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 patch addresses static analyzer concerns where `TSI` could be
dereferenced after being assigned a null value from `SubstType` in
`ConvertConstructorToDeductionGuideTransform()`.
The fixes now check null value of `TSI` after the call to `SubstType`
and return `nullptr` to prevent potential null pointer dereferences when
calling getTypeLoc() or getType() and ensure safe execution.
This patch improves the preservation of qualifiers and loss of type
sugar in TemplateNames.
This problem is analogous to https://reviews.llvm.org/D112374 and this
patch takes a very similar approach to that patch, except the impact
here is much lesser.
When a TemplateName was written bare, without qualifications, we
wouldn't produce a QualifiedTemplate which could be used to disambiguate
it from a Canonical TemplateName. This had effects in the TemplateName
printer, which had workarounds to deal with this, and wouldn't print the
TemplateName as-written in most situations.
There are also some related fixes to help preserve this type sugar along
the way into diagnostics, so that this patch can be properly tested.
- Fix dropping the template keyword.
- Fix type deduction to preserve sugar in TST TemplateNames.
This solves some ambuguity introduced in P0522 regarding how template
template parameters are partially ordered, and should reduce the
negative impact of enabling `-frelaxed-template-template-args` by
default.
When performing template argument deduction, we extend the provisional
wording introduced in https://github.com/llvm/llvm-project/pull/89807 so
it also covers deduction of class templates.
Given the following example:
```C++
template <class T1, class T2 = float> struct A;
template <class T3> struct B;
template <template <class T4> class TT1, class T5> struct B<TT1<T5>>; // #1
template <class T6, class T7> struct B<A<T6, T7>>; // #2
template struct B<A<int>>;
```
Prior to P0522, `#2` was picked. Afterwards, this became ambiguous. This
patch restores the pre-P0522 behavior, `#2` is picked again.
This has the beneficial side effect of making the following code valid:
```C++
template<class T, class U> struct A {};
A<int, float> v;
template<template<class> class TT> void f(TT<int>);
// OK: TT picks 'float' as the default argument for the second parameter.
void g() { f(v); }
```
---
Since this changes provisional implementation of CWG2398 which has not
been released yet, and already contains a changelog entry, we don't
provide a changelog entry here.
This is an enabler for https://github.com/llvm/llvm-project/pull/92855
This allows an NTTP default argument to be set as an arbitrary
TemplateArgument, not just an expression.
This allows template parameter packs to have default arguments in the
AST, even though the language proper doesn't support the syntax for it.
This allows NTTP default arguments to be other kinds of arguments, like
packs, integral constants, and such.
This is an enabler for a future patch.
This allows an type-parameter default argument to be set as an arbitrary
TemplateArgument, not just a type.
This allows template parameter packs to have default arguments in the
AST, even though the language proper doesn't support the syntax for it.
This will be used in a later patch which synthesizes template parameter
lists with arbitrary default arguments taken from template
specializations.
There are a few places we used SubsType, because we only had a type, now
we use SubstTemplateArgument.
SubstTemplateArgument was missing arguments for setting Instantiation
location and entity names.
Adding those is needed so we don't regress in diagnostics.
Clang incorrectly accepts the following when using C++14 or later:
```
struct A {
template<typename T>
void f() const;
template<>
constexpr void f<int>();
};
```
Non-static member functions declared `constexpr` are only implicitly
`const` in C++11. This patch makes clang reject the explicit
specialization of `f` in language modes after C++11.
According to [expr.prim.id.general] p2:
> If an _id-expression_ `E` denotes a non-static non-type member of some
class `C` at a point where the current class is `X` and
> - `E` is potentially evaluated or `C` is `X` or a base class of `X`,
and
> - `E` is not the _id-expression_ of a class member access expression,
and
> - if `E` is a _qualified-id_, `E` is not the un-parenthesized operand
of the unary `&` operator,
>
> the _id-expression_ is transformed into a class member access
expression using `(*this)` as the object expression.
Consider the following:
```
struct A
{
void f0();
template<typename T>
void f1();
};
template<typename T>
struct B : T
{
auto g0() -> decltype(T::f0()); // ok
auto g1() -> decltype(T::template f1<int>()); // error: call to non-static member function without an object argument
};
template struct B<A>;
```
Clang incorrectly rejects the call to `f1` in the _trailing-return-type_
of `g1`. Furthermore, the following snippet results in a crash during
codegen:
```
struct A
{
void f();
};
template<typename T>
struct B : T
{
template<typename U>
static void g();
template<>
void g<int>()
{
return T::f(); // crash here
}
};
template struct B<A>;
```
This happens because we unconditionally build a
`CXXDependentScopeMemberExpr` (with an implicit object expression) for
`T::f` when parsing the template definition, even though we don't know
whether `g` is an implicit object member function yet.
