Moving an std::vector is almost always profitable.
A clang::CXXScopeSpec contains an owned
clang::NestedNameSpecifierLocBuilder which currently does not benefit
from being moved, but may structurally in the future.
A clang::MultiLevelTemplateArgumentList contains an llvm::SmalVector
which may benefit from being moved dependiong on its size.
A clang::Environment contains an llvm::ImmutableMap which itself
contains an llvm::IntrusiveRefCntPtr that benefits from being moved.
Changes suggested by performance-use-std-move from #179467
---------
Co-authored-by: Timm Baeder <tbaeder@redhat.com>
Fold constraints can contain packs expanded from different locations.
For `C<Ps...>`, where the ellipsis immediately follows the argument, the
pack should be expanded in place regardless of the fold expression. For
`C<Ps> && ...`, the fold expression itself is responsible for expanding
Ps.
Previously, both kinds of packs were expanded by the fold expression,
which broke assumptions within concept caching. This patch fixes that by
preserving PackExpansionTypes for the first kind of pack while rewriting
them to non-packs for the second kind.
This patch also removes an unused function and performs some cleanup of
the evaluation contexts. Hopefully it is viable for backporting.
No release note, as this issue was a regression.
Fixes https://github.com/llvm/llvm-project/issues/177245
A generic lambda inside a generic function is (currently) instantiated twice. Thus the argument expression of a loop hint inside such a lambda may still be value dependent after the first instantiation and we must protect against this in `TransformLoopHintAttr`. We also fix a bug in this function where the special handling of an unroll(0|1) hint could be applied to *other* loop hints, if they receive an argument 1 after instantiation.
Fixes#165346
This patch renames stale variable names where `TypeSourceInfo` objects
were still using the old `DI` (`DeclaratorInfo`) naming convention.
Specifically, variables of type `TypeSourceInfo` have been updated from
`DI` to `TSI` to improve code clarity and maintain consistency with the
current naming.
This makes pushing / popping CodeSynthesisContexts much cheaper, as it
delegates to another class this functionality which is not actually
needed in most cases.
It also converts a bunch of these uses into just asserts.
This improves compiler performance a little bit:
Some diagnostics change a little bit, because we avoid printing a
redundant context notes.
This relands #162224 with no changes, turns out the buildbot failure was
unrelated.
This makes pushing / popping CodeSynthesisContexts much cheaper, as it
delegates to another class this functionality which is not actually
needed in most cases.
It also converts a bunch of these uses into just asserts.
This improves compiler performance a little bit:
<img width="1460" height="35" alt="image"
src="https://github.com/user-attachments/assets/ed1f7f39-e85e-481d-938f-e227c62994be"
/>
Some diagnostics changes, because we avoid printing redundant context
notes.
This is
```
to form CE, any non-dependent concept template argument Ai
is substituted into the constraint-expression of C.
If any such substitution results in an invalid concept-id,
the program is ill-formed; no diagnostic is required.
```
https://eel.is/c++draft/temp.constr.normal#1.4
And continues the implementation of P2841R7 (C++26).
No changelog, we will add an entry for P2841R7 closer to the next
release, depending on the state of avancement.
This rename was made as part of
https://github.com/llvm/llvm-project/pull/147835 in order to ease
rebasing the PR, and give a nice window for other patches to get rebased
as well.
It has been a while already, so lets go ahead and rename it back.
The redundant notes were introduced with the workaround for finding the
template instantiationa args for lambdas inside template type aliases.
This removes the notes for the cases where we are simply instantiating
an outer template, and when diagnosing uses of the alias template.
Also adds comments calling the workaround explicitly.
In the standard, constraint satisfaction checking is done on the
normalized form of a constraint.
Clang instead substitutes on the non-normalized form, which causes us to
report substitution failures in template arguments or concept ids, which
is non-conforming but unavoidable without a parameter mapping
This patch normalizes before satisfaction checking. However, we preserve
concept-id nodes in the normalized form, solely for diagnostics
purposes.
This addresses https://github.com/llvm/llvm-project/issues/61811 and
related concepts conformance bugs, ideally to make the remaining
implementation of concept template parameters easier
Fixes https://github.com/llvm/llvm-project/issues/135190
Fixes https://github.com/llvm/llvm-project/issues/61811
Co-authored-by: Younan Zhang
[zyn7109@gmail.com](mailto:zyn7109@gmail.com)
---------
Co-authored-by: Younan Zhang <zyn7109@gmail.com>
In the standard, constraint satisfaction checking is done on the
normalized form of a constraint.
