This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
unevaluated context
Closes https://github.com/llvm/llvm-project/issues/58133
The direct cause for this issue is that the compilation process
continues after it found it is in a invalid state. [expr.await]p2 says
clearly that the co_await expressions are not allowed to appear in
unevaluated context. So we can exit early in this case. It also reduces
many redundant diagnostic messages (Such as 'expression with side
effects has no effect in an unevaluated context').
Now when the compiler can't find the sized deallocation function
correctly in promise_type if there are multiple deallocation function
overloads there.
According to [dcl.fct.def.coroutine]p12:
> If both a usual deallocation function with only a pointer parameter
> and a usual deallocation function with both a pointer parameter and a
> size parameter are found, then the selected deallocation function
> shall be the one with two parameters.
So when there are multiple deallocation functions, the compiler should
choose the sized one instead of the unsized one. The patch fixes this.
We should only use 'auto' in case we can know the type from the right
hand side of the expression. Also we need keep '*' around if the type is
a pointer actually. Few uses of 'auto' in SemaCoroutine.cpp and
CGCoroutine.cpp violates the rule. This commit tries to fix it.
Previously we may call Sema::FindAllocationFunctions directly to lookup
allocation functions directly instead of using our wrapped lambda
LookupAllocationFunction, which is slightly incosnsistent. It will be
helpful to refactor this for further changes.
Also previously, when we lookup 'operator new(std::size_t, std::nothrow_t)' in
case we found `get_return_object_on_allocation_failure` in the
promise_type, the compiler will try to look at the allocation function
in promise_type. However, this is not wanted actually. According to
[dcl.fct.def.coroutine]p10:
> if a global allocation function is selected, the
> ::operator new(size_t, nothrow_t) form is used.
So we should only lookup for `::operator (size_t, nothrow_t)` for the
global allocation function. For the allocation function in the
promise_type, the requirement is that it shouldn't throw, which has
already been checked.
Given users generally include headers from standard libs so it will
generally include the <new> header, so this change should be a trivial
one and shouldn't affect almost any user.
Previously the Expr returned by getOperand() was actually the
subexpression common to the "ready", "suspend", and "resume"
expressions, which often isn't just the operand but e.g.
await_transform() called on the operand.
It's important for the AST to expose the operand as written
in the source for traversals and tools like clangd to work
correctly.
Fixes https://github.com/clangd/clangd/issues/939
Differential Revision: https://reviews.llvm.org/D115187
function in promise_type
According to https://cplusplus.github.io/CWG/issues/2585.html, this
fixes https://github.com/llvm/llvm-project/issues/54881
Simply, the clang tried to found (do lookup and overload resolution. Is
there any better word to use than found?) allocation function in
promise_type and global scope. However, this is not consistent with the
standard. The standard behavior would be that the compiler shouldn't
lookup in global scope in case we lookup the allocation function name in
promise_type. In other words, the program is ill-formed if there is
incompatible allocation function in promise type.
Reviewed By: erichkeane
Differential Revision: https://reviews.llvm.org/D125517
This patch tries to implement RVO for coroutine's return object got from
get_return_object.
From [dcl.fct.def.coroutine]/p7 we could know that the return value of
get_return_object is either a reference or a prvalue. So it makes sense
to do copy elision for the return value. The return object should be
constructed directly into the storage where they would otherwise be
copied/moved to.
Test Plan: folly, check-all
Reviewed By: junparser
Differential revision: https://reviews.llvm.org/D117087
See the discussion in https://reviews.llvm.org/D100282. The coroutine
marked always inline might not be inlined properly in current compiler
support. Since the coroutine would be splitted into pieces. And the call
to resume() and destroy() functions might be indirect call. Also the
ramp function wouldn't get inlined under O0 due to pipeline ordering
problems. It might be different to what users expects to. Emit a warning
to tell it.
This is what GCC does too: https://godbolt.org/z/7eajb1Gf8
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D115867
Now when we are checking if the expression `co_await
promise.final_suspend()` is not throw, we would check unconditionally
for its child expressions recursively. It takes unnecessary time. And
the compiler would complains if the implementation in final_suspend()
may throw even if the higher level function signature marked noexcept
already.
This fixes bug48453 too.
This is that diff I was aiming for. When transitioning code from
coroutines-ts to c++20, it can be useful to add a using declaration to
std::experimental pointing to std::coroutine_traits. This permits
that use by checking whether lookup in std::experimentl finds a
different decl to lookup in std. You still get a warning about
std::experimental::coroutine_traits being a thing, just not an error.
Reviewed By: ChuanqiXu
Differential Revision: https://reviews.llvm.org/D115943
First, let's check we get a TemplateDecl, before complaining about
where it might have been found.
