedicate to this
functionality.
This patch also extends the parsing logic to parse the `counted_by`
argument as an expression, which will allow us to extend the model to
support arguments beyond an identifier, e.g., `__counted_by(n + m)` in
the future as specified by `-fbounds-safety`.
This also adjusts `__bdos` and array-bounds sanitizer code that already
uses `CountedByAttr` to check `CountAttributedType` instead to get the
field referred to by the attribute.
Admittedly a bit awkward, `visionos` is the correct and accepted
spelling for annotating availability for xrOS target triples. This patch
detects errors and handles cases when `xros` is mistakenly passed.
In addition, add APIs for introduced/deprecated/obsoleted versioning in
DarwinSDKInfo mappings.
Make TopLevelStmtDecl a DeclContext so that variables defined in statements
are attached to the TopLevelDeclContext. This fixes redefinition errors
from variables declared in if conditions and for-init statements. These
must be local to the inner context (C++ 3.3.2p4), but they had generated
definitions on global scope instead.
This PR makes the TopLevelStmtDecl looking more like a FunctionDecl and
that's fine because the FunctionDecl is very close in terms of semantics.
Additionally, ActOnForStmt() requires a CompoundScope when processing a
NullStmt body.
---------
Co-authored-by: Vassil Vassilev <v.g.vassilev@gmail.com>
The implementation mostly reuses C++ code paths where possible,
including narrowing check in order to provide diagnostic messages in
case initializer for constexpr variable is not exactly representable in
target type.
The following won't work due to lack of support for other features:
- Diagnosing of underspecified declarations involving constexpr
- Constexpr attached to compound literals
Also due to lack of support for char8_t some of examples with utf-8
strings don't work properly.
Fixes https://github.com/llvm/llvm-project/issues/64742
This was reported (sort of) in a PR: #77703. The problem is that a
declarator 'owns' an attributes allocation via an `AttributePool`.
However, this example tries to copy a DeclaratorChunk from one
Declarator to another, so when the temporary Declarator goes out of
scope, it deletes the attribute it has tried to pass on via the chunk.
This patch ensures that we copy the 'ownership' of the attribute
correctly, and adds an assert to catch any other casess where this
happens.
Additionally, this was put in as a bug report, so this
Fixes#83611
EnumArgument may be a string or an identifier. If it is a string, it
should be parsed as unevaluated string literal. Add IsString flag to
EnumArgument so that the parser can choose the correct parsing method.
Target-specific attributes that share spelling may have different
attribute "prototypes". For example, ARM's version of "interrupt"
attribute accepts a string enum, while MSP430's version accepts an
unsigned integer. Adjust ClangAttrEmitter so that the generated
`attributeStringLiteralListArg` returns the correct mask depending on
target triple.
It is worth noting that even after this change some string arguments are
still parsed as identifiers or, worse, as expressions. This is because
of some special logic in `ParseAttributeArgsCommon`. Fixing it is out of
scope of this patch.
Our usual pattern when issuing an extension warning is to also issue a
default-off diagnostic about the keywords not being compatible with
standards before a certain point. This adds those diagnostics for C11
keywords.
In C++, alignas is an attribute specifier, while in C23, it's an alias
of _Alignas, which is a type specifier/qualifier. This means that they
parse differently in some circumstances.
Fixes https://github.com/llvm/llvm-project/issues/81472
According to [temp.names] p5:
> The keyword template shall not appear immediately after a declarative nested-name-specifier.
[expr.prim.id.qual] p2 defines a declarative nested-name-specifier as follows:
> A nested-name-specifier is declarative if it is part of
> - a class-head-name,
> - an enum-head-name,
> - a qualified-id that is the id-expression of a declarator-id, or
> - a declarative nested-name-specifier.
Note: I believe this definition is defective as it doesn't include _nested-name-specifiers_ appearing in _elaborated-type-specifiers_ that declare partial/explicit specializations and explicit instantiations. See my post to the core reflector. Minus a few bugs that are addressed by this PR, this is how we implement it.