Clang instead substitutes on the non-normalized form, which causes us to
report substitution failures in template arguments or concept ids, which
is non-conforming but unavoidable without a parameter mapping
This patch normalizes before satisfaction checking. However, we preserve
concept-id nodes in the normalized form, solely for diagnostics
purposes.
This addresses #61811 and related concepts conformance bugs, ideally to
make the remaining implementation of concept template parameters easier
Fixes#135190
Fixes #61811
Co-authored-by: Younan Zhang <zyn7109@gmail.com>
This makes the instantation depth limit be checked whenever the code
synthesis context is pushed, not only when creating a
InstantiatingTemplate RAII object.
Also fix the note suggesting the user increases `-ftemplate-depth` so it
is printed even in a SFINAE context.
This simplifies those transforms a lot, removing a bunch of workarounds
which were introducing problems.
The transforms become independent of the template instantiator, so they
are moved to TreeTransform instead.
Fixes#131342
This PR was already reviewed and approved at
https://github.com/llvm/llvm-project/pull/160777, but I accidentally
merged that into another PR, instead of main.
This reintroduces `Type.h`, having earlier been renamed to `TypeBase.h`,
as a redirection to `TypeBase.h`, and redirects most users to include
the former instead.
This is a preparatory patch for being able to provide inline definitions
for `Type` methods which would otherwise cause a circular dependency
with `Decl{,CXX}.h`.
Doing these operations into their own NFC patch helps the git rename
detection logic work, preserving the history.
This patch makes clang just a little slower to build (~0.17%), just
because it makes more code indirectly include `DeclCXX.h`.
This is a preparatory patch, to be able to provide inline definitions
for `Type` functions which depend on `Decl{,CXX}.h`. As the latter also
depends on `Type.h`, this would not be possible without some
reorganizing.
Splitting this rename into its own patch allows git to track this as a
rename, and preserve all git history, and not force any code
reformatting.
A later NFC patch will reintroduce `Type.h` as redirection to
`TypeBase.h`, rewriting most places back to directly including `Type.h`
instead of `TypeBase.h`, leaving only a handful of places where this is
necessary.
Then yet a later patch will exploit this by making more stuff inline.
This makes sure NestedNameSpecifierLocs don't apply to the replacement
TemplateName of SubstTemplate* nodes.
Also removes improper name qualification over these Subst Nodes, causing
some canonical TemplateNames to not be fully qualified when printed.
Since this is a regression introduced in #147835, which was never
released, there are no release notes.
Fixes#155281
The new builtin `__builtin_dedup_pack` removes duplicates from list of
types.
The added builtin is special in that they produce an unexpanded pack
in the spirit of P3115R0 proposal.
Produced packs can be used directly in template argument lists and get
immediately expanded as soon as results of the computation are
available.
It allows to easily combine them, e.g.:
```cpp
template <class ...T>
struct Normalize {
// Note: sort is not included in this PR, it illustrates the idea.
using result = std::tuple<
__builtin_sort_pack<
__builtin_dedup_pack<int, double, T...>...
>...>;
}
;
```
Limitations:
- only supported in template arguments and bases,
- can only be used inside the templates, even if non-dependent,
- the builtins cannot be assigned to template template parameters.
The actual implementation proceeds as follows:
- When the compiler encounters a `__builtin_dedup_pack` or other
type-producing
builtin with dependent arguments, it creates a dependent
`TemplateSpecializationType`.
- During substitution, if the template arguments are non-dependent, we
will produce: a new type `SubstBuiltinTemplatePackType`, which stores
an argument pack that needs to be substituted. This type is similar to
the existing `SubstTemplateParmPack` in that it carries the argument
pack that needs to be expanded further. The relevant code is shared.
- On top of that, Clang also wraps the resulting type into
`TemplateSpecializationType`, but this time only as a sugar.
- To actually expand those packs, we collect the produced
`SubstBuiltinTemplatePackType` inside `CollectUnexpandedPacks`.
Because we know the size of the produces packs only after the initial
substitution, places that do the actual expansion will need to have a
second run over the substituted type to finalize the expansions (in
this patch we only support this for template arguments, see
`ExpandTemplateArgument`).
If the expansion are requested in the places we do not currently
support, we will produce an error.
