This relands https://github.com/llvm/llvm-project/pull/135119, after
fixing crashes seen in LLDB CI reported here:
https://github.com/llvm/llvm-project/pull/135119#issuecomment-2794910840
Fixes https://github.com/llvm/llvm-project/pull/135119
This changes the TemplateArgument representation to hold a flag
indicating whether a tempalte argument of expression type is supposed to
be canonical or not.
This gets one step closer to solving
https://github.com/llvm/llvm-project/issues/92292
This still doesn't try to unique as-written TSTs. While this would
increase the amount of memory savings and make code dealing with the AST
more well-behaved, profiling template argument lists is still too
expensive for this to be worthwhile, at least for now.
This also fixes the context creation of TSTs, so that they don't in some
cases get incorrectly flagged as sugar over their own canonical form.
This is captured in the test expectation change of some AST dumps.
This fixes some places which were unnecessarily canonicalizing these
TSTs.
This changes the TemplateArgument representation to hold a flag
indicating whether a template argument of expression type is supposed to
be canonical or not.
This gets one step closer to solving
https://github.com/llvm/llvm-project/issues/92292
This still doesn't try to unique as-written TSTs. While this would
increase the amount of memory savings and make code dealing with the AST
more well-behaved, profiling template argument lists is still too
expensive for this to be worthwhile, at least for now. Without this
uniquing, this patch stands neutral in terms of performance impact.
This also fixes the context creation of TSTs, so that they don't in some
cases get incorrectly flagged as sugar over their own canonical form.
This is captured in the test expectation change of some AST dumps.
This fixes some places which were unnecessarily canonicalizing these
TSTs.
A NestedNameSpecifier of TypeSpec kind can be non-dependent even if its
prefix is dependent, when for example the prefix is an injected class
type but the type itself is a simple alias to a non-dependent type.
This issue was a bit hard to observe because if it is an alias to a
class type, then we (for some unknown reason) ignored that the NNS was
dependent in the first place, which wouldn't happen with an enum type.
This could have been a workaround for previous dependency bugs, and is
not relevant anymore for any of the test cases in the tree, so this
patch also removes that.
The other kinds of dependencies are still relevant. If the prefix
contains an unexpanded pack, then this NNS is still unexpanded, and
likewise for errors.
This fixes a regression reported here:
https://github.com/llvm/llvm-project/pull/133610#issuecomment-2787909829
which was introduced by https://github.com/llvm/llvm-project/pull/133610
There are no release notes since the regression was never released.
This reverts commit ce4aada6e2135e29839f672a6599db628b53295d and a
follow-up patch 8ef26f1289bf069ccc0d6383f2f4c0116a1206c1.
This new warning can not be fully suppressed by the
`-Wno-missing-dependent-template-keyword` flag, this gives developer no
time to do the cleanup in a large codebase, see https://github.com/llvm/llvm-project/pull/98547#issuecomment-2228250884
Reapplies #92957, fixing an instance where the `template` keyword was
missing prior to a dependent name in `llvm/ADT/ArrayRef.h`. An
_alias-declaration_ is used to work around a bug affecting GCC releases
before 11.1 (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94799) which
rejects the use of the `template` keyword prior to the
_nested-name-specifier_ in the class member access.
CWG1835 was one of the many core issues resolved by P1787R6: "Declarations and where to
find them" (http://wg21.link/p1787r6). Its resolution changes how
member-qualified names (as defined by [basic.lookup.qual.general] p2) are looked
up. This patch implementation that resolution.
Previously, an _identifier_ following `.` or `->` would be first looked
up in the type of the object expression (i.e. qualified lookup), and
then in the context of the _postfix-expression_ (i.e. unqualified
lookup) if nothing was found; the result of the second lookup was
required to name a class template. Notably, this second lookup would
occur even when the object expression was dependent, and its result
would be used to determine whether a `<` token is the start of a
_template-argument_list_.
The new wording in [basic.lookup.qual.general] p2 states:
> A member-qualified name is the (unique) component name, if any, of
> - an _unqualified-id_ or
> - a _nested-name-specifier_ of the form _`type-name ::`_ or
_`namespace-name ::`_
>
> in the id-expression of a class member access expression. A
***qualified name*** is
> - a member-qualified name or
> - the terminal name of
> - a _qualified-id_,
> - a _using-declarator_,
> - a _typename-specifier_,
> - a _qualified-namespace-specifier_, or
> - a _nested-name-specifier_, _elaborated-type-specifier_, or
_class-or-decltype_ that has a _nested-name-specifier_.
