This patch makes remaining cases of #embed to emit int type since there
is an agreement to do that for C. C++ is being discussed, but in general
we don't want to produce different types for C and C++.
When #embed appears in an initializer list, we may choose a "fast path"
if the target declaration is a char array. We simply initialize it with
string literal that contains embedded data. However we need to be
careful when checking that we actually can use this "fast path" since
char array may be nested in a struct.
We ran into a FE crash and root caused to `ER.get()` on line 5584 here
being nullptr. I think this is a result of not checking if ER here is
invalid.
Example of crash-on-valid C++
https://gist.github.com/yuxuanchen1997/576dce964666f0f8713fccacf5847138
Note that this crash happens only with `-std=c++20`.
As discussed before with @cor3ntin before
(https://github.com/llvm/llvm-project/pull/94752) here is the
simplification of the release note written for the previously mentioned
PR and the removal of a comment that is no longer useful.
(Sorry for creating this PR this late.)
Co-authored-by: Gabor Spaits <Gabor.Spaits@hightec-rt.com>
This patch moves documentation of `Sema` functions from `.cpp` files to `Sema.h` when there was no documentation in the latter, or it can be trivially subsumed. More complicated cases when there's less trivial divergence between documentation attached to declaration and the one attached to implementation are left for a later PR that would require review.
It appears that doxygen can find the documentation for a function defined out-of-line even if it's attached to an implementation, and not declaration. But other tools, e.g. clangd, are not as powerful. So this patch significantly improves autocompletion experience for (at least) clangd-based IDEs.
This checks if the layout of `std::initializer_list` is something Clang
can handle much earlier and deduplicates the checks in
CodeGen/CGExprAgg.cpp and AST/ExprConstant.cpp
Also now diagnose `union initializer_list` (Fixes#95495), bit-field for
the size (Fixes a crash that would happen during codegen if it were
unnamed), base classes (that wouldn't be initialized) and polymorphic
classes (whose vtable pointer wouldn't be initialized).
This commit implements the entirety of the now-accepted [N3017
-Preprocessor
Embed](https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3017.htm) and
its sister C++ paper [p1967](https://wg21.link/p1967). It implements
everything in the specification, and includes an implementation that
drastically improves the time it takes to embed data in specific
scenarios (the initialization of character type arrays). The mechanisms
used to do this are used under the "as-if" rule, and in general when the
system cannot detect it is initializing an array object in a variable
declaration, will generate EmbedExpr AST node which will be expanded by
AST consumers (CodeGen or constant expression evaluators) or expand
embed directive as a comma expression.
This reverts commit
682d461d5a.
---------
Co-authored-by: The Phantom Derpstorm <phdofthehouse@gmail.com>
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Co-authored-by: H. Vetinari <h.vetinari@gmx.com>
Fixes#62925.
The following code:
```cpp
#include <map>
int main() {
std::map m1 = {std::pair{"foo", 2}, {"bar", 3}}; // guide #2
std::map m2(m1.begin(), m1.end()); // guide #1
}
```
Is rejected by clang, but accepted by both gcc and msvc:
https://godbolt.org/z/6v4fvabb5 .
So basically CTAD with copy-list-initialization is rejected.
Note that this exact code is also used in a cppreference article:
https://en.cppreference.com/w/cpp/container/map/deduction_guides
I checked the C++11 and C++20 standard drafts to see whether suppressing
user conversion is the correct thing to do for user conversions. Based
on the standard I don't think that it is correct.
```
13.3.1.4 Copy-initialization of class by user-defined conversion [over.match.copy]
Under the conditions specified in 8.5, as part of a copy-initialization of an object of class type, a user-defined
conversion can be invoked to convert an initializer expression to the type of the object being initialized.
Overload resolution is used to select the user-defined conversion to be invoked
```
So we could use user defined conversions according to the standard.
```
If a narrowing conversion is required to initialize any of the elements, the
program is ill-formed.
```
We should not do narrowing.
```
In copy-list-initialization, if an explicit constructor is chosen, the initialization is ill-formed.
```
We should not use explicit constructors.
Fixes two issues in two ways:
1) The `braced-init-list` consisted of `initializer-list` and
`designated-initializer-list`, and thus the designated initializer is
subject to [over.match.class.deduct]p1.8, which means the brace elision
is also applicable on it for CTAD deduction guides.