More follow-up work will be needed to fully shape this:
- adding the builtin that sorts types,
- remove the restrictions for expansions,
- implementing P3115R0 (scheduled for C++29, see
https://github.com/cplusplus/papers/issues/2300).
This is a major change on how we represent nested name qualifications in
the AST.
* The nested name specifier itself and how it's stored is changed. The
prefixes for types are handled within the type hierarchy, which makes
canonicalization for them super cheap, no memory allocation required.
Also translating a type into nested name specifier form becomes a no-op.
An identifier is stored as a DependentNameType. The nested name
specifier gains a lightweight handle class, to be used instead of
passing around pointers, which is similar to what is implemented for
TemplateName. There is still one free bit available, and this handle can
be used within a PointerUnion and PointerIntPair, which should keep
bit-packing aficionados happy.
* The ElaboratedType node is removed, all type nodes in which it could
previously apply to can now store the elaborated keyword and name
qualifier, tail allocating when present.
* TagTypes can now point to the exact declaration found when producing
these, as opposed to the previous situation of there only existing one
TagType per entity. This increases the amount of type sugar retained,
and can have several applications, for example in tracking module
ownership, and other tools which care about source file origins, such as
IWYU. These TagTypes are lazily allocated, in order to limit the
increase in AST size.
This patch offers a great performance benefit.
It greatly improves compilation time for
[stdexec](https://github.com/NVIDIA/stdexec). For one datapoint, for
`test_on2.cpp` in that project, which is the slowest compiling test,
this patch improves `-c` compilation time by about 7.2%, with the
`-fsyntax-only` improvement being at ~12%.
This has great results on compile-time-tracker as well:
This patch also further enables other optimziations in the future, and
will reduce the performance impact of template specialization resugaring
when that lands.
It has some other miscelaneous drive-by fixes.
About the review: Yes the patch is huge, sorry about that. Part of the
reason is that I started by the nested name specifier part, before the
ElaboratedType part, but that had a huge performance downside, as
ElaboratedType is a big performance hog. I didn't have the steam to go
back and change the patch after the fact.
There is also a lot of internal API changes, and it made sense to remove
ElaboratedType in one go, versus removing it from one type at a time, as
that would present much more churn to the users. Also, the nested name
specifier having a different API avoids missing changes related to how
prefixes work now, which could make existing code compile but not work.
How to review: The important changes are all in
`clang/include/clang/AST` and `clang/lib/AST`, with also important
changes in `clang/lib/Sema/TreeTransform.h`.
The rest and bulk of the changes are mostly consequences of the changes
in API.
PS: TagType::getDecl is renamed to `getOriginalDecl` in this patch, just
for easier to rebasing. I plan to rename it back after this lands.
Fixes#136624
Fixes https://github.com/llvm/llvm-project/issues/43179
Fixes https://github.com/llvm/llvm-project/issues/68670
Fixes https://github.com/llvm/llvm-project/issues/92757
This is a first pass at implementing
[P2841R7](https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2025/p2841r7.pdf).
The implementation is far from complete; however, I'm aiming to do that
in chunks, to make our lives easier.
In particular, this does not implement
- Subsumption
- Mangling
- Satisfaction checking is minimal as we should focus on #141776 first
(note that I'm currently very stuck)
FTM, release notes, status page, etc, will be updated once the feature
is more mature. Given the state of the feature, it is not yet allowed in
older language modes.
Of note:
- Mismatches between template template arguments and template template
parameters are a bit wonky. This is addressed by #130603
- We use `UnresolvedLookupExpr` to model template-id. While this is
pre-existing, I have been wondering if we want to introduce a different
OverloadExpr subclass for that. I did not make the change in this patch.
In the development of P1061 (Structured Bindings Introduce a Patch), I
found this bug in the template instantiation of a
local class. The issue is caused by the instantiation of the original
template and not the partially instantiated template. In
the example (sans the fix) the instantiation uses the first template
parameter from the previous instantiation and not the current one so the
error hits an assertion when it is expecting an NTTP. If they were both
types then it might gladly accept the type from the wrong template which
is kind of scary.
In the test, the reference to `i` is substituted with a placeholder AST
object that represents the resolved value when instantiating `g`.
However, since the old template is used, the instantiation sees an AST
object that only contains the template argument index in the context of
instantiating the lambda which has a type template parameter (ie auto).
I question if we should use `getTemplateInstantiationPattern` at all
here. Other errors involving local classes in nested templates could
also be caused by the misuse of this function (because it gets the
uninstantiated template).
