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 reverts commit f949f876daeda520a5b7dbeb2cbb35b8c4383acb.
This commit introduces an llvm_unreachable call that is actually
reachable. I posted a reproducer on the pull request discussion.
ast-print: A DeclRef to an anonymous NTTP will print
'value-parameter-DEPTH-INDEX',
similar to how type parameters are printed.
ast-dump: A bareDeclRef to an anonymous entity will print some extra
identifying information,
instead of an empty name, like indexes.
Falls back to source locations if nothing else is available.
Given the following invalid code,
```cpp
template <class T>
struct S {
T *a;
};
S s = {1};
```
we produce such diagnostics currently:
```
<source>:2:8: note: candidate template ignored: could not match 'S<T>' against 'int'
2 | struct S {
| ^
<source>:2:8: note: candidate template ignored: could not match 'T *' against 'int'
```
Which I think is confusing because there's no `S<T>` nor `T *` at the
location it points to. This is because we're deducing the initializer
against implicitly generated deduction guides, and their source
locations just point to the corresponding `RecordDecl`. Hence the
misleading notes.
This patch alleviates the issue by adding extra notes demonstrating
which implicit deduction guide we're deducing against. In other words,
in addition to the note of `could not match 'T *' against 'int'`, we
would also say the implicit deduction guide we're trying to use:
`template <class T> S(T *) -> S<T>`, which looks clearer IMO.
---------
Co-authored-by: Sirraide <aeternalmail@gmail.com>
See PR51872 for the original repro.
This fixes a crash when converting a templated constructor into a deduction
guide, in case any of the template parameters were invalid.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D110460
deduction for invalid functions
The fabricated template parameters cause an assertion because their depth
is invalid.
rdar://34109988
Differential Revision: https://reviews.llvm.org/D37341
llvm-svn: 316778
template partial specialization.
In passing, fix the deduction-crash.cpp test to actually run all the tests. Due
to a typo, the last third of the file was being skipped by the parser and some
of the tests were not actually testing anything as a result. Switch from
FileCheck to -verify to make the problem more obvious and prevent this
happening again.
llvm-svn: 304604
When an undeclared identifier in a context that requires a type is followed by
'<', only look for type templates when typo-correcting, tweak the diagnostic
text to say that a template name (not a type name) was undeclared, and parse
the template arguments when recovering from the error.
llvm-svn: 302732
Armed with a much better understanding of what
TemplateSpecializationTypeLoc::initializeArgLocs actually does, I now
understand that it's fine to just use an empty TemplateArgumentLocInfo
for Integral, Declaration, and NullPtr TemplateArguments.
Fixes PR14281. (The testcases are actually derived from libcxx_test in
deduction-crash.cpp because the original testcase was impossible to reduce.)
llvm-svn: 185038
defined here, but not semantically, so
new struct S {};
is always ill-formed, even if there is a struct S in scope.
We also had a couple of bugs in ParseOptionalTypeSpecifier caused by it being
under-loved (due to it only being used in a few places) so merge it into
ParseDeclarationSpecifiers with a new DeclSpecContext. To avoid regressing, this
required improving ParseDeclarationSpecifiers' diagnostics in some cases. This
also required teaching ParseSpecifierQualifierList about constexpr... which
incidentally fixes an issue where we'd allow the constexpr specifier in other
bad places.
llvm-svn: 152549
in the classification of template names and using declarations. We now
properly typo-correct the leading identifiers in statements to types,
templates, values, etc. As an added bonus, this reduces the number of
lookups required for disambiguation.
llvm-svn: 130288
template specialization types. This also required some parser tweaks,
since we were losing track of the nested-name-specifier's source
location information in several places in the parser. Other notable
changes this required:
- Sema::ActOnTagTemplateIdType now type-checks and forms the
appropriate type nodes (+ source-location information) for an
elaborated-type-specifier ending in a template-id. Previously, we
used a combination of ActOnTemplateIdType and
ActOnTagTemplateIdType that resulted in an ElaboratedType wrapped
around a DependentTemplateSpecializationType, which duplicated the
keyword ("class", "struct", etc.) and nested-name-specifier
storage.
- Sema::ActOnTemplateIdType now gets a nested-name-specifier, which
it places into the returned type-source location information.
- Sema::ActOnDependentTag now creates types with source-location
information.
llvm-svn: 126808
definition, we're likely going to end up breaking the invariants of
the template system, e.g., that the depths of template parameter lists
match up with the nesting template of the template. So, make sure we
mark such ill-formed declarations as invalid or don't even build them
at all.
llvm-svn: 108372