2) When forming a deduction guide where the brace elision is applicable,
we should also consider the presence of braces within the initializer.
For example, given
template <class T, class U> struct X {
T t[2];
U u[3];
};
X x = {{1, 2}, 3, 4, 5};
we should establish such deduction guide AFAIU: `X(T (&&)[2], U, U, U) -> X<T, U>`.
Fixes https://github.com/llvm/llvm-project/issues/64625
Fixes https://github.com/llvm/llvm-project/issues/83368
This commit implements the entirety of the now-accepted [N3017 -
Preprocessor
Embed](https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3017.htm) and
its sister C++ paper [p1967](https://wg21.link/p1967). It implements
everything in the specification, and includes an implementation that
drastically improves the time it takes to embed data in specific
scenarios (the initialization of character type arrays). The mechanisms
used to do this are used under the "as-if" rule, and in general when the
system cannot detect it is initializing an array object in a variable
declaration, will generate EmbedExpr AST node which will be expanded
by AST consumers (CodeGen or constant expression evaluators) or
expand embed directive as a comma expression.
---------
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
Co-authored-by: cor3ntin <corentinjabot@gmail.com>
Co-authored-by: H. Vetinari <h.vetinari@gmx.com>
Co-authored-by: Podchishchaeva, Mariya <mariya.podchishchaeva@intel.com>
Make sure we count the anonymous union as an initialized field, so we
properly construct the AST.
Included bonus testcase Test3, which shows a remaining gap: an anonymous
union can contain a partially initialized anonymous struct, and we
handle that inconsistently.
Fixes#91257
This reverts commit 17daa204feadf9c28fc13b7daa69c3cbe865b238.
Multiple examples on the PR
https://github.com/llvm/llvm-project/pull/87933
show regressions, so reverting until they can be fixed in the followup.
This PR complete [DR1815](https://wg21.link/CWG1815) under the guidance
of `FIXME` comments. And reuse `CXXDefaultInitExpr` rewrite machinery to
clone the initializer expression on each use that would lifetime extend
its temporaries.
---------
Signed-off-by: yronglin <yronglin777@gmail.com>
[temp.deduct.general] p6 states:
> At certain points in the template argument deduction process it is
necessary to take a function type that makes use of template parameters
and replace those template parameters with the corresponding template
arguments.
This is done at the beginning of template argument deduction when any
explicitly specified template arguments are substituted into the
function type, and again at the end of template argument deduction when
any template arguments that were deduced or obtained from default
arguments are substituted.
[temp.deduct.general] p7 goes on to say:
> The _deduction substitution loci_ are
> - the function type outside of the _noexcept-specifier_,
> - the explicit-specifier,
> - the template parameter declarations, and
> - the template argument list of a partial specialization
>
> The substitution occurs in all types and expressions that are used in
the deduction substitution loci. [...]
Consider the following:
```cpp
struct A
{
static constexpr bool x = true;
};
template<typename T, typename U>
void f(T, U) noexcept(T::x); // #1
template<typename T, typename U>
void f(T, U*) noexcept(T::y); // #2
template<>
void f<A>(A, int*) noexcept; // clang currently accepts, GCC and EDG reject
```
Currently, `Sema::SubstituteExplicitTemplateArguments` will substitute
into the _noexcept-specifier_ when deducing template arguments from a
function declaration or when deducing template arguments for taking the
address of a function template (and the substitution is treated as a
SFINAE context). In the above example, `#1` is selected as the primary
template because substitution of the explicit template arguments into
the _noexcept-specifier_ of `#2` failed, which resulted in the candidate
being ignored.
This behavior is incorrect ([temp.deduct.general] note 4 says as much), and
this patch corrects it by deferring all substitution into the
_noexcept-specifier_ until it is instantiated.
As part of the necessary changes to make this patch work, the
instantiation of the exception specification of a function template
specialization when taking the address of a function template is changed
to only occur for the function selected by overload resolution per
[except.spec] p13.1 (as opposed to being instantiated for every candidate).
