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 clears up the printing of a NestedNameSpecifier so a trailing '::'
is not printed, unless it refers into the global scope.
This fixes a bunch of diagnostics where the trailing :: was awkward.
This also prints the NNS quoted consistenty.
There is a drive-by improvement to error recovery, where now we print
the actual type instead of `<dependent type>`.
This will clear up further uses of NNS printing in further patches.
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.
This fixes the core issue described in P3579, following the design
intent of P0522 to not introduce any new cases where a template template
parameter match is allowed for a template which is not valid for all
possible uses.
With this patch, narrowing conversions are disallowed for TTP matching.
This reuses the existing machinery for diagnosing narrowing in a
converted constant expression.
Since P0522 is a DR and we apply it all the way back to C++98, this
brings that machinery to use in older standards, in this very narrow
scope of TTP matching.
This still doesn't solve the ambiguity when partial ordering NTTPs of
different integral types, this is blocked by a different bug which will
be fixed in a subsequent patch (but the test cases are added).
It turns out `SemaTemplate` handles this type of diagnostic already,
however when template gets encountered, it never gets parsed as a
possible statement or declaration, only as an expression.
Fixes#17959.
According to [temp.expl.spec] p2:
> The declaration in an _explicit-specialization_ shall not be an
_export-declaration_. An explicit specialization shall not use a
_storage-class-specifier_ other than `thread_local`.
Clang partially implements this, but a number of issues exist:
1. We don't diagnose class scope explicit specializations of variable
templates with _storage-class-specifiers_, e.g.
```
struct A
{
template<typename T>
static constexpr int x = 0;
template<>
static constexpr int x<void> = 1; // ill-formed, but clang accepts
};
````
2. We incorrectly reject class scope explicit specializations of
variable templates when `static` is not used, e.g.
```
struct A
{
template<typename T>
static constexpr int x = 0;
template<>
constexpr int x<void> = 1; // error: non-static data member cannot be
constexpr; did you intend to make it static?
};
````
3. We don't diagnose dependent class scope explicit specializations of
function templates with storage class specifiers, e.g.
```
template<typename T>
struct A
{
template<typename U>
static void f();
template<>
static void f<int>(); // ill-formed, but clang accepts
};
````
This patch addresses these issues as follows:
- # 1 is fixed by issuing a diagnostic when an explicit
specialization of a variable template has storage class specifier
- # 2 is fixed by considering any non-function declaration with any
template parameter lists at class scope to be a static data member. This
also allows for better error recovery (it's more likely the user
intended to declare a variable template than a "field template").
- # 3 is fixed by checking whether a function template explicit
specialization has a storage class specifier even when the primary
template is not yet known.
One thing to note is that it would be far simpler to diagnose this when
parsing the _decl-specifier-seq_, but such an implementation would
necessitate a refactor of `ParsedTemplateInfo` which I believe to be
outside the scope of this patch.
This patch will finally allow us to mark C++17 support in clang as
complete.
In order to implement this as a DR and avoid breaking reasonable code
that worked before P0522, this patch implements a provisional resolution
for CWG2398: When deducing template template parameters against each other,
and the argument side names a template specialization, instead of just
deducing A, we deduce a synthesized template template parameter based
on A, but with it's parameters using the template specialization's arguments
as defaults.
The driver flag is deprecated with a warning.
Fixes https://github.com/llvm/llvm-project/issues/36505
This reverts commit 2d7fba5f95f0614f6f2c4a4ed966b307d617898b.
The patch was reverted because it caused regression with rocThrust
due to ambiguity of template specialization.
For details please see https://reviews.llvm.org/D109496
A resolution to the ambiguity issues created by P0522, which is a DR solving
CWG 150, did not come as expected, so we are just going to accept the change,
and watch how users digest it.
For now we deprecate the flag with a warning, and make it on by default.
We don't remove the flag completely in order to give users a chance to
work around any problems by disabling it.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D109496
does not match any declaration in the class (or class template), be
sure to mark it as invalid. Fixes PR10924 / <rdar://problem/10119422>.
llvm-svn: 143504
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).
llvm-svn: 91446
template template parameter, substitute any prior template arguments
into the template template parameter. This, for example, allows us to
properly check the template template argument for a class such as:
template<typename T, template<T Value> class X> struct Foo;
The actual implementation of this feature was trivial; most of the
change is dedicated to giving decent diagnostics when this
substitution goes horribly wrong. We now get a note like:
note: while substituting prior template arguments into template
template parameter 'X' [with T = float]
As part of this change, enabled some very pedantic checking when
comparing template template parameter lists, which shook out a bug in
our overly-eager checking of default arguments of template template
parameters. We now perform only minimal checking of such default
arguments when they are initially parsed.
llvm-svn: 86864
qualified name does not actually refer into a class/class
template/class template partial specialization.
Improve printing of nested-name-specifiers to eliminate redudant
qualifiers. Also, make it possible to output a nested-name-specifier
through a DiagnosticBuilder, although there are relatively few places
that will use this leeway.
llvm-svn: 80056
their members, including member class template, member function
templates, and member classes and functions of member templates.
To actually parse the nested-name-specifiers that qualify the name of
an out-of-line definition of a member template, e.g.,
template<typename X> template<typename Y>
X Outer<X>::Inner1<Y>::foo(Y) {
return X();
}
we need to look for the template names (e.g., "Inner1") as a member of
the current instantiation (Outer<X>), even before we have entered the
scope of the current instantiation. Since we can't do this in general
(i.e., we should not be looking into all dependent
nested-name-specifiers as if they were the current instantiation), we
rely on the parser to tell us when it is parsing a declaration
specifier sequence, and, therefore, when we should consider the
current scope specifier to be a current instantiation.
Printing of complicated, dependent nested-name-specifiers may be
somewhat broken by this commit; I'll add tests for this issue and fix
the problem (if it still exists) in a subsequent commit.
llvm-svn: 80044
the logic is there for out-of-line definitions with multiple levels of
nested templates, but this is still a work-in-progress: we're having
trouble determining when we should look into a dependent
nested-name-specifier.
llvm-svn: 80003
member templates declared inside other templates. This allows us to
match out-of-line definitions of member function templates within
class templates to the declarations within the class template. We
still can't handle out-of-line definitions for member class templates,
however.
llvm-svn: 79955
<rdar://problem/6952203>.
To do this, we actually remove a not-quite-correct optimization in the
C++ name lookup routines. We'll revisit this optimization for the
general case once more C++ is working.
llvm-svn: 73659