Second, if it came from an unexpected place, show where that location is.
Reviewed By: ChuanqiXu
Differential Revision: https://reviews.llvm.org/D116164
According to [dcl.fct.def.coroutine]p6, the promise_type is allowed to
not define return_void nor return_value:
> If searches for the names return_void and return_value in the scope
> of the promise type each find any declarations, the program is
> ill-formed.
> [Note 1: If return_void is found, flowing off the end of a coroutine is
> equivalent to a co_return with no operand. Otherwise, flowing off the
> end of a coroutine results in
> undefined behavior ([stmt.return.coroutine]). — end note]
So the program isn't ill-formed if the promise_type doesn't define
return_void nor return_value. It is just a potential UB. So the program
should be allowed to compile.
Reviewed By: urnathan
Differential Revision: https://reviews.llvm.org/D116204
To allow transition from the TS-specified
std::experimental::coroutine_traits to the C++20-specified
std::coroutine_traits, we lookup in both places and provide helpful
diagnostics. This refactors the code to avoid separate paths to
std::experimental lookups.
Reviewed By: ChuanqiXu
Differential Revision: https://reviews.llvm.org/D116029
The diagnostics concerning mixing std::experimental and std are
somewhat wordy and have some typographical errors. Diagnostics do not
start with a capital letter nor end with a fullstop. Usually we try
and link clauses with a semicolon, rather than start a new sentence.
So that's what this patch does. Along with avoiding repetition about
std::experimental going away.
Differential Revision: https://reviews.llvm.org/D116026
Since we've decided the to not support std::experimental::coroutine*, we
should tell the user they need to update.
Reviewed By: Quuxplusone, ldionne, Mordante
Differential Revision: https://reviews.llvm.org/D113977
Now in libcxx and clang, all the coroutine components are defined in
std::experimental namespace.
And now the coroutine TS is merged into C++20. So in the working draft
like N4892, we could find the coroutine components is defined in std
namespace instead of std::experimental namespace.
And the coroutine support in clang seems to be relatively stable. So I
think it may be suitable to move the coroutine component into the
experiment namespace now.
This patch would make clang lookup coroutine_traits in std namespace
first. For the compatibility consideration, clang would lookup in
std::experimental namespace if it can't find definitions in std
namespace. So the existing codes wouldn't be break after update
compiler.
And in case the compiler found std::coroutine_traits and
std::experimental::coroutine_traits at the same time, it would emit an
error for it.
The support for looking up std::experimental::coroutine_traits would be
removed in Clang16.
Reviewed By: lxfind, Quuxplusone
Differential Revision: https://reviews.llvm.org/D108696
See PR51862.
The consumers of the Elidable flag in CXXConstructExpr assume that
an elidable construction just goes through a single copy/move construction,
so that the source object is immediately passed as an argument and is the same
type as the parameter itself.
With the implementation of P2266 and after some adjustments to the
implementation of P1825, we started (correctly, as per standard)
allowing more cases where the copy initialization goes through
user defined conversions.
With this patch we stop using this flag in NRVO contexts, to preserve code
that relies on that assumption.
This causes no known functional changes, we just stop firing some asserts
in a cople of included test cases.
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D109800
This reverts commit 2fbd254aa4, which broke the libc++ CI. I'm reverting
to get things stable again until we've figured out a way forward.
Differential Revision: https://reviews.llvm.org/D108696
Summary: Now in libcxx and clang, all the coroutine components are
defined in std::experimental namespace.
And now the coroutine TS is merged into C++20. So in the working draft
like N4892, we could find the coroutine components is defined in std
namespace instead of std::experimental namespace.
And the coroutine support in clang seems to be relatively stable. So I
think it may be suitable to move the coroutine component into the
experiment namespace now.
But move the coroutine component into the std namespace may be an break
change. So I planned to split this change into two patch. One in clang
and other in libcxx.
This patch would make clang lookup coroutine_traits in std namespace
first. For the compatibility consideration, clang would lookup in
std::experimental namespace if it can't find definitions in std
namespace and emit a warning in this case. So the existing codes
wouldn't be break after update compiler.
Test Plan: check-clang, check-libcxx
Reviewed By: lxfind
Differential Revision: https://reviews.llvm.org/D108696
This patch replaces the workaround for simpler implicit moves
implemented in D105518.
The Microsoft STL currently has some issues with P2266.
Where before, with -fms-compatibility, we would disable simpler
implicit moves globally, with this change, we disable it only
when the returned expression is in a context contained by
std namespace and is located within a system header.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: aaron.ballman, mibintc
Differential Revision: https://reviews.llvm.org/D105951
This patch adds a new clang builtin, __arithmetic_fence. The purpose of the
builtin is to provide the user fine control, at the expression level, over
floating point optimization when -ffast-math (-ffp-model=fast) is enabled.