Implement P2748R5 "Disallow Binding a Returned Glvalue to a Temporary"
https://wg21.link/P2748R5
---------
Signed-off-by: yronglin <yronglin777@gmail.com>
This allows the implicitly-generated deduction guide for the copy
constructor to be recognised as an initializer-list constructor,
allowing CTAD for std::initializer_list
OpenACC is going to need an array sections implementation that is a
simpler version/more restrictive version of the OpenMP version.
This patch moves `OMPArraySectionExpr` to `Expr.h` and renames it `ArraySectionExpr`,
then adds an enum to choose between the two.
This also fixes a couple of 'drive-by' issues that I discovered on the way,
but leaves the OpenACC Sema parts reasonably unimplemented (no semantic
analysis implementation), as that will be a followup patch.
We were crashing due to stack exhaustion on rather reasonable C++
template code. After some investigation, I found that we have a
stack-allocated object that was huge: `InitializationSequence` was 7016
bytes. This caused an overflow with deep call stacks in initialization
code.
With these change, `InitializationSequence` is now 248 bytes.
With the original code, testing RelWithDebInfo on Windows 10, all the
tests in SemaCXX took about 6s 800ms. The max template depth I could
reach on my machine using the code in the issue was 708. After that, I
would get `-Wstack-exhausted` warnings until crashing at 976
instantiations.
With these changes on the same machine, all the tests in SemaCXX took
about 6s 500ms. The max template depth I could reach was 1492. After
that, I would get `-Wstack-exhausted` warnings until crashing at 2898
instantiations.
This improves the behavior of #88330 but there's still an outstanding
question of why we run out of stack space and crash in some
circumstances before we're able to issue a diagnostic about stack space
exhaustion.
Fixes https://github.com/llvm/llvm-project/issues/85767.
The aggregate deduction guides are handled in a separate code path. We
don't generate dedicated aggregate deduction guides for alias templates
(we just reuse the ones from the underlying template decl by accident).
The patch fixes this incorrect issue.
Note: there is a small refactoring change in this PR, where we move the
cache logic from `Sema::DeduceTemplateSpecializationFromInitializer` to
`Sema::DeclareImplicitDeductionGuideFromInitList`
HLSL constant sized array function parameters do not decay to pointers.
Instead constant sized array types are preserved as unique types for
overload resolution, template instantiation and name mangling.
This implements the change by adding a new `ArrayParameterType` which
represents a non-decaying `ConstantArrayType`. The new type behaves the
same as `ConstantArrayType` except that it does not decay to a pointer.
Values of `ConstantArrayType` in HLSL decay during overload resolution
via a new `HLSLArrayRValue` cast to `ArrayParameterType`.
`ArrayParamterType` values are passed indirectly by-value to functions
in IR generation resulting in callee generated memcpy instructions.
The behavior of HLSL function calls is documented in the [draft language
specification](https://microsoft.github.io/hlsl-specs/specs/hlsl.pdf)
under the Expr.Post.Call heading.
Additionally the design of this implementation approach is documented in
[Clang's
documentation](https://clang.llvm.org/docs/HLSL/FunctionCalls.html)
Resolves#70123
This reverts commit ca4c4a6758d184f209cb5d88ef42ecc011b11642.
This was intended not to introduce new consistency diagnostics for
smart pointer types, but failed to ignore sugar around types when
detecting this.
Fixed and test added.
GNU and MSVC have extensions where flexible array members (or their
equivalent) can be in unions or alone in structs. This is already fully
supported in Clang through the 0-sized array ("fake flexible array")
extension or when C99 flexible array members have been syntactically
obfuscated.
Clang needs to explicitly allow these extensions directly for C99
flexible arrays, since they are common code patterns in active use by
the
Linux kernel (and other projects). Such projects have been using either
0-sized arrays (which is considered deprecated in favor of C99 flexible
array members) or via obfuscated syntax, both of which complicate their
code bases.
For example, these do not error by default:
```
union one {
int a;
int b[0];
};
union two {
int a;
struct {
struct { } __empty;
int b[];
};
};
```
But this does:
```
union three {
int a;
int b[];
};
```
Remove the default error diagnostics for this but continue to provide
warnings under Microsoft or GNU extensions checks. This will allow for
a seamless transition for code bases away from 0-sized arrays without
losing existing code patterns. Add explicit checking for the warnings
under various constructions.
Additionally fixes a CodeGen bug with flexible array members in unions
in C++, which was found when adding a testcase for:
```
union { char x[]; } z = {0};
```
which only had Sema tests originally.