>
> The _lookup context_ of a member-qualified name is the type of its
associated object expression (considered dependent if the object
expression is type-dependent). The lookup context of any other qualified
name is the type, template, or namespace nominated by the preceding
_nested-name-specifier_.
And [basic.lookup.qual.general] p3 now states:
> _Qualified name lookup_ in a class, namespace, or enumeration performs
a search of the scope associated with it except as specified below.
Unless otherwise specified, a qualified name undergoes qualified name
lookup in its lookup context from the point where it appears unless the
lookup context either is dependent and is not the current instantiation
or is not a class or class template. If nothing is found by qualified
lookup for a member-qualified name that is the terminal name of a
_nested-name-specifier_ and is not dependent, it undergoes unqualified
lookup.
In non-standardese terms, these two paragraphs essentially state the
following:
- A name that immediately follows `.` or `->` in a class member access
expression is a member-qualified name
- A member-qualified name will be first looked up in the type of the
object expression `T` unless `T` is a dependent type that is _not_ the
current instantiation, e.g.
```
template<typename T>
struct A
{
void f(T* t)
{
this->x; // type of the object expression is 'A<T>'. although 'A<T>' is dependent, it is the
// current instantiation so we look up 'x' in the template definition context.
t->y; // type of the object expression is 'T' ('->' is transformed to '.' per [expr.ref]).
// 'T' is dependent and is *not* the current instantiation, so we lookup 'y' in the
// template instantiation context.
}
};
```
- If the first lookup finds nothing and:
- the member-qualified name is the first component of a
_nested-name-specifier_ (which could be an _identifier_ or a
_simple-template-id_), and either:
- the type of the object expression is the current instantiation and it
has no dependent base classes, or
- the type of the object expression is not dependent
then we lookup the name again, this time via unqualified lookup.
Although the second (unqualified) lookup is stated not to occur when the
member-qualified name is dependent, a dependent name will _not_ be
dependent once the template is instantiated, so the second lookup must
"occur" during instantiation if qualified lookup does not find anything.
This means that we must perform the second (unqualified) lookup during
parsing even when the type of the object expression is dependent, but
those results are _not_ used to determine whether a `<` token is the
start of a _template-argument_list_; they are stored so we can replicate
the second lookup during instantiation.
In even simpler terms (paraphrasing the meeting minutes from the review of P1787; see https://wiki.edg.com/bin/view/Wg21summer2020/P1787%28Lookup%29Review2020-06-15Through2020-06-18):
- Unqualified lookup always happens for the first name in a
_nested-name-specifier_ that follows `.` or `->`
- The result of that lookup is only used to determine whether `<` is the
start of a _template-argument-list_ if the first (qualified) lookup
found nothing and the lookup context:
- is not dependent, or
- is the current instantiation and has no dependent base classes.
An example:
```
struct A
{
void f();
};
template<typename T>
using B = A;
template<typename T>
struct C : A
{
template<typename U>
void g();
void h(T* t)
{
this->g<int>(); // ok, '<' is the start of a template-argument-list ('g' was found via qualified lookup in the current instantiation)
this->B<void>::f(); // ok, '<' is the start of a template-argument-list (current instantiation has no dependent bases, 'B' was found via unqualified lookup)
t->g<int>(); // error: '<' means less than (unqualified lookup does not occur for a member-qualified name that isn't the first component of a nested-name-specifier)
t->B<void>::f(); // error: '<' means less than (unqualified lookup does not occur if the name is dependent)
t->template B<void>::f(); // ok: '<' is the start of a template-argument-list ('template' keyword used)
}
};
```
Some additional notes:
- Per [basic.lookup.qual.general] p1, lookup for a
member-qualified name only considers namespaces, types, and templates
whose specializations are types if it's an _identifier_ followed by
`::`; lookup for the component name of a _simple-template-id_ followed
by `::` is _not_ subject to this rule.