Since the function template isn't instantiated before constraint
checking, we'll not be able to find the outer template arguments through
function specialization when evaluating the inner constraint that is
nested within a larger constraint expression.
The only practical solution is to get them back through the code
synthesis context, which also allows us to eliminate an overload of
getTemplateInstantiationArgs.
No release note because it's a regression on trunk.
Fixes https://github.com/llvm/llvm-project/issues/147772
When a specialization was ambiguous, we would mark it as invalid, even
if the specialization occured in an immediate context.
This would subsequently lead to scenarios where invalid specialization
produced no diagnostics, causing crashes during codegen.
Fixes#51866
The previous approach broke code generation for the MS ABI due to an
unintended code path during constraint substitution. This time we
address the issue by inspecting the evaluation contexts and thereby
avoiding that code path.
This reapplies 96eced624 (#102857).
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
We check the accessibility of constructors when initializing a default
argument whose type is not an aggregate.
Make sure the check is performed within the correct DeclContext.
Otherwise, it will be delayed until the end of the declaration, at which
point the context is mismatched.
Fixes#62444
Fixes https://github.com/llvm/llvm-project/issues/83608
This code was flagged by static analysis. It was a false positive but
the reason why this code is valid is subtle and folks refactoring this
code in the future could easily miss it.
There are some limitations.
Because we only know which partial specialization to refer to when
instantiating, and because we can't instantiate the class before we
require a complete type, we can only use the partial specialization once
we have a complete class.
Similarly, because we don't know if a class is ever going to be
complete, we always warn on availability of the primary. Therefore, we
only warn for the partial specialization if we did not warn on the
primary.
I considered alternatives to address that second limitation:
- Delay warnings to the end of the TU
- Tracking where each availability attribute originally comes from.
However, both of these have drawbacks, and the use case is probably less
motivated than wanting to deprecate the use of a specific
specialization.
Fixes#44496
This patch adds templated `operator<<` for diagnostics that pass scoped
enums, saving people from `llvm::to_underlying()` clutter on the side of
emitting the diagnostic. This eliminates 80 out of 220 usages of
`llvm::to_underlying()` in Clang.
I also backported `std::is_scoped_enum_v` from C++23.
This reapplies #134038
Since the last patch, this fixes a null pointer dereference where the
TSI of the destructor wasn't properly propagated into the
DeclarationNameInfo. We now construct a LocInfoType for dependent cases,
as done elsewhere in getDestructorName, such that GetTypeFromParser can
correctly obtain the TSI.
---
This patch fixes two long-standing bugs that prevent Clang from
instantiating local class members inside a dependent context. These bugs
were introduced in commits
21eb1af469
and
919df9d75a.
21eb1af469
introduced a concept called eligible methods such that it did an attempt
to skip past ineligible method instantiation when instantiating class
members. Unfortunately, this broke the instantiation chain for local
classes - getTemplateInstantiationPattern() would fail to find the
correct definition pattern if the class was defined within a partially
transformed dependent context.
919df9d75a
introduced a separate issue by incorrectly copying the
DeclarationNameInfo during function definition instantiation from the
template pattern, even though that DNI might contain a transformed
TypeSourceInfo. Since that TSI was already updated when the declaration
was instantiated, this led to inconsistencies. As a result, the final
instantiated function could lose track of the transformed declarations,
hence we crash: https://compiler-explorer.com/z/vjvoG76Tf.
This PR corrects them by
1. Removing the bypass logic for method instantiation. The eligible flag
is independent of instantiation and can be updated properly afterward,
so skipping instantiation is unnecessary.
2. Carefully handling TypeSourceInfo by creating a new instance that
preserves the pattern's source location while using the already
transformed type.
This patch fixes two long-standing bugs that prevent Clang from
instantiating local class members inside a dependent context. These bugs
were introduced in commits 21eb1af469c3 and 919df9d75a.
21eb1af469c3 introduced a concept called eligible methods such that it
did an attempt to skip past ineligible method instantiation when
instantiating class members. Unfortunately, this broke the instantiation
chain for local classes - getTemplateInstantiationPattern() would fail
to find the correct definition pattern if the class was defined within a
partially transformed dependent context.