The builtin prevents the optimizer from rearranging floating point expression
evaluation. The new option fprotect-parens has the same effect on
parenthesized expressions, forcing the optimizer to respect the parentheses.
Reviewed By: aaron.ballman, kpn
Differential Revision: https://reviews.llvm.org/D100118
This patch adds a new clang builtin, __arithmetic_fence. The purpose of the
builtin is to provide the user fine control, at the expression level, over
floating point optimization when -ffast-math (-ffp-model=fast) is enabled.
The builtin prevents the optimizer from rearranging floating point expression
evaluation. The new option fprotect-parens has the same effect on
parenthesized expressions, forcing the optimizer to respect the parentheses.
Reviewed By: aaron.ballman, kpn
Differential Revision: https://reviews.llvm.org/D100118
This expands NRVO propagation for more cases:
Parse analysis improvement:
* Lambdas and Blocks with dependent return type can have their variables
marked as NRVO Candidates.
Variable instantiation improvements:
* Fixes crash when instantiating NRVO variables in Blocks.
* Functions, Lambdas, and Blocks which have auto return type have their
variables' NRVO status propagated. For Blocks with non-auto return type,
as a limitation, this propagation does not consider the actual return
type.
This also implements exclusion of VarDecls which are references to
dependent types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D99696
This change caused build errors related to move-only __block variables,
see discussion on https://reviews.llvm.org/D99696
> This expands NRVO propagation for more cases:
>
> Parse analysis improvement:
> * Lambdas and Blocks with dependent return type can have their variables
> marked as NRVO Candidates.
>
> Variable instantiation improvements:
> * Fixes crash when instantiating NRVO variables in Blocks.
> * Functions, Lambdas, and Blocks which have auto return type have their
> variables' NRVO status propagated. For Blocks with non-auto return type,
> as a limitation, this propagation does not consider the actual return
> type.
>
> This also implements exclusion of VarDecls which are references to
> dependent types.
>
> Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
>
> Reviewed By: Quuxplusone
>
> Differential Revision: https://reviews.llvm.org/D99696
This also reverts the follow-on change which was hard to tease apart
form the one above:
> "[clang] Implement P2266 Simpler implicit move"
>
> This Implements [[http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p2266r1.html|P2266 Simpler implicit move]].
>
> Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
>
> Reviewed By: Quuxplusone
>
> Differential Revision: https://reviews.llvm.org/D99005
This reverts commits 1e50c3d785 and
bf20631782.
This expands NRVO propagation for more cases:
Parse analysis improvement:
* Lambdas and Blocks with dependent return type can have their variables
marked as NRVO Candidates.
Variable instantiation improvements:
* Fixes crash when instantiating NRVO variables in Blocks.
* Functions, Lambdas, and Blocks which have auto return type have their
variables' NRVO status propagated. For Blocks with non-auto return type,
as a limitation, this propagation does not consider the actual return
type.
This also implements exclusion of VarDecls which are references to
dependent types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D99696
This expands NRVO propagation for more cases:
Parse analysis improvement:
* Lambdas and Blocks with dependent return type can have their variables
marked as NRVO Candidates.
Variable instantiation improvements:
* Fixes crash when instantiating NRVO variables in Blocks.
* Functions, Lambdas, and Blocks which have auto return type have their
variables' NRVO status propagated. For Blocks with non-auto return type,
as a limitation, this propagation does not consider the actual return
type.
This also implements exclusion of VarDecls which are references to
dependent types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: Quuxplusone
Differential Revision: https://reviews.llvm.org/D99696
This renames the expression value categories from rvalue to prvalue,
keeping nomenclature consistent with C++11 onwards.
C++ has the most complicated taxonomy here, and every other language
only uses a subset of it, so it's less confusing to use the C++ names
consistently, and mentally remap to the C names when working on that
context (prvalue -> rvalue, no xvalues, etc).
Renames:
* VK_RValue -> VK_PRValue
* Expr::isRValue -> Expr::isPRValue
* SK_QualificationConversionRValue -> SK_QualificationConversionPRValue
* JSON AST Dumper Expression nodes value category: "rvalue" -> "prvalue"
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D103720
Implement all of P1825R0:
- implicitly movable entity can be an rvalue reference to non-volatile
automatic object.
- operand of throw-expression can be a function or catch-clause parameter
(support for function parameter has already been implemented).
- in the first overload resolution, the selected function no need to be
a constructor.
- in the first overload resolution, the first parameter of the selected
function no need to be an rvalue reference to the object's type.
This patch also removes the diagnostic `-Wreturn-std-move-in-c++11`.
Differential Revision: https://reviews.llvm.org/D88220
Kazu Hirata