- The wording which specifies when the second unqualified lookup occurs
appears to be paradoxical. We are supposed to do it only for the first
component name of a _nested-name-specifier_ that follows `.` or `->`
when qualified lookup finds nothing. However, when that name is followed
by `<` (potentially starting a _simple-template-id_) we don't _know_
whether it will be the start of a _nested-name-specifier_ until we do
the lookup -- but we aren't supposed to do the lookup until we know it's
part of a _nested-name-specifier_! ***However***, since we only do the
second lookup when the first lookup finds nothing (and the name isn't
dependent), ***and*** since neither lookup is type-only, the only valid
option is for the name to be the _template-name_ in a
_simple-template-id_ that is followed by `::` (it can't be an
_unqualified-id_ naming a member because we already determined that the
lookup context doesn't have a member with that name). Thus, we can lock
into the _nested-name-specifier_ interpretation and do the second lookup
without having to know whether the _simple-template-id_ will be followed
by `::` yet.
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.
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.
Implements https://isocpp.org/files/papers/P2662R3.pdf
The feature is exposed as an extension in older language modes.
Mangling is not yet supported and that is something we will have to do before release.
Current context set to where alias was met, not where it is declared
caused incorrect access check in case alias referenced private members
of the parent class.
This is a recommit of 6b1aa31 with a slight modification in order to fix
reported regression.
Fixes https://github.com/llvm/llvm-project/issues/41693
It was reported in the PR that commit caused clang giving errors for
code previously considered valid.
This reverts commit 6b1aa319754e76366edd88e10034e0539710d946.
Current context set to where alias was met, not where it is declared
caused incorrect access check in case alias referenced private members
of the parent class.
Fixes https://github.com/llvm/llvm-project/issues/41693
This patch moves ElaboratedTypeKeyword before `Type` definition so that the enum is complete where bit-field for it is declared. It also converts it to scoped enum and removes `ETK_` prefix.
The last use was removed by:
commit 04f131da0b19abff611773c03be9bafb53c753ce
Author: Richard Smith <richard@metafoo.co.uk>
Date: Fri Jan 24 15:14:25 2020 -0800
Differential Revision: https://reviews.llvm.org/D152634
This implements P2036R3 and P2579R0.
That is, explicit, int, and implicit capture become visible
at the start of the parameter head.
Reviewed By: aaron.ballman, rupprecht, shafik
Differential Revision: https://reviews.llvm.org/D124351
This reverts commit d708a186b6a9b050d09558163dd353d9f738c82d (and typo fix e4bc9898ddbeb70bc49d713bbf863f050f21e03f). It causes a compilation error for this:
```
struct StringLiteral {
template <int N>
StringLiteral(const char (&array)[N])
__attribute__((enable_if(N > 0 && N == __builtin_strlen(array) + 1,
"invalid string literal")));
};
struct Message {
Message(StringLiteral);
};
void Func1() {
auto x = Message("x"); // Note: this is fine
// Note: "xx\0" to force a different type, StringLiteral<3>, otherwise this
// successfully builds.
auto y = [&](decltype(Message("xx"))) {};
// ^ fails with: repro.cc:18:13: error: reference to local variable 'array'
// declared in enclosing function 'StringLiteral::StringLiteral<3>'
(void)x;
(void)y;
}
```
More details posted to D124351.
This implements P2036R3 and P2579R0.
That is, explicit, int, and implicit capture become visible
at the start of the parameter head.
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D124351
Removes a bunch of obsolete methods in favor of a single one returning
an ArrayRef of TemplateArgument.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Differential Revision: https://reviews.llvm.org/D136602
This reverts commit 69dd89fdcbd846375a45e2fe3a88710887236d7a.
This reverts commit 04000c2f928a7adc32138a664d167f01b642bef3.
The current states breaks libstdc++ usage (https://reviews.llvm.org/D119136#3455423).
The fixup has been reverted as it caused other valid code to be disallowed.
I think we should start from the clean state by reverting all relevant commits.
Implement P2036R3.
Captured variables by copy (explicitely or not), are deduced
correctly at the point we know whether the lambda is mutable,
and ill-formed before that.
Up until now, the entire lambda declaration up to the start of the body would be parsed in the parent scope, such that capture would not be available to look up.
The scoping is changed to have an outer lambda scope, followed by the lambda prototype and body.
The lambda scope is necessary because there may be a template scope between the start of the lambda (to which we want to attach the captured variable) and the prototype scope.
We also need to introduce a declaration context to attach the captured variable to (and several parts of clang assume captures are handled from the call operator context), before we know the type of the call operator.