919df9d75a introduced a separate issue by incorrectly copying the
DeclarationNameInfo during function definition instantiation from the
template pattern, even though that DNI might contain a transformed
TypeSourceInfo. Since that TSI was already updated when the declaration
was instantiated, this led to inconsistencies. As a result, the final
instantiated function could lose track of the transformed declarations,
hence we crash: https://compiler-explorer.com/z/vjvoG76Tf.
This PR corrects them by
1. Removing the bypass logic for method instantiation. The eligible flag
is independent of instantiation and can be updated properly afterward,
so skipping instantiation is unnecessary.
2. Carefully handling TypeSourceInfo by creating a new instance that
preserves the pattern's source location while using the already
transformed type.
Fixes https://github.com/llvm/llvm-project/issues/59734
Fixes https://github.com/llvm/llvm-project/issues/132208
This fixes partial ordering of pack expansions of NTTPs, by procedding
with the check using the pattern of the NTTP through the rules of the
non-pack case.
This also unifies almost all of the different versions of
FinishTemplateArgumentDeduction (except the function template case).
This makes sure they all follow the rules consistently, instantiating
the parameters and comparing those with the argument.
Fixes#132562
This introduces a new class 'UnsignedOrNone', which models a lite
version of `std::optional<unsigned>`, but has the same size as
'unsigned'.
This replaces most uses of `std::optional<unsigned>`, and similar
schemes utilizing 'int' and '-1' as sentinel.
Besides the smaller size advantage, this is simpler to serialize, as its
internal representation is a single unsigned int as well.
This reverts an earlier attempt
(adb0d8ddceb143749c519d14b8b31b481071da77 and
50e5411e4247421fd606f0a206682fcdf0303ae3) to support these expansions,
which was limited to type arguments and which subverted the purpose
of SubstTemplateTypeParmType.
This propagates the ArgumentPackSubstitutionIndex along with the
AssociatedConstraint, so that the pack expansion works, without
needing any new transforms or otherwise any changes to the template
instantiation process.
This keeps the tests from the reverted commits, and adds a few more
showing the new solution also works for NTTPs.
Fixes https://github.com/llvm/llvm-project/issues/131798
This is the last item of the OpenACC 3.3 spec. It includes the
implicit-name version of 'routine', plus significant refactorings to
make the two work together. The implicit name version is represented as
an attribute on the function call. This patch also implements the
clauses for the implicit-name version, as well as the A.3.4 warning.
Instead of manually adding a note pointing to the relevant template
parameter to every relevant error, which is very easy to miss, this
patch adds a new instantiation context note, so that this can work using
RAII magic.
This fixes a bunch of places where these notes were missing, and is more
future-proof.
Some diagnostics are reworked to make better use of this note:
- Errors about missing template arguments now refer to the parameter
which is missing an argument.
- Template Template parameter mismatches now refer to template
parameters as parameters instead of arguments.
It's likely this will add the note to some diagnostics where the
parameter is not super relevant, but this can be reworked with time and
the decrease in maintenance burden makes up for it.
This bypasses the templight dumper for the new context entry, as the
tests are very hard to update.
This depends on #125453, which is needed to avoid losing the context
note for errors occuring during template argument deduction.
The 'routine' construct has two forms, one which takes the name of a
function that it applies to, and another where it implicitly figures it
out based on the next declaration. This patch implements the former with
the required restrictions on the name and the function-static-variables
as specified.
What has not been implemented is any clauses for this, any of the A.3.4
warnings, or the other form.
This patch makes it so the correct instantiation context is printed for
diagnostics suppessed by template argument deduction.
The context is saved along with the suppressed diagnostic, and when the
declaration they were attached to becomes used, we print the correct
context, instead of whatever context was at this point.
This merges the functionality of ResolvedUnexpandedPackExpr into
FunctionParmPackExpr. I also added a test to show that
https://github.com/llvm/llvm-project/issues/125103 should be fixed with
this. I put the removal of ResolvedUnexpandedPackExpr in its own commit.
Let me know what you think.
Fixes#125103
When substituting for rewrite purposes, as in rebuilding constraints for
a synthesized deduction guide, it assumed that packs were in
PackExpansion* form, such that the instantiator could extract a pattern.
For type aliases CTAD, while rebuilding their associated constraints,
this might not be the case because we'll call
`TransformTemplateArgument()` for the alias template arguments, where
there might be cases e.g. a non-pack expansion type into a pack
expansion, so the assumption wouldn't hold.
This patch fixes that by making it treat the non-pack expansions as
direct patterns when rewriting.
Fixes#124715