Fixes#84565
In PR #79382, I need to add a new type that derives from
ConstantArrayType. This means that ConstantArrayType can no longer use
`llvm::TrailingObjects` to store the trailing optional Expr*.
This change refactors ConstantArrayType to store a 60-bit integer and
4-bits for the integer size in bytes. This replaces the APInt field
previously in the type but preserves enough information to recreate it
where needed.
To reduce the number of places where the APInt is re-constructed I've
also added some helper methods to the ConstantArrayType to allow some
common use cases that operate on either the stored small integer or the
APInt as appropriate.
Resolves#85124.
This reverts commit 92a09c0165b87032e1bd05020a78ed845cf35661.
This is triggering a bunch of new -Wnullability-completeness warnings
in code with existing raw pointer nullability annotations.
The intent was the new nullability locations wouldn't affect those
warnings, so this is a bug at least for now.
This enables clang and external nullability checkers to make use of
these annotations on nullable C++ class types like unique_ptr.
These types are recognized by the presence of the _Nullable attribute.
Nullable standard library types implicitly receive this attribute.
Existing static warnings for raw pointers are extended to smart
pointers:
- nullptr used as return value or argument for non-null functions
(`-Wnonnull`)
- assigning or initializing nonnull variables with nullable values
(`-Wnullable-to-nonnull-conversion`)
It doesn't implicitly add these attributes based on the assume_nonnull
pragma, nor warn on missing attributes where the pragma would apply
them.
I'm not confident that the pragma's current behavior will work well for
C++ (where type-based metaprogramming is much more common than C/ObjC).
We'd like to revisit this once we have more implementation experience.
Support can be detected as `__has_feature(nullability_on_classes)`.
This is needed for back-compatibility, as previously clang would issue a
hard error when _Nullable appears on a smart pointer.
UBSan's `-fsanitize=nullability` will not check smart-pointer types.
It can be made to do so by synthesizing calls to `operator bool`, but
that's left for future work.
Discussion:
https://discourse.llvm.org/t/rfc-allowing-nonnull-etc-on-smart-pointers/77201/26
Fixes#54051
This patch implements the C++20 feature -- CTAD for alias templates (P1814R0, specified in https://eel.is/c++draft/over.match.class.deduct#3). It is an initial patch:
- it cover major pieces, thus it works for most cases;
- the big missing piece is to implement the associated constraints (over.match.class.deduct#3.3) for the synthesized deduction guides, see the FIXME in code and tests;
- Some enhancements on the TreeTransform&TemplateInstantiator to allow performing instantiation on `BuildingDeductionGuides` mode;
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
#56628 changed the behavior of `-Wmissing-field-initializers`, which
introduces many new warnings in C++ code that uses partial designated
initializers. If such code is being built with `-Wextra -Werror`, this
change will break the build.
This PR adds a new flag that allows to disable these new warnings and
keep the old ones, as was suggested by @AaronBallman in the original
issue:
https://github.com/llvm/llvm-project/issues/56628#issuecomment-1761510850
Fixes #68933
Emit a warning if pointer/reference to compound literal is returned from
a function.
In C, compound literals in block scope are lvalues that have automatic
storage duration. In C++, compound literals in block scope are
temporaries.
In either case, returning a pointer/reference to a compound literal can
cause a use-after-free bug.
Fixes#8678
HLSL supports vector truncation and element conversions as part of
standard conversion sequences. The vector truncation conversion is a C++
second conversion in the conversion sequence. If a vector truncation is
in a conversion sequence an element conversion may occur after it before
the standard C++ third conversion.
Vector element conversions can be boolean conversions, floating point or
integral conversions or promotions.
[HLSL Draft
Specification](https://microsoft.github.io/hlsl-specs/specs/hlsl.pdf)
---------
Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
Reland of #78387
Use the template pattern in determining whether to synthesize the
aggregate deduction guide, and update
DeclareImplicitDeductionGuideFromInitList to substitute outer template
arguments.
The tests in the original patch made an assumption about the size of a
pointer type, and this led to them failing on targets with 32-bit
pointers. The tests have been updated to not depend on the size of any
type. This only requires updates to the test file, no functionality has
otherwise changed between this and the original patch.