The order of operations is as follow:
* Parse the init capture in the lambda's parent scope
* Introduce a lambda scope
* Create the lambda class and call operator
* Add the init captures to the call operator context and the lambda scope. But the variables are not capured yet (because we don't know their type).
Instead, explicit captures are stored in a temporary map that conserves the order of capture (for the purpose of having a stable order in the ast dumps).
* A flag is set on LambdaScopeInfo to indicate that we have not yet injected the captures.
* The parameters are parsed (in the parent context, as lambda mangling recurses in the parent context, we couldn't mangle a lambda that is attached to the context of a lambda whose type is not yet known).
* The lambda qualifiers are parsed, at this point We can switch (for the second time) inside the lambda context, unset the flag indicating that we have not parsed the lambda qualifiers,
record the lambda is mutable and capture the explicit variables.
* We can parse the rest of the lambda type, transform the lambda and call operator's types and also transform the call operator to a template function decl where necessary.
At this point, both captures and parameters can be injected in the body's scope. When trying to capture an implicit variable, if we are before the qualifiers of a lambda, we need to remember that the variables are still in the parent's context (rather than in the call operator's).
Reviewed By: aaron.ballman, #clang-language-wg, ChuanqiXu
Differential Revision: https://reviews.llvm.org/D119136
Implement P2036R3.
Captured variables by copy (explicitely or not), are deduced
correctly at the point we know whether the lambda is mutable,
and ill-formed before that.
Up until now, the entire lambda declaration up to the start
of the body would be parsed in the parent scope, such that
captures would not be available to look up.
The scoping is changed to have an outer lambda scope,
followed by the lambda prototype and body.
The lambda scope is necessary because there may be a template scope
between the start of the lambda (to which we want to attach
the captured variable) and the prototype scope.
We also need to introduce a declaration context to attach the captured
variable to (and several parts of clang assume captures are handled from
the call operator context), before we know the type of the call operator.
The order of operations is as follow:
* Parse the init capture in the lambda's parent scope
* Introduce a lambda scope
* Create the lambda class and call operator
* Add the init captures to the call operator context and the lambda scope.
But the variables are not capured yet (because we don't know their type).
Instead, explicit captures are stored in a temporary map that
conserves the order of capture (for the purpose of having a stable order in the ast dumps).
* A flag is set on LambdaScopeInfo to indicate that we have not yet injected the captures.
* The parameters are parsed (in the parent context, as lambda mangling recurses in the parent context,
we couldn't mangle a lambda that is attached to the context of a lambda whose type is not yet known).
* The lambda qualifiers are parsed, at this point,
we can switch (for the second time) inside the lambda context,
unset the flag indicating that we have not parsed the lambda qualifiers,
record the lambda is mutable and capture the explicit variables.
* We can parse the rest of the lambda type, transform the lambda and call operator's types and also
transform the call operator to a template function decl where necessary.
At this point, both captures and parameters can be injected in the body's scope.
When trying to capture an implicit variable, if we are before the qualifiers of a lambda,
we need to remember that the variables are still in the parent's context (rather than in the call operator's).
This is a recommit of adff142dc2 after a fix in d8d793f29b4
Reviewed By: aaron.ballman, #clang-language-wg, ChuanqiXu
Differential Revision: https://reviews.llvm.org/D119136
This reverts commit adff142dc253d65b6560e420bba6b858d88d4a98.
This broke clang bootstrap: it made existing C++ code in LLVM invalid:
llvm/include/llvm/CodeGen/LiveInterval.h:630:53: error: captured variable 'Idx' cannot appear here
[=](std::remove_reference_t<decltype(*Idx)> V,
^
Implement P2036R3.
Captured variables by copy (explicitely or not), are deduced
correctly at the point we know whether the lambda is mutable,
and ill-formed before that.
Up until now, the entire lambda declaration up to the start of the body would be parsed in the parent scope, such that capture would not be available to look up.
The scoping is changed to have an outer lambda scope, followed by the lambda prototype and body.
The lambda scope is necessary because there may be a template scope between the start of the lambda (to which we want to attach the captured variable) and the prototype scope.
We also need to introduce a declaration context to attach the captured variable to (and several parts of clang assume captures are handled from the call operator context), before we know the type of the call operator.
The order of operations is as follow:
* Parse the init capture in the lambda's parent scope
* Introduce a lambda scope
* Create the lambda class and call operator
* Add the init captures to the call operator context and the lambda scope. But the variables are not capured yet (because we don't know their type).