This patch fixes these issues by instead building
`DependentScopeDeclRefExpr`s for such expressions, and only transforming
them into implicit class member access expressions during instantiation.
Since we implemented the MS "unqualified lookup into dependent bases"
extension by building an implicit class member access (and relying on
the first component name of the _nested-name-specifier_ to be looked up
in the context of the object expression during instantiation), we
instead pre-append a fake _nested-name-specifier_ that refers to the
injected-class-name of the enclosing class. This patch also refactors
`Sema::BuildQualifiedDeclarationNameExpr` and
`Sema::BuildQualifiedTemplateIdExpr`, streamlining their implementation
and removing any redundant checks.
This solves some ambuguity introduced in P0522 regarding how
template template parameters are partially ordered, and should reduce
the negative impact of enabling `-frelaxed-template-template-args`
by default.
When performing template argument deduction, a template template
parameter
containing no packs should be more specialized than one that does.
Given the following example:
```C++
template<class T2> struct A;
template<template<class ...T3s> class TT1, class T4> struct A<TT1<T4>>; // #1
template<template<class T5 > class TT2, class T6> struct A<TT2<T6>>; // #2
template<class T1> struct B;
template struct A<B<char>>;
```
Prior to P0522, candidate `#2` would be more specialized.
After P0522, neither is more specialized, so this becomes ambiguous.
With this change, `#2` becomes more specialized again,
maintaining compatibility with pre-P0522 implementations.
The problem is that in P0522, candidates are at least as specialized
when matching packs to fixed-size lists both ways, whereas before,
a fixed-size list is more specialized.
This patch keeps the original behavior when checking template arguments
outside deduction, but restores this aspect of pre-P0522 matching
during deduction.
---
Since this changes provisional implementation of CWG2398 which has
not been released yet, and already contains a changelog entry,
we don't provide a changelog entry here.
Fixes https://github.com/llvm/llvm-project/issues/85192
Fixes https://github.com/llvm/llvm-project/issues/84492
This patch implements the "IsDeducible" constraint where the template
arguments of the alias template can be deduced from the returned type of
the synthesized deduction guide, per C++ [over.match.class.deduct]p4. In
the implementation, we perform the deduction directly, which is more
efficient than the way specified in the standard.
Also update relevant CTAD tests which were incorrectly compiled due to
the missing constraint.
When partial ordering alias templates against template template
parameters, allow pack expansions when the alias has a fixed-size
parameter list.
These expansions were generally disallowed by proposed resolution for
CWG1430.
By previously diagnosing these when checking template template
parameters, we would be too strict in trying to prevent any potential
invalid use.
This flows against the more general idea that template template
parameters are weakly typed, that we would rather allow an argument that
might be possibly misused, and only diagnose the actual misuses during
instantiation.
Since this interaction between P0522R0 and CWG1430 is also a
backwards-compat breaking change, we implement provisional wording to
allow these.
Fixes https://github.com/llvm/llvm-project/issues/62529
In the clang AST, constraint nodes are deliberately not instantiated
unless they are actively being evaluated. Consequently, occurrences of
template parameters in the require-clause expression have a subtle
"depth" difference compared to normal occurrences in places, such as
function parameters. When transforming the require-clause, we must take
this distinction into account.
The existing implementation overlooks this consideration. This patch is
to rewrite the implementation of the require-clause transformation to
address this issue.
Fixes#90177
source location in `ConvertConstructorToDeductionGuideTransform`.
The commit fec471649fffaa3ec44e17801e5c9605825e58bb was reverted by accident in 7415524b45392651969374c067041daa82dc89e7.
Reland it with a testcase.
I'm planning to remove StringRef::equals in favor of
StringRef::operator==.
- StringRef::operator==/!= outnumber StringRef::equals by a factor of
24 under clang/ in terms of their usage.
- The elimination of StringRef::equals brings StringRef closer to
std::string_view, which has operator== but not equals.
- S == "foo" is more readable than S.equals("foo"), especially for
!Long.Expression.equals("str") vs Long.Expression != "str".
This fixes a regression introduced by bee78b88f.
When we form a deduction guide for a constructor, basically, we do the
following work:
- Collect template parameters from the constructor's surrounding class
template, if present.
- Collect template parameters from the constructor.
- Splice these template parameters together into a new template
parameter list.
- Turn all the references (e.g. the function parameter list) to the
invented parameter list by applying a `TreeTransform` to the function
type.