This means that declarations like:
```
template<typename>
struct A
{
template<typename>
struct B
{
void f();
};
};
template<typename T>
template<typename U>
void A<T>::template B<U>::f() { } // error: 'template' cannot be used after a declarative nested name specifier
```
are ill-formed. This PR add diagnostics for such declarations. The name of the diagnostic group is `template-in-declaration-name`.
Regarding the aforementioned "few bugs that are addressed by this PR" in order to correctly implement this:
- `CheckClassTemplate` did not call `diagnoseQualifiedDeclaration` when the semantic context was dependent. This allowed for constructs like:
```
struct A
{
template<typename T>
struct B
{
template<typename U>
struct C;
};
};
template<typename T>
template<typename U>
struct decltype(A())::B<T>::C { };
```
- `ActOnClassTemplateSpecialization` did not call `diagnoseQualifiedDeclaration` at all, allowing for qualified partial/explicit specializations at class scope and other related nonsense
- `TreeTransform::TransformNestedNameSpecifierLoc` would rebuild a `NestedNameSpecifier::TypeSpecWithTemplate` as a `NestedNameSpecifier::TypeSpec`
- `TemplateSpecializationTypeLoc::initializeLocal` would set the `template` keyword `SourceLocation` to the provided `Loc` parameter, which would result in a `TemplateSpecializationTypeLoc` obtained via `ASTContext::getTrivialTypeSourceInfo` being displayed as always having a `template` prefix (since the presence of the keyword is not stored anywhere else).
According to [temp.pre] p5:
> In a template-declaration, explicit specialization, or explicit instantiation the init-declarator-list in the declaration shall contain at most one declarator.
A member-declaration that is a template-declaration or explicit-specialization contains a declaration, even though it declares a member. This means it _will_ contain an init-declarator-list (not a member-declarator-list), so [temp.pre] p5 applies.
This diagnoses declarations such as:
```
struct A
{
template<typename T>
static const int x = 0, f(); // error: a template declaration can only declare a single entity
template<typename T>
static const int g(), y = 0; // error: a template declaration can only declare a single entity
};
```
The diagnostic messages are the same as those of the equivalent namespace scope declarations.
Note: since we currently do not diagnose declarations with multiple abbreviated function template declarators at namespace scope e.g., `void f(auto), g(auto);`, so this patch does not add diagnostics for the equivalent member declarations.
This patch also refactors `ParseSingleDeclarationAfterTemplate` (now named `ParseDeclarationAfterTemplate`) to call `ParseDeclGroup` and return the resultant `DeclGroup`.
Implements https://isocpp.org/files/papers/P2662R3.pdf
The feature is exposed as an extension in older language modes.
Mangling is not yet supported and that is something we will have to do before release.
This upstreams more of the Clang API Notes functionality that is
currently implemented in the Apple fork:
https://github.com/apple/llvm-project/tree/next/clang/lib/APINotes
This is the largest chunk of the API Notes functionality in the
upstreaming process. I will soon submit a follow-up patch to actually
enable usage of this functionality by having a Clang driver flag that
enables API Notes, along with tests.
This patch replaces the `__arm_new_za`, `__arm_shared_za` and
`__arm_preserves_za` attributes in favour of:
* `__arm_new("za")`
* `__arm_in("za")`
* `__arm_out("za")`
* `__arm_inout("za")`
* `__arm_preserves("za")`
As described in https://github.com/ARM-software/acle/pull/276.
One change is that `__arm_in/out/inout/preserves(S)` are all mutually
exclusive, whereas previously it was fine to write `__arm_shared_za
__arm_preserves_za`. This case is now represented with `__arm_in("za")`.
The current implementation uses the same LLVM attributes under the hood,
since `__arm_in/out/inout` are all variations of "shared ZA", so can use
the existing `aarch64_pstate_za_shared` attribute in LLVM.
#77941 will add support for the new "zt0" state as introduced
with SME2.
Invalid (direct) initializer would invalid `VarDecl` so
`InitializerScopeRAII` cannot restore scope stack balance.
As with other kind of initializer, `InitializerScopeRAII::pop()` is
moved up before `Sema::ActOnInitializerError()` which invalidates the
`VarDecl`, so scope can be balanced and current `DeclContext` can be
restored.
Fixes#30908