Instead, explicit captures are stored in a temporary map that conserves the order of capture (for the purpose of having a stable order in the ast dumps).
* A flag is set on LambdaScopeInfo to indicate that we have not yet injected the captures.
* The parameters are parsed (in the parent context, as lambda mangling recurses in the parent context, we couldn't mangle a lambda that is attached to the context of a lambda whose type is not yet known).
* The lambda qualifiers are parsed, at this point We can switch (for the second time) inside the lambda context, unset the flag indicating that we have not parsed the lambda qualifiers,
record the lambda is mutable and capture the explicit variables.
* We can parse the rest of the lambda type, transform the lambda and call operator's types and also transform the call operator to a template function decl where necessary.
At this point, both captures and parameters can be injected in the body's scope. When trying to capture an implicit variable, if we are before the qualifiers of a lambda, we need to remember that the variables are still in the parent's context (rather than in the call operator's).
Reviewed By: aaron.ballman, #clang-language-wg, ChuanqiXu
Differential Revision: https://reviews.llvm.org/D119136
This reverts commit cc56c66f27e131b914082d3bd21180646e842e9a.
Fixed a bad assertion, the target of a UsingShadowDecl must not have
*local* qualifiers, but it can be a typedef whose underlying type is qualified.
Currently there's no way to find the UsingDecl that a typeloc found its
underlying type through. Compare to DeclRefExpr::getFoundDecl().
Design decisions:
- a sugar type, as there are many contexts this type of use may appear in
- UsingType is a leaf like TypedefType, the underlying type has no TypeLoc
- not unified with UnresolvedUsingType: a single name is appealing,
but being sometimes-sugar is often fiddly.
- not unified with TypedefType: the UsingShadowDecl is not a TypedefNameDecl or
even a TypeDecl, and users think of these differently.
- does not cover other rarer aliases like objc @compatibility_alias,
in order to be have a concrete API that's easy to understand.
- implicitly desugared by the hasDeclaration ASTMatcher, to avoid
breaking existing patterns and following the precedent of ElaboratedType.
Scope:
- This does not cover types associated with template names introduced by
using declarations. A future patch should introduce a sugar TemplateName
variant for this. (CTAD deduced types fall under this)
- There are enough AST matchers to fix the in-tree clang-tidy tests and
probably any other matchers, though more may be useful later.
Caveats:
- This changes a fairly common pattern in the AST people may depend on matching.
Previously, typeLoc(loc(recordType())) matched whether a struct was
referred to by its original scope or introduced via using-decl.
Now, the using-decl case is not matched, and needs a separate matcher.
This is similar to the case of typedefs but nevertheless both adds
complexity and breaks existing code.
Differential Revision: https://reviews.llvm.org/D114251
This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.
As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith, #libc, ldionne
Differential Revision: https://reviews.llvm.org/D110216
This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.
As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D110216
This implements the following changes:
* AutoType retains sugared deduced-as-type.
* Template argument deduction machinery analyses the sugared type all the way
down. It would previously lose the sugar on first recursion.
* Undeduced AutoType will be properly canonicalized, including the constraint
template arguments.
* Remove the decltype node created from the decltype(auto) deduction.
As a result, we start seeing sugared types in a lot more test cases,
including some which showed very unfriendly `type-parameter-*-*` types.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Reviewed By: rsmith
Differential Revision: https://reviews.llvm.org/D110216
This implements the 'using enum maybe-qualified-enum-tag ;' part of
1099. It introduces a new 'UsingEnumDecl', subclassed from
'BaseUsingDecl'. Much of the diff is the boilerplate needed to get the
new class set up.
There is one case where we accept ill-formed, but I believe this is
merely an extended case of an existing bug, so consider it
orthogonal. AFAICT in class-scope the c++20 rule is that no 2 using
decls can bring in the same target decl ([namespace.udecl]/8). But we
already accept:
struct A { enum { a }; };
struct B : A { using A::a; };
struct C : B { using A::a;
using B::a; }; // same enumerator
this patch permits mixtures of 'using enum Bob;' and 'using Bob::member;' in the same way.
Differential Revision: https://reviews.llvm.org/D102241
This prepatch for using-enum breaks out the enum completion that that
will need from the existing scope completion logic.
Differential Revision: https://reviews.llvm.org/D102239