In the previous fix, we handled cases of nested class templates by
substituting the "outer" template parameters (i.e. those not declared at
the surrounding class template or the constructor) with the
instantiating template arguments. The approach per se makes sense, but
there was a flaw in the following case:
```cpp
template <typename U, typename... Us> struct X {
template <typename V> struct Y {
template <typename T> Y(T) {}
};
template <typename T> Y(T) -> Y<T>;
};
X<int>::Y y(42);
```
While we're transforming the parameters for `Y(T)`, we first attempt to
transform all references to `V` and `T`; then, we handle the references
to outer parameters `U` and `Us` using the template arguments from
`X<int>` by transforming the same `ParamDecl`. However, the first step
results in the reference `T` being `<template-param-0-1>` because the
invented `T` is the last of the parameter list of the deduction guide,
and what we're substituting with is a corresponding parameter pack
(which is `Us`, though empty). Hence we're messing up the substitution.
I think we can resolve it by reversing the substitution order, which
means handling outer template parameters first and then the inner
parameters.
There's no release note because this is a regression in 18, and I hope
we can catch up with the last release.
Fixes https://github.com/llvm/llvm-project/issues/88142
Consider the following snippet from the discussion of CWG2847 on the core reflector:
```
template<typename T>
concept C = sizeof(T) <= sizeof(long);
template<typename T>
struct A
{
template<typename U>
void f(U) requires C<U>; // #1, declares a function template
void g() requires C<T>; // #2, declares a function
template<>
void f(char); // #3, an explicit specialization of a function template that declares a function
};
template<>
template<typename U>
void A<short>::f(U) requires C<U>; // #4, an explicit specialization of a function template that declares a function template
template<>
template<>
void A<int>::f(int); // #5, an explicit specialization of a function template that declares a function
template<>
void A<long>::g(); // #6, an explicit specialization of a function that declares a function
```
A number of problems exist:
- Clang rejects `#4` because the trailing _requires-clause_ has `U`
substituted with the wrong template parameter depth when
`Sema::AreConstraintExpressionsEqual` is called to determine whether it
matches the trailing _requires-clause_ of the implicitly instantiated
function template.
- Clang rejects `#5` because the function template specialization
instantiated from `A<int>::f` has a trailing _requires-clause_, but `#5`
does not (nor can it have one as it isn't a templated function).
- Clang rejects `#6` for the same reasons it rejects `#5`.
This patch resolves these issues by making the following changes:
- To fix `#4`, `Sema::AreConstraintExpressionsEqual` is passed
`FunctionTemplateDecl`s when comparing the trailing _requires-clauses_
of `#4` and the function template instantiated from `#1`.
- To fix `#5` and `#6`, the trailing _requires-clauses_ are not compared
for explicit specializations that declare functions.
In addition to these changes, `CheckMemberSpecialization` now considers
constraint satisfaction/constraint partial ordering when determining
which member function is specialized by an explicit specialization of a
member function for an implicit instantiation of a class template (we
previously would select the first function that has the same type as the
explicit specialization). With constraints taken under consideration, we
match EDG's behavior for these declarations.
Our current method of storing the template arguments as written for
`(Class/Var)Template(Partial)SpecializationDecl` suffers from a number
of flaws:
- We use `TypeSourceInfo` to store `TemplateArgumentLocs` for class
template/variable template partial/explicit specializations. For
variable template specializations, this is a rather unintuitive hack (as
we store a non-type specialization as a type). Moreover, we don't ever
*need* the type as written -- in almost all cases, we only want the
template arguments (e.g. in tooling use-cases).
- The template arguments as written are stored in a number of redundant
data members. For example, `(Class/Var)TemplatePartialSpecialization`
have their own `ArgsAsWritten` member that stores an
`ASTTemplateArgumentListInfo` (the template arguments).
`VarTemplateSpecializationDecl` has yet _another_ redundant member
"`TemplateArgsInfo`" that also stores an `ASTTemplateArgumentListInfo`.
This patch eliminates all
`(Class/Var)Template(Partial)SpecializationDecl` members which store the
template arguments as written, and turns the `ExplicitInfo` member into
a `llvm::PointerUnion<const ASTTemplateArgumentListInfo*,
ExplicitInstantiationInfo*>` (to avoid unnecessary allocations when the
declaration isn't an explicit instantiation). The template arguments as
written are now accessed via `getTemplateArgsWritten` in all cases.
The "most breaking" change is to AST Matchers, insofar that `hasTypeLoc`
will no longer match class template specializations (since they no
longer store the type as written).
For alias templates, our current way of constructing their aggregate
deduction guides deviates from the standard approach. We should align it
with how we handle implicit deduction guides.
This patch has a refactoring change which pulls the construction logic
out from `DeclareImplicitDeductionGuidesForTypeAlia` and reusing it for
building aggregate deduction guides.
This patch revolves around the misuse of UnresolvedLookupExpr in
BuildTemplateIdExpr.
Basically, we build up an UnresolvedLookupExpr not only for function
overloads but for "unresolved" templates wherever we need an expression
for template decls. For example, a dependent VarTemplateDecl can be
wrapped with such an expression before template instantiation. (See
617007240c)
Also, one important thing is that UnresolvedLookupExpr uses a
"canonical"
QualType to describe the containing unresolved decls: a DependentTy is
for dependent expressions and an OverloadTy otherwise. Therefore, this
modeling for non-dependent templates leaves a problem in that the
expression
is marked and perceived as if describing overload functions. The
consumer then
expects functions for every such expression, although the fact is the
reverse.
Hence, we run into crashes.
As to the patch, I added a new canonical type "UnresolvedTemplateTy" to
model these cases. Given that we have been using this model
(intentionally or
accidentally) and it is pretty baked in throughout the code, I think
extending the role of UnresolvedLookupExpr is reasonable. Further, I
added
some diagnostics for the direct occurrence of these expressions, which
are supposed to be ill-formed.
As a bonus, this patch also fixes some typos in the diagnostics and
creates
RecoveryExprs rather than nothing in the hope of a better error-recovery
for clangd.
Fixes https://github.com/llvm/llvm-project/issues/88832
Fixes https://github.com/llvm/llvm-project/issues/63243
Fixes https://github.com/llvm/llvm-project/issues/48673
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
Reapplies #84050, addressing a bug which cases a crash when an
expression with the type of the current instantiation is used as the
_postfix-expression_ in a class member access expression (arrow form).
Fix https://github.com/llvm/llvm-project/issues/68885
When build expression from a deduced argument whose kind is
`Declaration` and `NTTPType`(which declared as `decltype(auto)`) is
deduced as a reference type, `BuildExpressionFromDeclTemplateArgument`
just create a `DeclRef`. This is incorrect while we get type from the
expression since we can't get the original reference type from
`DeclRef`. Creating a `SubstNonTypeTemplateParmExpr` expression and make
the deduction correct. `Replacement` expression of
`SubstNonTypeTemplateParmExpr` just helps the deduction and may not be
same with the original expression.
Co-authored-by: huqizhi <836744285@qq.com>
attempt to fix
https://github.com/llvm/llvm-project/issues/68885#issuecomment-1764201896
Deduction of NTTP whose type is `decltype(auto)` would create an
implicit cast expression to dependent type and makes the type of primary
template definition (`InjectedClassNameSpecialization`) and its partial
specialization different. Prevent emitting cast expression to make clang
knows their types are identical by removing `CTAK == CTAK_Deduced` when
the type is `decltype(auto)`.
Co-authored-by: huqizhi <836744285@qq.com>
Consider the following:
```cpp
template<typename T>
struct A
{
auto f()
{
return this->x;
}
};
```
Although `A` has no dependent base classes and the lookup context for
`x` is the current instantiation, we currently do not diagnose the
absence of a member `x` until `A<T>::f` is instantiated. This patch
moves the point of diagnosis for such expressions to occur at the point
of definition (i.e. prior to instantiation).
This relands the c8e65e193d542464421ad4f9a9965d45b302ac0c, which was
reverted in b48ea2d394911efcc56880fde58f806282db1e8a due to the breakage
of windows builtbot.
The reland contains some adjustments in the lit test deduction-gudie.cpp, to
make the checking text less strict.
Fixes https://github.com/llvm/llvm-project/issues/89013
When building the deduction guide, we use the
TemplateArgsForBuildingFPrime to transform the require-clause from the
underlying class deduction guide. However, we do this at the wrong place
where not all elements of TemplateArgsForBuildingFPrime are initialized.
The fix involves rearranging the transformRequireClause call to the
correct location.
As part of the fix, we extend the TemplateInstantiator to support more
types in the template-rewrite mode. Otherwise, we will encounter an
assertion error when attempting to rewrite the template type parameter
type like D with a complex type like Derived<U>.
This patch converts the enum into scoped enum, and moves it into its own header for the time being. It's definition is needed in `Sema.h`, and is going to be needed in upcoming `SemaObjC.h`. `Lookup.h` can't hold it, because it includes `Sema.h`.
This patch adds a `Typename` bit-field to `TemplateTemplateParmDecl`
which stores whether the template template parameter was declared with
the `typename` keyword.
I forgot to tidy up these lines that should've been done in the previous
commit, specifically:
1. Merge two `CodeSynthesisContext`s into one in `CheckTemplateIdType`.
2. Remove some gratuitous `Sema::` specifiers.
3. Rename the parameter `Template` to `Entity` to avoid confusion.
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`
